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本文采用透射电子显微镜(TEM)研究了低温PVA水凝胶的结构,直接观察到该体系呈明显的相分离结构,可将所形成结构视为聚集态水平上的宏观网络结构,认为正是这种网络结构的形成而赋予了体系强度和弹性.观察到,随着冷冻时间的增长,逐渐形成完善的网络结构,随着体系中PVA浓度的增大,网络结合得更加紧密.还从DSC测定了该相分离结构解体的热焓变化,进一步证实了显微镜的观察结果,提出了该体系凝胶化过程的宏观机制.
In this paper, the structure of low temperature PVA hydrogels was investigated by transmission electron microscopy (TEM). The structure of the low temperature PVA hydrogels was directly observed to be a phase separation structure, which can be regarded as the macroscopic network structure at the aggregation level, The formation of network structure gives the strength and flexibility of the system.It is observed that with the increase of freezing time, a perfect network structure is gradually formed, and the network becomes more compact as the concentration of PVA in the system increases.Furthermore, The change of enthalpy of disassembly of the phase separation structure further confirmed the observation result of the microscope and proposed the macroscopic mechanism of the gelation process of the system.