Improvement of Polystyrene by Blending SPS

Current polystyrenes such as GPPS and HIPS have good properties and have well established applications in the market however, they are poor in chemical resistance because they are amorphous polymers. If their chemical resistance were improved, their applications would be widely extended and could replace ABS or SAN, which have better chemical resistance than GPPS and HIPS. 

Blending a small amount of SPS improves the chemical resistance of GPPS and HIPS. HIPS/SPS blend and GPPS/SPS blend have chemical resistances 

When chemicals are weak solvents for polystyrene, stress cracks are formed in the products. Chemical resistances to practical chemicals are compared in Table 18.5. HIPS-SPS blend exhibits better resistance to chemicals which are used in the kitchen and bathroom. In HIPS/SPS blend, SPS may work to prevent the formation of crazes and their propagation to cracks initiated from contact with chemicals. 

Recycling is another important aspect recycling of ABS and SAN is generally difficult because they have acrylonitrile in their molecule, whereas HIPS-SPS blend is recyclable because its chemical component is styrene. 

With all these characteristics, HIPS/SPS blend will be very competitive in broad applications where HIPS, ABS and SAN have been used but increased chemical resistance is required. 

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