• extrusion;
  • fibers;
  • mechanical properties;
  • poly(propylene) (PP);
  • polysaccharides


Recently, cellulose fiber–thermoplastic composites have played an important role in some applications. Plastics reinforced with cellulose and natural fibers have been widely studied. However, composites with regenerated cellulose have rarely been investigated. In this study, the lyocell fiber of Lenzing AG (cellulose II) and its raw material a bleached hardwood pulp (cellulose I) were used as reinforcement materials. The mechanical and thermal properties of polypropylene (PP) reinforced with pulp and lyocell fibers were characterized and compared with regard to the content of the fiber and the addition of maleated polypropylene (MAPP). PPs with cellulose I or II as a reinforcement material had similar mechanical properties. However, when MAPP was used as coupling agent, the mechanical properties of the composites were different. The crystallinity of the composites were determined by differential scanning calorimetry. Cellulose I (pulp) promoted the crystallization of PP, whereas cellulose II did not. MAPP reduced this effect in cellulose I fibers, but it induced crystallization when cellulose II (lyocell) was used as a reinforcement material. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 364–369, 2006