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Spun cellulose fibres from the viscose, lyocell and carbamate processes have been used to reinforce thermoplastic commodity polymers, such as polypropylene (PP), polyethylene (PE) and (high impact) polystyrene (HIPS) as well as poly(lactic acid) (PLA) and a thermoplastic elastomer (TPE) for injection moulding applications. A specially developed double pultrusion technique has been employed for compounding. Fibres were analysed in single fibre tensile tests. Strength, stiffness, impact strength, and heat distortion temperature (HDT) were determined for injection-moulded standard test specimen and structural features were revealed by scanning electron microscopy. A strong reinforcing effect was observed in all cases. In particular, high tenacity tyre cord rayon gives excellent composite strength and impact strength, often doubling or tripling the pristine matrix values. In the case of PP, Lyocell type fibres provide enhanced stiffness and HDT, and thus the combination of both fibre types leads to a balanced composite property profile. The PE case is very similar to PP. For HIPS mainly strength and stiffness is increased, while for TPE the property profile is changed completely. With PLA, a biogenic and biodegradable composite with excellent mechanical properties is presented

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Samples of ball milled cellulose were prepared by ball milling pulps from eucalyptus and softwood (spruce/pine). Water sorption isotherms were obtained by both dynamic vapor sorption and equilibration over saturated salt solutions, in the water content range of 5-42% db (db = dry basis; water as a % age of total solids). Dynamic mechanical analysis using a pocket technique showed a water content dependent thermal transition occurring at the same temperature for the two pulp samples, which was interpreted as a glass transition. Fitting the data to a Couchman-Karasz relationship predicted a value for T g of the dry cellulose of approximately 478 K, which was similar to values previously reported for other dry polysaccharides. No clear glass transition could be observed calorimetrically, although an endotherm at approximately 333 K was measured, which in polymers is normally attributed to enthalpic relaxation, however the lack of dependence of this endotherm on water content suggests that the melting of some weak associations, such as residual hydrogen bonds, could be a more credible explanation. An exotherm was also observed on heating, which was dependent on water content and which was attributed to partial crystallization of the cellulose. This was confirmed by Wide angle X-ray diffraction and cross polarization magic angle spinning 13C NMR (CPMAS NMR). The recrystallisation was predominantly to form I of cellulose. This was thought to be caused by a small amount of residual form I (probably less than 5%) acting as a template for the crystallizing material. Differential scanning calorimetry reheat curves showed the appearance of freezable water for water contents higher than 20%, as a result of a transfer of water to the amorphous phase following crystallization. The increase in cellulose rigidity following crystallization was also confirmed by CPMAS NMR relaxation. Low resolution proton NMR T 2 relaxation suggested the presence of proton water/cellulose exchange, which was active at water contents of 20% and above

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