Functionalized cellulose nanocrystals as biobased nucleation agents in poly(l-lactide) (PLLA) – Crystallization and mechanical property effects

This article presents the results of a study of the processing and physicomechanical properties of environmentally friendly wood-fiber-reinforced poly(lactic acid) composites that were produced with a microcompounding molding system. Wood-fiber-reinforced polypropylene composites were also processed under similar conditions and were compared to wood-fiber-reinforced poly(lactic acid) composites. The mechanical, thermomechanical, and morphological properties of these composites were studied. In terms of the mechanical properties, the wood-fiber-reinforced poly(lactic acid) composites were comparable to conventional polypropylene-based thermoplastic composites. The mechanical properties of the wood-fiber-reinforced poly(lactic acid) composites were significantly higher than those of the virgin resin. The flexural modulus (8.9 GPa) of the wood-fiber-reinforced poly(lactic acid) composite (30 wt % fiber) was comparable to that of traditional (i.e., wood-fiber-reinforced polypropylene) composites (3.4 GPa). The incorporation of the wood fibers into poly(lactic acid) resulted in a considerable increase in the storage modulus (stiffness) of the resin. The addition of the maleated polypropylene coupling agent improved the mechanical properties of the composites. Microstructure studies using scanning electron microscopy indicated significant interfacial bonding between the matrix and the wood fibers. The specific performance evidenced by the wood-fiber-reinforced poly(lactic acid) composites may hint at potential applications in, for example, the automotive and packaging industries. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4856–4869, 2006

Wood-fiber-reinforced poly(lactic acid) composites: Evaluation of the physicomechanical and morphological properties

Nanocomposites of isotactic polypropylene reinforced with rod-like cellulose whiskers

On transcrystallinity in semi-crystalline polymer composites

Morphology and properties of isotropic and oriented samples of cellulose fibre–polypropylene composites

The thermal and viscoelastic properties of polypropylene (PP)/cellulose as well as PP/Xylan composites were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermoanalysis (DMTA). Morphological aspects were available by using polarizing light microscopy and scanning electron microscopy (SEM). Three types of fillers were incorporated in PP: xylan fillers (XL), cellulose microfibers (CM) and short fibers of spun cellulose (CS). The compatibilizer maleic anhydride modified PP (MAPP) was added to the composites. The crystallization temperature and crystallinity of PP apparently increased in the presence of all fiber types. The cellulose fiber surfaces act as nucleating agents for PP, resulting in the formation of transcrystalline regions around the fibers. The DMTA spectra of PP/filler composites revealed a significant increase in the stiffness and a remarkable decrease of the damping values. This effect was stronger for PP/CS than for the other composites. The results verify that improved compatibility and interfacial adhesion between fiber and matrix markedly contribute to an improvement of the mechanical properties.

A. Amash

Papers

Study on cellulose and xylan filled polypropylene composites