【作者】 王港；

【导师】 黄锐；

【作者基本信息】 四川大学 ， 材料加工工程， 2003， 博士

【摘要】 聚合物复合材料的制备是实现其高性能化的重要途径之一。聚合物基纳米复合材料由于综合性能优越倍受人们关注，特别是熔融共混法制备聚合物基纳米复合材料由于工艺简便极具研究和商业价值。本论文针对熔融共混法制备聚合物/纳米无机粒子复合材料中纳米无机粒子难分散的问题，根据“纳米粒子表面有限钝化”机理，利用自行设计的超高速混合器对纳米碳酸钙进行有效的表面处理，制得了高性能的聚丙烯/纳米碳酸钙复合材料。对超高速混合器的结构、工艺设计及纳米碳酸钙在超高速混合器中的受力情况进行了研究，并就纳米碳酸钙的表面处理工艺对复合材料的力学性能、结晶及流变性能的影响进行了细致分析，主要结果如下： 1．从纳米粒子团聚机理及高速混合器混合原理出发，自行设计了处理无机纳米材料用的超高速混合器，已获实用新型专利一项、申请发明一项专利。对超高速混合器结构及工艺参数，如桨叶与混合锅壁间隙、上下桨叶形式、桨叶倾角、侧壁切刀、雾化喷嘴、叶轮转速及切刀转速等进行了设计或选型。 2．首次对高速混合器设计中的重要参数--下桨叶最大回转半径与混合锅内壁间隙内的纳米粒子所受动态剪切进行了数学模拟。建立了间隙中纳米粒子受力的物理模型，并在物理模型的基础上建立了初步的数学模型。针对具体情况，对间隙内纳米碳酸钙所受最大剪切力进行了估算，计算出不同间隙、不同叶轮转速下纳米碳酸钙所受最大剪切力，结合不同粒径纳米碳酸钙团聚强度的计算，为超高速混合器的转速设计提供依据。计算结果间隙设计为0.5mm，高速混合器转速4000r/min以上，即可满足粒径70nm以上纳米碳酸钙磨蚀的要求。证明纳米碳酸钙团聚体在超高速混合器中有进行破碎及有效表面处理的可能性。为四川大学博士学位论文处理粒径更小的纳米碳酸钙，超高速混合器转速设计为6000r/min，间隙为0 .snlr以。 3.研究了高速混合器的放大问题，根据几何相似算法，对工业用超高速混合器的放大进行了讨论及计算，以其剪切与混合效果作为放大的依据，在IOL试验机的基础上成功放大并制造了500L工业用超高速混合器。高速混合器的放大计算目前尚未见文献报道。 4.在利用高速混合器处理纳米碳酸钙制备纳米碳酸钙/聚丙烯复合材料的研究中，发现新型超高速混合器(600or/mln)比传统高速混合器(1 000一2000对min)能更有效地对纳米碳酸钙粒子进行表面处理。扫描电子显微镜(SEM)观察表明经超高速混合器处理的纳米碳酸钙即使添加量较高(35%左右)，在聚丙烯中大多数也能以原生纳米粒子状态分散，从而获得性能优异的纳米碳酸钙/聚丙烯复合材料，冲击强度较普通高速混合器制备的复合材料高150%，较纯聚丙烯高370%。经超高速混合器处理后的纳米碳酸钙一般在聚丙烯中添加35wt%时，复合材料的冲击强度才达最大值，在保证复合材料力学性能的同时，添加量较以前文献中有大量提高。 5.新型超高速混合器中采用剪切为主的周向流叶轮比传统的以混合为主的轴向流叶轮能更有效地对纳米碳酸钙进行表面处理，所制得复合材料冲击强度前者比后者最大可提高33%(添加35wt%);而且采用同样的剪切型叶轮时较高转速(6000r/min)可比较低转速(3000r/min)获得更好地处理效果。所制得复合材料冲击强度前者比后者最大可提高95%(添加35wt%)。说明纳米粒子的表面处理和分散需要较强的剪切力与较高的能量。 6.研究表明，应用超高速混合器对纳米碳酸钙进行表面处理时，与处理微米级填料不同，硬脂酸表面处理剂比含有较长有机键的钦酸醋、铝酸醋等偶联剂效果更好。说明纳米碳酸钙的表面处理机理已与普通填料不同，表面处理剂不再发挥界面粘接的作用，其主要作用已变为适当降低纳米粒子的表面活性，防止其在聚合物基体中的团聚。利用超高速混合器对纳米碳酸钙进行表面处理时，表面处理剂的用量也非常重要，处理微米级填料的单分子层理论计算处理齐U用量的方法也不再适用。表面处理剂较合适用量经实验确定为4v改%左右，此用量可较好地解决纳米碳酸钙良好分散与保持其高表面活性之间的矛盾。且四川大学博士学位论文在此添加量下，不可能对纳米粒子表面形成分子层包覆，因此与微米级粒子的表面处理已有本质的区别。通过表面处理剂种类、用量对纳米碳酸钙/复合材料力学性能及纳米碳酸钙分散形态影响的研究，初步验证了“纳米粒子表面有限钝化机理”。 7.纳米碳酸钙的加入对纳米碳酸钙/聚丙烯复合材料的冲击性能影响显著，纳米碳酸钙经过超高速混合器较好的表面处理，复合材料的冲击强度可提高4倍以上，对不同粒径的纳米碳酸钙，粒径越小，增韧效果越明显。但对复合材料的增强效果影响不明显，在纳米碳酸钙加入量较少时(10wt%以下)，拉伸强度略有提高，最多可提高ro%，之后随纳米碳酸钙的加入呈缓慢下降趋势，但拉伸模量则随纳米碳酸钙加入量增大呈上升趋势。与传统的橡胶或弹性体增韧聚丙烯方法相比，达到相同冲击强度时，纳米碳酸钙/聚丙烯复合材料拉伸强度及模量有大幅度提高。 8.毛细管流变研究表明，?更多还原

【Abstract】 Preparation of polymer composites is one of the important methods to realize high performance of polymer materials. Polymer/nano-CaCOs composite have been rapidly developed recently because of their excellent comprehensive properties, in particular, the composite prepared with melt dispersion technology have great commercial value as consequence of convenient and economical technology. Using the ultra-high-speed mixer we designed , the key problems of PP/nano-CaCO3 were studied in detail on the paper, including the design of ultra-high-speed mixer, nano-CaCO3 surface modification and dispersion law of nano-CaCO3 in polymeric melt base on finite passivation theory of nano-CaCO3 surface and the rheological and crystallization behaviors of PP/nano- CaCO3 blends. The goal of the paper was to find whys of these problems and how to solve these problems, in order to promote development of nano material industry in the field of theory and practice. The key works and conclusions were listed as follows:1.According to the aggregation law of nano-particle and mixing theory of high-speed mixer, a kind of ultra-high speed mixer was designed by us to treat inorganic nano-particle, which has obtained a new type patent and is applying inventive patent. Structure and technologic parameters of the ultra-high speed mixer has been designed or chosen, such as the clearance between vane and wall, shape of vane, obliquity of vane, shear blade of side wall, atomization muzzle, rotate speed of impeller and shear blade, etc.2.For the first time dynamic shear bearing nano-particle was mathematics simulated in the clearance between the most circumgyrate radius of underside vaneand inside chamber of mixer. Physics model of stress of nano-particle in the clearance bearing was build, and on the basis of physics model elementary mathematics model was build. Aim at actual case to estimate and calculate the most shear stress of nano-particle in the clearance, and achieve the most shear stress of nano-particle in the difference clearance and rotate speed of impeller, which combining with calculation of aggregation intension of nano-particle offer evidence to design rotate speed of the ultra-high speed mixer. The result shows that when the clearance is designed as 0.5mm and rotate speed exceed 4000r/min, the ablation request of nano-particle could be satisfied whose diameter exceeds 70nm. This result approves the possibility, namely nano-CaCO3 agglomerate was treated effectively and break inhigh speed mixer. In order to treat smaller diameter nano-CaCO3, rotate speed of the ultra-high speed mixer is designed as 6000r/min and the clearance is designed as 0.5mm.3.The magnifition of the ultra-high speed mixer is studied. According to geometry analogical arithmetic, the magnifition of the ultra-high speed mixer that applied to industry is discussed and calculated, and effect of shear and blend are acted as amplificatory foundation. On the basis of 1OL lab machine, the ultra-high speed mixer with volume 500L is magnify and manufacture successfully that can be applied to industry. The magnifition calculation of the high-speed mixer has not been reported at present.4.In the study of preparation nano-CaCO3/PP composite using high-speed mixer treating nano-particle, the phenomenon is found that the new ultra-high speed mixer (6000r/min) is more effective than traditional high-speed mixer (1000-2000r/min) to treat surface of nano-CaCO3. Using SEM find that nano-CaCO3 treated by the ultra-high speed mixer can disperse mostly with crude nano-particle state in matrix PP, even if its content is very high (about 35%). So excellent performance nano-CaCO3/PP composite could be gained, and impact strength is higher 150% than one of composite treated by normal high-speed mixer, and 370% than pure PP. When the content of nano-CaCO3 is 35wt%, the peak of impact strength of composite appears. Content of nano-CaCO3 increase largely than one of prevenient report, aswell as mechanic performance of composite could be kept.5.The new ultra-high speed mixe更多还原