Stuart Bateman

Wood Fiber Reinforced Polyethylene and Polypropylene Composites with High Modulus and Impact Strength

Wood plastic composite with high modulus and impact strength were manufactured by combining polyethylene (PE) or polypropylene (PP) with wood fiber (WF) using twin-screw extruder techniques. The advantage of using low melt viscosity polymer matrices is that it enhances the modulus and reduces the overall viscosity of the system. SEM analysis of the composites indicates that the polymer molecules penetrate into the vessels and cracks of the cellulose fiber, which decreases the number of voids and produces a higher density composite with improved mechanical performance. The addition of maleic anhydride-grafted polyolefin as a compatibilizer improves the level of adhesion between the wood fiber and the polyolefin matrix. The impact strength of the composites with compatibilizer is 60% higher than those without. Youngs moduli of WF/PE and WF/PP with compatibilizer were 4.4 and 5.4 GPa, respectively, meanwhile the impact strengths of WF/PE and WF/PP were 44 and 24J/m, where the WF content was 50wt%.

Effect of surfactant architecture on the properties of polystyrene-montmorillonite nanocomposites.

A series of surfactants were designed and synthesized for use as clay modification reagents to investigate the impact of their chemical structure on the nanocomposites morphology obtained following polymerization. The behavior of the surfactant-modified clays at three different stages were investigated: after ion exchange, following dispersion in styrene monomer, and once polymerization was complete. The propensity of the styrene monomer to swell the surfactant-modified clay was observed to be a useful indicator of compatibility and predictor of the resultant polystyrene nanocomposite morphology which was directly observed using small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (TEM). It was found that the key components of surfactant design driving exfoliated morphologies were (1) the position of the ammonium group, (2) the inclusion of a polymerizable group, (3) the solubility of the surfactant in the monomer, (4) the length of the alkyl chain, and (5) sufficient concentration of surfactant used to exchange the clay. This understanding should lead to better design of clay modifications for use in polymer nanocomposites.

Mechanical and Conductive Properties of Carbon Black-filled High-density Polyethylene, Low-density Polyethylene, and Linear Low-density Polyethylene

High conductive composites were manufactured using single screw extruder melt compound method with carbon black (CB)-filled high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). A low percolation threshold value was achieved from the composites consisting of 2 wt% CB (Printex) with HDPE (HDPE3690). The impact strength of CB/LDPE and CB/LLDPE composites were almost 20 times higher than that of CB/HDPE3690. The tensile modulus and strength of conductive composites increased with the content of CB. Microstructures of conductive composites were analyzed using scanning electron microscope and transmission electron microscope. At the 2 wt% CB content, the CB particles have built a conductive network, which lead to high conductivity.

Thermal behaviour of high amylose cornstarch studied by DSC

The thermal behaviour of high amylose cornstarches (80% amylose content) was studied by DSC using high pressure stainless steel pans in the temperature range between 0-350 °C. The number of endotherms and the enthalpy of gelatinization were found to depend on moisture content. Up to four endotherms and one exotherm were determined when the moisture content was above 40%. The meaning of each endotherm has been discussed. The enthalpy of gelatinization was calculated based on the summation of all the gelatinization endotherms and found to increase with increasing water content.

High electrical conductivity and elastic modulus composites comprising glass fiber-reinforced carbon-filled high-density polyethylene

Electrically conductive composites with very low percolation threshold values and high elastic modulus have been developed using single-screw extruder from short E-glass fiber (GF) reinforced carbon black (CB) filled high-density polyethylene (HDPE). The percolation threshold values of composites decreased with increased content of GF. The elastic modulus, tensile strength, and impact strength of composites were improved after addition of GF into CB/PE (PE, polyethylene). Three coupling agents, namely glycidyl methacrylate-grafted ethylene copolymer, maleic anhydride-grafted PE, and maleic anhydride-grafted polypropylene were used to study the effect on the conductivity and mechanical properties of GF/CB/PE composites. The tensile strength and modulus of composites increased after addition of coupling agent, meanwhile the conductivity of composites were decreased. The interface strength between GF and PE was improved after addition of coupling agent. The images of scanning electronic microscope showed that coupling agent improved the bonding between GF and matrix in an effective manner.

Starch Based Blends, Composites and Nanocomposites

The development and production of biodegradable starch-based materials has attracted more and more attention in recent years due to the depletion in the world’s oil resources and the growing interest in easing the environmental burden from petrochemically derived polymers. Furthermore, the unique microstructures of different starches can be used as an outstanding model system to illustrate the conceptual approach to understanding the relationship between the structures and properties in polymers.

Thermal and Mechanical Properties of PAN- and Pitch-Based Carbon Fiber Reinforced PEEK Composites

Thermal and mechanical properties of different short carbon fibers (CF) reinforced polyether-ether-ketone (PEEK) composites are investigated, where CF is made from polyacrylonitrile (PAN-CF) and pitch (Pitch-CF). The thermal properties of both composites are studied using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The crystallinity of PEEK increases with the content of PAN-CF, but it is independent of Pitch-CF content. At the isothermal condition, the crystallite rate of Pitch-CF/PEEK composite is faster than that of PAN-CF/PEEK composites. Dynamic tensile modulus of PAN-CF/PEEK increases with the CF content. An increase of glass transverse temperature with an increase in CF content is found in PAN-CF/PEEK, but not in Pitch-CF/PEEK. The fracture toughness of PAN-CF/PEEK composites increases with CF contents; whereas it remains the same value for Pitch-CF composite. The fracture surface of both composites is analysed using scanning electron microscopy.

Thermal Properties and Fire Performance of Woven Glass Fibre Reinforced Nylon 6 Nano-Composites with Carbon Nanotubes

This paper presents the effects of incorporating carbon nanotubes (CNT) into nylon 6 on thermal properties and fire performance of woven glass reinforced CNT/nylon 6 nanocomposite laminates. Incorporation of CNT in nylon 6 improved the thermal stabilities, thermal conductivity and fire performance of laminates without compromising their mechanical properties. The thermal conductivity of laminates with 2 wt% CNT increased up to 42% compared to that without CNT. The ignition time and peak HRR time was delayed approx. 31% and 118%, respectively, in laminates with 4 wt% CNT in nylon 6 over that without CNT.

Stiff and Tough Conductive Composites Using Carbon Black-Filled Polyethylene

Stiff and tough conductive composites were manufactured using carbon black compounded with high and low density polyethylene, as well as linear low density polyethylene. A low percolation threshold value for the composites was achieved at 2 wt% carbon black. The impact strengths of the composites incorporating low density and linear low density polyethylene were found to be almost 16 and 26 times greater, respectively, than that of high density polyethylene composites. On the other hand, the modulus of high density polyethylene filled with carbon black was 2 times as high as low and linear low density polyethylene-based composites. Tensile modulus increased with the content of carbon black, however the impact strength of the composites decreased.

Effect of Processing Method on Conductivity and Mechanical Properties of Glass Fibre Reinforced Carbon Black Filled Polyethylene

The conductivity and mechanical properties of carbon black (CB) filled polyethylene (PE) composites depend on the conductive filler, molecular structure of polymer matrix, and the processing methods which are applied. CB filled high density polyethylene without and with glass fibre (GF) composites have been manufactured using single and twin screws extruder. The composite made from the single screw extruder showed a much higher conductivity than that made from twin screws extruder for CB/PE composites with and without glass fibre. The conductive paths are formed at very low CB content (1wt% CB for GF/CB/PE) when using single screw extruder to manufacture. The microstructure of these composites were analysed using SEM.