4,4'-二羟基二苯硫醚对聚甲醛结晶和熔融行为的影响

为了探究4,4'-二羟基二苯硫醚(TDP)的添加对聚甲醛(POM)熔融与结晶行为的影响,本文利用熔融共混的方法制备了POM/TDP共混材料。通过差示扫描量热仪(DSC)对共混材料的熔融与结晶行为进行了研究,利用广角X射线衍射仪(WAXD)对共混材料的晶体结构进行了研究。结果表明,在POM中添加TDP后,POM的晶面间距变大,晶体结构变的疏松,使POM的结晶温度(Tc)、结晶焓(ΔHc)、熔融温度(Tm)与熔融焓(ΔHm)均降低。当TDP质量分数增加到30%时,共混物的熔点与结晶温度较纯POM分别下降了15.2和12.8℃。在等温结晶过程中,随着TDP含量的增大,POM完成结晶所需的时间显著加长,共混物的结晶速率逐渐降低,结晶活化能逐渐升高,但TDP的加入对POM的晶型并没有影响。以上结果说明TDP的添加对POM的熔融与结晶行为影响很大,这将为POM结晶行为的调控提供依据。

Effects of 4,4'-Thiobisphenol on the Crysatllization and Melting Behavior of Polyoxymethylene

In order to explore the melting and crystallization behaviors of polyoxymethylene(POM) with the addition of 4,4'-thiobisphenol(TDP), a series of POM/ TDP alloys was prepared by melt blending of POM and TDP. The melting, crystallization behavior and crystal structure were studied by differential scanning calorimeter(DSC) and wide-angle X-ray diffraction(WAXD). The results demonstrate that POM has a less compact crystal structure with addition of TDP, which makes the melt crystallization temperatures(T_c), heat of crystallization(ΔH_c), melting temperatures(T_m) and heat of fusion(ΔH_m) decrease with the increase of the content of TDP. Incorporation of TDP with a mass fraction of 30% leads to reduction of melting point and crystallization temperature by 15.2 ℃ and 12.8 ℃ compared with pure POM, respectively. Meanwhile, it is worth noting that the crystallization time of POM increases with the increase of the content of TDP, the crystallization rate decreases, and crystallization activation energy increases gradually during isothermal crystallization process. The addition of TDP does not influence the crystal structure of POM, but has a great influence on the crystallization and melting behaviors of POM.