MORPHOLOGY DEVELOPMENT IN TOUGHENED ALIPHATIC POLYAMIDES

The morphology of binary blends of a maleated triblock copolymer (with an ethylene/butene midblock and styrene endblocks, SEBS-g-MA) with a series of nylon materials (nylon 4,6, nylon 6,9, nylon 6,10, nylon 6,12, nylon 11, nylon 12 and nylon 12,12) was investigated and the results compared with previous work for nylon 6 and nylon 6,6. The nylon x materials (nylon 11 and nylon 12) yielded small, regular particles similar to that observed in nylon 6. These nylons have one amine endgroup per molecule and are only capable of end-grafting. The nylon x,y materials, on the other hand, led to much larger and more complex-shaped particles; their size decreased as the aliphatic content of the nylon increased. These polyamides contain a certain fraction of molecules with two amine endgroups and are capable of forming loops or crosslinks which dramatically affect the morphology generation in a single-screw extruder. The results further revealed that the large particles are formed because of the failure of the single-screw extruder to break them into smaller ones rather than by increased coalescence. There is evidence that thickness of the interface influences both the particle size and the extent of reaction in these blends as described.