Sustainability has been a driving factor in the recent development of protective coating systems, from reducing volatile organic compounds (VOC’s), integrating biomass for the replacement of petrochemicals, to reducing the number of synthetic or processing steps within a coating system. Incorporating changes to established technologies requires research initiatives focused on matching or exceeding performance properties while maintaining or lowering costs. As a result, sustainable changes to protective coating systems have been under heavy investigation as market demands shift from petrochemicals to renewable materials. This research focuses on the development of unique thermoset coating systems and sustainable improvements. The first study explores the hydrolytic stability between a silanol and an isocyanate, a frequently used reaction that has been relatively understudied. Incorporation of potential hydrolytically unstable silyl carbamates into polyurethane systems may decrease the crosslinking efficiency of the overall network, negatively impacting coating performance. As a result, investigation into the stability of silyl-carbamates may prevent further inefficiencies by eliminating use of this chemistry within polyurethane systems. The second study focuses on the development of alkoxysilane sol-gel consolidants for the protection of stone materials. Sustainable approaches to consolidant formulation include the reduction and elimination of solvent while improving consolidating properties through material selection. The last two studies focus on the incorporation of lignin-derived vanillin into epoxy thermosets and melamine formaldehydes, increasing the overall biobased content of each system. / Office of Naval Research (FAR0025712) / National Center For Preservation Technology and Training, NCPTT (FAR0028305) / EPSCoR/NSF (FAR0030160)

Biobased Thermosets from Vegetable Oils. Synthesis, Characterization, and PropertiesGerard Lligadas PuigEl desenvolupament sostenible va esdevenir com una de les idees claus del segle 20. S'entén per desenvolupament sostenible aquell tipus de desenvolupament que és capaç de satisfer les necessitats actuals sense comprometre els recursos i possibilitats de les futures generacions. Per assolir un desenvolupament sostenible és necessari promoure un desenvolupament social i econòmic pendent en tot moment del medi ambient. La conservació i la gestió dels residus és especialment important en aquest procés. La creixent demanda de productes derivats del petroli, juntament amb la disminució progressiva de les reserves de petroli són algunes de les moltes raons que han encoratjat la industria química a començar a utilitzar les fonts renovables com a matèria prima.En aquest context, en els darrers anys l'atenció s'ha centrat en la utilització de recursos anualment renovables, com són els recursos agrícoles, en la producció d'una gran varietat de productes industrials. Un dels recursos renovables més interessants per a la indústria química són els olis vegetals degut a la seva elevada disponibilitat i el seu ampli ventall d'aplicacions. Els olis vegetals formen part de la família de compostos químics coneguts com lípids, i estan constituïts majoritàriament per molècules de triglicèrids. Els triglicèrids estan formats per tres molècules d'àcid gras unides a una molècula de glicerol mitjançant enllaços ester. Els àcids grassos que es troben en la majoria d'olis vegetals estan constituïts per cadenes alifàtiques insaturades de entre 14 i 22 àtoms de carboni.La explotació industrial dels recursos naturals està actualment en el punt de mira de la comunitat científica. Concretament, el desenvolupament de materials polimèrics derivats de fonts renovables està rebent un interès creixent degut a la incertesa en el preu i les reserves de petroli. La substitució del petroli per productes derivats de fonts renovables és consistent amb el concepte de desenvolupament sostenible. El propòsit del treball portat a terme en aquesta tesi doctoral va ser desenvolupar nous materials termoestables utilitzant olis vegetals com a productes de partida. En el capítol 1 es discuteix la contribució de la química en el desenvolupament sostenible i es descriuen les possibilitats dels olis vegetals com a productes de partida en la síntesi de materials polimèrics. El capítol 2 descriu la preparació de dos noves famílies de materials híbrids orgànics-inorgànics derivats d'olis vegetals. Es descriu síntesi i caracterització de polímers híbrids derivats d'àcids grassos que contenen dobles enllaços carboni-carboni terminals utilitzant la reacció d'hidrosililació com a reacció d'entrecreuament, i la preparació de polímers derivats d'oli de llinosa epoxidat nanoreforçats amb silsesquioxans polièdrics. En el capítol 3 es descriu la síntesi d'un nou compost fosforat derivat de fonts renovables. Aquest compost s'ha utilitzat com a compost retardant a la flama reactiu en la preparació de resines epoxi derivades de fonts renovables amb propietats de resistència a la flama. La incorporació de fòsfor en resines epoxi d'aquest tipus ha donat lloc a polímers amb bones propietats de resistència a la flama. Finalment, en el capítol 4 es descriu la preparació d'una nova família de polièter poliols derivats d'oleat de metil epoxidat com a font renovable. Aquests poliols s'han utilitzat en la síntesi de poliuretans amb aplicacions específiques: poliuretans que incorporen silici amb propietats de resistència a la flama, i poliuretans segmentats amb aplicacions en biomedicina.Biobased Thermosets from Vegetable Oils. Synthesis, Characterization, and PropertiesGerard Lligadas PuigSustainable development, which became a key idea during the 20th century, may be regarded as the progressive and balanced achievement of sustained economic development, and improved social equity and environmental quality. Sustainable development comprises the three components of society, environment, and economy, and its goals can only be achieved if all three components can be satisfied simultaneously.The conservation and management of resources is especially important to this process. The growing demand for petroleum-based products and the resulting negative impact on the environment, plus the scarcity of non-renewable resources, are some of the many factors that have encouraged the chemical industry to begin using renewable resources as raw materials.This situation has led to considerable attention being focused recently on the use of annually renewable agricultural feedstock to produce a wide range of base chemicals and other industrial products. The renewable raw materials that are most important to the chemical industry are natural oils and fats because of their high availability and versatile applications. Vegetable oils constitute about 80% of the global oil and fat production, with 20% (and declining) being of animal origin. The use of these materials offers an alternative approach that is both sustainable and, with the right application, far more environmentally benign than fossil sources.Vegetable oils and fats form part of a large family of chemical compounds known as lipids. Vegetable oils are predominantly made up of triglyceride molecules, which have the three-armed star structure. Triglycerides comprise of three fatty acids joined at a glycerol junction. Most of the common oils contain fatty acids that vary from 14 to 22 carbons in length, with 0 to 3 double bonds per fatty acid.Research into the industrial exploitation of products derived from renewable resources is currently of immense international importance. In particular, the development of polymer materials from renewable resources is receiving considerable attention since the availability of crude oil will become severely restricted within the foreseeable future. The replacement of crude oil by renewable raw materials is also consistent with the aim of global sustainability.The purpose of the study reported in this thesis was to develop new biobased thermosetting polymers from vegetable oils as renewable resources. To achieve this goal, the experimental work focused on exploiting the reactivity of unsaturated fatty compounds. Chapter 1 discusses the contribution of chemistry to sustainable development, and also presents an overview of recent developments in the chemistry of vegetable oil-based polymers. Chapter 2 describes the preparation of two new types of organic-inorganic hybrid materials from vegetable oils. Hybrids with promising properties for optical applications were prepared by the hydrosilylation of alkenyl-terminated fatty acid derivatives with several hydrosilylating agents, and the first example of the preparation of biobased polyhedral oligomeric silsesquioxanes-nanocomposites from vegetable oil derivatives is reported. Chapter 3 describes the synthesis of a new phosphorus-containing fatty acid derivative. This compound is used as a reactive flame-retardant in the preparation of flame-retardant epoxy resins from terminal epoxy fatty acid derivatives. The incorporation of phosphorous into biobased epoxy resins yields polymers with good flame-retardant properties. Finally, chapter 4 describes the preparation of a new family of epoxidized methyl oleate based polyether polyols. These polyols are used in the synthesis of polyurethanes, some with specific applications: silicon-containing polyurethanes with enhanced flame-retardant properties, and polyurethane networks with potential applications in biomedicine.

No description available.

L’étude porte sur la propagation lente de fissure à température ambiante dans deux classes de polymères à l’état vitreux : le PMMA et la résine époxy-amine stœchiométrique DGEBA-IPD comme prototypes respectifs de thermoplastique (TP) et de thermodurcissable (TD). Des mélanges TD/TP présentant une séparation de phase de nano-domaines de thermoplastique dans une phase dominante de thermodurcissable ont été aussi explorés en vue de leur intérêt en tant que matrice à morphologie complexe utilisée dans les composites à renfort de fibre de carbone destinés à l’aéronautique. Un montage expérimental original a été développé pour le suivi in situ de propagation lente de fissures, combinant une caméra optique, un microscope à force atomique (AFM) et un échantillon sollicité en géométrie Double Cleavage Drilled Compression (DCDC). La possibilité d’accéder ainsi à une gamme de vitesses de propagation entre le pm/s et le nm/s a permis de mettre en évidence pour la toute première fois un régime de propagation stationnaire dans les thermodurcissables (résines pures et mélanges TD/TP) analogue au comportement établi pour les thermoplastiques, et de le caractériser en termes d’une loi cinétique reliant la vitesse de propagation au facteur d’intensité des contraintes (SIF). L’analyse in situ AFM a de plus permis de caractériser les différentes modalités de déformation à l’échelle de la zone de process en combinant l’imagerie topographique et des techniques de corrélation d’images numériques (DIC). Un modèle de prédiction des énergies de rupture en propagation stationnaire ainsi qu’en régime de stick-slip a été développé, en intégrant les champs de déformation visco-plastiques mesurés dans la zone de process, la vitesse de déformation locale, et la loi de comportement des matériaux mesurée à l’échelle macroscopique. / This work deals with the slow crack growth in glass polymer materials at room temperature, namely PMMA and stoechiometric epoxy-amine DGEBA-IPD resin as archetypes of thermoplastic (TP) and thermoset (TS) respectively. TS/TP blends developing phases separation in nano-domains of thermoplastic during the cure process have also been studied since they are used as matrix with a complex morphology in carbon fibers reinforced composites materials for aircrafts. An innovative experimental setup has been developed for in situ investigation of slow crack growth by combining optical measurements, in situ atomic force microscopy (AFM) and a Double Cleavage Drilled Compression (DCDC) sample. By this way, a steady state crack propagation regime has been highlighted for a first time in thermosets (pure and TS/TP blends) with crack speed ranging from pm/s to nm/s. Thus crack speed and stress intensity factor (SIF) diagrams were established for each material. Furthermore, in situ AFM images allowed characterizing deformations at the process zone scale by combining topographic imaging with Digital Images Correlation (DIC) technique. Finally, we developed a model for predicting fracture energy for steady state propagation and stick-slip regime, based on the visco-plastic strain fields measured round the process zone, the local strain rate, and the constitutive laws of materials measured at the macroscopic scale.

Thermosets show excellent mechanical properties and chemical resistance (for most automotive fluids) even at high temperatures up to 300 °C. Furthermore they can be highly efficient processed by injection molding. So they should be particularly suited for e.g. under the bonnet applications. However, the reality shows that thermosets are, except fiber reinforced composites, heavily underrepresented in technical applications. E.g. thermosetting components only account 0,2 % to a vehicle’s weight. Therefore reasons can be found in limited knowledge, e.g. relating mold filling behavior. The objective of the study is to analyze the influence of the mold filling behavior during injection molding of highly filled phenolic compounds on mechanical properties. Injection molding filling studies, mechanical testing and optical microscopy were done while varying mold geometry (injection gate and cavity height), mold temperature and injection rate during injection molding a highly filled phenolic compound. It was found that the mold filling behavior varies with altered injection molding parameters as well as the mold geometry. In consequence of this the mechanical properties change according to the resulting reinforcement orientation. The results can help to improve part and mold design for optimal load transmission.

Two different research projects were investigated for this thesis, which has consequently been presented in two parts. PART 1 An attempt has been made to improve the high temperature performance of phenol-formaldehyde thermosets by modification of their structure with inorganic phosphate groups. Transesterification of tri-phenyl phosphate with resorcinol has given a resorcinol phosphate resin, which cured with hexamethylenetetramine. A pilot scale batch of this resin has been made and used in high temperature stability studies. Post-cured resorcinol phosphate resin-chrysotile asbestos (30: 70) moulded bars retained 59.5% of their flexural strength after ageing at 523K for 1000 hr in air. Similar phenol-formaldehyde composite bars aged under identical conditions retained only 5.3% of their initial flexural strength. The utility of the resorcinol phosphate resin composite as a commercial product is limited, since the bars had a much lower initial flexural strength (30.85 MNm-2) than the phenol-formaldehyde resin composite bars (108.5 MNm-2). Thermogravimetry and isothermal heating studies have indicated that the degradation of resorcinol phosphate resin was greatly accelerated by chrysotile asbestos, which may catalyse a bond re-organisation process that has been tentatively proposed as a mechanism for the fragmentation of the resin. PART 2 Recently an ionomer dental cement (ASPA), prepared from aqueous poly(acrylic acid) and an ion-leachable aluminosilicate glass, has been developed. The system has been extended by studying other aqueous polymers. The factors influencing the gelation and the properties of the set cements have been examined. Poly(carboxylic acids) with hydrophobic, or no pendant substituents were found to be the most satisfactory polymers for preparing water stable cements. To study the influence of the nature of the cation and polymer structure on the gelation and water stability of ionomer cements, a wide range of metal oxide-polyacid products have been studied. The formation of water stable cements depended markedly on the type of oxide and polyacid employed and appeared to involve factors such as the co-ordination geometry and radius of the cation and the nature of the cation-polyanion bonding in the matrix. A comparison between the water stabilities of ASPA cement and poly(acrylic acid)-CaO, Al2O3, or Al(OH)3 cements has shown that the chemistry of ASPA cement is more complex than has been hitherto reported. Stability constants have been determined for Ca 2+ and Cd 2+ with poly(acrylic acid) and ethyl ethylene-maleic acid copolymer by a potentiometric titration method developed by Gregor and modified by Mandel and Leyte. The stability constants obtained in 1.0M NaNO3 at 298.2 ± 0.2K were: for poly(acrylic acid), with Cat2+, log b1 Ca2+ PAA ~ -3.35 with Cd2+, log Bav Cd2+ PAA = -2.30 for ethylene-maleic acid copolymer, with Cat2+, log b1 CA2+ EMA ~ -4.05 with Cd2+, log Bav Cd2+ EMA = -1.95 The log b1 values probably had little precise meaning, although to a first approximation, log b1 Ca2+ PAA > log b1 Ca2+ EMA The determined stability constants have been used with limited success in predicting the water stabilities of the corresponding metal oxide-polyacid cements.

The phase separation process of a rubber modified epoxy system during cure was analyzed by a model developed on the basis of a thermodynamic description of binary mixture and constitutive equations for nucleation and growth rates. As epoxy resins are cured, rubber molecules are precipitated from the epoxy matrix to a non-equilibrium composition due to the decrease in the configurational entropy and the increase in the viscosity with conversion. If phase separation takes place in a metastable region, this model can monitor the changes of rubber compositions in both phases as well as the changes in the number and size of rubber particles upon conversion of polymerization. The particle size distribution at the completion of phase separation was also calculated. The effect of cure temperature on the final morphologies of a rubber modified epoxy system was discussed. The computed particle size distributions for piperidine and diaminodiphenyl sulfone cured systems showed good agreements with experimentally measured values. Depending on the activation energy for viscous flow of the epoxy matrix relative to that for the polymerization, the particle size distribution may show bimodal or unimodal distribution. The size of rubber rich phase increases to a maximum and then decreases with an increase in cure temperature. However, due to limitations of temperature range to probe in an actual experiment, one may observe only either decreasing or increasing particle size as cure temperature increases. The number of rubber particles per unit volume increases for the DGEBA/DDS/ETBN system as cure temperature increases in the temperature range of 30 °C to 220 °C. Fracture toughness of cured DGEBA/DDS/ETBN system was analyzed in terms of morphologies generated by the temperature variation. Since the volume fraction of rubber particles did not change with cure temperature, the critical stress intensity factor did not vary significantly with cure temperature as expected. However, increases in cure temperature produced smaller but more numerous particles. The critical stress intensity factor normalized by the number density of particles exhibited dependence on the radius of particles to the third power. On the other hand, the critical stress intensity factor normalized by the radius of particles showed a linear dependence with respect to the number density of particles. / Ph. D.

No description available.

The effects of material/fabrication parameters on vapor-grown carbon nanofiber (VGCNF) reinforced vinyl ester (VE) nanocomposite flexural moduli and strengths were investigated. Statistically reliable empirical response surface models were developed to quantify the effects of VGCNF type, use of dispersing agent, mixing method, and VGCNF loading on flexural properties. Optimal nanocomposite formulation and processing (0.74 phr oxidized VGCNFs, dispersing agent, and high-shear mixing) resulted in predicted flexural modulus and strength values 1.18 and 1.26 times those of the neat resin. Additional flexural, tensile, and compressive tests were performed for optimally configured nanocomposites cured in a nitrogen environment. While flexural and tensile moduli significantly increased with increasing VGCNF loading, the corresponding strengths fell below those of the neat resin. In contrast, nanocomposite ultimate compressive strengths significantly exceeded the neat resin strengths. Nanocomposites prepared using aggressive high-shear mixing displayed improved elastic moduli and substantially increased strengths relative to nanocomposites prepared using baseline methods.

No description available.