Today’s environmental concerns have led a renewed search in industry to find new sustainable materials to replace non-renewable resources. President Barack Obama also quoted in the recent 2012 Presidential Debate “that there is a need to build the energy sources of the future and invest in solar, wind, and bio-fuels.” Bio-composites are believed to be the future and the new substitute for non-renewable resources. Bio-composites are similar to composites in that they are made up of two constituent materials; however the main difference is that bio-composites are made from natural fibers and a biopolymer matrix. This research investigates the buckling behavior of bamboo and will analyze and determine the slender ratio that will induce buckling when bamboo is used as a column. Along with the investigation of the bamboo under buckling, this study will also show the potential of bio-composites to replace non-renewable resources in industry through experimental and numerical analysis. However, in order to study the buckling behavior of the bamboo, the mechanical characteristics of the bamboo and optimal curing treatment first had to be established. This is because, in order for bamboo to acquire proper strength characteristics, the bamboo must first be treated. Due to the scarcity of bamboo material in the lab, the obtainment of the mechanical properties of the bamboo as well as the optimal curing treatment was done in collaboration with Jay Lopez. In order for bamboo to acquire proper strength characteristics, the bamboo must be treated. In the first study, a total of four different types of natural treatments were analyzed to optimize the mechanical characteristics of bamboo. To assess each curing method, tensile and compression tests were performed to obtain the mechanical properties. Due to each bamboo culm having different thicknesses and cross sections, the specific strength property is used to normalize the data and allow for easy comparison and assessing of each curing method equally. The specific strength parameter is defined as the ultimate stress divided by the density of the material. These curing treatments consisted of four thermo-treatments, three different percentages of salt treatments, one lime treatment, and one oil treatment. The thermo-treatments consisted of heating the bamboo internodes in an autoclave with no pressure at 150oF, 180°F, 200°F, and 220°F. The experimental results of the thermo-treatments determined that bamboo obtains higher mechanical properties as well as reduced weight when heated at higher temperatures. This is explained by the increasing bound water extracted from the bamboo material at higher temperatures. In addition to finding the optimal heat treatment, the internodes of bamboo were soaked in natural additives that included a 3%, 6%, and 9% Instant Ocean sea salt solution, a Bonide hydrated lime solution, and a Kirkland canola oil solution for approximately five days and then heat treated at the optimal temperature of 220°F. The experimental results showed that all of the different additives had a significant effect on the mechanical properties. After determining the mechanical properties of each curing method, the results were then analyzed through a trade study. The trade study parameters consisted of weight-drop of the material, the specific strength, and the ultimate stress for both compression and tension. Each parameter of the trade study is kept unbiased as the weighting of each parameter is set equal to each other. The results of the trade study indicated that the 3% salt solution was the optimal curing treatment, yielding a higher specific strength value for both compression and tension, along with a significantly lower weight-drop after curing. After we came up with the optimal treatment, the buckling behavior of bamboo was investigated. The buckling analysis was investigated to determine at what slenderness ratio the bamboo would buckle when used as a column. A total of seven cases were investigated using different lengths, that ranged from 1.5” to 10”. Through experimental results, it was determined that a slenderness ratio above approximately 34.7 would induce global buckling to the bamboo column. The last investigation of this study consisted of building a small prototype wall structure using bio-composites. The prototype wall structure was manufactured using a combination of bamboo and a bi-directional woven hemp fabric. The dimensions of the prototype were 15.13” long and 7.75” tall. The wall structure was tested under compression in the Aerospace Structures/Composites Lab and the Architectural Engineering Department’s high bay laboratory. The results of the experimental test on the wall showed great potential for bio-composites, as the structure withstood a force of 46,800 pounds. A numerical analysis technique was also employed through the finite element method using the Abaqus software. The purpose of the finite element method was to validate the experimental results by comparing the buckling behavior of the tests. The numerical analysis showed very good agreement with the experimental results.

Les matériaux composites sont utilisés dans beaucoup de domaines pour leurs propriétés mécaniques spécifiques, leur mise en forme facile et leur bas coût. Cependant, lorsque les composites pétro-sourcées sont en fin de vie, le traitement des déchets a un fort impact environnemental. C’est pour cette raison que les industriels se tournent vers des matériaux bio-sourcés. Ils souhaitent ainsi abaisser le coût des matières premières mais aussi se donner une image plus « verte » grâce à l’utilisation de matériaux renouvelables et/ou compostables. Le projet présenté s’inscrit dans dans cette optique où il est question d’élaborer de nouveaux composites à renfort et matrices bio-sourcés et tout particulièrement des composites fibre de lin/acide polylactique (PLA). Ces derniers sont généralement appelés bio-composites. L’originalité de cette étude réside dans le traitement des fibres de lin afin de les compatibilité avec la matrice PLA. Le traitement consiste au greffage de dioxyde de titane sur la surface de fibres de lin fonctionnalisée par oxydation au TEMPO. Ces fibres longues sont ensuite utilisées comme renfort sous forme de tissu unidirectionnel dans la matrice PLA. Le comportement mécanique en traction, flexion et la résistance à l’impact de ces biocomposites sont étudiés afin d’analyser l’influence du traitement des fibres sur leur performances.

Compared to conventional fibers, carbon nanotubes possess several significant properties, which make them as an excellent alternative reinforcement in multi-functional material industry. In this study, the possibility of dispersion of the multi-wall carbon nanotube (MWCNTs) in a thermoset bio-based resin (synthesized based on end-functionalized glycerol-lactic acid oligomers, GLA, at university of Borås) was investigated. Furthermore, the addition of the MWCNTs as reinforcement to improve the mechanical and thermal properties of was investigated. The nanocomposites were prepared in three different concentrations of MWCNTs, 0.3 wt.%, 1.0 wt.%, and 2.0 wt.%, and each sample was prepared using three different dispersion methods such as the high speed mixer(HSM), the ultra-sonication (US), and a combined method of HSM & US. The mechanical and thermal properties were analyzed by flexural test, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results confirm that the nanotubes can be dispersed in GLA but the cured nanocomposite didn’t exhibit any considerable improvement in their thermal properties. Considering to the mechanical properties, the addition of 0.3 wt. % MWCNTs to the GLA increased the flexural strength a little but increasing the nanotubes to 1.0 wt. % decreases the flexural strength to almost 50%. This is mainly due to increase in the brittleness of the produced nanocomposites. Both the distribution methods dispersed the nanomaterials in the matrix initially but they are not efficient enough to stop the re-agglomeration which leads to undesired curing dynamics and low efficiency. Thus, these dispersion methods need to be optimized for improvement of nanocomposites’ properties.

Biocomposites exhibit properties like many petrochemical-based polymers composites. They have the potentials be used in the automotive and decking industries and as biodegradable packaging. However, the high cost as well as, poor mechanical and thermal properties have restricted their widespread use. There are a number of technical issues that need to be addressed before bio-composites can be widely used. In this research Polylactic acid (PLA) composites, reinforced with natural fibres (wood, flax) and mineral fillers (talc) were investigated. The thermal and mechanical properties of the composites were studied by means of Differential Scanning Calorimetry (DSC), Tensile Testing and Dynamic Mechanical Analysis (DMA), while morphology and crystallization processes of the composites were studied by hot stage optical microscopy. The experimental results are also compared with different theoretical models of the response of the composites. PLA / wood composites were developed by mixing PLA with wood in different ratios using a melt compounding process. PLA/wood (90/10. 80/20, 60/40), PLA/wood/copolymers (85/10/05, 80/10/10, 75/20/05, 70/20/10, 55/40/05, 50/40/10) and PLA/wood/coupling agent (80/20/silane coating) were the three different composite systems that were developed. Adding increasing amount of wood into the PLA, the thermal properties remain unchanged but the mechanical properties increased significantly, bringing a stiffening effect to the composites. Tensile modulus increased from 4.1± 0.6 to 9.8 ± 1.2 (GPa) as the wood content increased from 0 to 40 (wt %), but the tensile strength at break reduced from 43.8 ± 3.1 to 31.8 ± 2.8 MPa. The experimental results of the PLA-wood composites were modelled according to the Halpin-Tsai equation. The addition of copolymer affected the thermal properties considerably by decreasing the glass transition temperature of the composite. The glass transition temperature dropped from 54 ± 0.7 (0C) to 48 ± 0.36 (0C) when the content of copolymer was increased from 0 to 10 (wt %). The cold crystallization temperature also decreased from 127 ± 1.41 (0C) to 103 ± 2.58 (0C) when the copolymer was incorporated into the PLA/wood composites. The significant aspect was the occurrence of a double peak in the melting endotherm. The degree of crystallinity also increased from 2 ± 0.83 (%) to 11 ± 1.23 (%) when the amount of copolymer was increased to 10 (wt %). PLA, flax and expoidizied natural rubber (ENR) composites were also developed using a melt compounding process. The mechanical properties were affected significantly when the flax fibres were mixed with PLA in the ratios of 10, 20 and 30 (wt %). Addition of flax fibres increased the elastic modulus significantly but reduced the tensile strength and strain at break. To improve the toughness of the PLA- Flax composites, ENR was incorporated into the PLA- Flax composites. In order to balance the modulus of the reinforcement and the matrix, the PLA- Flax and ENR composites were annealed above the glass transition temperature and the degree of crystallinity increased from 2 to 35 (%). The integral blending of PLA, Flax and ENR did not affect the brittle fracture but introducing a masterbatch of flax fibres and ENR into the PLA matrix during melt processing had a considerable effect on the fracture behaviour of the composites. The elastic modulus of the composites decreased due to the elastomeric content in the composites and there was an increase in elongation-to-break. The effect of talc on the crystallinity and mechanical properties of a series of polylactic acid (PLA) / talc composites was investigated. PLA talc composites were developed by incorporating different types of the talc into the PLA in the ratios of 10, 20 and 30 (wt %). The composites were prepared by melt blending followed by compression moulding. It was found that talc acted as a nucleating agent and increased the crystallinity of the PLA from 2% to 25%. There was significant improvement in Young s modulus of the composites with increasing talc addition and these results were found to fit the Halpin Tsai model. Thermo-mechanical tests confirmed that the combination of increased crystallinity and storage modulus leads to improvement in the heat distortion properties.

With the population expected to grow dramatically in the future. The existing state of the ecosystem appears to be worse in the future. One of the key culprits that has been wreaking havoc on the ecosystem is the use of plastic that is used to produce composites. Composites, because to its versatility, has applications in all areas, and as the population grows, so will the demand for them. This can be reduced by using biodegradable and natural materials. The study is done in collaboration with the company Trifilon. The raw materials of the mixture are compared, and the best polymer, fibers, and additives are chosen. Composites made from synthetic raw materials are being replaced by bio-composites, which contain one natural component. The material selected are polypropylene as the polymer, maleic anhydride as compatibilizer and glass fiber for composite while hemp fiber for Bio-composite. To achieve optimal mechanical qualities, the mixture is created using varied amounts of essential components. The mechanical properties aid in defining the industries in which the material can be employed. There are various combinations of raw materials available with varying fiber content, from which the best proportion of the fiber is chosen. For composites and Bio-composites, the fiber content in the mixture is 10% to generate the best material with the appropriate adaptability and flexibility, allowing the material to be used and have applications in several industries. A comparative life cycle evaluation is used to compare the environmental impact of both materials' production procedures. The assessment model was created with the help of a literature review to generate the optimal recipe for composite and bio-composite materials. In most impact categories, bio-composite materials were found to be more sustainable than composite materials. The usage of Polypropylene as a raw material has the greatest influence on global warming, with glass fiber contributing more to global warming than hemp fiber. Future studies could include replacing Polypropylene with natural polymer and hemp fiber with a combination of synthetic and natural fiber to have strong mechanical properties from the synthetic and eco-friendliness from the natural fiber respectively. / Med befolkningen som förväntas växa dramatiskt i framtiden. Ekosystemets befintliga tillstånd verkar vara sämre i framtiden. En av de viktigaste bovarna som har orsakat förödelse på ekosystemet är användningen av plast som används för att producera kompositer. Kompositer har, på grund av sin mångsidighet, tillämpningar inom alla områden, och när befolkningen växer kommer efterfrågan på dem att öka. Detta kan minskas genom att använda biologiskt nedbrytbara och naturliga material. Studien görs i samarbete med företaget Trifilon. Blandningens råmaterial jämförs och den bästa polymeren, fibrerna och tillsatserna väljs. Kompositer tillverkade av syntetiska råvaror ersätts av biokompositer som innehåller en naturlig komponent. Materialet som väljs är polypropen som polymer, maleinsyraanhydrid som kompatibiliseringsmedel och glasfiber för komposit medan hampafiber för biokomposit. För att uppnå optimala mekaniska egenskaper skapas blandningen med olika mängder väsentliga komponenter. De mekaniska egenskaperna hjälper till att definiera de branscher där materialet kan användas. Det finns olika kombinationer av råvaror med varierande fiberhalt, från vilka den bästa andelen av fibern väljs. För kompositer och biokompositer är fiberinnehållet i blandningen 10 % för att generera det bästa materialet med lämplig anpassningsförmåga och flexibilitet, vilket gör att materialet kan användas och ha tillämpningar inom flera industrier. En jämförande livscykelutvärdering används för att jämföra miljöpåverkan från båda materialens produktionsprocedurer. Bedömningsmodellen skapades med hjälp av en litteraturöversikt för att generera det optimala receptet för komposit- och biokompositmaterial. I de flesta påverkanskategorier visade sig biokompositmaterial vara mer hållbara än kompositmaterial. Användningen av polypropen som råvara har störst inflytande på den globala uppvärmningen, med glasfiber som bidrar mer till den globala uppvärmningen än hampafiber. Framtida studier kan innefatta att ersätta polypropen med naturlig polymer och hampafiber med en kombination av syntetiska och naturliga fibrer för att ha starka mekaniska egenskaper från syntet respektive miljövänlighet från naturfiber.