【作者】 张夏丽；

【导师】 杜强国；

【作者基本信息】 复旦大学 ， 高分子化学与物理， 2008， 博士

【摘要】 复合材料是由有机高分子、无机非金属材料或金属等几类不同材料通过复合工艺组合而成的新型材料,具有单一材料所不具备的优异性能。高分子复合材料由于其优异的性能倍受人们的青睐,得到了飞速的发展,成为材料研究领域的热点之一,并已广泛应用于工业、农业、航空航天、国防、民用生活等各个领域。通过加入填料,尤其是功能性填料可以改善复合材料制品某些方面的性能,或赋予高分子复合材料制品全新的性能。反气相色谱法(IGC)是一种十分有效的表征方法,它可以较全面的了解材料表面的宏观热力学性质,研究表面热力学参数与表面的组成及形态的关系,它可以用于研究填充材料表面改性的效果,表征表面改性对聚合物复合材料的组成及形态的影响,从而预测填充材料与聚合物之间可能的相互作用;它可以表征材料的表面活性,从而为材料的使用、复合材料的设计提供理论依据。本论文的主要研究工作和结果如下:(1)采用IGC法表征了经过化学改性的碳纳米管的表面性能,通过对未改性的多壁碳纳米管(MWNTs)、用丙烯酸接枝改性的多壁碳纳米管(PAA-g-MWNTs)和表面带有羟基的多壁碳纳米管(MWNTols)等三种碳管的表面热力学参数的测试和计算,包括非极性表面能,表面极性吸附自由能、吸附焓和酸碱性参数等,定量表征了碳管的表面改性效果。研究结果表明碳管的表面经过化学改性后与未处理的碳管相比,表面能的色散分量大大降低,表面极性基团增加,这有利于防止碳管的自身吸附团聚,加强与聚合物之间的界面作用。丙烯酸接枝改性后的PAA-g-MWNTs,表面偏酸性,而羟基改性的MWNTols表面偏碱性。而碳纳米管经过化学改性后,表面带有少量基团的改性产物的表面性能很难用其他方法表征,如红外(FTIR)等。(2)以甲酚为第二酚单体,氢氧化镁为催化剂,在膨胀石墨的存在下,通过原位聚合合成了热固性酚醛树脂复合材料,石墨片层均匀分散在高分子基体中。对材料电性能分析发现该体系中石墨剥离片层的逾渗阈值在3.2 wt%,当石墨含量达到4 wt%时,电导率达到1 S/m,实现绝缘体和导体的相互转变。采用IGC法测试并计算了缩聚反应前后石墨的表面热力学性质,包括非极性表面能、极性表面吸附自由能、吸附焓和酸碱性等参数的变化,研究酚醛树脂和石墨的界面相互作用。结果表明缩聚反应后石墨片层的非极性表面能下降,极性吸附自由能、酸碱性参数等大大增加,表明表面极性增强。这样既降低了石墨自身的团聚,又加强石墨与树脂界面的相互作用,有利于石墨在树脂中的分散,形成网络结构,从而使电导率提高。(3)采用浸渍法制备了不同负载量的铑负载氢化β沸石(Rh/H-β-zeolite),利用IGC法研究了氢化β沸石(H-β-zeolite)和Rh/H-β-zeolite的表面性能,测试计算了沸石的表面吸附自由能、吸附焓、极性和非极性表面能,以及与极性探针之间的极性相互作用参数。结果表明H-β-zeolite的表面吸附性能由于铑的负载而发生改变,负载后比表面积、吸附焓和非极性表面能都有所下降。铑的负载显著增强了沸石对苯的吸附,由于这个特性,Rh/H-β-zeolite有望用于催化含苯的化学反应和分离工程。(4)由于铑负载沸石与苯的特殊相互作用,我们设计将负载1.0%铑的β-沸石添加在PVC膜中,利用铑沸石对苯的选择性吸附,以及沸石的巨大比表面积,用于渗透汽化法分离苯/环己烷混合溶液,提高膜对苯的选择渗透性。论文详细考察了了料液中苯的含量、沸石的添加量、沸石种类以及料液温度对复合膜的分离性能的影响。研究结果发现相同料液组成下,PVC/H-β-zeolite复合膜的选择性高于PVC膜,添加Rh/H-β-zeolite的复合膜的渗透汽化性能则高于添加H-β-zeolite的复合膜,这是由铑沸石对苯的选择吸附引起。膜的渗透通量可以用Arrhenius定律表征,拟合得到添加Rh/H-β-zeolite的复合膜的渗透表观活化能低于添加H-β-zeolite的复合膜。含7.0%的Rh/H-β-zeolite的复合膜具有最高的分离选择性。当沸石添加量低于7.0%时,随着沸石的添加量增加,膜的通量降低,分离因子增加,这主要是由于沸石的添加降低了膜的溶胀;当沸石添加量大于7.0%,膜的通量增加,分离因子下降,这可能是缺陷增多引起的。随着苯在料液中含量的增加,所有膜的渗透通量增大,选择性下降,这是由于苯的溶胀作用引起。更多还原

【Abstract】 Composite is a kind of novel materials consisted of polymer,nonmetallic or metallic materials.It has better properties than neat materials.People prefer polymer composites because of the excellent performance.They attract many researchers in the materials fields and have been applied in many fields,such as industry,agriculture, aviation and spaceflight,national defence et al.Fillers,especially functional fillers can improve some properties or bring some new properties for composites.Inverse gas chromatography（IGC） is an effective method to obtain the macro thermodynamic properties of the surface of solid materials and study the relationship between the thermodynamic parameters and the composition and conformation of surface.It can be used to characterize the effect of the surface modification of fillers and the influence of the surface modification on the polymer composites, consequently predict the interactions between fillers and polymers.It can be used to characterize the surface activity of materials and provide the theoretical base for the use of the materials and the design of composites.The main research content and results are as follows.（1） Inverse gas chromatography（IGC） was used to characterize the surface properties of pristine multi-walled carbon nanotubes（MWNTs）,as well as the poly（acrylic acid） sidewall covalently functionalized MWNTs（PAA-g- MWNTs） and hydroxyl group directly grafted MWNTs（MWNTols）.The surface thermodynamic parameters were calculated,including the dispersive component of the surface energy（γ_S^D）,the specific free energy(△G^AB),the enthalpy(△H^AB) of adsorption corresponding to acid-base surface interactions and the acidic（K_A） and the basic（K_D） parameters.The results show that chemical modification successfully reduces the dispersive component of the surface energy of MWNTs. Furthermore,MWNTs grafted with hydroxyl groups exhibit a more basic character,while MWNTs grafted with poly（acrylic acid） show a more acidic character,which can reduce the agglomeration of CNTs and strengthen the interaction between CNTs and polymer at the same time.IGC can provide useful complementary information on the changes resulted from the chemical modifications of the surface which is difficult for other technologies,such as FTIR et al.（2） Phenolic resin/expanded graphite（EG） composites were synthesized via in situ condensation polymerization of the monomers in the presence of foliated graphite. SEM observation showed that the graphite flakes were well dispersed in the phenolic resin matrix.The electrical conductivity of the composites was investigated as a function of the foliated graphite fraction.The composites containing graphite sheets exhibited an electrical conductivity percolation threshold with 3.2 wt%graphite content in polymer matrix.Inverse gas chromatography measurements were carried out to characterize the surface of the foliated graphite before and after condensation polymerization of phenolic resin using a series of both non-polar and polar acid-base probe gases.The data obtained indicated that the character of graphite surface changed after the polymerization of phenolic resin.The dispersive component of surface free energy decreased greatly.Before polymerization the graphite surface is predominantly acidic while the surface turns to basic after polymerization.The increased polarity of surface contributed to the stronger interactions between graphite and phenolic resin and the fine dispersion of expanded graphite in the matrix,and resulted in the low conductivity percolation threshold.（3） Zeolite loading rhodium（Rh）was prepared by the wet impregnation method using H-β-zeolite as support.Retention time of three n-alkanes（C5-C7）,cyclohexane, benzene,trichloroethylene and tetrachloroethylene on the Rh/H-β-zeolite catalysts （0.5-2.0 wt%of Rh） and H-β-zeolite were measured by inverse gas chromatography（IGC） in the 473.2～513.2 K temperature range.Standard free energy of adsorption,dispersive component of surface free energy of adsorbent and specific interaction parameters between polar probes and catalysts were evaluated.The results indicate that the adsorption characteristics of H-β-zeolite can be modified by rhodium.Surface area,enthalpy of adsorption and dispersive component of surface free energy of the zeolite decrease after the impregnation of rhodium.Besides,it was found that rhodium dispersed in the framework of H-β-zeolite had special adsorption for benzene which may be useful for making catalysts for certain reactions and separation engineering involving benzene in the future.（4） Because of the specific interaction between benzene and the zeolite loaded with rhodium（Rh/H-β-zeolite）,novel hybrid membranes were prepared by incorporating Rh/H-β-zeolite into polyvinyl chloride（PVC） for the pervaporative separation of benzene and cyclohexane.The characteristics of these membranes for separating benzene/cyclohexane mixtures were investigated by varying zeolite type,zeolite content,feed composition and operating temperature. The results showed that the pervaporation performances for membranes filled with Rh/H-β-zeolite were higher than those for membranes filled with H-β-zeolite which was caused by the special interactions between benzene and Rh/H-β-zeolite proved by IGC previously.And the PVC-RhB-7 membrane exhibited much lower activation energy E_J value compared to PVC-B-7 membrane.The membrane containing 7%of Rh/H-β-zeolite had the highest separation selectivity of benzene at all feed composition.When zeolite content is lower than 7%,the membrane flux decreases and separation factor increases with the increase of zeolite loading. The reason was that the zeolite particles were more resistant to membrane swelling and reduced possibility of loosening of polymeric chains.When zeolite content is higher than 7%,the membrane flux increases and separation factor increases because of the defects on the interface.更多还原