Wood Plastic Composites (WPCs) have experienced a healthy growth during the last decade. However, improvement in properties is necessary to increase their utility for structural applications. The toughness of WPCs can be improved by creating a fine cellular structure while reducing the density. Extrusion processing is one of the most economical methods for profile formation. For our study, rectangular profiles were extruded using a twin-screw extrusion system with different grades of HDPE and with varying wood fibre and lubricant contents together with maleated polyethylene (MAPE) coupling agent to investigate their effects on WPC processing and mechanical properties. Work has been done to redesign the extrusion system setup to achieve smoother and stronger profiles. A guiding shaper, submerged in the water, has been designed to guide the material directly through water immediately after exiting the die; instead of passing it through a water cooled vacuum calibrator and then through water. In this way a skin was formed quickly that facilitated the production of smoother profiles. Later on chemical blowing agent (CBA) was used to generate cellular structure in the profile by the same extrusion system. CBA contents die temperatures, drawdown ratios (DDR) and wood fibre contents (WF) were varied for optimization of mechanical properties and morphology. Cell morphology and fibre alignment was characterized by a scanning electron microscope (SEM). A new compression molding system was developed to help in quick evaluation of different material formulations. This system forces the materials to flow in one direction to achieve higher net alignment of fibres during sample preparation, which is the case during profile extrusion. Operation parameters were optimized and improvements in WPC properties were observed compared to samples prepared by conventional hot press and profile extrusion. / UOIT

Yes / Polypropylene (PP) reinforced with 2 and 4 wt% of multi-walled carbon nanotubes (MWNT) were melt-blended in twin screw extruder and then molded by compression or micromolding process. The impact of injection speed on the surface morphology, rheological and tensile characteristics was investigated by using a scanning electron microscope, parallel plate rheometry, and tensiometry. Results showed that the tensile properties of micro-molded specimens were remarkably higher than those of the compression molded sheets. Compared to compression molded sheets, micromolded specimens demonstrated up to 40 and 244% higher tensile stiffness and yield strength, respectively, most likely due to the alignment of polymer chain segments in the flow direction induced during the micromolding process. It was observed that the fast filling speed caused a drop in the tensile properties of the nanocomposites and polymer. Rheological examination revealed that the presence of a rheological percolation network in the nanocomposites produced by micromolding and the fast injection speed was beneficial for establishing the percolated network. Morphological examination revealed that the size of nanotube agglomerations that appeared in micromolded specimens was up to five times smaller than in compression molded sheets and the agglomeration size decreased with the increase of the injection speed.

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Flax fibers are often used as reinforcement for thermoset and thermoplastic to produce biocomposite products. These products exhibit numerous advantages such as good mechanical properties, low density, and biodegradability. Thermoplastics are usually reinforced with flax fiber using injection molding technology and limited research has been done on compression molded thermoplastic biocomposite. Therefore, commercial thermoplastic high density polyethylene (HDPE) and polypropylene (PP) were selected for developing compression molded flax reinforced biocomposites in this research project. The main goal of this research was to develop compression molded biocomposite board using Saskatchewan flax fiber and investigate the effect of flax fiber and processing parameters (molding temperature and molding pressure) on the properties of biocomposite. <p>The fiber was cleaned and chemically treated with alkaline and silane solution that modified the fiber surface. Chemical treatments significantly increased the mechanical properties due to better fiber-polymer interfacial adhesion and also reduced the water absorption characteristics. The silane treatment showed better results than alkaline treatment. Differential scanning calorimetry (DSC) test and scanning electron microscopy (SEM) test were performed to study the thermal and morphological properties of the untreated and chemically treated flax fiber. Flax fiber and thermoplastic resin was mixed using a single-screw extruder to ensure homogenous mixing. HDPE- and PP-based biocomposites were developed through compression molding with three different pretreated flax fiber (untreated, alkaline, silane treated fiber), three levels of fiber content, two levels of molding temperature and two levels of molding pressure. <p>Increase in fiber content increased composite color index, density, water absorption, tensile strength, Youngs modulus, bending strength, and flexural modulus. However for the HDPE composites, tensile and bending strength decreased after 20% flax fiber loading. For the PP composites the, tensile and bending strength decreased after 10% flax fiber loading. Analysis of variance (ANOVA) was performed to quantitatively show the significant effects of the process variables (molding temperature, pressure, and fiber content) and their interactions on the response variables (physical and mechanical properties of biocomposites). The duncan multiple range test (DMRT) was also performed to compare the treatment means. Superposition surface methodology was adapted for both HDPE and PP composites to determine the optimum values of process variables.

Canadian grown oilseed flax is known for its oils that are used for industrial products. The flax fiber may also have a use as a potential replacement for synthetic fibers as reinforcement in plastic composites. It can also be utilized as a cost effective and environmentally acceptable supplement in the biodegradable composites. Tire rubber is a complex material which does not decompose naturally. As a result, many researchers have been trying to develop new applications for recycling scrap tires. The conversion of flax straw and scrap tire into a profitable product may benefit the agricultural economy, tire recycling market, and our environment. The main goal of this research was to develop a biocomposite material containing recycled ground tire rubber (GTR), untreated flax fiber, and linear low-density polyethylene (LLDPE).<p> In this study, the new biocomposite material was successfully prepared from flax fiber/shives, GTR, and LLDPE through extrusion and compression molding processes. The composites were compounded through a single-screw extruder. Then the pelletized extrudates were hot pressed into the final biocomposites. The properties of the flax fiber-GTR-LLDPE biocomposites were defined by using tearing, tensile, water absorption, hardness, and differential scanning calorimetry (DSC) tests. The effects of the independent variables (flax fiber content and GTR-LLDPE ratio) on each of the dependent variables (tear strength from tearing test, tensile yield strength and Youngs modulus from tensile test, and weight increase from water absorption test) were modeled. The properties of the composites can be predicted by using the mathematical model with known flax fiber content and GTR-LLDPE ratio.<p> The tensile yield strength and stiffness of the biocomposite were improved with the addition of flax fiber. The optimal composition of the biocomposite material (with strongest tensile yield strength or highest Youngs modulus) was calculated by using the model equations. The maximum yield strength was found to exist for a flax fiber content of 10.7% in weight and GTR-LLDPE ratio of one. The largest Youngs modulus was found for a fiber content of 17.7% by weight and the same GTR-LLDPE ratio. Both of these fiber contents were less than the amount that would give a composite with a 2% weight increase in water absorption.

Flax fibers are often used as reinforcement for thermoset and thermoplastic to produce biocomposite products. These products exhibit numerous advantages such as good mechanical properties, low density, and biodegradability. Thermoplastics are usually reinforced with flax fiber using injection molding technology and limited research has been done on compression molded thermoplastic biocomposite. Therefore, commercial thermoplastic high density polyethylene (HDPE) and polypropylene (PP) were selected for developing compression molded flax reinforced biocomposites in this research project. The main goal of this research was to develop compression molded biocomposite board using Saskatchewan flax fiber and investigate the effect of flax fiber and processing parameters (molding temperature and molding pressure) on the properties of biocomposite. <p>The fiber was cleaned and chemically treated with alkaline and silane solution that modified the fiber surface. Chemical treatments significantly increased the mechanical properties due to better fiber-polymer interfacial adhesion and also reduced the water absorption characteristics. The silane treatment showed better results than alkaline treatment. Differential scanning calorimetry (DSC) test and scanning electron microscopy (SEM) test were performed to study the thermal and morphological properties of the untreated and chemically treated flax fiber. Flax fiber and thermoplastic resin was mixed using a single-screw extruder to ensure homogenous mixing. HDPE- and PP-based biocomposites were developed through compression molding with three different pretreated flax fiber (untreated, alkaline, silane treated fiber), three levels of fiber content, two levels of molding temperature and two levels of molding pressure. <p>Increase in fiber content increased composite color index, density, water absorption, tensile strength, Youngs modulus, bending strength, and flexural modulus. However for the HDPE composites, tensile and bending strength decreased after 20% flax fiber loading. For the PP composites the, tensile and bending strength decreased after 10% flax fiber loading. Analysis of variance (ANOVA) was performed to quantitatively show the significant effects of the process variables (molding temperature, pressure, and fiber content) and their interactions on the response variables (physical and mechanical properties of biocomposites). The duncan multiple range test (DMRT) was also performed to compare the treatment means. Superposition surface methodology was adapted for both HDPE and PP composites to determine the optimum values of process variables.

Fuel cells are electrochemical energy conversion devices that convert chemical energy to electrical energy efficiently. Bipolar plates form an integral part of a fuel cell and their high manufacturing cost and low production rate have hindered the commercialization of fuel cells. Bipolar plates require high electrical conductivity, strength, chemical resistance and thermal conductivity. This thesis presents efforts to manufacture bipolar plates which meet these requirements using compression or injection molding. Compression or injection molding processes allow cost-effective, large-scale manufacturing of bipolar plates. A variety of material systems for the fabrication of bipolar plates are processed, molded and characterized. / text

The project Kera-Plast aims to re-loop humans and nature by questioning the current systems and ethics through materiality. Human hair, currently considered as waste, functions as the base for the material exploration fabricated through thermo-compression molding. The flexible, short and opaque keratin-fibers get glued together with heat, pressure and water, acting as a plasticizer during the compression molding process. The results are stiff and remind on plastic due to shine and translucency. Aesthetics and function of the resulting material are controlled and designed by traditional textile techniques as knitting, weaving and non-woven processes. The material samples display the potential of Kera-Plast in the categories of 3D surface structures, patterns, shapeability and the influence of light. The findings also provide information about the parameters for designing with keratin fibers through the thermo-compression process. It can be concluded that despite all ethical and cultural factors, Kera-Plast and its fabrication method has the potential to add a sustainable, functional and aesthetical value to the design field and our future material consumption.

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