【作者】 刘少杰；

【导师】 陈礼辉；

【作者基本信息】 福建农林大学 ， 制浆造纸工程， 2008， 硕士

【摘要】 化学制浆碱回收工段会产生大量的白泥,目前,我国对制浆造纸白泥的处理方法主要为填埋法,但这种方法又会造成地下水污染,给制浆造纸厂带来沉重的固体废弃物处理负担。开发高效制浆造纸白泥应用新技术迫在眉睫。本文筛选出一种优良的白泥表面改性剂,在国内外率先开发出白泥/PVC共混复合材料,揭示了白泥/PVC共混复合材料增强机理,为制浆造纸白泥固体废弃物高效利用开辟一条途径,可大力促进白泥废弃资源向高附加值产品转化,从而加快我国造纸工业和材料工业的发展。论文研究了白泥的烘干和粉碎工艺。经过150℃、120min条件干燥后,去除了白泥中的游离水和结晶水,白泥基本达到了绝干。经过30min球磨,白泥的平均粒径从4.28μm降到2.00μm;球磨时间超过30min,白泥的粒径降低幅度不大。综合考虑粒径及成本,白泥的球磨时间以30min为宜。论文研究了白泥/PVC共混复合材料热压工艺条件,优化工艺条件为热压温度175℃、热压成型时间12min。论文对钛酸酯A、铝酸酯B与铝酸酯C进行筛选,铝酸酯改性剂B是白泥/PVC共混复合材料较佳的表面改性剂,铝酸酯改性剂B较佳的用量为0.5%。论文研究了白泥用量对白泥/PVC共混复合材料性能的影响。结果表明,当白泥用量为25份时,白泥/PVC共混复合材料具有较好的力学性能、热学性能和加工流变性能,复合材料冲击强度28.33KJ·m^-2,拉伸强度41.51MPa,弯曲强度84.13MPa,弯曲模量4273.67MPa,洛氏硬度59.93HRR,维卡软化温度（VST）112.60℃。与纯PVC材料相比较,冲击强度、拉伸强度、弯曲强度、弯曲模量、维卡软化温度分别提高了87.99%、0.41%、9.74%、35.68%、10.22%、36.32%。论文对弹性体改性剂增韧白泥/PVC共混复合材料抗击性能进行了研究。结果表明,ACR是白泥/PVC共混复合材料较为合适的抗冲击改性剂,能有效提高白泥/PVC共混复合材料的冲击强度,对白泥/PVC共混复合材料加工流变性能影响不大,但会降低白泥/PVC共混复合材料拉伸强度、弯曲强度、弯曲模量、硬度和维卡软化温度（VST）。论文研究了改性剂对白泥接触角变化的影响,结果表明,钛酸酯A、铝酸酯C、铝酸酯B三种改性剂均可不同程度提高改性白泥的接触角。0.5%铝酸酯B处理后白泥的接触角与聚氯乙烯的接触角较接近,铝酸酯B处理后白泥热重曲线与未改性白泥的热重曲线也有较大区别,说明铝酸酯B改性效果最好,改性处理后的白泥/PVC共混复合材料性能较好。论文对改性白泥的红外光谱进行了研究,揭示了白泥表面改性的机理。结果表明,钛酸酯A改性处理且经过抽提的白泥与未改性白泥红外光谱图没有明显的区别,表明钛酸酯A与白泥的作用力弱,改性效果较差。铝酸酯B、C改性处理且经过抽提的白泥在2960～2850cm^-1出现了一组C-H伸缩振动的吸收峰,是长链烷基所致,改性剂与白泥产生了较强的结合。论文对白泥/PVC共混复合材料的微观形态进行分析。纯PVC材料冲击断面凹凸不平且呈片状,未改性白泥/PVC共混复合材料的断面粗糙且多空穴,具有比较明显的脆性断裂特征;白泥用量为25份时,材料断面没有明显的空穴现象,有明显的“拉丝”现象,具有比较明显的韧性断裂特征;当白泥的用量超过40份时,材料断面凹凸不平,且出现了大量的空穴,材料的性能受到严重影响;ACR/白泥/PVC共混复合材料的断面具有大量的微孔,呈现“蜂窝状”,具有典型的韧性断裂特征。论文研究了白泥/PVC共混复合材料的热失重情况。白泥/PVC共混复合材料热失重可分为四个阶段。不同白泥用量的复合材料快速失重阶段失重率并无太大区别,均达到了70%左右。材料脱HCl降解和无规降解失重起始温度随白泥用量的增加而不断提高。纯PVC材料脱HCl降解和无规降解的失重起始温度分别为220.20℃和451.90℃。白泥用量25份时,白泥/PVC共混复合材料脱HCl降解和无规降解的失重起始温度分别提到246.10℃和462.90℃。论文对白泥/PVC共混复合材料的增强机理进行了分析。经过表面改性处理的白泥粒径越小、分散越好、用量越大,则白泥与基体的界面黏结力更强。当复合材料受到应力作用,白泥粒子在引发空穴、银纹和中止银纹时能够消耗大量的应力,使得基体不易受到破坏,性能提高。复合材料的性能和微观形态分析表明,复合材料白泥的用量存在一个较佳范围。更多还原

【Abstract】 Alkali recovery section of chemical pulping will produce abundant of lime mud. At present,landfill is the main treatment of lime mud in our country,but this kind of treatment would lead to groundwater pollution,and it brings in a heavy burden to the solid waste treatment of paper mill.Then it’s very urgent to develop a new technology of treating lime mud with high efficiency.One superior surface modifier of lime mud had been screened out in this paper,and it took the lead in developing the technology of lime-mud/PVC blended composite in the world,the reinforce mechanism of the composite has been revealed and a new approach to apply the solid waste of lime mud efficiently has been opened up.The approach could convert the scrap resource of lime mud into the products of high added value,and speed up the development of the papermaking industry and material industry in our country.Drying and milling processes of lime mud were studied in this paper.On the condition of 150℃and dried for 120 min,free water and crystal water were removed, then the lime mud became absolutely dry.After milling for 30min,the average diameter of lime mud was decreased from 4.28μm to 2.00μm.When milling time exceeded 30min,the decrease range of average diameter was very little.Considered both the diameter and the cost of lime mud,the optimal milling time should be 30min.The hot-pressed process of lime-mud/PVC blended composite was studied.The condition of optimal hot-pressed process was hot-pressed temperature 175℃and molding time 12min.Titanate A,aluminate C and aluminate B were compared,then the results showed that aluminate B was the optimal modifier to the surface of lime mud and its appropriate dosage was 0.5%.The influence of lime mud dosage on the properties of lime-mud/PVC blended composite had been studied.The results indicated that,when the lime mud dosage was 25 phr,the lime-mud/PVC blended composite possessed preferable mechanics property,thermal property and processing rheological property:the impact strength of the composite was 28.33KJ·m^-2,the tensile strength was 41.51MPa,the flexural strength was 84.13MPa,the flexural modulus was 4273.67MPa,the hardness was 59.93 HRR and the VST was 112.60℃.Compared with the properties of pure PVC, the impact strength,tensile strength,flexural strength,flexural modulus,hardness and VST increased respectively 87.99%,0.41%,9.74%,35.68%,10.22%,36.32%.The impact of the lime mud/PVC blended composite toughened by the elastomer modifier has been studied.The results showed that,ACR was the comfortable impact modifier for the lime mud/PVC blended composite.It could increase the impact strength efficiently and it nearly had no effect on the rheological property of the composite.But the ACR would reduce the tensile strength,flexural strength,flexural modulus,hardness and VST of the lime mud/PVC blended composite.The effect of surface modifier on surface contact angle of lime mud was studied. The results suggested that,the titanate A,aluminate B and aluminate C can increase the surface contact angle of lime mud at different degree.After modified by 0.5% aluminate B,the surface contact angle of lime mud was close to PVC’s.The thermal weight loss curves of lime mud modified by aluminate B and unmodified were distinct greatly.It meant that the modified effect of aluminate B was better, correspondingly,the properties of lime mud/PVC blended composite modified by aluminate B were better.The research on the surface modifier was carried out by the means of FTIR, revealing the mechanism of lime mud modified by the surface modifier.The FTIR of the lime mud which was modified by titanate A and extracted later had no different with that of unmodified lime mud.It meant that the force between titanate A and lime mud was weak,and the modified effect of titanate A was not good.Among the 2960-2850 cm^-1of the lime mud FTIR,we found the lime mud modified by aluminate B or C and extracted later,owned one set of C-H stretch vibration absorption peaks,it benefited from the long-chain alkyl of aluminate modifier and the strong force between lime mud and aluminate.The micro-morphology of the composite was analyzed.The results showed that the impact fracture of pure PVC was coarse and showed itself to sheet.The impact fracture of unmodified-lime-mud/PVC blended composite was coarse and had many cavities,the characteristic of brittleness fracture was obvious.When the lime mud dosage was 25 phr,composite fracture had no obvious cavity but had the drawbench phenomenon and it was toughness fracture.When lime mud dosage was 40 phr, composite fracture was coarse and it had lots of cavities,the properties were serious damaged.The fracture of ACR/lime-mud/PVC blended composite had lots of microcellular area,and it looked like honeycomb,and its drawbench phenomenon was obvious,those meant that it was typical toughness fracture.Thermal weight loss of lime-mud/PVC blended composite was studied,and it showed that the thermal weight loss could be parted to four phases.It had no much different at the fast weight loss phase of all composites when lime mud dosage was diverse,and the weight loss rate was about 70%.But the weight loss temperature of degradation of HCl phase and ruleless degradation phase increased continually as the lime mud dosage increased.The weight loss temperature of two phases of pure PVC was started respectively from 220.45℃and 451.90.When the lime mud dosage was 25phr,the temperature was increased to 246.10℃and 462.90℃correspondingly.The reinforce mechanism of lime-mud/PVC blended composite was analyzed.It revealed that interface binding force between lime mud and PVC matrix would be more stronger when the modified lime mud was more finer,more dispersive and more much dosage.Modified lime mud could iniciate and suspend the craze in the polym matrix,then the composite would not be destroied when it was subjected to stress.But the analysis to the properties and microphology of composite showed that there was an optimal lime mud dosage.更多还原