INFLUENCE OF ABS LOW MOLECULAR WEIGHT SPECIES ON ABS PROPERTIES

A commercial ABS has been treated with methanol in a Soxhlet apparatus, at the boiling temperature of the solvent, for various procedures and times, in order to extract from it different amounts of low molecular (MW) weight species, a very impor­ tant parameter in determining the fina l properties of PCIABS blends. Thermal, mechanical, dynamic mechanical, and impact proper­ ties have been performed on the obtained samples as a function of the amount of the extracted species. The molten state results seem to be very sensitive to the subtrac­ tion of low MW species from the ABS, as shown by the viscosi­ ty, increasing with enhancing the extraction extent. The glass transitions, detected by dynamic mechanical tests, show that both SAN and B low MW species are extracted from the ABS. Other low MW additives, such as antioxidants and sta- bilizers, are extracted from the ABS as well, giving rise to degradative effects, particularly effective for the materials under­ going processing treatments for prolonged times at high temper­ atures (i.e., for large extraction amounts). Tensile performances, at a temperature just below the SAN Tg (100°C), show a sensitive influence of this parameter as well as ofthe above mentioned degradative effects at such a temperature. Impact properties slowly worsen with increasing low MW extracted amounts, and, for high extraction amounts, they exhib­ it a brittle behavior.