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Thin mono-layer films of metallocene catalysed polyethylene, linear low density and conventional low density polyethylene, as well as polypropylene, were producedfrom a 38mm extruder through a 75mm diameter blownplm die and a 6OOmm castfilm die. By using the same die gap on each die to achieve equal draw-down ratios, the influence of orientation j?om the two processes on the mechanical properties of each firm was investigated. Tensile strength at break, Young's Modulus, percentage elongation at break, tear propagation resistance, in both machine and transverse direction all gave significant differences in properties with cast film when compared to different blow-up ratios for blown film. Di@erentiaI Scanning Calorimetry was used to measure the percentage of ctystallinity in each film. Differences were found to show that the cooling process as the melt exits the die has a signtficant effect on the percentage of crystallinity.

Determination of the dispersion characteristics/or morphology of additives in polymer melts by fast, reliable and accurate on-line methods is highly desired in the polymer industry. An ultraviolet-visible (UV-Vis) spectroscopic methodology is described which meets these demands. It is demonstrated that the applied methodology may be developed on a cheap, packaging grade of Polylactic Acid (PLLA), an important bioresorbable polymer for the medical device industry, and still be accurate when implemented on a production line using a more expensive (medical) grade of the polymer compound. Simple chemometric algorithms are applied allowing the data processing step to be carried out in near real time, thus providing vital information to process operators which allows any out of control process to be identified and rectified without product loss.

Polyvinylchloride (PVC), polypropylene (PP), and low density polyethylene (LDPE)were used to prepare a range of wood-polymer blends containing 20, 40, and 60% w/w medium density fibreboard sawdust (90-150 microns and 212-850 microns In trod u c tionWood-polymer composites are a fascinating area in both polymers and wood, which arose due to a desire to recycle plastic and wood dust. When using the composites for outdoor applications it is necessary to balance the physical properties against water up-take. A wood-polymer composite with a high MFI polymer enhances properties but increases water up-take, whereas a low MFI polymer has reduced mechanical performance but an increased resistance to water up-take [ 11. Wood-filled polyethylene exhbits a greater degree of creep strain in freshwater than in air or saltwater [2]. Polyethylene-based wood composites reportedly offer a hgher degree of heat resistance with a heat distortion temperature of about 82OC at 264 psi, and they may also be somewhat less expensive than PVC formulations. The key advantage of PVC-based wood composites is their stainability or paintability. Little, if any, treatment is required for the stain or paint to adhere to the PVC-composite. It was found that for both cellular and solid PVC-composites, the moisture content should be kept in the 0.5-1% range. PVC-wood composites offer many advantages over conventional lumber. However, one of the major disadvantages is the increased density [3]. Other studies have used compatibilisers such as maleic anhydride and various processing aids to improve the mechanical properties and the water up-take of wood-polymer composites [4-61.When wood is compounded w i t h a polymer, the wood acts as a filler decreasing the mechanical properties. At high wood loadings there exists a non-continuous layer of polymer on the composite surface, and the associated disadvantage is water being absorbed into the matrix further decreasing the properties. Coupling agents are used in an attempt to convert wood filler into a reinforcing agent by creating chemical bonds between the wood surface and the polymer chains. Two commonly used coupling agents are maleic anhydride and titanates which are used to increase the composites mechanical properties. Coupling agents are molecular bridges at the interface between two substrates. Titanium-derived coupling agents are unique in that their reaction with the free protons in the inorganic interface results in the formation of organic monomolecular layers on the inorganic surface. Typically, titanate-treated inorganics are hydrophobic, organophilic and organofunctional. When incorporated into polymer systems they often have several effects, such as: promote adhesion; catalyse; improve dispersion and rheology; improve impact strength; do not create embrittlement; improve mechanical properties, and inhibit corrosion [7]. Titanates are able to crosslink or cure a variety of polymers such as polyolefin's, polystyrene, etc. During extrusion the effect of the titanate coupling agent is perman...

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