【作者】 谭井华；

【导师】 罗远芳； 贾德民；

【作者基本信息】 华南理工大学 ， 材料学， 2012， 博士

【摘要】 有机/无机杂化材料是一种在纳米水平均匀分散的多相材料，兼备有机聚合物和无机材料的性能优势。它们可以是无机改性有机聚合物，也可以是有机改性无机材料。通过调节有机相与无机相的组成、比例及结构形态，可实现对其性能或功能的“剪裁”和“组装”。本论文通过机械混炼原位反应法制备了新型聚氨酯/白炭黑（PU/silica）有机-无机杂化材料。这种新型PU/silica杂化材料在无扩链剂和交联剂情况下，直接通过PU预聚体链端的-NCO与白炭黑表面的-OH发生化学键合反应，形成有机/无机杂化网络，其中白炭黑充当了PU交联剂和扩链剂的作用。该方法不仅在理论上创新性显著，而且具有工艺简单、成本低廉、环境污染小、能显著提升材料的综合性能等优点。由于PU预聚体和白炭黑的混合物粘度大，易与橡胶均匀混合并同步交联，本论文通过机械共混法，采用PU/silica杂化材料对极性的丁腈橡胶（NBR）、非极性的丁苯橡胶（SBR）分别进行互穿网络改性，制备了相容性好、综合性能优异的NBR/(PU-silica)和SBR/(PU-silica)两种互穿网络聚合物（IPN），深入研究和探讨了PU/silica对橡胶的改性机理以及IPN的结构与性能之间的关系。通过机械混炼原位反应法制备了PU/silica有机-无机杂化材料。红外光谱（FTIR）、X射线光电子能谱（XPS）、固体核磁共振（29Si-HMR）和差示扫描量热法（DSC）分析结果表明，在一定温度和压力下，PU预聚体链端的-NCO与白炭黑表面的-OH发生化学键合反应，形成有机/无机杂化网络。固化动力学研究表明PU/silica体系最佳固化温度为120℃，其固化反应遵循一级反应动力学规律，表观反应活化能为76.16kJ/mol。由n(NCO):n(OH)等于2.3:1制备的NCO封端PU预聚体中，当白炭黑表面的羟基与PU预聚体中NCO当量比为1.06:1.00时，得到的杂化材料的交联网络最完善，综合性能最好。与异佛尔酮二异氰酸酯（IPDI）相比，由2,4-甲苯二异氰酸酯（TDI）制备的杂化材料结晶性能更强，微相分离程度更大，其综合力学性能更优。由聚己二酸乙二醇酯二醇（PEA1000）制备的PU/silica杂化材料的综合性能优于聚四氢呋喃二醇（PTMG1000）、聚氧化丙烯二醇（PPG1000）和聚己内酯二醇（PCL1000）的，其拉伸强度和撕裂强度高达48.3MPa和128.0kN/m，并且同时保持高达557%的扯断伸长率。通过机械共混法用PU/silica杂化材料对NBR、SBR进行互穿网络改性，制备了NBR/(PU-silica)和SBR/(PU-silica)两种IPN材料。固化动力学研究表明，IPN材料中橡胶体系（NBR或SBR）和PU/silica体系各自分别按照自由基聚合和加成反应机理进行交联，二者交联速率匹配，形成同步互穿聚合物网络，且橡胶与PU/silica两个体系相互之间有促进交联作用。PU/silica的加入降低了IPN材料的硫化活化能。透射电镜（TEM）、NBR橡胶与PU/silica相界面能谱扫描结果表明橡胶与PU/silica两相间发生了网络互穿缠结。NBR橡胶与PU/silica两组分的180°T剥离实验结果是橡胶基体发生断裂，表明两相界面结合性好。动态力学性能测试（DMA）结果显示IPN材料中橡胶体系的Tg向PU/silica体系的Tg方向靠拢，进一步表明两组分相容性得到改善。橡胶与PU/silica两相界面网络互穿缠结是IPN材料两组分间相容性提高和综合性能优异的主要原因。随着PU/silica用量的增加，IPN的综合力学性能提高，IPN中PU/silica相畴的连续性增加。当PU/silica用量为50wt%左右时，NBR与PU/silica形成明显的双相连续结构；而SBR与PU/silica的双相连续性稍差。PU/silica对NBR和SBR的耐屈挠龟裂性能和耐磨性能均有显著的改善作用。添加50wt%PU/silica杂化材料时，NBR/(PU-silica)-IPN和SBR/(PU-silica)-IPN的一级屈挠龟裂寿命分别达到62万次和56万次；其阿克隆磨耗体积分别0.71cm3/1.61km和0.94cm3/1.61km，相对于纯NBR和SBR分别下降73.8%和79.0%。IPN材料抗屈挠龟裂性能的显著提高主要是由于相互贯穿的柔性橡胶网络和刚性PU/silica网络两者之间的相互协调作用，以及IPN材料中PU/silica相硬段微区的氢键松弛应力阻止裂纹扩展。不同种类二元醇制备的IPN材料中，由PEA1000制备的NBR/(PU-silica)-IPN和SBR/(PU-silica) IPN材料的综合力学性能最好，其拉伸强度、扯断伸长率和撕裂强度分别达到34.3MPa、620%、59.0kN/m和27.2MPa、595%、50.4kN/m。更多还原

【Abstract】 Organic/inorganic hybrid materials are multiphase materials evenly dispersed at thenanometer level. It possesses the advantage of both organic polymer and inorganic materials.It can be organic polymers modified by inorganic materials, or inorganic materials modifiedby organic polymers. The function of the materials can be tailored and assembled throughadjusting the compositions and proportions of the organic and inorganic phases.Novel polyurethane (PU)/silica organic/inorganic hybrid materials were prepared bymechanical blending in situ reactive method. The PU/silica hybrid materials were formed bythe reaction of NCO groups in the PU prepolymer and OH groups of silica in the case of nochain extenders and crosslinking agents. Silica acted as the crosslinking agent and chainextender of the PU. The method is significantly innovative in theory, and has the advantagesof simple technology, low cost, little environment pollution and significantly improving thecomprehensive performance of the materials.The mixture of PU prepolymer and silica ishigh-viscosity, which can be easily evenly mixed with rubber and synchronized crosslinked.As a result, the PU/silica hybrid materials were used to modify polar nitrile rubber (NBR) andnonpolar styrene-butadiene rubber (SBR) through interpenetrating network (IPN) technology.NBR/(PU-silica)-IPN and SBR/(PU-silica)-IPN with good compatibility and excellentcomprehensive performance were prepared by mechanical blending method. A further andcomprehensive discussion is also made on the modification mechanism of PU/silica on rubberand the relationship between structure and performance of IPN.The PU/silica organic-inorganic hybrid materials were prepared by mechanical blendingin situ reactive method. Under certain temperature and pressure, the organic-inorganic hybridmaterials were formed through the reaction of NCO groups of PU prepolymer and OH groupsof silica, which was characterized by Fourier-transform infrared (FTIR) spectroscopy, X-rayphotoelectron spectroscopy (XPS), solid-state NMR (29Si-HMR) and differential scanningcalorimetry (DSC). Curing kinetics analysis results show that the best curing temperature is120oC, the curing reaction follows first order kinetics, and the apparent activation energy is76.16kJ/mol. The PU prepolymer prepared with the molar ratio of NCO and OH of2.3:1, arecrosslinked by silica according to the equivalent ratio of OH in silica and NCO in PUprepolymer of1.06:1.00, and the resulting hybrid materials possess the most perfectcrosslinked network and have the best comprehensive performance. Compared withisophorone diisocyanate (IPDI), the appearance of soft segment crystalline melting peak andincreased hard segment crystalline melting enthalpy of PU/silica hybrid materials prepared from toluene diisocyanate (TDI) indicating the good crystalline properties and greatermicro-phase separation. They have increased curing rate and better comprehensivemechanical properties as well. Compared with polytetrahydrofuran glycol (PTMG1000),polyoxypropylene glycol (PPG1000) and polycaprolactone glycol (PCL1000), thecomprehensive mechanical properties of PU/silica hybrid materials prepared frompoly(diethylene glycol adipate)(PEA1000) are the best, the tensile strength, tear strength andelongation at break of which are48.31MPa,128kN/m and557%respectively.NBR and SBR were modified by PU/silica hybrid materials through interpenetratingnetwork (IPN) technology by mechanical blending method, and the resultingNBR/(PU-silica)-IPN and SBR/(PU-silica)-IPN were prepared. The curing kinetics studiesshow that the rubber system (NBR or SBR) and PU/silica system in the IPN crosslinkedrespectively in accordance with the radical polymerization and addition reaction. Thecrosslinking rates of the two systems matched; as a result, simultaneous interpenetratingpolymer networks were formed. NBR system and PU/silica system have an accelerating effecton the cure. The activation energy of the IPN was decreased by the addition of PU/silica. Thenetworks interpenetrate in the interface of NBR and PU/silica, which is characterized bytransmission electronic microscopy (TEM) and energy spectrum scan. The NBR matrixfracture from180oT-peel experiments of NBR and PU/silica indicated good interfacecombination. Dynamic Mechanical Analysis (DMA) results show that the Tg of NBR systemin IPN moved closer to the direction of the Tg of PU/silica system, which further evidence theimproved compatibility. The increased compatibility between the two components of the IPNis mostly due to the interpenetrating polymer networks structures in the interface of rubberand PU/silica.With increasing PU/silica content, the mechanical properties of IPN improved, and thecontinuity of the PU/silica domains in the IPN increased. When the PU/silica content is about50wt%, the NBR and PU show co-continuous morphology, however the two-phase continuityof SBR and PU/silica is a little poor. The abrasion resistance and anti-flex cracking propertiesof rubber (NBR and SBR) are significantly improved by the incorporation of PU/silica. Whenthe PU/silica content is50wt%, the flex-fatigue life of NBR/(PU-silica)-IPN andSBR/(PU-silica)-IPN are620and560thousand cycles; and the Akron abrasion loss are0.71and0.94cm3/1.61km, which are73.8%and79.0%decreases compared with neat NBR andSBR respectively. The significantly improvement of anti-flex cracking properties is mostlydue to the coordinating role of the flexible rubber networks and the rigid PU/silica networksand the hydrogen bond in the hard segment which can relax stress to prevent crack propagation. Among the IPNs prepared by the different types of diols, theNBR/(PU-silica)-IPN and SBR/(PU-silica)-IPN prepared by PEA1000have the bestmechanical properties, the tensile strength, elongation at break and tear strength of them are34.3MPa,620%,59kN/m and27.2MPa,595%,50.4kN/m respectively.更多还原