DYNAMIC MECHANICAL BEHMIOR AND STRUCTURE STABILITY OF PMMA/α-MSAN BLENDS

研究了均相，相分离聚（甲基丙烯酸甲酯）（ＰＭＭＡ）／聚（α甲基苯乙烯丙烯腈）（α－ＭＳＡＮ）共混物的动态力学行为，结果表明，在１３０℃退火４８ｈ可使ＰＭＭＡ，α－ＭＳＡＮ及其均相共混物达到稳态结构；在２００℃退火１ｈ可使ＰＭＭＡ／α－ＭＳＡＮ共混物接近完全分离，引入注意的是，仅相分离的ＰＭＭＡ／α－ＭＳＡＮ（４０／６０）呈现两个动态损耗模量（Ｅ″）峰，且两峰的分离程度强烈地依赖于在２００℃退火的时     

聚砜改性环氧树脂共混体系相结构的控制

研究了双官能团环氧树脂（Ｅ５１，Ｅ３９）与聚砜（ＰＳＦ）共混体系，在用二氨基二苯基砜（ＤＤＳ）固化时相分离结构的控制，在反应初期为均相体系，随固化反应的进行，环氧的分子量增大，体系发生相分离，相差异微镜观察的结果表明，温度较低时相分离进行缓慢，遵循旋节相分离的机理，利用这一特点，在低温进行共混物预固化，调控反应程度，在环氧树脂达到不同的分子量时再行固化，电子显微镜（ＳＥＭ），红外（ＦＴＩＲ）分析，     

PVC／NBR（HNBR）／HDPE共混体系相容性的研究

以丁腈橡胶（ＮＢＲ）和氢化丁腈橡胶（ＨＮＢＲ）共聚物为增容剂，用扫描电镜（ＳＥＭ）对ＰＶＣ／ＨＤＰＥ共混物的形态进行了研究，共聚物ＮＢＲ（ＨＮＢＲ）加入共混物中后，使冲击面形貌发生变化。表明两相间粘合力增大，相分离程度减少小，改变增容剂的种类和用量以及共混组成的，均将对体系的形态结构产生影响。     

PVC／NBR（HNBR）／HDPE共混体系相容性的研究（Ⅱ）增容剂对共混物形态的作用

以丁腈橡胶（ＮＢＲ）和氢化丁腈橡胶（ＨＮＢＲ）共聚物为增容剂，用扫描电镜（ＳＥＭ）对ＰＶＣ／ＨＤＰＥ共混物的形态进行了研究。共聚物ＮＢＲ（ＨＮＢＲ）加入共混物中后，使冲击断面形貌发生变化。表明两相间粘合力增大，相分离程度减小，改变增容剂的种类和用量以及共混组成，均将对体系的形态结构产生影响。     

TMPS与PB共混物的形态结构研究

采用小角Ｘ射线散射（ＳＡＸＳ）法和偏光显微镜法测定不同组分比的聚四甲基苯撑硅氧烷（ＴＭＰＳ）与１，２聚丁二烯（ＰＢ）共混物的长周期、晶片厚度、无定形厚度及一维结晶度等超分子结构参数及球晶生长形态。结果表明，ＴＭＰＳ／ＰＢ共混物组分比和热历史，将影响系统中非晶共混物不同程度的微相分离及相倒转；相倒转又影响了系统中结晶相ＴＭＰＳ晶体的生成条件，使共混物的上述超分子结构参数产生了不连续的变化。     

PVC／LLDPE共混体系形态结构的控制

采用氢化聚丁二烯－ｂ－甲基丙烯酸甲酯（ＰＢＤ－ｂ－ＰＭＭＡ）共聚物作为聚氯乙烯／线性低密度聚乙烯（ＰＶＣ／ＬＬＤＰＥ）共混体系的增容剂，用扫描电子微镜（ＳＥＭ）和透射电子显微镜（ＴＥＭ）对共混体系的冲击缺口断面和相结构进行了研究。并用小角激光菜射技术了ＬＬＤＰＥ在共混物中的结晶行为，发现增容剂对共混体系的形态结构会产生极大的影响。     

聚氯乙烯／梯形聚苯基倍半硅氧烷共混物的相结构及流？…

由单螺杆挤出机制备了聚氯乙烯（ＰＶＣ）／梯形聚苯基倍半硅氧烷（ＰＰＳＱ）（１００／０、９５／５、９０／１０、８５／２０）机械共混物,通过扫描电镜（ＳＥＭ）观察了该共混物的相结构,富ＰＰＳＱ相形成２的球状颗粒较均匀地分散于ＰＶＣ的连续相中,ＰＶＣ／ＰＰＳＱ共混物的流动温度（Ｔｔ）均低于纯ＰＶＣ的Ｔｔ,而它们的玻璃化转变温度（Ｔｇ）略高于纯ＰＶＣ的Ｔｇ,随ＰＰＳＱ含量的增加,ＰＶＣ／ＰＰＳＱ共混物的Ｔ     

液晶共聚酯酰胺对PET/PA66共混体系的增容作用

将ＰＥＴ、ＰＡ６６和ＬＣ３０进行熔融共混，采用ＳＥＭ、热台偏光显微镜、ＤＳＣ、Ｉｎｓｔｒｏｎ３２１１型毛细管流变仪测定了共混物的形态结构、热行为和流变性能，系统地研究了热致液晶共聚酯酰胺（ＬＣ３０）对聚对苯二甲酸乙二酯（ＰＥＴ）／聚酰胺６６（ＰＡ６６）共混物的增容作用。结果表明，ＬＣ３０对ＰＥＴ／ＰＡ６６共混物的增容作用，有效地改善了ＰＥＴ／ＰＡ６６共混物的形态结构和流变性能，增强了ＰＥＴ链与ＰＡ６６链间的相互作用，使ＰＥＴ／ＰＡ６６共混物的熔点降低，结晶度提高，流变行为由原来的负偏差行为转变为正偏差行为。     

磺化聚苯乙烯锌盐离聚体对尼龙1010/聚苯乙烯共混体系增容作用研究

利用动态粘弹谱、广角Ｘ射线衍射和扫描电镜分析了磺化聚苯乙烯锌盐离聚体（ＺｎＳＰＳ）对尼龙１０１０／聚苯乙烯（ＰＡ１０１０／ＰＳ）共混物形态结构的影响。结果表明，ＺｎＳＰＳ的加入对共混物起了增容作用，其中低离子含量（３．２５ｍｏｌ％）ＺｎＳＰＳ的加入有利于ＰＳ渗进尼龙相中，而对ＰＳ相无明显影响；高离子含量（１０．６７ｍｏｌ％，１３．８７ｍｏｌ％）ＺｎＳＰＳ的加入在使ＰＳ与尼龙互相渗透的同时更有利于尼龙渗进ＰＳ相中。ＺｎＳＰＳ对尼龙１０１０分子链沿晶胞（００２），（１００）面的生长有抑制作用，这种抑制作用随ＺｎＳＰＳ加入量和离子含量的增大而愈加明显。ＺｎＳＰＳ的加入明显改善了ＰＡ１０１０／ＰＳ共混物的微观形态，使共混物力学性能得到了提高，初步实现了ＰＳ增韧尼龙１０１０的目的。     

HDPE／Surlyn共混体系的热学行为及相转变研究

利用示差扫描热量仪（ＤＳＣ），热机械分析装置（ＴＭＡ）、电子拉力机和扫描电镜等方法对ＨＤＰＥ Ｓｕｒｌｙｎ共混体系的热学行为和相态结构进行了研究，证实该共混体系属部分相容的非均相体系，当Ｓｕｒｌｙｎ含量在３０％到５０％时，该共混物发生了明显的相转变。     

Effect of nanoclay and carboxyl-terminated (butadiene-co-acrylonitrile) (CTBN) rubber on the reaction induced phase separation and cure kinetics of an epoxy/cyclic anhydride system

The effects of nano clay, carboxyl-terminated (butadiene-co-acrylonitrile) (CTBN) liquid rubber and the combination of both on the cure kinetics of diglycidyl ether of bisphenol-A (DGEBA)-based epoxy resin/nadic methyl anhydride were studied. Cure kinetics studies were carried out by performing dynamic and isothermal differential scanning calorimetric (DSC) experiments. The dynamic DSC experiments were carried out at four different heating rates. Dynamic kinetic modeling was performed using Kissinger and Ozawa approaches. Since these methods are based exclusively on the maximum rate of cure, which occurs approximately at the beginning of the cure reaction, the activation energy calculated using these methods is valid only for the initial stage of the cure. The clay (3 phr) filled epoxy system has an activation energy 24 % lower than the unfilled system. The role of the surfactant chemistry on the initial stage of the cure reaction was also studied. A plausible reaction mechanism which involves the effect of the nanoclay surfactant as an accelerator of the cure reaction was proposed. The phase separated CTBN rubber hindered the cure reaction and has 3 % higher activation energy for epoxy/CTBN system than the unfilled system. In the ternary epoxy/3 phr clay/15 phr CTBN system, the accelerating effect of clay on cure was highlighted. The cure activation observed in the presence of clay overshadows the hindrance created by the phase separated CTBN. Isothermal DSC scans were carried out at five different temperatures. The experimental datas showed an autocatalytic behavior of the reaction, and the isothermal modeling was carried out by Kamal autocatalytic model. The results showed a very good agreement within the whole conversion range for the unfilled and all the filled systems. The evolution of the morphology and phase separation was also studied using optical and scanning electron microscope. Faster cure reaction resulted in smaller phase-separated CTBN particles in epoxy/clay/CTBN ternary system as compared with those observed in epoxy/CTBN binary blend.     

聚醚砜-环氧树脂共混体系相分离过程的数值模拟

在热塑性聚醚砜（PES）增韧改性热固性环氧树脂复合材料的制备过程中,通过控制PES-环氧树脂树脂共混体系相分离过程实现共混物相结构的调控,能够明显改善热固性环氧基体树脂的冲击强度。考虑PES-环氧树脂共混体系在相分离过程中PES应力松弛现象以及环氧树脂固化反应现象,采用黏弹性模型描述微观相形态的具体演化路径,揭示了树脂共混体系相分离过程的机制及动力学过程,分析了PES含量、PES分子量大小、PES与环氧树脂的动力学不对称程度以及固化工艺条件等材料及工艺参数对共混体系相结构演变过程以及最终相形态的影响规律及程度,从而为优化PES-环氧树脂树脂共混体系的微观相结构打下基础。     

Poly(ether ether ketone) with pendent methyl groups as a toughening agent for amine cured DGEBA epoxy resin

A diglycidyl ether of bisphenol-A (DGEBA) epoxy resin was modified with poly(ether ether ketone) with pendent methyl groups (PEEKM). PEEKM was synthesised from methyl hydroquinone and 4,4′-difluorobenzophenone and characterised. Blends of epoxy resin and PEEKM were prepared by melt blending. The blends were transparent in the uncured state and gave single composition dependent T _g. The T _g-composition behaviour of the uncured blends has been studied using Gordon–Taylor, Kelley–Bueche and Fox equations. The scanning electron micrographs of extracted fracture surfaces revealed that reaction induced phase separation occurred in the blends. Cocontinuous morphology was obtained in blends containing 15 phr PEEKM. Two glass transition peaks corresponding to epoxy rich and thermoplastic rich phases were observed in the dynamic mechanical spectrum of the blends. The crosslink density of the blends calculated from dynamic mechanical analysis was less than that of unmodified epoxy resin. The tensile strength, flexural strength and modulus were comparable to that of the unmodified epoxy resin. It was found from fracture toughness measurements that PEEKM is an effective toughener for DDS cured epoxy resin. Fifteen phr PEEKM having cocontinuous morphology exhibited maximum increase in fracture toughness. The increase in fracture toughness was due to crack path deflection, crack pinning, crack bridging by dispersed PEEKM and local plastic deformation of the matrix. The exceptional increase in fracture toughness of 15 phr blend was attributed to the cocontinuous morphology of the blend. Finally it was observed that the thermal stability of epoxy resin was not affected by the addition of PEEKM.     

DDS含量对TGDDM—DDS体系固化反应机理的影响

报导了采用差示扫描量热仪(DSC)跟综4,4’-二氨基二苯甲烷四缩水甘油基环氧树脂(TGDDM)与4,4’-二氨基二苯砜(DDS)固化反应的研究结果。观察到随着DDS含量的变化固化反应的放热峰峰温、峰形和放热量有规律的变化。动力学分析结果表明随着DDS含量的增加,固化反应从叔胺催化下的羟基与环氧基的缩合反应机理转变为伯胺和仲胺基与环氧基的缩合反应。     

Double-phase morphology of high molecular weight poly(methyl methacrylate)-epoxy blend

The double-phase morphology of 5 wt% high molecular weight poly(methyl methacrylate) (PMMA) modified epoxy system was investigated by optical and scanning electron microscopic (SEM) techniques. PMMA-epoxy blend cured at 100 °C revealed that a bicontinuous secondary phase separation was observed in both epoxy and PMMA phases in the early stages of curing. Epoxy-rich particles were dispersed in the PMMA-rich phase, while PMMA-rich particles were segregated in the epoxy-rich phase, leading to double-phase bicontinuous morphology. The spinodal decomposition mechanism could probably be responsible for this secondary phase separation. From the SEM analysis, a morphology consisting of a rough striated continuous phase along with large smooth regions was observed. Rough striated domains are ascribed to the PMMA-rich phase and the smooth domains are assigned to the epoxy-rich phase, thus confirming the secondary phase separation. The PMMA-epoxy blend showed a slight increase in flexural properties and about 20% improvement in the fracture toughness.     

Characterization of double network epoxies with tunable compositions

This article reports the processing and characterization of epoxy resins with near constant molar cross-link density prepared from sequentially reacted amine cross-linking agents. Stoichiometric blends of curing agents with compositions ranging from all polyetheramine to all diaminodiphenylsulfone (DDS) are reacted with an epoxy monomer in a staged curing procedure. The low reactivity of the aromatic amine permits the selective reaction of the aliphatic amine in the first stage. The residual aromatic amine and epoxide functionality are reacted in a second stage at higher temperature. Above approximately 50% DDS content the first stage produces sol glasses which have not reached the gel point. The glass transition temperatures of the partially cured networks decrease monotonically with increasing DDS content. The partially cured networks can be characterized thermally and mechanically above their respective glass transitions without significantly advancing the reaction of the residual DDS and epoxide functionality. The networks formed after the second stage of the cure exhibit thermal and mechanical properties intermediate between those of the two individual amine cured networks, according to composition. The blends do not show any evidence of phase separation across the entire composition range in either the partially cured or fully cured state.     

Thermodynamically reversible and irreversible control on morphology of multiphase systems

Morphology and properties of polymer alloys can be controlled by thermodynamically reversible (structure freeze-in) or irreversible (structure lock-in) processes via simultaneously manipulating miscibility, mechanisms of phase separation, glass transition (structural relaxation), and cure kinetics of polymer systems. Using phase diagrams consisting of binodal and spinodal curves, the morphology of epoxy/carboxyl-terminated butadiene acrylonitrile copolymer (CTBN) systems can be controlled by the mechanism of nucleation and growth or by spinodal decomposition. We have found that the particle size of the rubber reinforcement in epoxies is affected by the mechanisms of phase separation. Phase separation by nucleation and growth gives larger rubber particles than the corresponding phase separation by spinodal decomposition. This contrast in the morphology development is the consequence of controlling phase separation through chemorheological behaviour. Modification of the phase separation kinetics in epoxy/CTBN systems was extremely effective at altering both morphology and properties of these alloys. This technique offers a means to shift the glass transition temperature of the rubber-rich phase while leaving the glass transition temperature of the epoxy-rich phase intact. Such control over morphology is the key to ultimately controlling material properties.     

E 51环氧树脂固化反应中动力学转变

采用等温DSC法研究了E-51环氧树脂与4, 4’-二氨基二苯基砜(DDS)体系的固化反应过程, 并与已有固化模型拟合得到了170、180、190、200 ℃下的等温固化反应动力学的参数, 根据决定系数R2确定了适合的固化模型。研究表明: 当固化度小于40%时属于Kamal自催化模型; 当固化度大于40%时属于n级固化模型, 即固化反应由Kamal自催化反应向n级反应转变。