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Synthesis and properties of monomer cast nylon-6-b-polyether amine copolymers with different structures

机译：不同结构的单体浇铸尼龙-6-b-聚醚胺共聚物的合成与性能

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TDI-polyether amine macro-initiators with different structures were synthesized to initiate the caprolactam monomer successfully, and monomer cast (MC) nylon-6-b-polyether amine copolymers with multi-branched molecular structure were prepared via an in situ polymerization. It was found that the apparent activation energy (E) and the pre-exponential factor (A) of the reaction increased for the copolymers, and the TDI-polyether amine macro-initiators presented low reactivity due to the steric effects of the multi-armed long-chain structure. The hydrogen bond and inter-molecular forces of the copolymers were weakened by the introduction of multi-branched molecular chains, which was in favor of the formation of a g-crystal. The crystallization ability decreased for the copolymers, among which MC nylon-6-b-PP3A with an extra branched-chain showed the highest melting and crystallization temperatures and crystallinity with a relatively large crystal grain size. A pseudo-plastic fluid characteristic of flow behavior was observed for MC nylon-6. The viscoelastic moduli (G) and entanglement density (nu(e)) of all copolymers were higher than that of neat MC nylon-6 due to severe entanglement of the large quantity of multi-branched molecular chains of the copolymers resulting in the formation of physical networks, of which MC nylon-6-b-PP3A presented the highest. In the meantime, the values of the loss factor of the copolymers increased and the storage modulus and glass transition temperature (T-g) decreased. The stress-strain curves of all copolymers showed an untypical yield point and presented obvious strain hardening behavior, while a hairy fibrous structure was observed on the fracture surface of the copolymers, indicating the notable toughening effect of polyether amine on the nylon-6 matrix. The toughening mechanism of the copolymers was deduced as a multi-layer crack extension mechanism.
机译：合成了具有不同结构的TDI-聚醚胺大分子引发剂，以成功引发己内酰胺单体，并通过原位聚合制备了具有多支链分子结构的单体浇铸（MC）尼龙-6-b-聚醚胺共聚物。发现该共聚物的表观活化能（E）和反应前指数因子（A）增加，并且由于多臂的空间效应，TDI-聚醚胺大分子引发剂表现出低反应性。长链结构。共聚物的氢键和分子间力通过引入多支链分子链而减弱，这有利于形成g-晶体。共聚物的结晶能力下降，其中具有额外的支链的MC尼龙-6-b-PP3A表现出最高的熔融和结晶温度以及具有相对大的晶粒尺寸的结晶度。对于MC尼龙6观察到流动行为的假塑性流体特征。所有共聚物的粘弹性模量（G）和缠结密度（nu（e））均比纯MC尼龙-6高，这是由于共聚物的大量多支链分子链严重缠结导致形成的物理网络，其中MC尼龙6-b-PP3A表现最高。同时，共聚物的损耗因子值增加，储能模量和玻璃化转变温度（T-g）降低。所有共聚物的应力-应变曲线均显示出非典型的屈服点，并表现出明显的应变硬化行为，而在共聚物的断裂表面上观察到毛状纤维结构，表明聚醚胺对尼龙6基体的显着增韧作用。得出共聚物的增韧机理为多层裂纹扩展机理。

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