Ferguson and Patsavoudis 2°8"2~6 studied the effect of SSC on properties of
polyurea-urethane fibers based on MDI, 1,3-propylenediamine as chain extender
and either Adiprene L-100 or Adiprene L-42 (having the same structure but with
MW about 5000). Soft segment concentrations were varied from 32% to 71%
in the series with Adiprene L-100, and between 32% and 81% for the series
based on Adiprene L-42. Actual breaking stress was found to increase steadily
with increasing SSC in the series (I) based on Adiprene L-100, whereas a
maximum was found at about 70% SSC with the other series (II). There were
no significant differences in the numerical values of the actual breaking stress,
at a given SSC, between the two series. Two linear regions of the actual breaking
stress-SSC curves could be discerned: one from 0 to 35% SSC and the other
from 55 to 71% SSC, with a transition region from 35 to 55% SSC. Elongation
at break in both series was found to increase with SSC. Also, two linear regions