Bulk Synthesis of Styrene– N ‐Phenylmaleimide–Maleic Anhydride Copolymer for Preparing Heat‐Resistant ABS Resins With Superior Toughness

ABSTRACT To overcome the limitation imposed by the low heat distortion temperature (HDT) of ABS, which restricts its use in electronic packaging and automotive components, a styrene– N ‐phenylmaleimide–maleic anhydride terpolymer (SMIH) was synthesized via bulk polymerization as a heat‐resistant modifier. The N ‐phenylmaleimide unit introduces a highly rigid five‐membered ring structure into the polymer backbone, thereby enhancing the heat resistance of the matrix resin, while the maleic anhydride (MAH) content is used to tailor the compatibility with the matrix. With increasing MAH content in the heat‐resistant modifier from 0 to 8 phr, the impact strength increased by 2.3‐fold. By adjusting the contents of the heat‐resistant modifier and the toughening agent, the dynamic balance between heat resistance and toughness was explored. When the SMIH content was increased to 20 phr, the impact strength decreased by 30% relative to that of neat ABS, whereas the HDT and VST increased by 10.5% and 11.2%, respectively. This work provides new insights for the high‐temperature application of engineering plastics and promotes the use of ABS in high‐temperature fields.