动态扭振法在树脂固化研究中的最新应用

用计算机全自动控制的LHX-Ⅱ型树脂固化仪对热固性树脂基蒙脱土纳米复合材料、热塑性树脂PMMA基蒙脱土纳米复合材料以及聚合物互穿网络等体系进行了固化反应的研究。借用Avrami理论来处理树脂基纳米复合材料的固化行为,求取固化反应表现动力学参数。     

热塑性/热固性聚合物共混体系研究——乙炔端基砜/聚砜共混物的动态固化动力学

近年来,半互穿聚合物网络(SIPN)概念被用来研制能结合热塑性聚合物的加工性和热固性聚合物的高温性能的大分子体系,用于复合材料耐高温树脂基体。例如:乙炔端基酰亚胺低聚物与热塑性聚酰亚胺基SIPN,线性聚酰亚胺与热固性双马来酰亚胺基SIPN以及热塑性树脂与双腈基SIPN已有报道。研究结果表明共混物起到协同作用,易于加工并具有优异的性能。乙炔端基砜(ATS)树脂具有与聚砜树脂相类似的结构,被认为在将来代替环氧用于高性能粘合剂和复合材料树脂基体的候选者之一。其另     

含二氮杂萘酮联苯结构热塑性聚芳醚树脂基复合材料研究进展

含二氮杂萘酮联苯结构聚芳醚是一类综合性能优异的耐高温热塑性树脂,可采用多种方式加工成型。与传统聚芳醚相比,具有低成本、优异的高温力学性能和良好的溶解性等优势,可作为基体树脂应用于制备复合材料。本文主要介绍了近几年在含二氮杂萘酮联苯结构热塑性聚芳醚树脂基复合材料方面的研究进展,包括玻璃纤维增强复合材料、碳纤维增强复合材料...     

热塑性树脂/蒙脱土纳米复合材料的研究进展

综述了热塑性树脂/蒙脱土(MMT)纳米复合材料近年来的研究进展,并重点介绍极性热塑性树脂/MMT纳米复合材料、非极性热塑性树脂/MMT纳米复合材料以及两种聚合物与MMT三元复合体系,讨论其改性方法,展望了热塑性树脂纳米复合材料的发展前景。     

玄武岩纤维增强树脂基复合材料界面改性策略

近年来,工业界和学术界都将注意力聚焦在可持续天然纤维复合材料的开发上。玄武岩纤维具有高强度、高模量、耐高温、耐酸碱、隔热隔音、热振稳定性好、介电性能优异、绿色无污染及成本低等优点,玄武岩纤维增强树脂基复合材料凭借其优异的机械性能和可设计性被广泛地应用于飞行器、汽车、船舶、建筑、石油化工管道及风力发电机叶片等领域。然而,玄武岩纤维与聚合物基底间差的相容性导致玄武岩纤维增强树脂基复合材料存在诸多缺陷和不足。其中,界面强度不够高、界面相易被破坏的问题成为制约玄武岩纤维增强树脂基复合材料发展的瓶颈之一,因此许多玄武岩纤维增强树脂基复合材料研究工作集中在提高其界面结合能力上。本文介绍了玄武岩纤维增强树脂基复合材料的主要研究方向,以及几种常见的复合材料界面作用机理,并综述了近年来国内外关于玄武岩纤维增强树脂基复合材料界面增强改性方面的研究工作。     

石墨烯改性树脂基复合材料力学性能研究进展

树脂基复合材料具有比强度高、比模量大、耐高温、耐腐蚀、质轻等诸多优点,在航天军工、生物医疗、电子封装、体育器材等众多领域得到广泛应用。石墨烯作为一种典型的二维纳米材料,凭借其独特结构以及优异的物理化学性能而备受关注。近年来的研究表明石墨烯可以通过对增强纤维改性和对基体树脂改性的方法来提高树脂基复合材料的力学性能。本文介绍了石墨烯改性树脂基复合材料的增强增韧机理,对石墨烯改性纤维(碳纤维、玻璃纤维、芳纶纤维)增强复合材料以及树脂的改性方法进行了综述;着重阐述了石墨烯改性树脂基复合材料力学性能的研究进展,分析了石墨烯改性树脂基复合材料研究中依旧存在的两大问题,即石墨烯的分散性和界面结合问题,并对石墨烯改性树脂基复合材料的未来发展前景进行了展望。     

磁性树脂基复合材料的研究进展

综合磁性树脂基复合材料的研究现状,着重介绍了磁性树脂基复合材料的三大类：粘结磁体、磁性高分子微球和磁性离子交换树脂的最新发展和研究状况。     

高性能复合材料——分子复合材料的研究进展

分子复合材料是一种在分子水平上分散的刚/柔性聚合物增强复合材料,其将传统增强纤维与树脂宏观复合的概念扩展到分子水平的微观复合上,具有高强度、高模量的优点。作为高性能复合材料的一类,研究与开发分子复合材料对高性能复合材料的扩展与创新具有重要意义。本文对分子复合材料的组成、制备方法及其相容性的控制进行了介绍,并综述了国内外分子复合材料的研究现状。最后提出分子复合材料亟需解决的问题并对其发展前景进行了展望。     

含磷聚芳醚酮颗粒层间增韧碳纤维/双马树脂RTM复合材料

选用一种在RTM双马来酰亚胺树脂(BMI)注射温度下不溶解的含磷聚芳醚酮(P-PAEK)热塑性树脂作为增韧剂,制备层间颗粒增韧碳纤维增强双马来酰亚胺树脂基复合材料.研究了不同热塑树脂含量对树脂浇铸体冲击性能的影响,利用扫描电镜表征了复相体系的微观形貌并分析其增韧机制,并通过层间断裂韧性测试表征了RTM双马树脂基复合材料增韧前后的层间韧性性能.结果表明,当附载热塑颗粒面密度为2 g/m2时,复合材料的I型层间断裂韧性(GIC)为0.54 k J/m2,II型层间断裂韧性(G_(IIC))为1.36 k J/m~2,较未增韧复合材料分别提升约56%和42%.增韧后的复合材料在保持原有力学性能的同时,其冲击后压缩强度(CAI)提升约29%,层间剪切强度达到111.7 MPa.     

植物纤维热塑料性树脂共混复合物的开发及问题

文章展示了植物纤维／热塑性树脂共混复合材料的应用前景，阐述了在应用开发中存在和应注意的问题，分析了植物纤维与塑料共混中的技术关键。     

Molecular composites prepared by in situ direct synthesis of wholly aromatic rigid‐rod polyamides via the phosphorylation reaction in a dissolved nylon‐6 matrix

Wholly aromatic rigid‐rod polyamides such as poly(p‐phenyleneterephthalamide) (PPD‐T) were synthesized in situ in a solution of nylon‐6 via the phosphorylation polycondensation method to form nanocomposites or so‐called “molecular composites.” The incorporation of PPD‐T into a nylon‐6 matrix was achieved by this approach in a more compatibilized form than that obtained by the conventional coagulation method that entails precipitation of a blend of PPD‐T and nylon‐6 in a solvent, for example, concentrated sulfuric acid. Gelation occurred during the synthesis, presumably because of the formation of interpenetrating networks accompanied by some block‐copolymer formation. The transparency and tensile properties of the resultant composite films from the rigid‐rod aromatic polyamide/nylon‐6 combination were improved over those of nylon‐6 film alone. Rainbow‐colored intense birefringence was observed for the composite films under crossed polarizers. These properties are discussed in context with the in situ synthesized rigid‐rod polyamides uniformly incorporated in nylon‐6. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1014–1026, 2003     

In situ thermoset molecular composites

The polymerization of rigid rod polymer precursors in a reactive matrix precursor, which is later cured in the mold, constitutes the in situ process. A poly-azomethine (PAM) was used as the rigid rod molecule. The resin used was an epoxy. We discuss the prediction of mechanical properties using micromechanics equations for chopped fiber composites. The chemistry used to synthesize the rigid rod polymer PAM in the epoxy precursor is reviewed. Approaches to better control the cure of these epoxy systems through cure kinetics and cure rheology studies completes the thermoset in situ molecular composite process. There was a 71% increase in tensile modulus in comparison to that of the neat epoxy resin. Molecular modeling simulations and continuum mechanics are used to help understand these findings. PAM/epoxy systems were used as a matrix material in the fabrication of unidirectional glass fiber/(PAM/epoxy) structural composites. © 1994 John Wiley & Sons, Inc.     

刚性链芳香聚酰胺片晶结构

应用透射电子显微术直接观察了刚性链芳香聚酰胺结晶取向膜的结晶形态结构．结果表明了，在聚对苯二甲酰对苯二胺（ＰＰＴＡ）和聚对苯甲酰胺（ＰＢＡ）的结晶取向膜中均存在有片晶结构．片晶的厚度对ＰＰＴＡ为２０ｎｍ；而对ＰＢＡ为４０ｎｍ，其大小恰好分别与该高聚物分子链的相关长度相当．最后提出一伸直链构象的结构模型来描述这类刚性链高聚物形成片晶结构的分子链堆砌排列方式．     

Shape of fluid vesicles anchored by rigid rod

A method combined the self-consistent field theory (SCFT) for the rigid rod with the Helfrich curvature elasticity theory for the vesicle has been developed for studying the shape of vesicles anchored by rigid rod. Both the deformation of the vesicle and the density distribution of rod segments can be obtained. Because of the vesicle's impenetrability for the rod segments and the decrease of the available space for the rod orientational configurations, the anchored rod segments exert the inhomogeneous entropic pressure on the vesicle and induce the change of vesicle shape. The interaction between the rod segments and the vesicle membrane exerts an extra tension to the membrane. Thus the interaction between the vesicle membrane and the rod segments, the rod length, and the bending rigidity of vesicle are investigated as the important factors to the shape transformation of the vesicle and the density distribution of rod segments. This method can be extended to more complicated and real biological systems, such as polymers with different topological architectures/vesicle, multiple chains/vesicle, protein inclusions, etc.     

Aqueous self-assembly of aromatic rod building blocks

One of the most fascinating subjects in areas such as nanoscience and biomimetic chemistry is concerned with the construction of novel supramolecular nanoscopic architectures with well defined shapes and functions. Supramolecular assemblies of aromatic rod molecules provide a facile entry into this area. Aromatic rigid rod molecules consisting of hydrophilic flexible chains, in aqueous solution can self-assemble into a variety of supramolecular structures through mutual interactions between aromatic rod molecules and water, including hydrophobic and hydrophilic interactions and pi-pi interaction. The supramolecular architecture in water can be manipulated by variation of the shape of the rigid segments, as well as the relative volume fraction of the flexible segment. The rigid aromatic segments have significant photonic and electronic properties. The self-assembly of aromatic rod molecules in water, therefore, can provide a strategy for the construction of well-defined and stable nanometer-size structures with chemical functionalities and physical properties as advanced materials for photonic, electronic and biological applications.     

Topics in the evolution of liquid crystal polymers

The relevance of scientific and technical research on liquid crystal polymers is examined and compared to the overall evolution of the general field of liquid crystals. It is shown that polymers have played a progressively increasing role during the last 25 years, and although they only became a quantitatively significant subject not much more than 10 years ago, their contribution to problems and materials now represents a considerable share. Three specific topics concerning rigid rod polymers, liquid crystalline networks and polymeric metallo-mesogens are examined and some related problems highlighted. In particular, some examples showing tractable thermotropic mesomorphic systems can be obtained with linear rigid homopolymers are examined; the phase behaviour of networks derived from segmented chain mesogenic polymers is discussed; inclusion of metallo-organic groups into polymeric mesogens is reviewed.     

Molecular recognition effects in polyaniline

Polyaniline (PANI) is known to dissolve in strong acids, such as sulphonic acids. PANI, in its electrically conductive form, is generally regarded to be poorly soluble in low-acidic solvents and to be infusible, closely resembling fully aromatic rigid rod polymers. We show that “less” acidic solvents and plasticizers can be found based on phenyl-phenyl interactions in combination with hydrogen bonding. The requirement is that the interactions are strong enough and, importantly, sterically match the complementary moieties of the sulphonic acid doped PANI. Dihydroxybenzenes and bisphenols are examples of such low-acidic compounds. This type of molecular recognition allows solution and melt processibility of PANI doped by generic sulphonic acid, such as methanesulphonic acid or alkylbenzenesulphonic acid. Molecular recognition is also offered as an explanation for the previously observed high solubility of camphorsulphonic acid (CSA) doped PANI in phenols.     

Effects of flexibility on liquid crystalline polymer behavior: The nematic broken rod

A new theory for liquid crystalline polymers is developed, and its behavior in simple shear flow is analyzed. The theory accounts for molecular flexibility by employing a microstructure consisting of two rigid rods linked by a joint with a tunable stiffness. The probability distribution function equation for the orientation of the arms of the broken rod is derived. The adaptation of the smoothed particle hydrodynamics (SPH) technique for obtaining numerical solutions to this theory is detailed. The behavior of the theory at equilibrium is derived analytically and compared with numerical results; the SPH technique is then used to obtain results in flow. It is found that in the limit of a nearly stiff joint, the model gives behavior that is very similar to that of rigid rod polymers, the only difference being a lesser tendency to tumble due to greater variation in the order parameter. For nearly free joints, the shear flow induces interesting dynamics for the transition between states with the arms outstretched and those where they are folded up (so‐called “hairpins” of main‐chain LCPs). © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 281–300, 1999     

Synthesis and characterization of thermally stable,high‐modulus polyimides containing benzimidazole moieties

A series of novel benzimidazole‐containing aromatic polyimides were prepared from synthesized 5,4′‐diamino‐2‐phenyl benzimidazole (DAPBI), and commercial dianhydrides by the conventional two‐step polymerization. The obtained films were amorphous and could afford flexible, transparent, and tough films with excellent thermal and mechanical properties. They showed high levels of tension strength of up to 234 MPa, modulus of up to 5.6 GPa without any stretching. According to thermal stability measurements, the glass‐transition temperatures of the polymers were observed between 329 and 425 °C. The 5% weight‐loss temperatures of most polyimides were above 600 °C in nitrogen. Excellent properties of these polyimides were proved to be attributed to the rigid‐rod structure and hydrogen bond of intermacromolecular. SAXS and SEM results showed self‐molecular orientation caused the formation of rod‐like extended conformations. It was demonstrated that high degree of supramolecular order led to the increase of thermal stability and mechanical properties of the polyimide films. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2024–2031, 2009