E. Andreassen et al., RELATIONSHIPS BETWEEN THE PROPERTIES OF FIBERS AND THERMALLY BONDED NONWOVEN FABRICS MADE OF POLYPROPYLENE, Journal of applied polymer science, 58(9), 1995, pp. 1633-1645
Typical polypropylene fibers for use in light nonwoven fabrics were pr
oduced in a full-scale compact-spinning line. Molecular weight distrib
ution (MWD), extrusion temperature, draw-down ratio, and draw ratio we
re varied. The fibers were thermally bonded (welded) into nonwoven fab
rics, at different bonding temperatures, using a pilot calender line.
The tensile properties of the fabrics are influenced by the MWD and th
e processing conditions of the fibers, and the effects of these fiber
parameters increase with increasing bonding temperature. The fabric st
rength increases with increasing M(w)/M(n), decreasing draw ratio, and
increasing extrusion temperature, while in all these cases the fiber
strength generally follows the opposite trend. Furthermore, the fabric
strength, as well as the fiber strength, have a maximum as a function
of draw-down ratio. The tensile properties of the fabrics seem to be
governed by the bonding properties of the constituent fibers, not the
fiber strength per se. Bond characteristics are discussed in terms of
skin-core structures. Some details of the macroscopic fracture mechani
sms of fabrics were revealed by scanning electron microscopy and the s
hape of load-elongation curves. (C) 1995 John Wiley & Sons, Inc.