Abstract :
The effect of weldline on tensile and flexural
properties of ABS reinforced with short glass fibres (ABS/
GF) and spherical glass beads (ABS/GB) was investigated
as a function of glass fibre and glass bead concentrations.
The weldline was formed in the moulded specimens by
direct impingement of two opposing melt fronts (i.e. cold
weld). It was found that elastic modulus of ABS/GF
composites, with or without weldlines increased linearly
with increasing volume fraction of fibres (/f), according to
the rule-of-mixtures for moduli. The presence of weldline
reduced tensile and flexural modulus of the ABS/GF
composites. Weldline integrity factor for elastic modulus of
ABS/GF composites decreased linearly with increasing /f.
Results showed that tensile and flexural strength of ABS/
GF increased with increasing /f in a nonlinear fashion.
Flexural strength was consistently greater than tensile
strength for the same /f. Weldline affected both strengths
in a significant way; weldline integrity factor decreased
with increasing /f and was independent of loading mode.
Tensile and flexural modulus of ABS/GB composites
increased linearly with increasing volume fraction of glass
beads (/b), showing no loading mode dependency.
Although modulus of the ABS/GB system was not affected
significantly by the weldline, its strength was affected, and
more so in flexure than in tension. Weld and unweld
strengths decreased with increasing /b in both tension and
flexure according to Piggott and Leidner relationship; for
the same /b, flexural strength was always greater than
tensile strength. Weldline integrity factor for tensile
strength of ABS/GF system was considerably lower than
that for ABS/GB system but weldline integrity factor for
flexural strength was almost the same for the two
composite systems.
