O crescimento populacional e a forma como os recursos vem sendo explorados estão afetando diretamente o meio ambiente. O mercado de fibras naturais, por exemplo, movimenta milhões de dólares anualmente e uma considerável parte dessas fibras se transforma em rejeito. Essa grande quantidade de resíduo disponível motiva o estudo de compósitos reforçados com fibra natural, sendo esse reaproveitamento interessante tanto para a manutenção da sustentabilidade ambiental quanto para o desenvolvimento técnico e comercial de novos materiais com boas propriedades e custo reduzido. Neste trabalho, um resíduo industrial da empresa Tapetes São Carlos constituído principalmente de fibras de juta e polipropileno foi reaproveitado através da fabricação de material compósito, utilizando como matriz polipropileno homopolímero (PP), compatibilizante e nanocarbonato de cálcio (NCC). Os componentes foram misturados em extrusora duplarosca co-rotacional e os corpos de prova foram moldados por injeção. Para a melhora da dispersão do NCC na matriz um masterbatch foi previamente processado. Os compósitos foram inicialmente caracterizados por ensaios de tração e dureza e ensaio de ângulo de contato para avaliação da permeabilidade da superfície. Realizou-se ensaio de degradação acelerada e posterior reavaliação das propriedades em tração e permeabilidade dos compósitos degradados térmica e fotooxidativamente. Para a avaliação das possíveis degradações mecânica e térmica das fibras foi realizada inicialmente dissolução seletiva e posteriormente microscopia óptica e espectroscopia de infavermelho (FTIR) das fibras isoladas. A avaliação morfológica foi realizada por microscopia eletro nica de varredura (MEV). Com o processamento obtiveram-se compósitos com 50% em massa de resíduo, boa mistura dispersiva do NCC e não houve degradação térmica ou mecânica das fibras. Os compósitos apresentaram melhores propriedades mecânicas se comparados ao PP puro. O NCC atuou como reforço mecânico e no aumento da impermeabilidade. A fim de estudar a aplicabilidade comercial dos compósitos foi utilizado o método de Technology Roadmap (TRM). Esse estudo revelou o excelente potencial de aplicação comercial do material em diversos mercados, devido as suas propriedades e flexibilidade de processamento. / Population growth and the way resources are being exploited are directly affecting the environment. The natural fiber market, for example, is worth million dollars and a huge amount of the fibers becomes waste. This considerable amount of waste motivates the study of the fibers as a reinforcement in polymeric matrix, which benefits both the environmental sustainability and technical-commercial development of new materials with good properties and reduced cost. In this work, an industrial waste from the carpet manufacturer Tapetes São Carlos, consisting mainly of jute and polypropylene fibers, was recycled through the manufacture of a composite material using polypropylene homopolymer (PP), a compatibilizer and calcium nanocarbonate (NCC). The components were mixed in a co-rotational double-screw extruder and the specimens were produced by injection moulding. A masterbatch was previously processed to improve the NCC dispersion in the matrix. The composites were initially tested by tensile and hardness tests and by contact angle test to evaluate surface permeability. The specimens were exposed to accelerated weathering for revaluation of tensile and permeability properties of the thermaly and photooxidatively degraded specimens. A selective dissolution followed by optical microscopy and infra-red spectroscopy of the isolated fibers were performed for measuring the potential mechanical and thermal degradation of the fibers. The morphological evaluation was performed by scanning electron microscopy (SEM). The processing techniques resulted in composites with 50% (w/w) of waste and good dispertion of the NCC, and no thermal or mechanical degradation of the fibers was observed. The composites showed better mechanical properties than pure PP. The NCC acted as mechanical reinforcement and increased impermeability. A Technology Roadmap (TRM) method was used to study the commercial applicability of the composites. This study revealed an excellent potential of commercial application of the material in several markets due to its properties and processing flexibility.

Preparation of thermoplastics composites using engineering thermoplastics and plant fibers or fillers is a technical challenge because the processing temperature of the thermoplastics is generally above the temperature of degradation of plant fibers of fillers. There have been numerous attempts for processing high melting point engineering thermoplastics like Nylon-6 with plant natural fibers and fillers. Low temperature processing methods, fiber modification or addition of additives which drops polymer melting point are some of proposed solutions for this problem. The objective of this thesis was to develop a formulation using wheat straw (WS) as a reinforcing fiber for Nylon-6. The concentration of WS was 15 wt-%. The thermoplastic composites were prepared by mixing grinded wheat straw and Nylon-6 using a laboratory scale twin-screw extruder; follow by preparation of samples using injection moulding. The strategy investigated in this thesis was utilization of additives to lower the melting point or to decrease the viscosity of Nylon-6. Lithium chloride salt (LiCl) and N-Butyl benzene Sulfon amide plasticizer (N-BBSA) were used as process additives to decrease melting point and to reduce the processing temperature and time. The addition of the wheat straw (15 wt-%) to the Nylon-6 increased modulus by 26.9 % but decreased the strength by 9.9 %. Effect of different level of these two additives on mechanical, thermal, physical properties and processability of the composite runs were studied. Addition of 4 wt-% LiCl was found to decrease the melting point from 222 °C to 191 °C, to increase modulus by 14 % in comparison to Nylon-6/wheat straw (15 wt-%). However, it decreased the processability and strength by 12.7 %. Plasticizer was investigated to easing processability and decreasing the degradation by reducing the residence time in the extruder, it does not affect the melting point of Nylon-6. The addition of 4 wt-% of plasticizer (N-BBSA) increased modulus and strength only by 2.6 % and 3 %, respectively, in comparison to Nylon-6/wheat straw (15 wt-%) composites. The results of mechanical properties were used as a benchmark for comparisons among samples with different formulations (levels of additives) to find out levels of LiCl and N-BBSA for the best mechanical properties. It was found that samples with 2 wt-% LiCl and 2 wt-% of N-BBSA had 29.3 % higher tensile modulus than neat Nylon-6, while its strength was almost same as neat Nylon-6 and 6.3 % higher than Nylon-6/WS (15 wt-%). These results were used to correlate the mechanical properties as a function of percentage of salt and plasticizer in the formulation. Differential scanning calorimetry (DSC) was used to evaluate the percentage of crystallinity and the melting point of the thermoplastic phase and thermal gravimetric analysis (TGA) was used to measure the thermal stability of different formulation. The kinetics of crystallization and degradation were evaluated using results from DSC and TGA, respectively. The activation energy for thermal degradation and the percentage of crystallinity of the thermoplastic composites were correlated to mechanical properties using linear regression. It was found that fiber degradation had a significant effect on strength but the effects of percentage of crystallinity on composites strength were insignificant. On the other hand, the percentage of crystallinity affects stiffness and impact strength. The ductility was a function of both crystallinity and thermal stability.

Preparation of thermoplastics composites using engineering thermoplastics and plant fibers or fillers is a technical challenge because the processing temperature of the thermoplastics is generally above the temperature of degradation of plant fibers of fillers. There have been numerous attempts for processing high melting point engineering thermoplastics like Nylon-6 with plant natural fibers and fillers. Low temperature processing methods, fiber modification or addition of additives which drops polymer melting point are some of proposed solutions for this problem. The objective of this thesis was to develop a formulation using wheat straw (WS) as a reinforcing fiber for Nylon-6. The concentration of WS was 15 wt-%. The thermoplastic composites were prepared by mixing grinded wheat straw and Nylon-6 using a laboratory scale twin-screw extruder; follow by preparation of samples using injection moulding. The strategy investigated in this thesis was utilization of additives to lower the melting point or to decrease the viscosity of Nylon-6. Lithium chloride salt (LiCl) and N-Butyl benzene Sulfon amide plasticizer (N-BBSA) were used as process additives to decrease melting point and to reduce the processing temperature and time. The addition of the wheat straw (15 wt-%) to the Nylon-6 increased modulus by 26.9 % but decreased the strength by 9.9 %. Effect of different level of these two additives on mechanical, thermal, physical properties and processability of the composite runs were studied. Addition of 4 wt-% LiCl was found to decrease the melting point from 222 °C to 191 °C, to increase modulus by 14 % in comparison to Nylon-6/wheat straw (15 wt-%). However, it decreased the processability and strength by 12.7 %. Plasticizer was investigated to easing processability and decreasing the degradation by reducing the residence time in the extruder, it does not affect the melting point of Nylon-6. The addition of 4 wt-% of plasticizer (N-BBSA) increased modulus and strength only by 2.6 % and 3 %, respectively, in comparison to Nylon-6/wheat straw (15 wt-%) composites. The results of mechanical properties were used as a benchmark for comparisons among samples with different formulations (levels of additives) to find out levels of LiCl and N-BBSA for the best mechanical properties. It was found that samples with 2 wt-% LiCl and 2 wt-% of N-BBSA had 29.3 % higher tensile modulus than neat Nylon-6, while its strength was almost same as neat Nylon-6 and 6.3 % higher than Nylon-6/WS (15 wt-%). These results were used to correlate the mechanical properties as a function of percentage of salt and plasticizer in the formulation. Differential scanning calorimetry (DSC) was used to evaluate the percentage of crystallinity and the melting point of the thermoplastic phase and thermal gravimetric analysis (TGA) was used to measure the thermal stability of different formulation. The kinetics of crystallization and degradation were evaluated using results from DSC and TGA, respectively. The activation energy for thermal degradation and the percentage of crystallinity of the thermoplastic composites were correlated to mechanical properties using linear regression. It was found that fiber degradation had a significant effect on strength but the effects of percentage of crystallinity on composites strength were insignificant. On the other hand, the percentage of crystallinity affects stiffness and impact strength. The ductility was a function of both crystallinity and thermal stability.

Biocomposites made from biodegradable polymer as matrix and natural fiber as reinforcement are certainly environmentally friendly materials. Both constituent materials are fully biodegradable and do not leave any noxious components on Earth. The natural fibers have been used as reinforcement due to their advantages compared to glass fibers such as low cost, high specific strength and modulus, low density, renewability and biodegradability. Major aims of this work were to produce natural fibers and/or nanoparticles with polyethylene (PE), polypropylene (PP) and polylactide (PLA), poly(hydroxybutyrate-co-hydroxyvalerate)(PHBV) matrices and determine their structure-property relationships. Following abstracts of the present research work are manifold: BINARY COMPOSITES Polylactide (PLA)/flax mat composites The polylactide (PLA)/flax mat and modified PLA/flax mat composites were produced by hot press technique. Two additives of non-regulated wax/ethylene acrylate copolymer/butyl acrylate and acrylic were used as modifier for PLA. The dispersion of the flax mat in the composites was studied by scanning electron microscopy (SEM). The PLA composites were subjected to instrumented falling weight impact test. The mechanical and thermal properties of the composites were determined in tensile test, thermogravimetric analysis (TGA) and dynamic-mechanical thermal analysis (DMTA), respectively. It was found that the PLA based composites increased the impact resistance. The tensile strength value of modified PLA/flax mat composite decreased slightly compared to the PLA. The elongation at break data indicated that an improvement in ductility of modified PLA and its composites. Moreover, addition of thermal modifier enhanced thermal resistance below processing temperature of PLA and had a marginal effect on the glass transition temperature of PLA. The storage modulus master curves were constructed by applying the time-temperature superposition (TTS) principle. The principle of linear viscoelastic material was fairly applicable to convert from the modulus to the creep compliance for all systems studied. Polylactide (PLA)/woven flax textiles composites The polylactide (PLA)/woven flax textiles 2x2 twill and 4x4 hopsack composites were produced by interval hot press technique. Two weave styles of flax used to reinforce in PLA. The dispersion of the flax composite structures in the composites was inspected in scanning electron microscopy (SEM). The PLA composites were subjected to instrumented falling weight impact test. The mechanical properties (tensile, stiffness and strength) of the composites were determined in tensile and dynamic-mechanical thermal analysis (DMTA) tests, respectively. SEM observed that the interfacial gaps around pulled-out fibers were improved when produced by the interval hot press. It was also found that the both styles of flax composites increased the impact resistance compared to the neat PLA. The tensile strength and stiffness value of PLA/flax composites were markedly higher than that of the neat PLA and reflect the effects of composite structures. The calculated storage creep compliance was constructed by applying the time-temperature superposition (TTS) principle. The calculated creep response of these flax composites was much lower than that of the neat PLA. Polyethylene and polypropylene/nano-silicon dioxide/flax composites Composites composed of polylactide (PLA), modified PLA and woven flax fiber textiles (Flax weave style of 2x2 twill and 4x4 hopsack) were produced by hot press technique. Two structurally different additives used to modify PLA. The dispersion of the flax composite structures in the composites was studied by scanning electron microscopy (SEM) and computed microtomography system (µCT). The PLA composites were subjected to water absorption and instrumented falling weight impact tests. The thermomechanical and creep properties of the composites were determined in thermogravimetric analysis (TGA), dynamic-mechanical thermal analysis (DMTA)and short-time creep tests, respectively. It was found that the modified PLA and its composite increased the impact resistance compared to the unmodified PLA. Incorporation of flax decreased resistance to thermal degradation and increased water uptake. The impact energy and stiffness value of PLA/flax composites was markedly higher than that of PLA but reflect the effects of composite structures and flax content. The storage modulus master curves were constructed by applying the time-temperature superposition (TTS) principle. From the master curve data, the effect of modified PLA on the storage modulus was more pronounced in the low frequencies range. Polylactide (PLA)/woven flax fiber textiles/boehmite alumina (BA) composites The textile biocomposites made from woven and non-woven flax fibre reinforced poly(butylene adipate-co-terephthalate) (PBAT) were prepared by compression moulding using film stacking method. The mechanical properties (such as tensile strength and stiffness, flexural strength and modulus, and impact strength) of textile biocomposites were determined in tensile, flexural and impact tests, respectively. The PBAT-based composites were subjected to water absorption. The comparison of the mechanical properties was made between pure PBAT and textile composites. The influence of flax weave styles on the mechanical properties was also evaluated. The results showed that the strength of the textile biocomposites was increased according to weave types of fibers, especially in the stiffness was significantly increased with the higher densification of the fibers. The 4x4-plain woven fibers (4-yard-wrap and 4-yard-weft weave direction) reinforced biocomposite indicated the highest strength and stiffness compared to the other textile biocomposites and pure PBAT. This was considered to be as the result of the character of weave style of 4x4-plain woven fibers. The aminopropyltriethoxysilane affected the mechanical properties and water absorption of the resulting composites laminates due to the surface compatibility between flax fiber and PBAT. HYBRID COMPOSITES Polyethylene/nanoparticle, natural and animal composites Binary and ternary composites composed of high-density polyethylene (HDPE), boehmite alumina (BA) and different kinds of natural-, animal fibers, like flax, sponge gourd (SG), palm and pig hair (PH) were produced by hot press technique. Aqueous BA suspensions were sprayed on the HDPE/flax mat to prepare nanoparticle/natural fiber reinforced ternary polymer composites followed by drying. The dispersion of the natural-, animal fibers and BA particles in the composites was studied by scanning electron microscopy (SEM) and discussed. The thermomechanical and stress relaxation properties of the composites were determined in thermogravimetric analysis (TGA), dynamic-mechanical thermal analysis (DMTA) and short-time stress relaxation tests (performed at various temperatures), respectively. The HDPE based composites were subjected to water absorption and instrumented falling weight impact tests. It was found that the all composites systems increased the stiffness, stress relaxation and reduced the impact toughness. The stress relaxation modulus of natural-, animal fiber composites were higher compared to that of the neat HDPE. This modulus increased greatly with in corporation of BA. The relaxation master curves were constructed by applying the time-temperature superposition (TTS) principle. The inverse of Findley power law could fairly applicable to describe the relaxation modulus vs. time traces for all systems studied. Incorporation of BA particles enhanced the thermal resistance which started to degrade at higher temperature compared to the HDPE/flax mat composite. The HDPE/flax mat/BA composite could reduce the water uptake. Polyethylene/Flax/SiO2 Composites Composites composed of high-density polyethylene (HDPE), woven flax fiber textiles (Flax weave style of 2x2 twill and 4x4 hopsack) and silicon dioxide (SiO2) were produced by hot press with nano spraying technique. The SiO2 slurries were sprayed by a hand onto the both surface of the woven flax fiber. The HDPE /woven flax fibers composites with and without used nano-spraying technique were produced by hot pressing in a laboratory press. The dispersion of SiO2 particles and flax in the composites was studied by scanning electron microscopy (SEM). The related HDPE based composites were subjected to instrumented falling weight impact test. The thermal resistance, stiffness and tensile strength properties of the composites were determined in thermogravimetric analysis (TGA), dynamic-mechanical thermal analysis (DMTA) and tensile tests, respectively. It was found that the impact energy and stiffness value of HDPE/flax composites was markedly higher than that of HDPE but reflect the effects of composite structures and flax content. Incorporation of SiO2 particles enhanced resistance to thermal degradation. It was established that the linear viscoelastic material principle are fairly applicable to convert from the modulus to the creep compliance results. Un- and Modified Polylactide (PLA) /woven Flax Fiber composites Hybrid composites composed of polypropylene (PP) or high-density polyethylene (HDPE), different flax fibers (unidirectional-, biaxial and twill2x2) and silicon dioxide (SiO2) were produced by hot press technique. The ternary polymer composite was effectively fabricated by spraying SiO2 solvents onto the surface of flax fiber. The dispersion of SiO2 particles and flax in the composites was studied by scanning electron microscopy (SEM). The related PP and HDPE based composites were subjected to instrumented falling weight impact test. The thermal and mechanical properties of the composites were determined by thermogravimetric analysis (TGA), dynamic-mechanical thermal analysis (DMTA), creep and stress relaxation tests, respectively. It was found that thermal decomposition temperature of the PP or HDPE/flax composites increased by the addition of SiO2 particles. The impact energy, stiffness, creep resistance and relaxation modulus value of all flax composites increased markedly compared to the PP and HDPE matrix. Time–temperature superposition (TTS) was applied to estimate the creep and relaxation modulus of the composites as a function of time in the form of a master curve. The activation energies for the all PP and HDPE composites systems studied were also calculated by using the Arrhenius equation. The generalized Maxwell model was fairly applicable to the stress relaxation results. Polylactide (PLA)/woven flax fiber textiles/boehmite alumina (BA) composites Composites composed of polylactide (PLA), woven flax fiber textiles (weave style of 2x2 twill and 4x4 hopsack) and boehmite alumina (BA) were produced by hot press. The spraying technique served for the pre-dispersion of the alumina nanoparticles. The aqueous alumina slurry was produced by mixing the water with water dispersible alumina. The dispersion of the flax structures and alumina particles in the composites was studied by scanning electron microscopy (SEM). The PLA composites were subjected to water absorption and instrumented falling weight impact tests. The creep and thermomechanical properties of the composites were determined in short-time creep tests (performed at various temperatures), thermogravimetric analysis (TGA) and dynamic-mechanical thermal analysis (DMTA), respectively. It was found that the incorporation of alumina particles reduced the water uptake compared to the PLA/flax blends. The impact energy and stiffness value of PLA/flax blends was markedly higher than that of PLA but reflected the effects of composite structures. Incorporation of alumina particles enhanced storage modulus and the creep resistance compared to the PLA/flax blends but slightly incremented thermal resistance at high temperature. No clear trend in the flax weave style- effect was found in the thermal behaviour. The creep master curves were constructed by applying the time-temperature superposition (TTS) principle. The Findley power law could satisfactorily describe the creep compliance vs. time traces for all systems studied. Poly(hydroxybutyrate-co-hydroxyvalerate)/sisal natural fiber/clay composites Poly(hydroxybutyrate-co-hydroxyvalerate)(PHBV) biocomposites different sisal containing with the fiber length of 0.25 and 5 mm, and addition of clay particles were prepared by hot compression technique. Silane (Bis(triethoxysilylpropyl)tetrasulfide) treatment has been used to modify in order to enhance the properties of related hybrid composites. The all composites were subject to water absorption test. The mechanical properties of hybrid composites such as tensile stiffness and strength, toughness and hardness determined in tensile, impact and hardness tests, respectively. It was found that tensile strength, stiffness and impact strength of long sisal fiber improved with increasing fiber content. Hardness of short sisal fiber improved with increasing fiber content. Treated Silane of long fibers at 20 wt.% loading was found to enhance the tensile strength fiber by 10% and impact strength by 750% as compared to the neat PHBV. Note that this feature was also confirmed by the appearance of a scanning electron microscopy. Moreover, the hardness and water resistance of the PHBV/sisal composites increased by the addition of clay particles. The diffusion coefficient for the PHBV and hybrid composites systems studied were also calculated. / Bioverbundwerkstoffe aus biologisch abbaubarem Polymer als Matrix und Naturfasern als Verstärkung sind ohne weiteres umweltfreundliche Materialien. Beide Bestandsmaterialien sind vollständig biologisch abbaubar und hinterlassen keine schädlichen Bestandteile auf der Erde zurück. Die als Verstärkung verwendeten Naturfasern wurden aufgrund ihrer Vorteile gegenüber Glasfasern, wie z.B. geringe Kosten, hohe spezifische Festigkeit und Steifigkeit, geringe Dichte, Erneuerbarkeit und Kompostierbarkeit ausgesucht. Der Hauptfokus dieser Arbeit lag darin Naturfasern und/oder Nanopartikel mit Polyethylen (PE), Polypropylen (PP) und Polylactid (PLA) herzustellen, sowie Poly-Hydroxybutyrat-Co-Hydroxyvalerat (PHBV) Matrizen und deren Struktur-Eigenschaft-Verhältnis zu bestimmen. Die folgenden Kurzfassungen der vorliegenden Forschungsarbeit sind vielfältig: BINÄRE VERBUNDWERKSTOFFE Polylactid (PLA)/ Flachsmatten-Verbundwerkstoffe Die Polylactid (PLA)/Flachsmatte und modifizierte PLA/Flachsmatten-Verbundwerkstoffe wurden im Pressverfahren hergestellt. Als Modifikator für das PLA wurden zwei nicht regulierte Wachs/Ethylen-Acrylat-Copolymer/Butyl-Acrylat und Acryl Additive verwendet. Die Verteilung der Flachsmatte in den Verbundwerkstoffen wurde mit dem Rasterelektronenmikroskop (SEM) untersucht. Die PLA-Verbundwerkstoffe wurden dem instrumentalisierten Fallgewichtsschlagzähigkeitstest unterzogen. Die mechanischen und thermischen Eigenschaften der Verbundwerkstoffe wurden im Zugversuch, der thermogravimetrische Analyse (TGA) und der dynamisch mechanischen Thermoanalyse (DMTA) jeweils bestimmt. Es zeigte sich, dass die PLA/Flachsmatten-basierten Verbundwerkstoffe eine erhöhte Schlagzähigkeit aufwiesen. Die Zähigkeitswerte der modifizierten PLA/Flachsmatten-Verbundwerkstoffe waren leicht verringert im Vergleich zum PLA. Die Bruchdehnungswerte zeigten eine Verbesserung der Verformbarkeit des modifizierten PLAs und dessen Verbundwerkstoffe. Nach Zugabe eines Wärme-Modifikators verbesserte sich der Wärmewiderstand auf unter Verarbeitungstemperatur des PLA und hatte nur einen unwesentlichen Einfluss auf die Glasübergangstemperatur des PLA. Die Hauptkurve des Speichermoduls wurde mit der Zeit-Temperatur-Überlagerung (TTS) aufgestellt. Auf alle untersuchten Systeme konnte das dafür gut geeignete Prinzip der linear viskoelastischen Werkstoffe angewendet werden um die Steifigkeit in die Kriechneigung umzuwandeln. Polylactid (PLA)/Flachstextilgewebe-Verbundwerkstoffe Die Polylactid (PLA)/Flachstextilgewebe 2x2 Körper und 4x4 Gewebe mit Leinwandbindung-Verbundwerkstoffe wurden im Intervall-Pressverfahren hergestellt. Das PLA wurde mit zwei Flachsgewebeformen verstärkt. Die Verteilung der Flachs-Verbundwerkstoffstrukturen in den Verbundwerkstoffen wurde mit dem Rasterelektronenmikroskop (SEM) untersucht. Die PLA Verbundwerkstoffe wurden dem instrumentalisierten Fallgewichtsschlagzähigkeitstest unterzogen. Die mechanischen Eigenschaften (Zugfestigkeit, Steifigkeit und Festigkeit) der jeweiligen Verbundwerkstoffe wurden in Zugversuchen und dynamisch mechanischen Thermoanalysen (DMTA) bestimmt. Das Rasterelektronenmikroskop zeigte auf, das der Grenzflächenzwischenraum von rausgezogenen Fasern sich durch das Herstellen im Intervall-Pressverfahren verbessert hat. Auch zeigte sich, dass beide Arten der Flachs-Verbundwerkstoffe die Schlagzähigkeit der Verbundwerkstoffe erhöht im Vergleich zum puren PLA. Die Zugfestigkeit- und Steifigkeitswerte der PLA/Flachs-Verbundwerkstoffe waren deutlich höher als die der puren PLA und spiegeln die Effekte von Verbundwerkstoffstrukturen wieder. Die berechnete Kriechneigung im Speichermodul wurde durch die Anwendung des Zeit-Temperatur-Überlagerung (TTS) Prinzips aufgestellt. Die errechnete Kriechgeschwindigkeit der Flachs-Verbundwerkstoffe war wesentlich geringer als im puren PLA. Polyethylen und Polypropylen/Nanosilikon Dioxid/Flachs-Verbundwerkstoffe Verbundwerkstoffe hergestellt aus Polylactid (PLA), modifiziertem PLA und Flachsfasertextilgewebe (Flachsgewebeform von 2x2 Körper und 4x4 Gewebe mit Leinwandbindung) wurden im Pressverfahren hergestellt. Zwei strukturell unterschiedliche Additive wurden verwendet um das PLA zu modifizieren. Die Verteilung der Flachs-Verbundwerkstoffstruktur wurde unter dem Rasterelektronenmikroskop (SEM) und dem computergestütztes Computer-Tomography-System (µCT) untersucht. Die PLA Verbundwerkstoffe wurden dem Wasseraufnahme- und instrumentalisierten Fallgewichtsschlagzähigkeitstest unterzogen. Die Kriech- und thermomechanischen Eigenschaften der respektiven Verbundwerkstoffe wurden in der thermogravimetrischen Analyse (TGA), der dynamisch mechanischen Thermoanalyse (DMTA) und dem Kurzzeit-Kriechversuch bestimmt. Das modifizierte PLA und dessen Verbundwerkstoffe zeigten eine Erhöhung der Schlagzähigkeit im Vergleich zum unmodifizierten PLA. Die Einbindung von Flachs verringerte den Widerstand gegenüber thermischer Degradierung und erhöhte die Wasseraufnahme. Die Schlagenergie- und Steifigkeitswerte der PLA/Flachs-Verbundwerkstoffe war deutlich höher als die der PLA aber spiegelt die Effekte von Verbundwerkstoffstrukturen mit Flachsinhalt wieder. Die Hauptkurve des Speichermoduls wurde mit dem Zeit-Temperatur-Überlagerung (TTS) Prinzip aufgestellt. Das Datenmaterial der Hauptkurve zeigte den Effekt des modifizierten PLAs auf dem Speichermodul deutlich ausgeprägter im Bereich der Niederfrequenz. Polylactide (PLA)/Flachfasertextilgewebe/Böhmit Aluminumoxid (BA)-Verbundwerkstoffe Die textilen Bioverbundwerkstoffe wurden aus flachsfaserverstärkten Poly(Butylen Adipat-Co-Terephtalat) (PBAT) Gewebe und Vlies im Formpressverfahren mit der Folien-Stapelmethode hergestellt. Die mechanischen Eigenschaften (wie Zugfestigkeit und Steifigkeit, Biegefestigkeit, Steifigkeit und Schlagzähigkeit) der jeweiligen textilen Bioverbundwerkstoffe wurde in Zug-, Biege-, und Schlagtests ermittelt. Die PBAT basierten Verbundwerkstoffe wurden dem Wasseraufnahmetest unterzogen. Der Vergleich der mechanischen Eigenschaften wurde zwischen reinem PBAT und textilen Verbundwerkstoffen durchgeführt. Der Einfluss der Flachsgewebeformen auf die mechanischen Eigenschaften wurde ebenfalls untersucht. Die Ergebnisse zeigten das die Festigkeit der textilen Bioverbundwerkstoffe mit der Webart der Fasern anstieg, signifikant in Bezug auf die Steifigkeit bei einer erhöhten Verdichtung der Fasern. Die 4x4 flachfasergewebten (4-Schussfaden-Windung und 4-Kettfaden-Windung) verstärkten Bioverbundwerkstoffe zeigten die höchste Festigkeit und Steifigkeit im Vergleich zu den anderen textilen Bioverbundwerkstoffen und dem puren PBAT. Dieses Resultat wurde der Beschaffenheit der 4x4-flachfasergewebten Webart zugewiesen. Das Aminopropyltriethoxysilan beeinträchtigte die mechanischen Eigenschaften und Wasseraufnahme der entstandenen Verbundlaminate durch Oberflächenkompatibilität zwischen der Flachsfaser und dem PBAT. HYBRIDE VERBUNDWERKSTOFFE Polyethylen/Nanopartikel, natürliche und tierische Verbundwerkstoffe Binäre und ternäre Verbundwerkstoffe, bestehend aus hoch dichtem Polyethylen (HDPE), Böhmit Aluminumoxid (BA) und verschiedenen natürlichen und tierischen Fasern wie Flachs, Schwammgurke (SG), Palmfaser und Schweinehaar (PH), wurden im Pressverfahren hergestellt. Vorbereitend wurden wasserhaltige BA-Suspensionen auf die HDPE/Flachsmatte gesprüht um nanopartikel/naturfaserverstärkte ternäre Polymer-Verbundwerkstoffe nach dem Trocknen zu erhalten. Die Verteilung der Natur-,Tierfasern und der BA-Partikel in den Verbundwerkstoffen wurde unter dem Rasterelektronenmikroskop untersucht und diskutiert. Die thermomechanischen und Spannungsrelaxation-Eigenschaften der jeweiligen Verbundwerkstoffe wurden in der thermogravimetrischen Analyse (TGA), der dynamisch mechanischen Thermoanalyse (DMTA) und dem Kurzzeit-Stressrelaxationstest (bei unterschiedlichen Temperaturen durchgeführt) bestimmt. Die HDPE-basierten Verbundwerkstoffe wurden Wasseraufnahme- und instrumentalisierten Fallgewichtsschlagzähigkeitstests unterzogen. Es wurde festgestellt, dass alle Verbundwerkstoffsysteme eine Erhöhung der Steifigkeit und Spannungsrelaxation und eine Verminderung der Kerbschlagzähigkeit aufzeigten. Die Spannungsrelaxations-Steifigkeit von Naturfaser-, Tierfaserverbundwerkstoffen war größer im Vergleich zu reinem HDPE. Diese Steifigkeit steig deutlich an mit der Einbindung von BA. Die Hauptkurven der Relaxation wurden mit dem Zeit-Temperatur-Überlagerung (TTS) Prinzip aufgestellt. Die Umkehrung des Findley Potenzgesetzes konnte gut für die Beschreibung der Relaxations-Steifigkeit vs. Zeitüberwachung in allen untersuchten Systemen angewendet werden. Die Einbindung der BA-Partikel erhöhte den Wärmewiderstand, welcher bei höherer Temperatur zu sinken begann im Vergleich zu HDPE/Flachsmatten-Verbundwerkstoff. Der HDPE/Flachsmatte/BA-Verbundwerkstoff konnte die Wasseraufnahme verringern. Polyethylen/Flachs/SiO Verbundwerkstoffe Verbundwerkstoffe bestehend aus hoch dichtem Polyethylen (HDPE), Flachsfasertextilgewebe (Flachsgewebeform 2x2 Körper und 4x4 Gewebe mit Leinwandbindung) und Siliziumdioxid (SiO2) wurden im Pressverfahren mit Nanospritztechnik hergestellt. Die SiO2 Schlämme wurden auf beide Oberflächen des Flachsfasergewebes per Hand gesprüht. Die HDPE/ Flachsfasergewebe-Verbundwerkstoffe wurden in einer Laborpresse im Pressverfahren mit und ohne Nanospritztechnik hergestellt. Die Verteilung der SiO2-Partikel und des Flachs in den Verbundwerkstoffen wurde unter dem Rasterelektronenmikroskop (SEM) untersucht. Die ähnlichen HDPE-basierten Verbundwerkstoffe wurden dem instrumentalisierten Fallgewichtsschlagzähigkeitstest unterzogen. Der Wärmewiderstand, Steifigkeit- und Zugfestigkeit-Eigenschaften der jeweiligen Verbundwerkstoffe wurden in thermogravimetrischen Analysen (TGA), dynamisch mechanischen Thermoanalysen (DMTA) und Zugversuchen bestimmt. Es zeigte sich, dass die Aufprallenergie und Steifigkeitswerte der HDPE/Flachs-Verbundwerkstoffe deutlich höher als die des HDPE waren aber die Effekte von Verbundwerkstoffen mit Flachsinhalt widerspiegeln. Die Einbindung von SiO2-Partikeln erhöhte den Widerstand von thermischer Degradierung. Es wurde bestimmt, das das Prinzip der linear viskoelastischen Werkstoffe gut anwendbar auf die Umwandlung der Steifigkeit zu Kriechneigungsergebnissen ist. Modifizierte und nicht modifizierte Polylactid (PLA)/Flachsfasergewebe-Verbundwerkstoffe Hybride Verbundwerkstoffe aus Polypropylen (PP) oder hoch-dichtem Polyethylen (HDPE), verschiedenen Flachsfasern (unidirektional, biaxial und 2x2 Körper) und Siliziumdioxid (SiO2) wurden im Pressverfahren hergestellt. Der ternäre Polymer-Verbundwerkstoff wurde wirkungsvoll durch das Aufbringen von SiO2 Lösemitteln auf die Oberfläche der Flachsfaser hergestellt. Die Verteilung der SiO2-Partikel und des Flachs in den Verbundwerkstoffen wurde unter dem Rasterelektronenmikroskop (SEM) untersucht. Die ähnlichen PP- und HDPE-basierten Verbundwerkstoffe wurden dem instrumentalisierten Fallgewichtsschlagzähigkeitstest unterzogen. Die thermischen und mechanischen Eigenschaften der respektiven Verbundwerkstoffe wurde in thermogravimetrischen Analysen (TGA), dynamisch mechanischen Thermoanalysen (DMTA), Kriech- und Spannungsrelaxations-Tests bestimmt. Es zeigte sich, dass die thermische Zersetzungstemperatur der PP oder HDPE/Flachs-Verbundwerkstoffe durch das Auftragen der SiO2-Partikel ansteigt. Die Aufprallenergie-, Steifigkeit-, Kriechbeständigkeit- und Relaxation-Steifigkeitn-Werte aller Flachs-Verbundwerkstoffe stiegen deutlich an im Vergleich zur PP und HDPE Matrix. Die Zeit-Temperatur-Überlagerung (TTS) wurde angewandt um die Kriech- und Relaxation-Steifigkeit für die Verbundwerkstoffe als Funktion der Zeit in Form einer Hauptkurve zu schätzen. Die Aktivierungsenergien aller untersuchten PP und HDPE-Verbundwerkstoffsysteme wurden mit der Arrhenius Gleichung errechnet. Das generalisierte Maxwell Model war gut auf die Spannungsrelaxationsergebnisse anwendbar. Polylactide (PLA)/Flachsfasertextilgewebe/Böhmit Aluminiumoxid (BA)-Verbundwerkstoffe Verbundwerkstoffe bestehend aus Polylactid (PLA), Flachfasertextilgewebe (Gewebeform 2x2 Körper und 4x4 Gewebe mit Leinwandbindung) und Böhmit Aluminium (BA) wurden im Pressverfahren hergestellt. Für die Vordispergierung der Aluminiumoxid-Nanopartikel wurde die Spritztechnik angewendet. Die wasserhaltigen Aluminiumoxid-Schlämme wurden durch das Vermischen von Wasser mit wasserdispergierbarem Aluminiumoxid hergestellt. Die Verteilung der Flachsstrukturen und Aluminiumoxid-Partikeln in den Verbundwerkstoffen wurde mit einem Rasterelektronenmikroskop (SEM) untersucht. Die PLA-Verbundwerkstoffe wurden Wasseraufnahme- und instrumentalisierten Fallgewichtsschlagzähigkeitstests unterzogen. Die Kriech- und thermomechanischen Eigenschaften der jeweiligen Verbundwerkstoffe wurden in Kurzzeit-Kriechversuchen (bei unterschiedlichen Temperaturen durchgeführt), thermogravimetrischen Analysen (TGA) und dynamisch mechanischen Thermoanalysen (DMTA) bestimmt. Es zeigte sich, dass das Einbringen der Aluminiumoxid-Partikel die Wasseraufnahme im Vergleich zu PLA/Flachs-Gemischen reduziert. Die Aufprallenergie- und Steifigkeitswerte der PLA/Flachs-Gemische waren signifikant höher als die des PLA aber spiegelten die Effekte von Verbundwerkstoffstrukturen wieder. Das Einbringen von Aluminiumoxid-Partikeln verbesserte die Lagerungs-Steifigkeit und die Kriechbeständigkeit im Vergleich zu PLA/Flachs-Gemischen, erhöhte allerdings leicht den Wärmewiderstand bei hohen Temperaturen. Kein klarer Trend in der Flachswebart konnte dem Temperaturverhalten zugeordnet werden. Die Kriech-Hauptkurven wurden mit dem Zeit-Temperatur-Überlagerung (TTS) Prinzip aufgestellt. Das Findley Potenzgesetz konnte zufriedenstellend die Kriechneigung vs. Zeitüberwachung für alle untersuchten Systeme beschreiben. Poly(Hydroxybutyrat-Co-Hydroxyvalerat)/Natursisalfaser/Ton-Verbundwerkstoffe Poly(Hydroxybutyrat-Co-Hydroxyvalerat) (PHBV) Bioverbundwerkstoffe die Sisalfasern in Längen von 0,25 und 5 mm und Ton-Partikeln enthalten wurden im Heißpressverfahren hergestellt. Die Silan (Bis(Trithoxysilylpropyl)Tetrasulfide) Behandlung wurde für die Modifizierung verwendet um die Eigenschaften von ähnlichen hybriden Verbundwerkstoffen zu verbessern. Alle Verbundwerkstoffe wurden dem Wasseraufnahmetest unterzogen. Die mechanischen Eigenschaften der jeweiligen hybriden Verbundwerkstoffe wie Zugsteifigkeit und Festigkeit, Zähigkeit und Härte wurden in Zugversuchen, Schlagtests und Härteprüfungen bestimmt. Es zeigte sich, dass die Zugfestigkeit, Steifigkeit und Schlagzähigkeit von langen Sisalfasern sich mit der Erhöhung des Fasergehalts verbessert. Behandeltes Silan von langen Fasern mit 20 wt.% Belastung zeigte eine Verbesserung der Faser-Zugfestigkeit um 10% und Schlagzähigkeit von 750% im Vergleich zu reinem PHBV. Diese Besonderheit wurde auch von einem Rasterelektronenmikroskop bestätigt. Weiterhin ist die Härte und Wasserbeständigkeit in PHBV/Sisal-Verbundwerkstoffen durch das Einbringen von Ton-Partikeln angestiegen. Die Diffusionskoeffizienten für die untersuchten PHBV- und hybriden Verbundwerkstoffsysteme wurden auch errechnet.

The objective of this thesis is to investigate the effects of adding natural fiber (kenaf fiber, retted kenaf fiber, and sugarcane fiber) into polymer materials. The effects are obtained by considering three main parts. 1. Performance in thermoplastic composites. The effect of fiber retting on polymer composite crystallization and mechanical performance was investigated. PHBV/PBAT in 80/20 blend ratio was modified using 5% by weight kenaf fiber. Dynamic mechanical analysis of the composites was done to investigate the glass transition and the modulus at sub-ambient and ambient temperatures. ESEM was conducted to analyze fiber topography which revealed smoother surfaces on the pectinase retted fibers. 2. Performance in thermoset composites. The effect of the incorporation of natural fibers of kenaf and of sugarcane combined with the polyester resin matrix is investigated. A comparison of mechanical properties of kenaf polyester composite, sugarcane polyester composite and pure polyester in tensile, bending, dynamic mechanical thermal analysis (DMA) and moisture test on performance is measured.. 3. Performance in sandwich composites. The comparison of the performance characteristics and mechanical properties of natural fiber composites panels with soft and rigid foam cores are evaluated. A thorough test of the mechanical behavior of composites sandwich materials in tensile, bending and DCB is presented here.

The importance of using natural fiber composites (NFCs) has been addressed as a substitution for synthetic fibers, such as glass and carbon fibers. This substitution contributes significantly to reducing greenhouse gas emissions, aligning with the environmental responsibilities of engineering industries. Wood fiber(WF) is one of the natural fibers (NFs) dominating the market in various businesses. As an excellent alternative to non-renewable sources, the demand for injection-molded applications using natural fiber-reinforced plastics has expanded across various sectors. Despite extensive prior research on the mechanical properties of WFs, there remains a need for a deeper understanding of the connection between fiber orientation and mechanical characteristics. This understanding is essential for developing computational methods aimed at ensuring structural integrity, cost-efficiency, and sustainability in real-world components. This study aims to evaluate coupled injection molding simulation to finite element method with mapping of fiber orientation tensor for a wood fiber composite (WFC). To achieve this, WFC’s mechanical properties and behavior under tensile loading conditions are investigated. The research methodology involves conducting uniaxial tensile testing on dog bone-shaped specimens at different fiber orientations (0 degrees, 45 degrees, and 90 degrees). Experimental data is collected, analyzed, and compared with the obtained results with numerical simulations to validate the accuracy of the models used. Additionally, the aspect ratio and volume fraction of the WFs are measured through both mathematical calculations and image analysis using MATLAB. The main contribution of this study can be summarized in two key observations. Firstly, the investigation of mechanical characteristics across different fiber orientations has revealed distinct patterns. Specimens aligned at 0 degrees exhibit noticeable differences in behavior compared to those at 45 and 90 degrees, highlighting the material's anisotropic nature. Secondly, the comparison between experimental data and computational simulations exhibits the effectiveness of the developed models. The close agreement between the two validates the accuracy of the predictive approach. Moreover, the consistent aspect ratio, volume fraction, and fiber orientation value obtained through both mathematical calculations and image analysis add credibility to the reliability of our measurements. Notably, the comparison with glass fibers (GFs) reveals that WFs exhibit considerably less breakage, highlighting their durability and potential suitability for various applications. / Betydelsen av att använda naturfiberkompositer har behandlats som en ersättning för syntetiska fibrer, såsom glas- och kolbaserade fibrer. Denna substitution bidrar betydligt till att minska utsläpp av växthusgaser och överensstämmer med ingenjörsbranschens miljöansvar. Träfiber är en av de naturfibrer som dominerar marknaden inom olika branscher. Som ett utmärkt alternativ till icke-förnybara källor har efterfrågan på formsprutade applikationer med naturfiberförstärkta plaster ökat inom olika sektorer. Trots omfattande tidigare forskning om träfibrers mekaniska egenskaper finns det fortfarande ett behov av en djupare förståelse för sambandet mellan fiberns orientering och dess mekaniska egenskaper. Denna förståelse är avgörande för att utveckla beräkningsmetoder som syftar till att säkerställa strukturell integritet, kostnadseffektivitet och hållbarhet i komponenter i den verkliga världen. Denna studie syftar till att utvärdera kopplad formsprutningssimulering med ändelementmetod och kartläggning av fibrernas orienteringstensor för en träfiberkomposit. För att uppnå detta undersöks träfiberkompositens mekaniska egenskaper och beteende under dragbelastningsförhållanden. Forskningsmetodiken innefattar genomförande av enaxlig dragprovning på hundbenformade provkroppar vid olika fibrers orientering (0 grader, 45 grader och 90 grader). Experimentella data samlas in, analyseras och jämförs med de erhållna resultaten från numeriska simuleringar för att validera modellernas noggrannhet. Dessutom mäts träfibrernas aspektratio och volymfraktion genom både matematiska beräkningar och bildanalys med hjälp av MATLAB. Huvudbidraget från denna studie kan sammanfattas i två centrala iakttagelser. För det första har undersökningen av mekaniska egenskaper vid olika fibrers orienteringar avslöjat tydliga mönster. Prover som är riktade i 0 grader uppvisar märkbara skillnader i beteende jämfört med de vid 45 och 90 grader, vilket understryker materialets anisotropa natur. För det andra visar jämförelsen mellan experimentella data och beräkningsmässiga simuleringar effektiviteten hos de utvecklade modellerna. Den nära överensstämmelsen mellan de båda validerar noggrannheten i den prediktiva metoden. Dessutom lägger de konsekventa värdena för aspektratio, volymfraktion och fibrernas orientering som erhållits genom både matematiska beräkningar och bildanalys trovärdighet till våra mätningar. Det bör noteras att jämförelsen med glasfiber visar att träfibrer uppvisar betydligt mindre brytning, vilket betonar deras hållbarhet och potentiella lämplighet för olika tillämpningar.

Nowadays, when environmental concerns are becoming increasingly important are there great interest in natural materials and recyclability. The possibility of reusing materials with maintained mechanical properties are essential for sustainability. Today produced approximately 90,000 tons of natural fiber reinforced composites in Europe of those are 40,000 tons compression molded of which the automotive industry uses 95%. Natural fiber reinforced composites is recyclable and therefore interesting in many applications. Also, natural fiber reinforced composites is inexpensive, light in weight and shows decent mechanical properties which makes them attractive to manufactures. However, the problem with natural fiber reinforced composites is the poor adhesion between fiber and matrix, the sensitivity of humidity and their low thermal stability. Those problems could be overcome by addition of compatibilizer and reactive filler. This study will examine the technical requirement in order to develop a sustainable and recyclable biocomposite. It investigates the composition of matrix (polypropylene), fiber (flax), compatibilizer (maleic anhydride grafted polypropylene) and reactive filler (CaO) in order to obtain various combinations of stiffness, strength and processability. The two main methods used for preparing samples were compounding and injection molding. Results shows that 20 wt% flax was the optimal fiber content and that maleic anhydride grafted polypropylene is a very good compatibilizer by enhancing the strength significant. Surprisingly was the strength impaired due to the addition of CaO. The composition of 20 wt% flax, 1 wt% maleic anhydride grafted polypropylene and 79 wt% polypropylene is the technically most favorable composition.

Karton ist ein aus nachwachsenden Rohstoffen hergestelltes Halbzeug, biologisch abbaubar und mit sehr guter Wiederverwertbarkeit. Damit stellt Karton eine zukunftsträchtige Grundlage für die Herstellung von Verpackungen für die Lebensmittel- und Konsumgüterproduktion dar. Schon heute werden in vielen Verpackungslösungen Kunststoffe durch naturfaserbasierte Halbzeuge ersetzt, um von den genannten Vorteilen zu profitieren. Um die Verbreitung dieses Naturstoffes weiter zu unterstützen, werden intelligente und effektive Herstellungsverfahren benötigt, die eine Massenfertigung von Packmitteln in hoher Qualität ermöglichen. [... aus der Einleitung]

Made available in DSpace on 2014-12-17T14:58:00Z (GMT). No. of bitstreams: 1 RuiCSM_MESTRE.pdf: 3074589 bytes, checksum: ce573ec9d691a895e59153850a53bf18 (MD5) Previous issue date: 2010-02-26 / This paper aims to present the feasibility of using a composite using discarded material from the cultivation of banana tree (pseudostem), which is fibrillated together with synthetic resin replacing glass fiber to be used in structural elements that do not demand large mechanical stress such as reservoirs, troughs, domes, sewage pipes etc.. For this, there were studies about the mechanical properties of a composite made with polyester resin and fiber of banana tree (Musa sp, musac), in which the splints were removed from the pseudostem, being made fibrillation by hand, with the aid of a brush steel, followed by natural drying. After treatment for cleaning and removal of wax, the fiber was cut into pieces of approximately 60 mm to 100 mm, for, together with synthetic resin, make cards of a features fiber composite with random orientation relative to the weight of the resin. We used three different percentages of fiber (3%, 6% and 9%), in order to make a comparative study between them and what would be the one with the best performance. Were manufactured specimens of each material and then subjected to uniaxial tensile tests, three point bending, moisture absorption and thermal characteristics. The results show that, in general, the use of banana tree fiber is feasible simply by an improvement in the production process (machining of the procedure) and greater care in the manufacture of parts / Este trabalho tem como objetivo apresentar a viabilidade de um comp?sito utilizando material descartado da lavoura da bananeira (pseudocaule), o qual ? fibrilado juntamente com resina sint?tica em substitui??o ? fibra de vidro, a ser utilizado em elementos estruturais que n?o demandem grandes esfor?os mec?nicos, tais como reservat?rios, calhas, domos, tubula??es de esgotamento etc. Para isso foram efetuados estudos sobre as propriedades mec?nicas de um comp?sito de resina poli?ster e fibra de bananeira (musa s.p., mus?cea), nos quais foram retiradas as talas do pseudocaule, sendo feita a fibriliza??o de forma manual, com o aux?lio de uma escova de a?o, seguido de secagem ao natural. Ap?s tratamento para limpeza e retirada de cera, a fibra foi cortada em peda?os de aproximadamente 60 mm a 100 mm para, juntamente com a resina sint?tica, fabricar placas de um comp?sito de caracter?sticas fibrosas com orienta??o aleat?ria em rela??o ao peso da resina. Foram utilizadas tr?s percentagens distintas de fibras (3%, 6% e 9%), a fim de se efetuar um estudo comparativo entre elas e determinar qual seria aquela com o melhor desempenho mec?nico. Foram fabricados corpos de prova de cada material, sendo ent?o submetida aos ensaios de tra??o uniaxial, flex?o em tr?s pontos, absor??o de umidade e caracter?sticas t?rmicas. Os resultados demonstram que, de forma geral, o uso de fibra de bananeira ? vi?vel, bastando uma melhoria no seu processo de obten??o (mecaniza??o do procedimento) e um maior cuidado durante a fabrica??o das pe?as

Le fractionnement de quatre biomasses herbacées modèles présentes ou cultivées dans l’estuaire de la Loire est étudié pour la production d’agrofibres adaptées à leur usage dans les matériaux composites écoconçus pour la construction. Les biomasses caractérisées chimiquement et physicochimiquement sont traitées par trois technologies de complexité croissante : le broyeur à marteaux permettant une fragmentation transversale et longitudinale radiale, le défibrage mécanique orientant les contraintes de façon longitudinale radiale et tangentielle, et le défibrage thermomécanique permettant un raffinage à l’échelle de la fibre élémentaire. Le Foin des Marais, modèle de mélange d’herbacées composé de tiges portant des feuilles, endémiques de prairies mésohygrophiles, est une source d'agrofibres cellulo-hémicellulosiques peu lignifiées (ratio cellulose/hémicelluloses/lignines 50/40/10) présentant un très fort taux de composés hydrosolubles (17 à 27% de MS), très hydrophiles (ratio liquide/solide à saturation L/Ssat entre 5,2 et 9,7), relativement fines (facteur de forme L/D >10) et de petites dimensions (moins de 5 cm) permettant l’obtention d’une grande gamme de densité de mats (37 à 112 kg/m3) et ayant une bonne aptitude à l’auto-assemblage sous contrainte. La Rouche, modèle de mélange d’herbacée composés de feuilles ayant des tiges, endémique de prairies hygrophiles, est une source d'agrofibres cellulo-hémicellulosiques peu lignifiées (ratio 50/40/10) présentant un fort taux de composés hydrosolubles (16% de MS), hydrophiles (L/Ssat entre 4,1 et 10,7), fournissant une large gamme de morphologie d’agrofibres allant jusqu’à 13cm de long pour des L/D de 100, formant des mats de 32 à 121 kg/m3, et ayant une bonne aptitude à l’autoassemblage. La Canne de Roseau (Phragmites australis), modèle de tiges creuses rigides, endémiques des bas marais, est une source d'agrofibres rigides beaucoup plus lignifiées (ratio 50/30/20) contenant peu de composés hydrosolubles (6 à 8% de MS), thermostables jusqu’à 220°C et relativement peu hydrophiles (L/Ssat de 3,4) si elles ne sont pas trop déstructurées, ne générant que de agrofibres courtes (moins de 5 cm) et de faible finesse (L/D <15). Les tiges de Mélilots jaune et blanc (Melilotus officinalis et Melilotus alba), dicotylédones à croissance secondaire adaptée à la culture sur les terrains de l’estuaire de la Loire, s’est avéré produire deux classes d’agrofibres. La première est composée d’agrofibres longues, extractibles du cortex de la tige, souples et essentiellement cellulosiques (ratio 75/15/10) pouvant aller jusqu’à 16cm de long (L/D>100), formant des mats de 38 à 42 kg/m3; la seconde classe d’agrofibres macroporeuses courtes et rigides extractibles du bois, beaucoup plus lignifiées (ratio 65/15/20), ayant très peu d’extractibles (2 à 3% de MS), et peu hydrophiles (L/Ssat entre 2,5 et 2,8). Un nouveau procédé d’extraction d’agrofibres longues (dm à cm) courtes (cm à mm), et ultra courtes (mm à μm) est développé. Des agrofibres sélectionnées sont mises en oeuvre avec de la colle de caséine dans des agrocomposites basse densité type blocs isolants thermiques (40 à 82 mW/m*K) et phoniques (indice d'affaiblissement sonore entre 0,18 et 1,2 dB(A)/mm) ; avec de la colle d’os dans des agrocomposites haute densité type panneaux de particules et de fibres (D jusqu’à 1,3 g/cm3, Eflexion jusqu’à 3,9 GPa et σmax flexion jusqu’à 39 MPa) ; ainsi qu’avec une matrice thermoplastique recyclable (PP+PPMA) chargées jusqu’à 40% en agrofibres et présentant une tenue mécanique jusqu’à 5 fois plus élevée en traction et en flexion. Parallèlement, les graines de Mélilots sont caractérisées, et se révèlent être riche en protéines (31 à 32% de MS) et avoir un fort potentiel en fraction extractible aqueuse (34 à 36% de MS) contenant des galactomannanes. Le raffinage de cette agroressources a été entrepris en vue de l'obtention de liants pour des agrocomposites. / The fractionation of four Loire estuary herbaceous biomasses models, endemic or cultivated, have been studied for their agrofibre production potential and adapted for their use in composite materials for ecodesigned construction. Chemically and physicochemically characterized biomasses have been processed by three increasingly complex technologies: hammer-mill that provides transversal and radial longitudinal fragmentation, mechanical defibration orienting the constraints in radial and tangential longitudinal way, and thermomechanical defibration that provides a refining at the scale of elementary fibre. Hay of Swamps, a herbaceous model made of a mix of stem bearing leaves, endemic of mésohygrophile land, is a source of few lignified cellulo-hemicellulosic agrofibres (50/40/10 ratio cellulose/hemicelluloses/lignin) with a very high rate of water-soluble compounds (17 to 27% of DM), very hydrophilic (saturation liquid/solid ratio L/Ssat between 5.2 and 9.7), relatively thin (shape factor L/D >10) and small size (less than 5 cm) allowing mats with large density range (37 to 112 kg/m3) with good self-assembling properties. Rouche, a herbaceous model made of a mix of leaves with stem, endemic of hygrophile land, is a source of little lignified cellulo-hemicellulosic agrofibres (50/40/10 ratio) with a high rate of water-soluble compounds (16% de DM), hydrophilic (L/Ssat between 4.1 et 10.7), producing a large agrofibres morphology range, up to 13cm long and L/D to 100, and allowing mats with density of 32 to 121 kg/m3, with good self-assembling properties. Reed (Phragmites australis), stiff hollow stems model, endemic of low-marsh, is a source of highly lignified stiff agrofibres (50/30/20 ratio) with a low rate of water-soluble compound (6 to 8% of DM), thermostable up to 220°C and relatively little hydrophilic (L/Ssat= 3.4) if they are not too much destructured, producing only short agrofibres (less than 5 cm) with low thinness (L/D <15). Yellow and white sweet clovers stem (Melilotus officinalis and Melilotus alba), secondary growth dicotyledon able to be cultivated on estuary land, provides two kinds of agrofibre. The first kind is stem cortex extractable long agrofibres, flexible and primarily cellulosic (75/15/10 ratio) up to 16cm long (L/D>100 and allowing light mat with density of 38 to 42 kg/m3. The second kind is secondary xylem extractable macroporous short and stiff agrofibres, highly lignified (ratio 65/15/20), with a very low rate of water-soluble compounds (2 to 3% of DM), and little hydrophilic (L/Ssat between 2.5 and 2.8). A new extraction process of long (from decimetric to centimetric length), short (from centimetric to millimetric length), and ultra-short (from millimetric to micrometric length) agrofibres had been developed. Selected agrofibres are processed with casein glue in low density agrocomposites such as insulating material (40 to 82 mW/m*K and sound reduction factor between 0.18 to 1.2 dB(A)/mm) ; with bones glue in high density agrocomposites such as particle board and fibreboard (D until 1.3 g/cm3, Eflexion until 3.9 GPa et σmax flexion until 39 MPa) ; thus with a recyclable thermoplastic matix (PP+PPMA) loaded until 40% of agrofibres, having a tensile and flexure mechanical strength almost 5 time higher. In parallel the sweet clover seeds had been characterized, and demonstrate to be rich in proteins (31 to 32% of DM) and to have a great potential in being water-extractable (34 to 36% of DM) containing, among other, galactomannans. The refining of this agroresources has been undertaken in the development of new binding materials for agrocomposites.