共混合金力学性能的研究 Ⅰ.双组分合金力学性能的研究

对弹性体分散相和刚性体分散相对共混合金力学性能的影响进行了研究。将ＣＰＥ、ＡＣＲ、ＡＢＳ、ＰＰ和ＣＰＰ分别与ＰＶＣ基质共混，得到的实验结果是不论刚性体分散相，还是弹性体分散相皆对ＰＶＣ共混合金有增韧作用，但增韧的效果有所不同。其中弹性体增韧的结果是随着弹性体分散相用量的增加，共混合金的冲击强度持续增加，在某一点后增加速度变快；而刚性体增韧的结果是随着刚性体分散相用量的增加，共混合金的冲击强度在某一点达到最大值     

共混合金力学性能的研究

对弹性体分散相和刚性体分散相对共混合金力学性能的影响进行了研究。将ＣＰＥ、ＡＣＲ、ＡＢＳ、ＰＰ和ＣＰＰ分别与ＰＶＣ基质共混，得到的实验结果是不讼刚性体分散相，还是性体分散相皆对ＰＶＣ共混合金有增韧作用，但增韧的效果有所不同。其中弹性体增 结果是随着弹性体分散相用量的增加，共混合金的冲击强度持续增加，在某一点后增加速度变快；而刚性体增韧的结果是随着刚性体分散相用量的增加，共混合金的冲击强度在某一点达     

MBS增韧PVC的脆韧转变

以ＭＢＳ增韧质ＰＶＣ,改变ＭＢＳ的填充量,得到材料的脆韧转变,得到发生脆韧转变时分散相的填充份数和分数粒径,计算出材料的临界断裂特征长度。     

聚合物共混体脆韧转变的损伤竞争理论Ⅲ．分散相形态和界面粘接对脆韧转变的影响

应用前文提出的聚合物共混体脆韧转变（ＢＤＴ）的损伤竞争准数（Ｄａ）判据，研究了共混体分散相形态与界面粘接对ＢＤＴ的影响。由Ｄａ判据预示，在一定范围内，增加分散相含量，减小分散相粒径，减小粒子在基体中的聚集程度以及增大粒子的形状不规则性，皆有利于ＢＤＴ的发生。界面粘接强度的增加在一定范围内也能够使共混体的韧性增加。这些理论预示与实验结果相一致，从而表明Ｄａ判据能够反映分散相形态与界面粘接等多种因素对共混体损伤过程的影响规律，是聚合物共混体脆韧转变的控制参量。     

含球形分散相周围基体中的形变能密度及其对聚合物共混体脆韧转变的影响

从Goodier方程出发,研究了球形分散相周围基体中的形变能密度分布及其与分散相力学性能的关系,将所得结果结合前文给出的聚合物共混体的脆韧转变方程讨论了分散相的力学性能对聚合物共混体脆韧转变的影响,结果与实验一致。     

含球形分散相周围基体中的形变能密度及其对聚合物共混体 …

从Ｇｏｏｄｉｅｒ方程出发，研究了球形分散相周围基体中的形变能密度分布及其与分散相力学性能的关系。将所得结构结合前文给出的聚合物共混体的脆韧转变方程讨论了分散相的力学性能对聚合物昆体脆韧转变的影响。结果与实验一致。     

超高韧半晶聚合物PP多相体系的结构及脆韧转变的研究

通过严格控制工艺条件，得到了不同分散相含量和不同粒径的ＰＰ／ＥＰＤＭ／ＨＤＰＥ和ＰＰ／ＥＰＤＭ共混体。利用ＳＥＭ分析了ＰＰ／ＥＰＤＭ／ＨＤＰＥ的结构特点，通过测量Ｉｚｏｄ缺口冲击强度，得到了ＰＰ／ＥＰＤＭ／ＨＤＰＥ的脆韧转变主曲线，证明其符合脆韧性转变规律；同时利用ＳＥＭ照片，分析了主曲线不同区域的增韧机理。     

NBR对POM树脂的增韧行为

研究了ＮＢＲ和ＰＯＭ树脂的增韧行为，发现在具有较高的丙烯腈含量，具在添加有效的热稳定剂的情况下ＮＢＲ可对ＰＯＭ树脂起到良好的增韧作用，随ＮＢＲ添加量的增加。ＰＯＭ／ＮＢＲ共混体系的缺口冲击强度呈线性增加的趋势，当ＮＢＲ添加量达４０５时，体系将发生急剧的脆－韧转变。     

聚合物共混体脆韧转变的损伤竞争理论：Ⅲ.分散相形态和…

应用前文提出的聚合物共混体脆韧转变（ＢＤＴ）的损伤竞争准数（Ｄａ）判据，研究了共混体分散相形态与界面粘接对ＢＤＴ的影响。由Ｄａ判据预示，在一定范围内，增加分散相含量，减小分散相粒径，减小粒子在基体中的聚集程度以及增大粒子的形状不规则性，皆有利于ＢＤＴ的发生。界面粘接强度的增加在一定范围内也能够使共混体的韧性增加。这些理论预示与实验结果相一致，从而表明Ｄａ判据能够反映分散相形态与界面粘接等多种因素对     

界面对ABS/PA6共混体系脆韧转变及断裂行为的影响

合成了反应性核壳结构增韧剂ABS-g-MA和ABS-g-AA增韧PA6, 2种增韧剂的唯一差别在于壳层接枝的反应性单体不同, 从而在与PA6共混过程中相界面存在差异, 研究在其他参数都相同的条件下, 界面性质对ABS/PA6共混体系脆韧转变及断裂行为的影响。Molau试验与扭矩试验证实ABS-g-MA/PA6共混物具有更佳的界面强度。TEM结果表明2种增韧剂在PA6中均匀分散, 然而力学测试结果表明ABS-g-MA/PA6共混物在分散相质量分数为25%~30%时发生脆韧转变,冲击强度可以达到900 J/m以上, ABS-g-AA/PA6共混物在分散相质量分数为30%~35%时发生脆韧转变。SEM结果表明ABS-g-MA/PA6共混物断面发生显著的塑性形变。TEM表明ABS-g-MA/PA6共混物的形变机制为橡胶粒子的空洞化与塑料基体的剪切屈服, 而ABS-g-AA/PA6体系没有空洞化现象, 基体剪切屈服不明显。Vu---Khanh方法测试表明, 由于ABS-g-MA/PA6共混物更高的界面强度, 共混物具有更高的G_i值, 因此冲击韧性极佳。      

Pre-yield tensile set of a semi-crystalline polymer,its blend and composite

Tensile set was studied at low strains on polypropylene, aliphatic polyketone, rubber toughened blends and CaCO₃ particle toughened composites. The rubber in the rubber toughened blends had a particle size of 0.7 μm. The CaCO₃ particles had a size of 0.7 μm and had been coated with stearic acid. Step-cyclic loading was applied in 1% strain incrementals at a strain rate of 10⁻² s⁻¹. The maximum strain applied was 20%. The temperature of the test bar was studied with an infra-red camera. Pre-yield deformation is normally assumed to take place in a nonlinear elastic manner. However, for polypropylene and polyketone elastoplastic deformation starts at low strains. For PP the onset of tensile set is at very low strains and increases with strain. The tensile set at the yield point was only 50% and at the drawing strain 100%. Polyketone had a similar tensile set development but shifted to slightly higher strains. Here too the tensile set at the yield point was about 50% and at the drawing strain 100%. The temperature of the non yielded material was found to rise in polyketone a 7 °C. The rubber toughened blends had at low strains a higher tensile set, but after the yield strain the set was similar to the base polymer. At 5% strain the tensile set increased with rubber content. The sub micron CaCO₃ particle toughened composites increased the tensile set too. The tensile set is a simple technique for studying the pre-yield behaviour of multi phase systems.     

Energy absorption in blends of polycarbonate with ABS and SAN

Polycarbonate and its blends with ABS and SAN were tested to study the energy absorbing properties and the deformation mechanism. In tension and impact tests, these blends were found to possess a high energy absorbing capability, high yield strength and large rupture elongation. ABS and SAN particles in the blends deform in a ductile manner to an elongation of more than 100% under a tensile stress. In an elongation test of ABS under a hydraulic pressure of 90×10⁵ N m^–2, the transformation from crazing to a cold-drawing mechanism was found to occur. The large elongation of ABS and SAN in the blends is attributed to the cold drawing which occurs under the influence of the pressure acting on the dispersed ABS and SAN, caused by the difference between the elastic moduli of the dispersoid and the matrix.     

Toughening mechanisms in elastomer-modified epoxies

Some brittle epoxies can be toughened significantly by the addition of an elastomeric phase. A great deal of controversy still exists on the nature of the toughening mechanisms. In this work tensile dilatometry at constant displacement rates was used to determine whether voiding, crazing or shear banding are the deformation mechanisms. Diglycidyl ether-bisphenol A epoxies toughened by various levels of several types of carboxyl-terminated butadiene nitrile liquid rubber were studied. The results indicate that at low strain rates the rubber particles simply enhance shear deformation. At sufficiently high strain rates the rubber particles cavitate and subsequently promote further shear deformation. No indication of crazing as an important toughening mechanism is found. No significant effect of rubber particle size or type can be ascertained.     

Rubber-toughening of plastics

The effects of matrix ductility upon mechanisms of rubber toughening have been studied in a set of materials having identical rubber contents, but differing in matrix composition. The materials were made by solution blending 50% of HIPS (high-impact polystyrene) with polystyrene and PPO^® poly-(2, 6-dimethyl-1, 4-phenylene oxide) in varying proportions. Crazing was studied quantitatively by measuring volume changes during creep. Analysis showed that in blends of HIPS with polystyrene, crazing is the only significant mechanism of tensile creep, whereas in blends containing polyphenylene oxide, shearing mechanisms are also important, and the contribution of crazing to creep deformation can be as low as 30%, depending upon matrix composition. Scanning electron microscopy showed that both crazes and shear bands were present in strained HIPS/PPO blends. Shear band formation appears to be responsible for the increased fracture resistance of blends containing a high proportion of polyphenylene oxide. A theory of toughening is proposed for these blends.     

具有自组装相形态的聚合物合金研究进展

详细介绍了两类具有自组装相形态的聚合物合金体系,即两分散相能形成核-壳结构分布于连续相中的三元不相容聚合物合金以及添加有固体纳米粒子的二元不相容聚合物混合物,讨论了前者的相形态及其影响因素和后者的相形态自组装行为及其影响因素。     

A mathematical relation between volume strain,elongational strain and stress in homogeneous deformation

A model is presented for the volume strain of a two-phase blend which elongates homogeneously in a tensile test apparatus. In the case when only elastic deformation and crazing take place the volume strain against elongation curve can be constructed and calculated from the data of the stress-strain curve alone. When, as well as crazing and elastic deformation, shearing takes place, the data of the stress against elongation curve and the volume strain against elongation curve can be used to calculate the separate contributions of the three deformation mechanisms at any elongation. In principle, the model can be also used for any homogeneous system which deforms without necking and where one or more deformation mechanism is present.     

细观结构参量对共混物基体屈服影响的数值模拟

进行了分散相颗粒形状较规则的单相连续两相共混物细观结构参量对共混物基体屈服的产生和屈服区扩展规律影响的研究。通过模拟获得了共混体系橡胶粒子分布形式、添加比例、粒子尺寸、两相间界面层性能、粒子形状等细观结构参量的改变对共混物基体屈服的影响规律。     

流场中高分子共混物分散相的形态变化

评述了高分子共混物分散相微粒在流场中形变、破裂和凝聚的研究进展。     

二元不相容共混物相形态控制

详细讨论了二元不相容共混物中分散相形态的控制和相反转的控制问题，提出了描述相反转的新判据。     

Thin film and bulk deformation behaviour of poly(ether ether ketone)/poly(ether imide) blends

The deformation behaviour of amorphous thin films of poly(ether ether ketone) (PEEK)/poly(ether imide) (PEI) blends was investigated over a wide temperature range by optical and transmission electron microscopy. All the materials showed localized shear deformation at temperatures well below Tg. In pure PEI and in blends with up to 60 wt% PEEK content, a transition from shear deformation to disentanglement crazing occurred as the temperature was raised. However, this transition was absent in PEEK, which deformed by shear over the whole temperature range, and similar behaviour was found for PEI/80 wt% PEEK. It is argued that at high PEEK content disentanglement crazing is suppressed by strain-induced crystallization and some evidence for crystalline order in deformed regions of initially amorphous PEEK thin films was obtained by electron diffraction. The thin film deformation behaviour of the blends was also shown to be consistent with their bulk deformation behaviour, a high temperature ductile–brittle transition being observed at low PEEK content in tensile tests. This revised version was published online in November 2006 with corrections to the Cover Date.