IMPROVEMENT OF ADHESION BETWEEN POLYETHYLENE AND REGENERATED CELLULOSE FIBERS BY SURFACE FIBRILLATION

Regenerated cellulose fibers spun from straw pulp using the N-methylmo rpholine N-oxide (NMMO) process were evaluated as a reinforcement for low-density polyethylene (LDPE). Surface fibrillation was carried out by a mechanical treatment to improve interfacial adhesion. Surface fib rillation resulted in a gradual change in surface topography, as detec ted by SEM. Long and numerous twisted fibrils were observed on the sur face of the treated fibers. The fiber perimeters, determined by the Wi lhelmy plate method, increased with an extended degree of fibrillation , while the strength of the fiber was not affected by the surface trea tment. Model composites were prepared by embedding untreated and surfa ce-fibrillated single fibers into an LDPE matrix, and the single fiber fragmentation (SFF) test was carried out to determine the critical fi ber length. The interfacial shear strength (tau) was then calculated b y applying a modified form of the Kelly-Tyson equation. It was found t hat the interfacial shear strength increased significantly as a result of surface fibrillation. The proposed mechanism for the improvement o f interfacial adhesion is a mechanical anchoring between the matrix an d the fiber.