The sport and leisure industry in New Zealand (NZ) has the potential to become a major user of composite materials. Given the size of NZ industry, design and manufacturing strategies based on virtual engineering should be developed to suit NZ requirements. Virtual methods use computer aided engineering capabilities to find faults, explore alternatives and optimise product performance before detailed design or prototyping. When doing computer aided simulation the required mechanical properties of individual reinforcement and matrix components are well documented. However, the mechanical properties of composite materials are not as simple to obtain. Micro-mechanical modelling could therefore be used to aid the design and development of composite equipment, where mechanical properties are unknown. In this study, solids modelling was used to produce an analog model of a composite, and it was found that it lead to reductions in file size and simulation time. Representing a composite with an analog model implies that the behavioural characteristics are modelled, but not the physical characteristics of the individual components. Three micro-mechanical models were developed to predict the flexural modulus of composite materials, based on perfect, partial and no adhesion. It was found that the partial adhesion model was both practical and consistently accurate. The partial adhesion model accounted for adhesion between components by considering an 'effective shear value' at the interface. Validation of the models was done by flexural testing injection moulded samples of glass, wood and carbon fibre reinforced polyethylene. It was shown that the adhesion coefficient range was 0.1 for carbon fibre, 0.5 for glass fibre and 0.9 for the wood fibre composites. It was concluded that the adhesion coefficient is crucial and it is recommended that further work is done to validate effective shear values by empirical means. The predicted flexural modulus values were used to enable finite element simulation of modelled analog beams as well as commercial kayak paddles. It was determined that accurate simulation is possible for composite equipment using the partial adhesion model.

To determine the effects of thermal accelerated aging on flexural strength and flexural modulus of conventional and CAD/CAM provisional crown and bridge restorative materials. Six provisional crown and bridge materials were selected for this study. Three conventional resins: Jet Set 4 (Lang), Luxatemp (DMG), and Protemp Plus (3M ESPE); and three CAD/CAM materials: ArtBloc Temp (Merz), Telio CAD-Temp (Ivoclar Vivadent), and Vita CAD-Temp (Vita). Specimens of conventional materials were fabricated using a custom-made aluminum mold 25 2 2 mm. CAD/CAM blocks were sectioned to the same dimensions. A total of 180 bar-shaped specimens were obtained (30 of each material) and were divided into three groups per treatment. Groups 1 and 2 were immersed in 37°C water for 24 hours, and 6 days, respectively. Group 3 was subjected to 5,000 thermal cycles between 5°C and 55°C in water with 35 seconds dwelling time. All specimens where tested for flexural properties using three-point bending protocol on an Instron 5566A at a crosshead speed of 0.5mm/min. The results were analyzed by one-way ANOVA and post hoc Tukey test with material type and aging conditions as the main variables. Significance level was set at (p<0.05).  Overall CAD/CAM materials demonstrated significantly higher flexural strength and flexural modulus over conventional resins. No significant difference in flexural strength and flexural modulus was found among three treatments except for: Luxatemp, which showed significant increased flexural strength and flexural modulus after thermal cycling, and Protemp Plus which showed increased flexural strength after 6 days of water storage.

O objetivo desse estudo foi verificar a influência da fotoativação com laser de argônio na tensão de contração (TC), microdureza (M), porcentagem de dureza máxima (PDM), resistência flexural (RF) e módulo de elasticidade (ME) de uma resina composta híbrida. A fotoativação foi realizada com laser de argônio 200mW por 10 segundos (L1), 200mW por 20 segundos (L2), 250mW por 10 segundos (L3) e 250mW por 20 segundos (L4). Como controle foi utilizada a luz hálógena por 20 segundos (H). A TC foi monitorada por 5 minutos em corpos-de-prova com 5mm de diâmetro e 1mm de altura. A M e a PDM foram obtidas em corpos-de-prova com 2mm de espessura após 7 dias a 37°C. Para obtenção da RF e do ME foram confeccionados corpos-de-prova nas dimensões 10 X 2 X 1mm (comprimento, largura e espessura), testados após 24h a 37°C. Os dados obtidos foram analisados por ANOVA/Teste de Tukey (p<0,05). Os valores de TC (MPa) foram estatisticamente mais baixos para o grupo L3 (1,3)c, seguido pelos grupos L1(2,7)b, L4 (3,4)a,b, L2 (3,7)a e H (4,5)a. Para os valores de M não houve diferença estatisticamente significante quando o mesmo tempo de fotoativação foi utilizado, sendo L1= 70,1a, L2= 78,1b, L3= 69,9a, L4= 78,1b e H= 79,9b. Todos os grupos apresentaram uma PDM de no mínimo 80%. Apenas o grupo L1 apresentou diferença estatisticamente significante na RF (MPa) e no ME (GPa), 86,2 e 5,4 respectivamente, sendo inferior. Dentro dos grupos estudados, o L3 apresentou propriedades mecânicas adequadas e mínima tensão de contração, além de possibilitar redução do tempo clínico para fotoativação de restaurações com a resina testada em 50%. / The objective of this study was to verify the influence of photoactivation with the argon ion laser on shrinkage stress (SS), followed by evaluation of Vickers microhardness (VM), percentage of maximum hardness (PMH), flexural strength (FS) and flexural modulus (FM) of a composite resin. Methods: The light curing units used were argon ion laser and halogen light. The groups were: L1- laser at 200mW for 10 seconds; L2- laser at 200mW for 20 seconds; L3- laser at 250mW for 10 seconds; L4- laser at 250mW for 20 seconds; and H- halogen light at 275mW for 20 seconds. The SS was monitored for 5 minutes in samples 5-mm in diameter by 1-mm in height. The VM and PHM were obtained in samples with a thickness of 2-mm after 7 days at 37°C. To FS and FM the samples were prepared using a stainless steel mold 10 x 2 x 1mm (length, width and height) and measured after 24h storage at 37°C. Data were analyzed by ANOVA/Tukey`s test (p<0.05). Results: The values of SS (MPa) were statistically lower for the group L3(1.3)c, followed by groups L1(2.7)b, L4 (3.4)a,b, L2(3.7)a and H(4.5)a. To the values of VM there was no difference when the same time of photo activation was used, being L1= 70.1a, L2=78.1b, L3= 69.9a, L4= 78.1b and H= 79.9b. All groups showed a PMH of at least 80%. Only the group L1 showed difference in FS (MPa) and FM (GPa), 86.2 and 5.4 respectively, being lower. Conclusion: within the studied groups, the L3 group presented adequate mechanical properties and minimum SS, reducing the clinical working time for photo activation of restorations with the tested resin in 50%.

O objetivo desse estudo foi verificar a influência da fotoativação com laser de argônio na tensão de contração (TC), microdureza (M), porcentagem de dureza máxima (PDM), resistência flexural (RF) e módulo de elasticidade (ME) de uma resina composta híbrida. A fotoativação foi realizada com laser de argônio 200mW por 10 segundos (L1), 200mW por 20 segundos (L2), 250mW por 10 segundos (L3) e 250mW por 20 segundos (L4). Como controle foi utilizada a luz hálógena por 20 segundos (H). A TC foi monitorada por 5 minutos em corpos-de-prova com 5mm de diâmetro e 1mm de altura. A M e a PDM foram obtidas em corpos-de-prova com 2mm de espessura após 7 dias a 37°C. Para obtenção da RF e do ME foram confeccionados corpos-de-prova nas dimensões 10 X 2 X 1mm (comprimento, largura e espessura), testados após 24h a 37°C. Os dados obtidos foram analisados por ANOVA/Teste de Tukey (p<0,05). Os valores de TC (MPa) foram estatisticamente mais baixos para o grupo L3 (1,3)c, seguido pelos grupos L1(2,7)b, L4 (3,4)a,b, L2 (3,7)a e H (4,5)a. Para os valores de M não houve diferença estatisticamente significante quando o mesmo tempo de fotoativação foi utilizado, sendo L1= 70,1a, L2= 78,1b, L3= 69,9a, L4= 78,1b e H= 79,9b. Todos os grupos apresentaram uma PDM de no mínimo 80%. Apenas o grupo L1 apresentou diferença estatisticamente significante na RF (MPa) e no ME (GPa), 86,2 e 5,4 respectivamente, sendo inferior. Dentro dos grupos estudados, o L3 apresentou propriedades mecânicas adequadas e mínima tensão de contração, além de possibilitar redução do tempo clínico para fotoativação de restaurações com a resina testada em 50%. / The objective of this study was to verify the influence of photoactivation with the argon ion laser on shrinkage stress (SS), followed by evaluation of Vickers microhardness (VM), percentage of maximum hardness (PMH), flexural strength (FS) and flexural modulus (FM) of a composite resin. Methods: The light curing units used were argon ion laser and halogen light. The groups were: L1- laser at 200mW for 10 seconds; L2- laser at 200mW for 20 seconds; L3- laser at 250mW for 10 seconds; L4- laser at 250mW for 20 seconds; and H- halogen light at 275mW for 20 seconds. The SS was monitored for 5 minutes in samples 5-mm in diameter by 1-mm in height. The VM and PHM were obtained in samples with a thickness of 2-mm after 7 days at 37°C. To FS and FM the samples were prepared using a stainless steel mold 10 x 2 x 1mm (length, width and height) and measured after 24h storage at 37°C. Data were analyzed by ANOVA/Tukey`s test (p<0.05). Results: The values of SS (MPa) were statistically lower for the group L3(1.3)c, followed by groups L1(2.7)b, L4 (3.4)a,b, L2(3.7)a and H(4.5)a. To the values of VM there was no difference when the same time of photo activation was used, being L1= 70.1a, L2=78.1b, L3= 69.9a, L4= 78.1b and H= 79.9b. All groups showed a PMH of at least 80%. Only the group L1 showed difference in FS (MPa) and FM (GPa), 86.2 and 5.4 respectively, being lower. Conclusion: within the studied groups, the L3 group presented adequate mechanical properties and minimum SS, reducing the clinical working time for photo activation of restorations with the tested resin in 50%.

Indiana University-Purdue University Indianapolis (IUPUI) / Background: Interim restoration for a lost anterior tooth is often needed for temporary esthetic and functional purposes. Materials for interim restorations usually have less strength than ceramic or gold and can suffer from fracture. Several approaches have been proposed to reinforce interim restorations, among which fiber reinforcement has been regarded as one of the most effective methods. However, some studies have found that the limitation of this method is the poor polymerization between the fibers and the composite resin, which can cause debonding and failure. 64 Purpose: The purpose of this study was to investigate the effects of different polymerization methods as well as fiber types on the mechanical behavior of fiberreinforced composite resin. Material and Methods: A 0.2-mm thick fiber layer from strip fibers or mesh fibers embedded in uncured monomers w as fabricated with polymerization (two-step method) or without polymerization (one-step method), on top of which a 1.8-mm composite layer was added to make a bar-shape sample, followed by a final polymerization. Seventy-five specimens were fabricated and divided into one control group and four experimental groups (n=15), according to the type of glass fiber (strip or mesh) and polymerization methods (one-step or two-step). Specimens were tested for flexural strength, flexural modulus, and microhardness. The failure modes of specimens were observed by scanning electron microscopy (SEM). Results: The fiber types showed significant effect on the flexural strength of test specimens (F = 469.48; p < 0.05), but the polymerization methods had no significant effect (F = 0.05; p = 0.82). The interaction between these two variables was not significant (F = 1.73; p = 0.19). In addition, both fiber types and polymerization steps affected the flexural modulus of test specimens (F = 9.71; p < 0.05 for fiber type, and F = 12.17; p < 0.05 for polymerization method). However, the interaction between these two variables was not significant (F = 0.40; p = 0.53). Both fiber types and polymerization steps affected the Knoop hardness number of test specimens (F = 5.73; p < 0.05 for polymerization method. and F = 349.99; p < 0.05 for fiber type) and the interaction between these two variables was also significant (F = 5.73; p < 0.05). SEM images revealed the failure mode tended to become repairable while fiber reinforcement was 65 existed. However, different polymerization methods did not change the failure mode. Conclusion: The strip fibers showed better mechanical behavior than mesh fibers and were suggested for use in composite resin reinforcement. However, different polymerization methods did not have significant effect on the strength and the failure mode of fiber-reinforced composite

The preparation of polymeric hybrid composite consisting of organic and inorganic fillers is of interest for industries like automotive, construction and packaging. In order to understand and predict the physical and chemical properties of these hybrid composites, it is necessary to fully understand the nature and properties of the employed fillers. In this study, the preparation of polypropylene hybrid composite consisting of wheat straw and clay was investigated. A detailed study was performed on wheat straw from South Western Ontario region. The effect of grinding the straw and compounding it with polypropylene was investigated. Experiments were carried out to identify the thermal stability of the ground wheat straw with respect to their size and composition. It was important to identify a correlation between these properties in order to minimize the straw degradation by processing and also to improve the final properties of the hybrid composite. The composite samples were prepared through melt blending method using a co-rotating twin-screw extruder. Sample test bars were prepared by injection moulding. The composition of the constituents of the hybrid composite; percentages of wheat straw, clay and coupling agent, were varied in order to investigate their influence on thermal stability, water resistance and mechanical properties. The results of the study indicated that grinding the wheat straw with a hammer mill produced particles with different sizes and shapes. It was found that through the grinding system all particles, regardless of their size, had a multi-layered structure similar to the plant structure. Further hammer milling did not produce plant particles with long aspect ratios that would be expected in a defibrillation process. Analysis of the chemical composition of wheat straw particles of different sizes and shapes was used to measure the ratio of hemicelluloses: lignin and the ash content. It was found that the large particles contained more amount of lignin whereas smaller particles had larger amount of ash content. The thermal stability of the particles was found to be a function of particle size rather than the lignin content. Particle size analysis on the wheat straw particles after the extrusion process indicated a reduction in the particle length and aspect ratio. The thermal stability of the composites was found to be enhanced by the addition of clay particles at higher temperature and the addition of coupling agent at lower temperatures. Increasing the amount of wheat straw and clay content increased the flexural modulus and reduced the resistance for water absorption. Increasing the amount of coupling agent also increased the flexural modulus and resistance for water absorption. The morphological study by scanning electron microscopy revealed that coupling agent increased the interfacial interaction between the particles and the polymer matrix.

The preparation of polymeric hybrid composite consisting of organic and inorganic fillers is of interest for industries like automotive, construction and packaging. In order to understand and predict the physical and chemical properties of these hybrid composites, it is necessary to fully understand the nature and properties of the employed fillers. In this study, the preparation of polypropylene hybrid composite consisting of wheat straw and clay was investigated. A detailed study was performed on wheat straw from South Western Ontario region. The effect of grinding the straw and compounding it with polypropylene was investigated. Experiments were carried out to identify the thermal stability of the ground wheat straw with respect to their size and composition. It was important to identify a correlation between these properties in order to minimize the straw degradation by processing and also to improve the final properties of the hybrid composite. The composite samples were prepared through melt blending method using a co-rotating twin-screw extruder. Sample test bars were prepared by injection moulding. The composition of the constituents of the hybrid composite; percentages of wheat straw, clay and coupling agent, were varied in order to investigate their influence on thermal stability, water resistance and mechanical properties. The results of the study indicated that grinding the wheat straw with a hammer mill produced particles with different sizes and shapes. It was found that through the grinding system all particles, regardless of their size, had a multi-layered structure similar to the plant structure. Further hammer milling did not produce plant particles with long aspect ratios that would be expected in a defibrillation process. Analysis of the chemical composition of wheat straw particles of different sizes and shapes was used to measure the ratio of hemicelluloses: lignin and the ash content. It was found that the large particles contained more amount of lignin whereas smaller particles had larger amount of ash content. The thermal stability of the particles was found to be a function of particle size rather than the lignin content. Particle size analysis on the wheat straw particles after the extrusion process indicated a reduction in the particle length and aspect ratio. The thermal stability of the composites was found to be enhanced by the addition of clay particles at higher temperature and the addition of coupling agent at lower temperatures. Increasing the amount of wheat straw and clay content increased the flexural modulus and reduced the resistance for water absorption. Increasing the amount of coupling agent also increased the flexural modulus and resistance for water absorption. The morphological study by scanning electron microscopy revealed that coupling agent increased the interfacial interaction between the particles and the polymer matrix.

Soy flour (SF), a by-product of the soybean oil extraction processing, was investigated for its application in soy-polypropylene composites for interior automotive applications. The emphasis of this work was the understanding of this new type of filler material and the contribution of its major constituents to its thermal stability and impact properties. For this reason, reference materials were selected to represent the protein (soy protein isolate (SPI)) and carbohydrate (soy hulls (SH)) constituents of the soy flour. Additional materials were also investigated: the residue obtained after the protein removal from the soy flour which was called insoluble soy (IS), and the remaining liquid solution after acid precipitation of the proteins, containing mostly sugars and minerals, which was called soluble sugar extract (SSE). Two treatments, potassium permanganate and autoclave, were analyzed for their potential to modify the properties of the soy composite materials. An acid treatment with sulfuric acid conducted on soy flour was also considered. The soy materials were studied by thermogravimetric analysis (TGA) under isothermal (in air) and dynamic (in nitrogen) conditions. SPI had the highest thermal stability and SSE the lowest thermal stability for the early stage of the heating process. Those two materials had the highest amount of residual mass at the end of the dynamic TGA in nitrogen. The two treatments showed minimal effect on the isothermal thermal stability of the soy materials at 200 ??C. A minor improvement was observed for the autoclave treated soy materials. Fourier transformed infrared (FTIR) spectroscopy indicated that the chemical surface composition differed according to type of the soy materials but no difference could be observed for the treatments within one type of soy material. Contact angle analysis and surface energy estimation indicated differences of the surface hydrophobicity of the soy materials according to type of material and treatment. The initial water contact angle ranged from 57 ?? for SF to 85 ?? for SH. The rate of water absorption increased dramatically after the autoclave treatment for IS and SPI. Both materials showed the highest increase in the polar surface energy fraction. In general, the major change of the surface energy was associated with change of the polar fraction. After KMnO4 treatment, the polar surface energy of SF, IS and SPI decreased while SH showed a slight increase after KMnO4 treatment. A relationship between protein content and polar surface energy was observed and seen to be more pronounced when high protein containing soy materials were treated with KMnO4 and autoclave. Based on the polar surface energy results, the most suitable soy materials for polypropylene compounding are SPI (KMnO4), SH, and IS (KMnO4) because their polar surface energy are the lowest which should make them more compatible with non-polar polymers such as polypropylene. The soy materials were compounded as 30 wt-% material loading with an injection moulding grade polypropylene blend for different combinations of soy material treatment and coupling agents. Notched Izod impact and flexural strength as well as flexural modulus estimates indicated that the mechanical properties of the autoclaved SF decreased when compared to untreated soy flour while the potassium permanganate treated SF improved in impact and flexural properties. Combinations of the two treatments and two selected (maleic anhydride grafted polypropylene) coupling agents showed improved impact and flexural properties for the autoclaved soy flour but decreased properties for the potassium permanganate treated soy flour. Scanning electron microscopy of the fractured section, obtained after impact testing of the composite material, revealed different crack propagation mechanisms for the treated SF. Autoclaved SF had a poor interface with large gaps between the material and the polypropylene matrix. After the addition of a maleic anhydride coupling agent to the autoclaved SF and polypropylene formulation, the SF was fully embedded in the polymer matrix. Potassium permanganate treated SF showed partial bonding between the material and the polymer matrix but some of the material showed poor bonding to the matrix. The acid treated SF showed cracks through the dispersed phase and completely broken components that did not bind to the polypropylene matrix. In conclusion, the two most promising soy materials in terms of impact and flexural properties improvement of soy polypropylene composites were potassium permanganate treated SF and the autoclaved SF combined with maleic anhydride coupling agent formulation.

The study examined the properties of stalk and cob fibres from recombinant inbred corn lines and their parents, grown at two locations, in a polylactic acid (PLA) matrix. The objectives were to: determine fibre compositions; evaluate the effects of fibres on the functional properties of biocomposites and identify quantitative trait loci (QTLs) and gene markers for fibre performance in biocomposites. Significant Genotype*Location effects were observed. Composites had lower strength (impact, tensile, and flexural) but higher tensile/flexural modulus values than pure PLA. The latter were positively affected by cellulose and hemicellulose but negatively affected by free phenolic levels and 93 fibre QTLs and 62 composite markers were detected. This study identified fibre traits and markers for genes that may be important for the use of corn fibres in biocomposites. / Ontario BioCar Initiative Project funded by Ontario Ministry of Research and Innovation, Agriculture and Agri-Food Canada, The Natural Sciences and Engineering Research Council, The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) and Ontario Public Sector