【作者】 黄梅；

【导师】 戴礼兴；

【作者基本信息】 苏州大学 ， 材料学， 2012， 硕士

【摘要】 本文主要研究聚乙烯醇(PVA)体系，首先在已有聚乙烯醇立构规整度研究的基础上，研究了无规聚乙烯醇(a-PVA)与间规聚乙烯醇(s-PVA)复合水凝胶的制备及性能，之后探索了水凝胶制备方法冷冻解冻循环这一物理交联法在水凝胶制备过程中实验条件对水凝胶性能的影响，最后在前面已有的对冷冻解冻循环对样品影响结果的基础上探索了冷冻解冻处理对PVA静电纺丝的影响。研究内容及结论如下：1.通过冷冻解冻循环这一物理交联法制备了a-PVA/s-PVA复合水凝胶，研究了其配比对复合水凝胶各项性能的影响，结果表明随着s-PVA含量的增加，溶液凝胶越容易，所形成的凝胶其结构越来越致密。s-PVA含量越高，凝胶样的硬度、凝胶分数、结晶性能及热稳定性随之提高。凝胶样的溶胀度及含水率随着s-PVA含量的增加而降低。经分析，配比为50/50的复合水凝胶的综合性能较好。2.通过冷冻解冻循环物理交联法制备了a-PVA/s-PVA复合水凝胶，研究了冷冻解冻条件对复合水凝胶各项性能的影响，结果表明随着冷冻解冻次数的增多，凝胶样的凝胶熔融温度越来越高，其结晶性能及热稳定性随之越来越好。此外，冷冻温度对凝胶样的各项性能也有较大影响，冷冻温度越低，所制得凝胶样的凝胶熔融温度越大，其结晶性能及热稳定性随着冷冻温度的降低而得到提高。因此在a-PVA与s-PVA共混的基础上，调整冷冻解冻条件可以得到热稳定性等性能更好的水凝胶。3.借鉴之前冷冻解冻对聚合物性能影响的结果，对PVA电纺溶液做冷冻解冻凝胶化处理，通过静电纺丝技术将其纺成纳米纤维。SEM结果表明冷冻解冻凝胶化处理可提高电纺溶液的可纺性及纳米纤维的连续性，且随着冷冻解冻处理次数的增加，纳米纤维的直径是逐渐增大的。另外，冷冻解冻凝胶化处理可显著提高纳米纤维的结晶性能及热稳定性，且冷冻解冻处理次数的增加使得这种影响更加明显。更多还原

【Abstract】 In this paper, poly (vinyl alcohol)(PVA) composites were studied. First,preparation and properties of atactic poly (vinyl alcohol)(a-PVA)/syndiotactic poly(vinyl alcohol)(s-PVA) blend hydrogels were investigated on the basis of PVA tacticity.Secend, the influence of preparation conditions on the properties of hydrogel infreezing-thawing process were explored. Third, PVA solutions were treated withfreezing-thawing method, the nanofibers electrospun from untreated and treatedsolutions were compared.Contents and conclusions:1. The hydrogels of a-PVA and s-PVA with different blend ratios were preparedby freezing-thawing processes. The results show that with the increase of s-PVA, blendsolution is easier to gel. The increase of cross-linking caused by s-PVA in the blendhydrogels results in denser structure, which in turn leads to increased gel fraction (G)and Hardness. The results also demonstrate s-PVA favors improvement of hydrogelscrystallinity and thermal stability. However, the equilibrium degree of swelling (EDS)and equilibrium water content (EWC) of hydrogel decrease with the increase of s-PVA.50/50(a-PVA/s-PVA) blend hydrogel has a denser structure with EWC of73.6%,Hardness of22.8HA and Tmof236.15oC, which is better than others.2. The a-PVA/s-PVA blend hydrogels were prepared under different preparationconditions. The effects of preparation conditions on hydrogels were investigated. Theincrement in Tgmof hydrogel and the enhancement in crystallinity and thermal stabilitywere observed with increasing freezing-thawing cycles or decreasing freezingtemperature. Thus, the better properties could be obtained by altering preparationconditions on the basis of blending a-PVA with s-PVA.3. The nanofibers were electrospun from treated and untreated solutions withfreezing-thawing method. According to SEM images of nanofibers, spinnability ofsolution and continuity of nanofibers were improved after treated, and the diameter ofnanofibers becomes larger with increasing freezing-thawing cycles. The crystallinity and thermal stability were enhanced which were found after treated, and the effect wasobvious with increasing freezing-thawing cycles.更多还原