Fiber-reinforced cellulosic thermoplastic composites

✍ Scribed by Wolfgang G. Glasser; Razaina Taib; Rajesh K. Jain; Ron Kander

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 528 KB
• Volume: 73
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19990815)73:7<1329::aid-app26>3.0.co;2-q

✦ Synopsis

Steam-exploded fibers from Yellow poplar (Liriodendron tulipifera) wood were assessed in terms of their thermal stability characteristics, their impact on torque during melt processing of a thermoplastic cellulose ester (plasticized CAB) matrix, their fiber-matrix adhesion and dispersion in composites, and their mechanical properties under tension. Fibers included water-extracted steam-exploded fibers (WEF), alkali extracted fibers (AEF), acetylated fibers (AAEF), and a commercial milled oat fiber sample (COF) (i.e., untreated control). The results indicate that the thermal stability of steam-exploded fibers increases progressively as the fibers are extracted with water and alkali and following acetylation. The greatest improvement resulted from the removal of water-soluble hemicelluloses. The modification by acetylation contributed to improved interfacial wetting that was revealed by increased torque during melt processing. Whereas modulus increased by between 0 and 100% with the incorporation of 40% fibers by weight, tensile strength either declined by 1 3 to 1 2 or it increased by a maximum of 10%, depending on fiber type. AAEF composites produced the best mechanical properties. Fiber-aspect ratio was reduced to an average of 25-50 from ӷ 200 during compounding. The superior reinforcing characteristics of AAEF fibers were also reflected by SEM, which revealed better fiber-matrix adhesion and failure by fiber fibrillation rather than by fiber pullout.