Knowledge Resource Center for Ecological Environment in Arid Area
| 兼具保水与固沙性能的PVAc乳液的制备及作用机理 | |
| 其他题名 | Preparation of PVAc emulsions with water retention and sand-fixing properties and mechanism of sand fixation |
| 杜泽川 | |
| 出版年 | 2017 |
| 学位类型 | 硕士 |
| 导师 | 陈华林 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 沙漠化是全世界最严峻的环境和社会经济发展问题之一，对农业、交通、水利和国防安全等造成严重威胁。因此，沙漠化治理是一项艰巨而急迫的任务。目前，以喷洒化学固沙材料进行固沙的化学固沙技术由于施工简便、见效迅速而成为沙漠化防治的重要方法，化学固沙材料也因此受到了广泛关注和研究。但目前研究与使用的化学固沙材料，其性能主要体现在对沙土颗粒的固定上，而保水性能不佳。造成这种现象的原因，主要是因为材料的保水性能与固沙性能在本质上的相互矛盾性，材料的保水性往往会导致其固沙性能的大幅度降低，而保水性又是沙漠地区植物生长、生态恢复的重要因素。因而，开发出兼具保水性与固沙性能的新型材料，是实现沙漠地区生态修复的迫切需要。聚醋酸乙烯酯（PVAc）乳液和聚丙烯酰胺（PAM）是两种环境友好的高分子材料，PVAc乳液强的粘接性能和PAM良好的保水性能使得它们在化学固沙和土壤改良中有普遍的使用。本论文采用共混与共聚的方式对PVAc乳液与PAM进行改性，通过对乳液制备与性能有重要影响的乳化体系的筛选，制备了兼具固沙性能与保水性能的沙漠化治理材料，并对合成材料的结构与其固沙性能、保水性能、水分入渗过程和对植物生长影响的关系进行了较详细的探讨，研究内容及取得结果如下：（1）用于乳液制备的乳化体系的确定。本研究中选择了4种生态安全性好的乳化剂，复配形成了3种复合型乳化体系，并制备了组分相同PVAc乳液，通过对不同乳化体系下制备的乳液的外观、稳定性、粒径等基本性能的考察筛选出了最佳的乳液体系及配比。研究表明，非离子型聚醚P65和两性离子型甜菜碱CAB复配型乳化体系乳化效果最佳，制备的乳液稳定性好、乳胶粒粒径分布均匀。（2）P(VAc-EHA)/PAM共混体系的制备及性能考察。将长链单体丙烯酸异辛酯（EHA）引入VAc分子结构中，制备了P(VAc-EHA)乳液，并与中低分子量PAM共混制得P(VAc-EHA)/PAM共混乳液，考察并探讨了共混乳液固沙时PVAc的分子结构与PAM分子量对固沙性能、保水性能、水分在沙土中的入渗过程和对植物生长状况的影响。试验结果表明，EHA的引入改善了PVAc乳液的耐热老化和抗冻融性能；而PAM中酰胺基团可以与水分子和沙粒表面的羟基形成氢键，从而提高了PVAc乳液的固沙强度和保水率，但还不能完全满足固沙需求；同时，由于聚合物分子链缠结在沙粒表面，减小了沙粒之间的孔隙，使得水分在沙土中的入渗速率而降低，但是饱和含水量未降低；植物栽培试验表明，共混乳液不会对植物的生长产生负面影响。（3）P(VAc-EHA-AM)共聚乳液的制备及性能考察。为了进一步提高乳液的固沙强度与保水性能，采取乳液共聚制备了不同AM含量的P(VAc-EHA-AM)共聚乳液，同样考察并探讨了AM含量与乳液基本性能之间的关系以及共聚乳液固沙时的固沙性能、保水性能、沙土中水分入渗过程和对植物生长状况的影响。发现由于AM具有强极性，对乳液的基本性能有很大影响；共聚乳液固沙时，由于AM可以更加均匀的分布在沙粒表面而具有优异的固沙性能和保水性能，在低的浓度下即可获得高的固沙强度和良好的保水性能。植物栽培试验同样表明，共聚乳液不会对植物的生长产生负面影响。 |
| 英文摘要 | Sandy desertification is one of the most severe environment and social economicdevelopment problem in the word today and poses a serious threat to agriculture, transportation, water conservancy, national defense, etc. Therefore, sandy desertification control is an urgent and formidable task. At present, the chemical sand-fixing technology has become one of the important sand-fixing methods due to its easy construction and quick effect. Hence the chemical sand-fixing materials have been studied with great attentions. However, in spite of their good sand-fixing ability, the current chemical sand-fixing materials usually have a poor water retention property. The main reason for the problem is the inherent contradiction between water retention and sand-fixation, that is to say, the water retention property of a materal always leads to a significant decrease in its sand-fixing performance. Because the water retention property is also the key factor for the growth of plants and ecological restoration, the development of novel materials with both water retention and sand-fixing properties is the urgent demand for the ecological restoration.Polyvinyl acetate (PVAc) emulsion and polyacrylamide (PAM) are two kind of environmental friendly chemical materials which are widely used in chemical sand-fixing and soil amendment based on the fact, that PVAc emulsion has strong bond behavior and PAM has good water retention ability. Therefore, the methods of blending and copolymerization were adopted to modify the PVAc emulsion and PAM for developing a set of novel materials with both water retention and sand-fixing properties. The conducted experiments and the main obtained results are as follows.(1) The emulsification system for preparation of emulsions. In this study, four ecological safety emulsifiers were selected and to form three emulsification systems. And PVAc emulsions with same composition were prepared. Then the appearance, particle size and stabilities of the obtained emulsions were tested. The results showed that the emulsification system composed of nonionicpolyether P65 and amphoteric ionic betaine CAB exhibit the best emulsification effect. The emulsion prepared with P65 and CAB presents the good stabilities, smallparticle size and narrow distribution.(2) The (VAc-EHA)/PAM blending system and their properties. EHA with long side chain was used to prepare the P(VAc-EHA) emulsion that then blended with PAM for making P(VAc-EHA)/PAM blending emulsions. The effects of the structure of PVAc emulsions and the MW of PAM have been investigated on the sand-fixing and water retention properties, as well the water infiltration in sand and plants growth of the P(VAc-EHA)/PAM blending emulsions. The results showed that the properties of the thermal aging and freeze-thaw resistance of PVAc emulsions are improved when long side chain EHA is introduced. The hydrogen bond formed between amide group with water molecular and sand particles surface can increase the sand-fixing strength and water retention rate, however, there is still a distance to meet the requirement of sand-fixing. For the water infiltration rate is reduced due to the polymer chains tangle on the surface of sand particles to minish the holes among sand particles. Plant cultivation experiments showed that the blending emulsions have no negative effect on growth of plants.(3)The P(VAc-EHA-AM) copolymerization emulsions and their properties. In order to further improve the sand-fixing strength and water retention capacity of emulsions used in sand-fixing, P(VAc-EHA-AM) copolymerization emulsions were prepared. The relationship between AM content and the basic properties of the copolymerization emulsions has been tested. The the sand-fixing and water retention properties of P(VAc-EHA-AM), as well theirwater infiltration in sand and the effect on plant growth were also studied. It was found that AM content has a great influence on basic properties of emulsions due to AM poses strong polarity. When P(VAc-EHA-AM) emulsions are used in sand fixation, a high sand-fixing strength and good water retention property are obtained with a low emulsion concentration, since AM can more evenly distribute on sand particle surface. Plant cultivation experiments showed that the blending emulsions have no negative effect on growth of plants as well. |
| 中文关键词 | 沙漠化治理 ; 化学固沙材料 ; 聚醋酸乙烯酯乳液 ; 丙烯酰胺 ; 保水性能 |
| 英文关键词 | sandy desertification control chemical sand-fixing materials poly(vinyl acetate) emulsions acrylamide water retention property |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 高分子化学与物理 |
| 来源机构 | 中国科学院成都有机化学研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287851 |
| 推荐引用方式 GB/T 7714 | 杜泽川. 兼具保水与固沙性能的PVAc乳液的制备及作用机理[D]. 中国科学院大学,2017. |
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