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以活性负离子聚合法合成的不同分子量和单体配比的苯乙烯-异戊二烯-丁二烯三元共聚物橡胶(SIBR)为增韧剂,以双官能团引发剂引发,采用本体聚合方法合成了系列ABS树脂,利用经典相分离技术、SEC、TEM和力学试验对聚合试样的结构、分子量、形态及性能进行了表征,并以SEM对冲击后的断面形貌进行观察以探究其断裂机理.结果发现,随着SIBR分子量的增大,橡胶相尺寸增大,接枝率下降,相界面明显,但冲击强度有所提高;SIBR中St组分含量增加,粒子均匀,但刚性增大,对抗冲击性能不利.高Mn、低St组分含量SIBR抵抗裂纹形成和扩展的能力强,ABS呈韧性断裂方式,以丰富的银纹化、明显的剪切屈服和大量系联带的撕裂为主要断裂机理;低Mn、高St组分含量SIBR抵抗裂纹形成和扩展的能力较低,ABS以半韧性方式断裂,断裂机理以基体塑化、剥离和界面的应力白化现象为主.
The styrene-isoprene-butadiene terpolymer rubber (SIBR) synthesized by living anionic polymerization with different molecular weight and monomer ratio was used as toughening agent to initiate with bifunctional initiator. The bulk polymerization method A series of ABS resins were synthesized. The structure, molecular weight, morphology and properties of the polymerized samples were characterized by means of classical phase separation, SEC, TEM and mechanical tests. SEM was used to observe the fracture morphology to investigate the fracture The results showed that with the increase of the molecular weight of SIBR, the rubber phase size increased, the grafting rate decreased, the phase interface was obvious, but the impact strength was improved; the content of St component in SIBR increased, the particles were uniform, , Adverse impact resistance.High Mn, low St content SIBR resistance to crack formation and expansion ability, ABS ductile fracture mode, with a rich silver grain, a significant shear yielding and a large number of associated with the tearing As the main fracture mechanism; SIBR with low Mn and high St content is less resistant to the formation and propagation of cracks, and the semi-ductile fracture of ABS is the mechanism of fracture. The fracture mechanism is dominated by matrix plasticization, delamination and interface stress whitening.