【作者】 白晓艳；

【导师】 王清文；

【作者基本信息】 东北林业大学 ， 生物材料工程， 2008， 博士

【摘要】 木塑复合材料的研制与生产应用对于寻求实体木材的替代材料和利用木材加工剩余物具有重要意义,也是回收塑料再生利用的有效途径之一。本文采用SJSZ50/105锥型双螺杆挤出生产设备,使用改性AC发泡剂,采用结皮发泡方法,以聚氯乙烯（PVC）为基体树脂,速生杨木木粉（简称木粉）为填料,无铅复合稀土为热稳定剂,制备低发泡木粉/PVC复合材料（WF-PVC）。主要研究内容:（1）对AC发泡剂进行了改性研究,并将改性AC发泡剂应用于木粉/PVC复合材料的制备中;（2）研究了发泡木粉/PVC复合材料界面改性及其对材料性能的影响;探索了加工过程中几种主要助剂及用量与材料的性能、微观结构之间的关系;（3）通过研究发泡调节剂、抗冲击改性剂对低发泡木粉/PVC复合材料熔体流变性能的影响,探索了熔体流变性能与加工性能、材料物理力学性能之间的关系。（4）研究了低发泡木粉/PVC复合材料加工工艺与材料性能的关系。（5）研究制备了适合低发泡木粉/PVC复合材料的无铅复合稀土热稳定剂,并研究了其对木粉/PVC复合材料热稳定性能及力学性能的影响;（6）通过对木粉/PVC复合材料燃烧和热解性能的研究,设计了高效阻燃抑烟剂AMPC,研究了其对木粉/PVC复合材料燃烧性能和力学性能的影响。主要成果:（1）进行了AC发泡剂的改性研究,使发泡剂分解温度在165～180℃范围内可控,分解的诱导时间缩短到10分钟,与木粉/PVC复合材料的加工温度相适应。本研究中使用改性AC发泡剂1.2份,获得的发泡材料性能较好。（2）在木粉/PVC复合材料界面改性研究方面,采用偶联剂（钛酸四丁酯偶联剂、ND1010钛酸酯偶联剂、硅烷偶联剂）、异氰酸酯和NaOH溶液等对木粉进行处理,同时也采用在配方中加入相容剂MAPP的方法,制备低发泡木粉/PVC复合材料,研究界面改性对低发泡木粉/PVC复合材料性能的影响。①采用相同的偶联剂处理木粉,在弹性模量方面,低发泡木粉/PVC复合材料的弹性模量比未发泡的木粉/PVC复合材料降低40%;采用不同偶联剂对木粉进行改性,对低发泡木粉/PVC复合材料的弹性模量影响不明显,低发泡木粉/PVC复合材料的弹性模量,不仅与木粉处理方法有关,还与获得的材料中泡孔结构有关。低发泡木粉/PVC复合材料的冲击强度与未发泡木粉/PVC复合材料相比得到提高,提高的幅度与界面改性处理有关。低发泡木粉/PVC复合材料冲击强度的改善不仅与界面结合有关,还与加工过程的熔体强度、形成的气泡孔形态有关。②在低发泡木粉/PVC复合材料中,采用偶联剂对木粉进行改性处理都能降低复合材料的密度,其中,用钛酸四丁酯偶联剂处理粒径为80～100目木粉,使低发泡木粉/PVC复合材料密度最低达到1.02g/cm³,与用未改性木粉制备的低发泡木粉/PVC复合材料密度1.21g/cm³相比明显降低,此时材料冲击强度明显提高。③不同的木粉改性方法,影响低发泡木粉/PVC复合材料加工过程中熔体粘度。与采用未改性木粉填充的体系相比,除了用钛酸酯偶联剂ND1010改性木粉的体系熔体粘度增加之外,其他改性方法都使体系粘度降低,其中使用MAPP改性的低发泡木粉/PVC复合材料熔体粘度降低最明显。（3）低发泡木粉/PVC复合材料成型技术有自身的特殊性。低发泡木粉/PVC复合材料的加工对原料、配方、挤出设备、模具等生产工艺都有特殊要求,影响发泡的因素较多。本研究使用实验室自行研制开发的SJSZ50/105锥形双螺杆挤出设备,挤出机机筒为四段控温。采用发泡模具和多段冷却真空定型装置。由于PVC树脂、木粉及发泡剂都是对温度敏感性材料,使低发泡木粉/PVC复合材料加工生产技术的难度增加。各种技术参数的设定与选用的生产设备、使用的原料有直接关系。本研究中挤出机机筒温度设定在150～175℃范围内,挤出压力控制在17MPa以上,选用SG5型PVC树脂,控制木粉的含水率在1%以下,加入适量发泡调节剂ZB-530。有待于进一步解决的问题是设备运行一定时间后出现的炭化现象。（4）制备了适合低发泡木粉/PVC复合体系的复合稀土热稳定剂以无毒硬脂酸镧为主稳定剂,采用正交实验设计得到了复合稀土稳定剂的最优基础配方。该稳定剂与季戊四醇、有机锡稳定剂之间有协同作用。自行开发设计的复合稀土稳定剂LS具有无毒及透明性,在低发泡木粉/PVC复合材料配方中使用该稳定剂10份,热稳定效果较好,同时能提高材料的力学性能,尤其在改善低发泡木粉/PVC复合材料冲击性能方面效果显著。（5）研究了木粉/PVC复合材料的阻燃抑烟性能。采用锥形量热仪分析、热重分析和热裂解-气相色谱-质谱分析（Py-GC-MS）手段揭示了木粉/PVC复合材料中木粉与PVC之间相互作用关系;研究了金属氧化物CuO、La₂O₃对木粉/PVC复合材料燃烧和热解以及阻燃抑烟性能的影响;制备了高效、无毒复合阻燃抑烟剂AMPC,研究了其对材料燃烧性能的影响。①木粉/PVC复合材料的燃烧和热解过程是复杂的。在木粉/PVC复合材料燃烧和热解过程中,木粉和PVC之间存在相互作用,其中,PVC促进了木粉的热解,木粉又推迟了PVC的降解过程,同时,木粉促进了PVC热解过程的交联成炭,提高体系成炭量。木粉/PVC复合材料的热降解行为,具有更多的PVC材料降解的特征。与PVC材料燃烧过程相比,木粉/PVC复合材料燃烧过程中平均热释放速率（av-HRR）和总热释放（THR）分别降低44%和9.2%,同时,总烟产量（TSP）和平均比消光面积（av-SEA）分别下降25.8%和29.9%,可见木粉的加入对PVC材料燃烧过程中的热释放和烟释放有抑制作用。②将木粉/PVC复合材料在500℃热裂解,对其热解产物进行Py-GC-MS分析。结果表明:木粉的加入使PVC热解产物的组分发生了明显变化。与PVC热裂解组分相比,HCl的释放量降低了59.7%,脂肪族化合物含量从2.49%增加到38.58%,芳香族化合物含量的比例下降96.5%,进一步解释了木粉/PVC复合材料在燃烧过程中烟释放量降低的主要原因。热裂解过程产生的含氯化合物和多环化合物这类有害物质含量明显降低,减少了木粉/PVC复合材料燃烧对人体健康和环境的危害。同时也发现在木粉/PVC复合材料中,由于木粉的存在,推迟了PVC的热解过程,改变了PVC热解途径,使其主要向着生成交联中间体,促进交联成炭的方向进行。③金属氧化物CuO和La₂O₃对木粉/PVC复合材料均有阻燃作用,在燃烧和热解过程中均能增加成炭量。CuO使木粉/PVC复合材料燃烧过程中热释放速率（HRR）、总热释放（THR）、烟释放速率（SPR）、总烟产量（TSP）等参数下降显著,表现出明显的阻燃与抑烟效果。④合成的新型阻燃抑烟剂AMPC能显著促进复合材料热解挥发性产物的充分燃烧,明显降低木粉/PVC复合材料燃烧时的烟释放量。AMPC的阻燃机理为凝聚相阻燃机理。木粉含量为30%～70%的木粉/PVC复合材料,用5份AMPC对其进行阻燃处理,总烟释放与未阻燃处理材料相比降低幅度在39.1%～57.4%。单位质量的一氧化碳产量降低37.5%。AMPC具有无毒、添加量少、抑烟效果显著的特点。更多还原

【Abstract】 Low Foaming wood-flour/PVC composites（WF-PVC） was prepared by crust foaming extrusion of the mixture of wood-flour as filler,poly（vinyl chloride）（PVC） as matrix, modified AC as foaming agent and rare-earth stabilizer using a SJSZ50/105 conical twin screw extruder.The study was carried out in the aspects as follows:（1） The modification of AC foaming agent（2） The interracial modification of foaming wood-flour/PVC composites and the effect of interracial modification on properties of composites（3） The influence of the additives on micro-morphology and properties of foaming wood-flour /PVC composites.The effects of foaming control agent ZB-530 and impact modifier ACR and CPE on rheological properties of the low foaming wood-flour/PVC composites as well as the relationship between rheological properties,processing and mechanical properties of foaming wood-flour/PVC composites were studied.（4） The relationship between the processing and properties of foaming wood-flour/PVC composites.（5） Composite lead-free rare-earth stabilizer was prepared and its influence on thermal stability of PVC and WF-PVC composites was studied.（6） The properties of fire-retardancy and smoke-suppression of WF-PVC composites were studied and a new fire retardant for WF-PVC was synthesized.Main research results of this study are as follows:（1） AC foaming agent was modified to apply to WF-PVC composites.The results showed that the induction time of modified AC foaming agent was shortened to 10min and the decomposition temperature can be controlled in the range from 165℃to 180℃,which is consistent with the processing temperature of foaming wood-flour/PVC composites.Improved properties were obtained when added this modified AC foaming agent 1.2phr to the formulation of foaming wood-flour/PVC composites.（2） The effects of interfacial modification on the properties of low foaming wood-flour /PVC composites were studied using coupling agents（tetrabutyl titanate,ND 1010 titanate coupling agent,silane coupling agent,isocyanate） and sodium hydroxide solution and interracial compatibillizer MAPP.The results are as follows:①There is difference between foaming and non-foaming wood-flour/PVC composites in flexural modulus.Flexural modulus of foaming wood-flour/PVC composites was decreased 40%compare with that of non-foaming composites when using the same treating agent to modify wood-flour.Flexural modulus have little changed when treated wood-flour with different treating agent for the same type of composites.Impact strength of foaming wood-flour /PVC composites was not only related to the treating agent but also affected by the cell morphology.Compare with non-foaming wood-flour/PVC composites,the impact strength of foaming wood-flour/PVC composite was enhanced and the change range was related to the interfacial modification of foaming wood-flour/PVC composites.Meanwhile,the impact strength was also affected by the melt strength and cell morphology.②Apparent density of low foaming wood-flour/PVC composites was decreased when using treated wood-flour in composites.The lowest apparent density among all samples was obtained when wood-flour was treated using tetrabutyl titanate and particle size is 80～100 mesh in formula.③Wood-flour with different treatment has influence on the melt viscosity of low foaming wood-flour/PVC composites.In the study,compare with the system of no-treated wood-flour,the melt viscosity of samples with treated wood-flour decreased.Besides the sample,in which wood-flour was treated with titanate coupling agent ND1010,the melt viscosity was increased.Melt viscosity of the sample was decreased most significantly in all samples when treated wood-flour with MAPP（3） The processing technology of low foaming wood-flour/PVC composites has its own characteristics.Compared with non-foaming wood-flour/PVC composites,the technique of the raw materials and formulation design,technology and equipment in the process of foaming wood-flour/PVC composites extrusion has special technology requirement.More factors affect the foaming process and the properties the product.In this research,the extrusion equipment SJSZ50/105 conical twin screw extruder was designed and assembly by our laboratory. Because of high temperature sensitivity of PVC,wood-flour and foaming agent decomposition temperature,all which made the producing technology of low foaming wood-flour/PVC composites becoming more difficult.Some deficiencies and questions such as the carbonization phenomenon when the equipment operating continuous has no avoided,that require further study.（4） Lead-free rare-earth thermal stabilizer was prepared which are suitable for foaming wood-flour/PVC composites.The orthogonal test design was adopted to study the optimal formula of composite lead-free rare-earth stabilizer based on rare earth stearate.Results showed that synergistic effect occurred between composite stabilizer and pentaerythritol or organotin stabilizer.Composite rare-earth stabilizer LS was prepared which is nontoxic, excellent in transparency and good thermal stability was obtained when used this stabilizer about 10phr in foaming wood-flour/PVC composites formula.Meanwhile,mechanical properties of low foaming wood-flour/PVC composites,especially in impact properties,were improved obviously when LS was used. （5） Fire-retardancy and smoke-suppression of wood-flour/PVC composites was investigated.The results revealed that there occurs the relationship between wood-flour and PVC in composites using cone calorimeter testing,TGA and Py-GC-MS analysis.The effects of different metal oxides CuO and La₂O₃ on the properties of combustion and degradation of wood-flour/PVC composites were investigated.High effective fire retardant AMPC was synthesized and applied to the formula of wood-flour/PVC composites.The results are listed in following:①The process of combustion and degradation of wood-flour/PVC composites is complicated.During the combustion and degradation of wood-flour/PVC composites the interaction occurred between wood-flour and PVC,in which decomposition of wood-flour was accelerated and the degradation of PVC was delayed.Meanwhile,residues of wood-flour/PVC composites were improved and the release rate of hydrogen chloride was decreased because of the addition wood-flour to PVC.Thermal degradation of wood-flour/PVC composites has more characteristics of PVC.During combustion of wood-flour/PVC composites average heat release rate（av-HRR）,total heat release（THR）,total smoke production（TSP） and average specific extinction area（av-SEA） was decreased 44%,9.2%,25.8%and 29.9%,respectively, compare to the burning of PVC.Therefore,the addition of wood-flour to PVC could obviously inhibit the heat release and smoke release.②The results of Py-GC-MS analysis at 500℃showed that the thermal degradation products of wood-flour/PVC composites were different from that of PVC.The yields of HCl and aromatic compounds decreased 59.7%and 96.5%,and aliphatic compounds increased from 2.49%to 38.58%.This further explained the reason that smoke release decreased obviously during the combustion of wood-flour/PVC composites.It was found that the degradation process of PVC was delayed by the addition of wood-flour and the path of PVC degradation was in the direction of forming cross-linked intermediates,promoting charring.③Metal oxides CuO and La₂O₃ play the role of flame-retardant in wood-flour/PVC composites and promote charring during combustion and degradation.Parameters,heat release rate（HRR）,total heat release（THR）,smoke production rate（SPR） and total smoke production （TSP）,obtained from cone calorimeter testing were decreased obviously by the addition of CuO to wood-flour/PVC composites.CuO is an effective fire-retardant which is effective in smoke suppression.④A novel fire retardant AMPC was synthesized which significantly promotes the complete combustion of the volatile components of the pyrolysis products of the wood-flour /PVC composites and made smoke release decreased obviously.The results showed AMPC is functioned in the condensed phase.When 5 phr AMPC was added to the formula of wood-flour/PVC composites with wood-flour content of 30%and 70%,total smoke production was decreased 39.1%and 57.4%respectively compare with the control（no AMPC）.更多还原