Strength Loss in Thermally Bonded Polypropylene Fibers

Abstract

Single fiber experiments to analyze the relationships between fiber structure, fiber properties and bonding conditions were performed with three structurally different polypropylene (PP) fibers. Bonds were formed between pairs of fibers at different temperatures and bond strengths were measured. Fiber strengths were measured before and after bonding to estimate changes caused by the bonding process. Bonded fiber strength was also compared with the strength of single fibers which experienced the same thermal conditions to assess the effect of mechanical damage from pressing fibers together with steel rolls while creating bonds. In all fiber types, significant bonding occurred simultaneously with degradation of fiber strength. The observed reduction in fiber strength was caused mainly by thermal, rather than mechanical, damage during bonding. Fibers with low birefringence skins formed strong interfiber bonds at lower temperatures with smaller losses in fiber strength.