Crystallization behavior of polyphenylenesulfide

Abstract

The crystallization behavior of poly(pheny1ene sulfide) (PPS) has been examined by differential scanning calorimetry as a function of melt temperature, residence time in the melt, and the presence of a liquid crystal polymer. The results suggest that the thermal history of the sample plays an important role in determining the crystallization kinetics. Short residence times at low melt temperatures and high melt temperatures alone resulted in a low value for the Avrami exponent n. The former effect was ascribed to incomplete melting of the polymer while the latter effect was attributed to thermal degradation. Blending a liquid crystal polymer, Vectra A950, with PPS had only a minor effect on the crystallization behavior.

A Review of the Measurement and Development of Crystallinity and Its Relation to Properties in Neat Poly(phenylene Sulfide) and Its Fiber Reinforced Composites

“…Multiple melting peaks are commonly observed in PPS. 23,24,25 In the case that amorphous PPS samples were annealed at a temperature and time sufficient to eliminate the cold crystallization in the DSC scan, a small endotherm is often observed at a temperature somewhat above the annealing temperature (often about 15°C above the annealing temperature). 26,27 This endotherm is thought to be associated with melting of small crystals formed during the annealing process, probably associated with secondary crystallization effects.…”

“…Many investigators [23][24][25]35,36,[39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] studied the crystallization kinetics of PPS and its composites. Most of these studies were reviewed previously, 3,6 so the approach taken here will be an overview of the most important observations.…”

“…The data in Figure 12 were obtained using a melt holding temperature of 310°C for the lower M w resin and 320°C for the higher M w resin. Budgell and Day, 24 Caramaro et al 57 and Auer et al 35 demonstrated that the rate of crystallization is dependent on the precrystallization melt holding temperature and time. Higher melt holding temperature up to about 330°C (for short periods) tends to increase the time required to crystallize PPS.…”

“…The value of n is a function of the nucleation and growth rate of the spherulites formed during crystallization. Most investigators have found values of n between 2 and 3 for PPS isothermal crystallization 24,25,35,36,[41][42][43]48,50,56 with crystallization from the melt giving values nearer 3 and cold crystallization giving values nearer 2. The values for crystallization from the melt have generally been interpreted to indicate three-dimensional growth of predetermined nuclei.…”

Morphology and thermal properties of PPS/ABS blend systems

“…5 Composite materials have also been prepared using carbon and glass fibers as reinforcement, 6 and blend systems using liquid crystalline polymers were also introduced to enhance its mechanical properties. 7,8 Also, CO 2 has been used as a plasticizer to decrease the melting point of PPS during melt processing. 9 ABS resin is a copolymer of styrene, acrylonitrile, and polybutadiene and is a multiphase polymeric resin with butadiene rubber distributed as relevantsized particles in the SAN matrix.…”