【作者】 邰晶磊；

【导师】 陈克复；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2014， 博士

【摘要】 随着环保意识的逐渐加强和石化资源的日益枯竭，目前广泛用于包装材料的石油基高聚物，因其非生物降解性，导致其废弃物难以回收再生，也无法进行有效的堆肥处理，给生态环境造成很大负担。而可再生资源来源的生物聚合物具有替代石油基高聚物的潜力，成为目前可生物降解包装材料的研究热点。但生物聚合物普遍存在性能上的缺陷，因此，其改性研究和应用研究是目前的主要研究方向。其中，纸基生物基聚合物复合材料具有很好的应用前景，逐渐受到重视，已有很多研究。聚乳酸（PLA）是一种植物资源来源、可完全生物降解的生物聚酯材料，综合性能优良，是最具发展前景的生物聚合物之一。聚乳酸涂塑纸或纸板是一种很有潜力的可生物降解的包装材料，本文提出了一种新的制备聚乳酸涂塑复合纸的方法。通过乳化溶剂挥发法和纳米均质法制备聚乳酸微纳米级颗粒颜料，分别用壳聚糖和聚乙烯醇的水溶液作为涂料胶黏剂配制聚乳酸涂料，采用纸张颜料涂布的方式制备聚乳酸涂布纸，再经滚压或平压使聚乳酸颗粒涂层微观混熔在纸面形成连续树脂层，制得聚乳酸涂塑复合纸，并对颗粒颜料及树脂涂层的特性进行了研究。通过聚乳酸溶液涂布的方法研究了氯仿、乙醇、正丙醇复合溶剂及聚乙二醇（PEG）和聚己内酯（PCL）对PLA涂层的增塑作用。通过研究成膜性、热性能、复合材料透湿性和透氧性、及热封性，发现复配溶剂、PEG和PCL均不同程度降低了PLA膜层的玻璃化转变温度和熔点，并具有一定的诱导结晶作用，普遍使PLA膜层的结晶度有所升高；但从透湿性、透气性和热封性来看，发现各因素的影响均不大。通过乳化溶剂挥发法和纳米均质法制备聚乳酸微粒，并用对制得的PLA微粒进行了粒度、扫描电镜（SEM）、傅里叶变换红外光谱分析（FT-IR）表征。乳化溶剂挥发法制备的PLA微粒多为多孔性球体，其中，阳离子表面活性剂制备的PLA微粒的粒度和粒径分布最小，得率最大。而且，乳化溶剂挥发法可以制备纳米蒙脱土改性PLA微粒。用纳米均质法可以制得PLA颗粒。通过高速料液在均质阀中的剪切、撞击、强压力降作用制备的PLA微粒是不规则形状的实心颗粒。此外，还对PLA颗粒进行了臭氧处理亲水性改性研究，发现在中性条件下进行臭氧处理可以改善PLA颗粒的表面水润湿性，不过，乳液溶剂挥发法制备的PLA微粒因其多孔性及残余表面活性剂而具有很好的水润湿性。分别以壳聚糖和聚乙烯醇的水溶液作为PLA涂料的胶黏剂，采用涂布法-热压的方法制备聚乳酸涂塑复合纸，并用SEM、原子力显微镜（AFM）、FT-IR、差示扫描量热仪（DSC）和热重分析仪（TG）对聚乳酸涂层进行了表征，并研究了涂塑复合材料的透湿性、透氧性及热封性。发现涂布-热压法制备聚乳酸涂塑复合纸是可行的，而且复合纸的各项性能可与聚乳酸溶液涂布纸相媲美。而且，胶黏剂树脂对涂层性能也有一定的影响，均不同程度地降低了聚乳酸树脂层的玻璃转化转变温度和熔点，但均使涂层的结晶度升高，不利于树脂层的柔性。另外，不同的热压方法制得的涂层质量也不同，滚压和平压在微观尺度上均具有取向作用，但滚压涂层的光泽度、平滑度较高，而平压涂层平滑度、光泽度较低。另外，对于PLA-聚乙烯醇涂层，热压处理提高了树脂层的结晶度，而热压使PLA-壳聚糖涂层结晶度降低，但退火处理可使二者的结晶度提高，虽然可以改善涂层阻隔性，但同时会使涂层变得脆韧，不利于提高树脂层的柔性。针对各种聚乳酸涂塑复合纸的透湿行为进行了综合的定性和定量分析，发现聚乳酸涂塑复合纸的透湿性遵循多层材料透湿性的一般规律。基于此规律，对水蒸气透过量和涂布量的关系进行了线性拟合，发现对于单面溶液涂塑纸、双面溶液涂塑纸、单面颜料-热压涂塑纸均得到很好的拟合效果，并得到了涂塑纸透湿量与涂布量之间的经验公式。而且，由于基纸对于树脂与基纸间形成的混合层的特性有决定性影响，基纸的特性及种类对纸塑复合材料的影响不可简单忽略不计。最后，研究了聚乳酸涂塑复合纸在纸张再生过程中的降解行为。聚乳酸涂层在二次纤维的脱墨漂白过程中存在的水、热、碎解、揉搓等的作用下，基本上可完全降解，终产物是水和二氧化碳，避免一般纸塑复合材料纤维回用过程中存在的胶粘物等问题，对造纸过程没有影响。更多还原

【Abstract】 Wiht the strengthening of environmental awareness and the increasing depletion of fossilresources, petroleum based polymer packaging materials widely used for now, due to its nonbiodegradability, cause the difficoulty to recycle the waste and can not be compostingeffectivly, which caused great burden to the ecological environment. The bio-plymers fromrenewable resources having the potential to replace petroleum based polymers, become theresearch hotspot of biodegradable packaging materials. But bio-polymers generally haveperformance defects, therefore, modification and applied research is the present main researchdirecitons. Paper based bio-polymer composite material with good application prospect hasobtained more and more attention, and there were many relevant research.Polylactic acid (PLA) is a kind of biological polyester material from renewable resources,wich is fully biodegradable and one of the most promising bio-polymers, with goodcomprehensive performance. PLA coated paper or paperboard is a promising biodegradablepackaging materials. A new method for preparation of PLA composite paper was presented.With the PLA nano particle pigment made through a chemical and mechanical perparationmethod, and aqueous solution of chitosan and polyvinyl alcohol used as the coating adhesiverespectively, PLA coating was prepared. PLA pigment coated paper was perpared, followedby hot rolling or pressing process, and the PLA particles melt to form a continuous coatinglayer on paper, then PLA coated paper obtained. And the properties of the PLA particles andPLA coating were studied.The plasticizing effect of chloroform and the co-solvent wiht ethanol or n-propanol,polyethylene glycol(PEG) and polycaprolactone(PCL) o n polylactic acid coating were studiedin solution coating process. By observation of filming process, thermal performance testing,oxygen permeability, moisture permeability, and the heat sealing tests, it was found that theco-solvent, PEG and PCL lowered glass transition temperature and melting point of PLA layerto different degrees, meanwhile, increased the crystalization of PLA layer somewhat, due tothe crystallization induction. But these factors above have little effect on moisturepermeability, oxygen permeability and the heat sealing property of PLA slution coating paper.PLA particles were prepared through the emulsion solvent evaporation method and nanohomogenization method respectively, and the obtained PLA particles were characterized byfourier transform infrared spectrometer (FT-IR), scanning electron microscopy (SEM) andmalvern particle size analyzer. Emulsion solvent evaporation prepared PLA microparticlesinto porous sphere, wherein, PLA microparticles prepared by the cationic surfactant is of minimum particle size and particle size distribution, maximum yield. Moreover, emulsionsolvent evaporation method can be used to prepare PLA nano particles modified bymontmorillonite. In addition, nano homogenization method can be used for the preparation ofPLA micro-nano particles. By high-speed liquid shear, impact, strong pressure drop inhomogeneous valve put strong effect on high-speed liquid feed, and prepared PLA particlesare solid particles with irregular shape. Finally, the hydrophilic modification of the PLAparticles through ozone treatment was researched, found that surface water wettability of PLAparticles can be improved by ozone treatment in the neutral condition. However, PLAprepared by emulsion solvent evaporation method has good surface water wettalility due toporosity and residual surfactant.Aqueous solution of chitosan and polyvinyl alcohol were used as PLA coating adhesiverespectively, and the PLA composite paper were made by coating and hot pressing method.The polylactic acid coating was characterized using SEM, atomic force microscopy (AFM),FT-IR, differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) and themoisture permeability, oxygen permeability and heat sealing properties of PLA compositepaper were studied. It is feasible to prepare PLA composite paper by coating-hot pressingmethod, and the PLA composite paper has similar properties to PLA solution coating paper.Moreover, the adhesive resin also has some influence on the properties of the P LA coatings.The glass transition temperature and the melting point of PLA layer were decreased indifferent degree, but the crystallinity increased, which is not conducive to a flexible resinlayer. In additon, the coating from different hot press method has different quality. Theorientation effect in micro scale occored in both rolling press process and flatten press process,but, coating with rolling pressing has higher gloss and smoothness, and coating with flattenpressing has poorer gloss and smoothness. For PLA-PVA coating, hot pressing treatmentincreases the crystallinity of resin layer, wihle, it decreases the crystallinity of PLA-chitosancoating. And the annealing treatment can make the crystallization of the two increased, thoughthe barrier properties of coating can be improved, but the coating becomes brittle ductilewhich is not conducive to improving the flexibility of the resin layer.Conducting a comprehensive qualitative and quantitative analysis on the water vaporpermeability behavior of PLA compsite paper, we found water vapor permeability of PLAcomposite paper follow the general rule of multilayer material’s moisture permeability. Basedon this rule, the water vapor transmission rate (WVTR) and coating weight of PLA compositepaper get a good linear fitting results and get the empirical formula. Moreover, since the basesheet has a decisive influence on the properties of the mixed layer formed between the resin and the base paper, the impact of properties of the base paper on paper-plastic compositematerials can not be simply ignored.Finally, the degradation behavior of PLA composite paper in paper recycling process wasstudied. Under the action of water, heat, crushing, rubbing in process of bleaching anddeinking of secondary fiber, the PLA coating was substantially completely degraded, andthe end products are water and carbon dioxide which avoid stickies problems existing in fiberregeneration process of ordinary paper-plastic composite materials, therefore, having no effecton the papermaking process.更多还原