Abstract
Commercial poly(p-phenylene sulfide) (PPS) was thermally cured, which resulted in an increase of molecular weight due to cross-linking. Non-isothermal crystallization studies of samples cured for up to 7 days at 250?C showed a monotonous increase of crystallization temperature compared to pure PPS. However, a further increase of curing time decreased the crystallization temperature. The change in the half-crystallization time (t1/2) was similar to the crystallization temperature. Thus, the cross-linking of PPS affected crystallization behaviors significantly. To a certain extent, crosslinks acted as nucleation agents, but excessive cross-linking hindered the crystallization. Morphologies observed by polarized optical microscopy suggested that thermal curing for as little as 1 day contributed to the spherulitic structure having a smaller size, that was not observed with pure PPS.
Highlights
High performance thermoplastics have been developed and commercialized to satisfy the increasing demand for polymeric materials with such properties as thermal stability, high strength and modulus, and chemical resistance
Morphologies observed by polarized optical microscopy suggested that thermal curing for as little as 1 day contributed to the spherulitic structure having a smaller size, that was not observed with pure PPS
We suggest that the cross-linking of PPS acted as nucleating agents to change the crystallization behaviors of uncross-linked PPS
Summary
High performance thermoplastics have been developed and commercialized to satisfy the increasing demand for polymeric materials with such properties as thermal stability, high strength and modulus, and chemical resistance. That the moderate molecular weight of virgin PPS could be conveniently increased by a post curing process after polymerization [7]. Ma et al reported the curing mechanism of PPS using various analytical techniques, such as FT-IR, solid-state 13C-NMR, and rheometric measurements [8]. They concluded that the two most important reactions in the melt cure of PPS were cross-linking and chain extension and that the distribution of molecular weight became broader and shifted toward higher molecular weight with increasing cure time [8].
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