【作者】 陈晓梅；

【导师】 沈经纬；

【作者基本信息】 四川大学 ， 材料加工工程， 2002， 博士

【摘要】 本论文以制备和研究新型高性能聚合物导电复合材料为目的，跟踪和借鉴国内外在聚合物／无机物纳米复合、聚合物／聚合物原位复合领域的最新研究成果，制备和研究了以聚丙烯（PP）为基体、膨胀石墨（EG）为导电填料、尼龙66（PA66）为改性剂、马来酸酐接枝聚丙烯（gPP）为EG插层剂和PP—PA66增容剂的二元及多元导电纳米复合材料和纳米复合与原位复合组合复合材料，取得了以下主要研究成果： 1．首次采用溶液插层法成功制备了gPP／EG导电纳米复合材料，其导电逾渗阈值（φ_c）仅0.67vol％（1.6wt％），远低于常规熔体混合法制得gPP／EG、PP／EG导电复合材料的φ_c值（3.82vol％、5.48vol％）；而其逾渗临界指数（b）达9.61，远高于PP／炭黑导电复合材料的b值（2.84～3.79）。证明gPP分子通过溶液插层已充分插入EG网络纳米尺度的石墨片层之间和从纳米到微米尺度的孔隙之中，所形成的EG—gPP复合网络具有大的结构占有体积，因而材料具有低φ_c、高b和优异的导电性，3.90vol％EG含量下，室温体积电导率达2.49×10^-3S／cm。 2．首次采用溶液插层法成功制备了PP／gPP／EG导电纳米复合材料，其φ_c值为6wt％，明显低于常规熔体混合法制得相应导电复合材料的φ_c值（11wt％）。8wt％EG含量下，前者的室温体积电阻率仅3.81×10⁷Ωcm，而后者的为3.22×10¹⁶Ωcm。证明溶液插层时部分PP分子借助与gPP的良好相容性而随gPP分子一起插入了EG网络的孔隙中，形成了稳定的具有较大结构占有体积的EG—gPP—PP纳米复合网络，因而材料具有低φ_c值和高导电性。 3．首次采用将PP／PA66熔体共混、再与溶液插层制备的gPP／EG母料熔体共混的方法，成功制备了PP／PA66／gPP／EG导电纳米复合材料，其φ_c值为4wt％，低于不含PA66时的φ_c=6wt％。证明部分PA66以粒子形式嵌入EG—gPP—PP纳米复合网络之中，增大了该网络的结构占有体积，另一部分PA66粒子存在于PP基体之中，增大了分散在PP基体中EG的浓度，产生了双逾渗效应，上述两种作用使材料的φ_c值降低。 4．首次采用挤出—拉伸—注塑法制备了PP／PA66、PP／PA66／gPP原位复合材料，取得了增强又增韧的效果。PP／PA66／gPP=85／15／0、85／15／4原位复合材 聚丙烯／M龙66／接枝聚丙烯／石墨二元及多元导电纳米复合材料的研究料的拉伸强度（。t＝34．0、38．6MPS）分另比 PP（Ot＝31．OMPP）提高 10％ 和 25％，缺口冲击强度（a。＝＝6．6、5．ZkJ／叶）分别＊PP（a。二4．skJ／。’）提高47％和 16％。发现和分析讨论了 PP仔A66原位复合材料中 PA66相形态随其含量ud)的变化中出现的未见文献报导的新现象：PA66纤维直径或宽度存在分散性，此分散性随Cd先变小后变大，另外PA66未成纤粒子数随Cd而趋增多。并据此解释了材料Ot随Cd的变化。 5．首次采用将PP仔A66巾PP原位复合、再与溶液插层制备的gPP北G母料在 PA66熔点以下的温度下共混的方法，成功制备了 PP”A66培PP亿G原位复合一纳米复合组合复合导电材料，其介值仍为4Wt兄与相应非组合复合导电材料的 ＆c相同，低于不含 PA66时的 fc＝6。t％。证明相互发生粘连、与 PP基体界面结合良好的PA66纤维和未成纤粒子基本上不妨碍EG—gPP网络粒子在PP基体中的分散，并有诱导它们在PP—PA66界面区域富集分布的趋势，产生双逾渗效应，从而使材料的＆。降低；同时借助PA66纤维对PP基体的增强和增韧作用，使组合复合导电材料的力学强度和冲击韧性高于非组合复合导电材料。更多还原

【Abstract】 In attempt to prepare and investigate the novel high-performance electrically conductive polymer composites, the binary and multicomponent electrically conductive nanocomposites as well as the combined nano and in-situ composites were prepared with polypropylene (PP) served as the matrix, expanded graphite (EG) as a conductive filler, nylon 66 (PA66) as a modifier, and maleic anhydride grafted polypropylene as an EG intercalater and the compatibilizer of PP-PA66, based on the state-of-art development in the realm of polymer/inorganic nanocomposites and polymer/polymer in-situ composites domestically and overseas. The main outcomes are obtained as follows:1. The gPP/EG electrically conductive nanocomposites were firstly prepared via solution intercalation. The percolation threshold at room temperature (?C) of the nanocomposites was merely 0.67 vol% (1.6 wt%), which was much lower than that of gPP/EG and PP/EG electrically conductive composites (3. 82 vol%, 5. 48 vol%) prepared via conventional melt-mixing. The critical index (b) was up to 9.61, which was much higher than that of PP/carbon black electrically conductive composites (2. 84~3. 79). This demonstrates that gPP molecules have intercalated into the nanoscale interlayers of graphite sheets as well as the pores (from nanoscale to microscale) of EG networks. The large structure-occupation of the formed EG-gPP networks results in low ?c, high b and excellent conductivity of the nanocomposites, for instance, the electrical conductivity at room temperature is up to 2.49X10-3 S/cm at 3.90 vol% EG content.2. The PP/gPP/EG electrically conductive nanocomposites with ?c of 6 wt%, which was much lower than that of corresponding electrically conductive composites (11 wt%) prepared via conventional melt-mixing, were firstly achieved via solution intercalation. At EG content of 8 wt%, the volume resistivity at room temperature of the former was only 3.81X 107 ?cm, whereas that of the latter was 3.22 X 1016 ?cm. This demonstrates that during solution intercalation, partial PP molecules intercalate into the pores of EG networks together with gPP molecules by means of their favorable compatibility, which leads to the stable EG-gPP-PP nanocomposite networks with larger structure occupation volume. As a result, the nanocomposites have lower ?c and higher conductivity.3. The PP/PA 66/gPP/EG electrically conductive nanocomposites with ?C of 4 wt%, which was lower than that of nanocomposites (6 wt%) without PA66, were firstly prepared via melt-mixing PP/PA66 pre-blends with gPP/EG master batches obtained via solution intercalation. This demonstrates that fractional PA66 intercalates into the EG-gPP-PP nanocomposite networks in the form of particles, which results in the increase of structure-occupation volume of the network, while the other PA66 particles are dispersed in the PP matrix, enhancing the EG concentration in PP matrix and consequently presenting the double percolation effect. The two effects mentioned above make the ?c of composites play down.4. The reinforced and toughened PP/PA66 and PP/PA66/gPP in-situ composites were firstly prepared via extrusion-drawing-injection method. The tensile strength (?t=34.0, 38.6 MPa) of PP/PA66/gPP=85/15/0 and 85/15/4 in-situ composites are enhanced by 10% and 25% than that of PP (?t=31. 0 MPa) respectively, and their Izod impact strength ( a k=6. 6, 5. 2 kJ/m2) are improved by 47% and 16% than that of PP (a k=4. 5 kJ/m2) respectively. The new phenomena, never previously reported in the references, of the PA66 phase morphology in the PP/PA66 in-situ composites varying with PA66 contents (Cd) are revealed as follows: the diameter or width of PA66 fibers has dispersity, which becomes smaller first and then larger lately with Cd. Additionally, the number of PA66 unfibrillized paticles increases with Cd. This can interpret the variation of ?t with Cd.5. The PP/PA66/gPP/EG combined in-situ and nano electrically conductive composites with ?C of 4 wt%, which was lower than that (?C =6wt%) of composites without PA66更多还原