【作者】 张力；

【导师】 李新平；

【作者基本信息】 陕西科技大学 ， 应用化学， 2021， 硕士

【摘要】 由于化石资源的枯竭以及严重的环境污染,生物质可降解材料的利用越来越受到许多研究学者的关注。然而,目前使用的高吸水性材料大多数是以石油为原料生产的,由于合成类高吸水性材料的成本高、潜在毒性大,其降解性和生物相容性差,存在潜在的环境危害。因此,基于天然高分子材料的吸水材料的研究逐渐成为近年来的研究热点之一。纤维素是最丰富的生物质材料,其来源广泛,是许多产品的理想原料。将纤维素掺入到高吸水性材料中,既能减少石油原料的用量,达到降低成本的目的,又能使其具备可生物降解性能,减少对环境的污染。本文以漂白竹浆为纤维素来源,通过复合纤维素酶+低温碱尿素体系预处理得到改性竹浆纤维,再以改性竹浆纤维素为原料分别制备纤维素骨架支撑的高吸水性树脂、半互穿网络高吸水性树脂以及纤维素树脂/海藻酸钠复合微球,并着重探究材料的吸水和保水性能。主要研究内容及结论如下:1.改性竹浆纤维接枝丙烯酸制备高吸水性树脂的探究。以竹浆为原料,通过复合纤维素酶+低温碱尿素体系预处理得到改性竹浆纤维(Modified bamboo pulp fiber,简称 MBPF),进一步将丙烯酸(Acrylic acid,简称 AA)接枝到改性竹浆纤维上,制备了一种新型纤维素骨架支撑的高吸水性树脂(MBPF-g-PAA)。主要研究结果表明,聚丙烯酸成功接枝到竹浆纤维上,纤维素作为骨架增强了树脂内部多孔结构,树脂的吸水效果有明显改进;在优化合成条件下,MBPF-g-PAA的吸水倍率最高达980.87 g/g。此外,MBPF-g-PAA的溶胀行为与溶液的pH和盐溶液中金属阳离子种类有关。受金属阳离子“电荷屏蔽效应”的影响,不同阳离子盐溶液对树脂溶胀的影响依次为:Na+>K+>NH4+>Mg2+>Ca2+>Fe3+。2.改性竹浆纤维/PVA半互穿网络高吸水树脂的探究。在MBPF-g-PAA的基础上,通过添加聚乙烯醇(Polyvinyl alcohol,简称PVA),成功合成了具有半互穿网络结构的高吸水性树脂(MBPF-g-PAA/PVA)。主要研究结果表明,单体AA与纤维素主链发生了接枝反应,PVA链在整个聚合物网络中相互渗透并通过氢键作用与网络结合。在最佳反应条件下,MBPF的含量为2g、AA的含量为16g、KPS的含量为0.6wt%、NMBA的含量为0.06wt%、AA的中和度为65%以及PVA的含量为6 wt%时,MBPF-g-PAA/PVA在蒸馏水中的最大平衡吸水倍率为1329.35g/g。同时,树脂在溶液中的溶胀行为受外界溶液特性的影响,符合二级溶胀动力学模型。3.纤维素树脂/海藻酸钠复合微球的探究。以MBPF-g-PAA为原料,利用海藻酸钠(Sodium alginate,简称SA)和氯化钙表面快速交联的方法制备纤维素/海藻酸钠复合微球(MBPF-g-PAA/SA)。主要研究结果表明,由MBPF、AA和SA合成的复合微球形态较好,大部分呈球形,分散性较好,粒度分布均匀,放大3000倍后呈现出清晰均匀的微孔结构。同时,MBPF-g-PAA/SA的最佳合成条件为:注射器口径2.0 mm、CaCl2溶液的浓度0.5 wt%以及海藻酸钠和高吸水性树脂的质量比2:1,在该条件下制备的复合微球最大平衡吸水倍率为78.5 g/g。在合成反应中,高吸水性树脂的含量对复合微球的吸水性能有一定的影响,而注射器口径控制了包裹在海藻酸钠“蛋壳”结构中树脂的含量,对复合微球的吸水倍率起到促进作用。更多还原

【Abstract】 Due to the exhaustion of fossil resource and serious environmental pollution,the utilization of biodegradable materials has attracted more and more attention from many researchers.However,most of the superabsorbent materials used at present are produced from petroleum.Due to the high cost and potential toxicity,poor degradability and biocompatibility of synthetic superabsorbent materials,there are potential environmental hazards.Therefore,the research of water-absorbing materials based on natural polymer materials have gradually become one of the research hotspots in recent years.Cellulose is the most abundant biomass materials,widely its source,it is the ideal raw material for many products.Adding the cellulose into superabsorbent materials can not only reduce the amount of petroleum raw materials,achieve the purpose of lessening costs,but also make it biodegradable and diminish environmental pollution.In this paper,bleached bamboo pulp was used as the source of cellulose,and the modified bamboo pulp fiber was prepared by pretreatment of complex cellulase and low temperature alkali urea system.Then,the modified bamboo pulp cellulose was used as the raw material to prepare cellulose-supported superabsorbent resin,semi-interpenetrating networks superabsorbent resin and cellulose resin/sodium alginate composite microspheres.The water absorption and retention properties of the materials were emphatically explored.The main research contents and conclusions were as follows:1.Study on the preparation of superabsorbent resin by grafting acrylic acid on modified bamboo pulp fiber.The modified bamboo pulp fiber(MBPF)was prepared by pretreatment of complex cellulase and low temperature alkali urea system using bamboo pulp as the raw material.Then the acrylic acid(AA)was grafted to MBPF,and a new cellulose-supported superabsorbent resin(MBPF-g-PAA)was prepared.The main results show that polyacrylic acid was successfully grafted onto the surface of cellulose fiber.The water absorption rate of the resin was improved obviously due to cellulose skeleton enhanced inner porous structure.Under optimum conditions,the water absorption rate of the MBPF-g-PAA was 980.87 g/g.In addition,the swelling behaviors of the MBPF-g-PAA depended on the pH and the metal cation types of the salt solutions.Influencing by the "charge shielding effect" of metal cations,the effects of different cationic salt solutions on resin swelling rate wre as follows:Na+>K+>NM4+>Mg2+>Ca2+>Fe3+.2.Study on the modified bamboo pulp fiber/PVA semi-interpenetrating network superabsorbent resin.On the basis of the MBPF-g-PAA,by adding polyvinyl alcohol(PVA),the superabsorbent resin(MBPF-g-PAA/PVA)with the semi-interpenetrating network structure was successfully synthesized.The main results show that monomer AA grafted with the cellulose backbone.PVA throughout the polymer chain,and with the network through hydrogen bonding.Under the optimal reaction conditions,the maximum equilibrium water absorption rate of the MBPF-g-PAA/PVA in distilled water was 1329.35 g/g,when the content of MBPF was 2 g,the content of AA was 16 g,the content of KPS was 0.6 wt%,the content of NMBA was 0.06 wt%,the neutralization degree of AA was 65%and the content of PVA was 6 wt%.At the same time,the swelling behavior of resin in solution was affected by the characteristics of the external solution,which conformed to the second-order swelling kinetic model.3.Study on the cellulose resin/sodium alginate composite microspheres.Using MBPF-g-PAA as the raw material,the cellulose/sodium alginate composite microspheres(MBPF-g-PAA/SA)were prepared by using sodium alginate(SA)and calcium chloride surface rapid cross-linking method.The main results show that the composite microspheres synthesized by MBPF,AA and SA had good good morphology,most of them were spherical,with good dispersion and uniform particle size distribution.After magnification of 3000 times,they presented a clear and uniform microporous structure.At the same time,the optimal synthesis conditions of MBPF-g-PAA/SA was as follows:syringe diameter was 2.0 mm,concentration of CaCl2 solution was 0.5 wt%and mass ratio of sodium alginate and superabsorbent resin was 2:1.Under these conditions,the maximum equilibrium water absorption rate of the composite microspheres were 78.5 g/g.In the synthesis reaction,the content of superabsorbent resin had a certain influence on the water absorption performance of the composite microspheres,while the syringe diameter controlled the content of resin wrapped in the "egg shell"structure,which played a role in promoting the water absorption rate of the composite microspheres.更多还原