Effect of terminal amino group content on non-isothermal crystallization kinetics of PA 6
Using polyamide 6(PA 6)respectively with terminal amino group contents of 57.5,70.7,and 83.4 mmol/kg(rel-ative viscosity of 2.8)as the research object,the effect of terminal amino group content on the non-isothermal crystallization ki-netics of PA 6 was investigated.The thermal stability of PA 6 was measured using a thermogravimetric analyzer,and the non-iso-thermal crystallization process of PA 6 was studied at different cooling rates(ϕ)using a differential scanning calorimeter,the non-isothermal crystallization kinetics of PA 6 were analyzed based on the modified Avrami equation by Jeziorny method and Mo Zhishen method,and the non-isothermal crystallization activation energy of PA 6 was calculated according to Kissinger equation.The results showed that PA 6 with different terminal amino group contents all had high thermal stability,which was gradually im-proved as the terminal amino group content increased;the crystallization intervals of PA 6 with different terminal amino contents tended to shift towards the low-temperature region with the increase of ϕ;PA 6 crystals grew in a coexistence of two-dimensional flakes and three-dimensional spherulites,and PA 6 with higher terminal amino group content tended to grow in the form of three-dimensional spherulites,and the crystallization process of PA 6 was promoted by increasing terminal amino group content;the Avrami equation modified by Mo Zhishen method can well describe the crystallization process,and the crystallinity of PA 6 was directly proportional to ϕ within unit time;the non-isothermal crystallization activation energy of PA 6 increased,the heat relea-sing during the crystallization process also increased,the mobility of molecular chains became greater,the crystallization rate in-creased,and the crystallization ability became stronger as the content of terminal amino group increased.
polyamide 6terminal amino group contentcooling ratenon-isothermal crystallization kineticscrystal activa-tion energy
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