Mechanical Properties of Neat SPS

SPS has high a melting point almost comparable to those of other engineering plastics (Table 18.2). In comparison with other crystalline engineering thermoplastics, of particular interest is that SPS has the lowest specific gravity and dielectric constant. 

In contrast, when SPS is molded at low mold temperatures far below the Tg, crystallization of SPS is restricted at the surface owing to fast cooling, resulting in a lower Xc and a poorly developed crystalline lamellar structure at the surface. However, in the center of the molded parts, spherulites are formed because the slower cooling allows the crystallization of SPS. The Xc profile across the cross-section is very different from what was molded at high mold 

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