Glass fiber reinforced composites of phenolic–urea–epoxy resin blends

The present work aims to modify conventional epoxy resin by blending with four different phenolic–urea oligomers. These oligomers are similar to phenolic–urea resin matrix and simultaneously function as amino curing agent for epoxy matrix. In this context, phenolic–urea oligomers were prepared respectively by polycondensation reaction of four phenols namely phenol, m-cresol, resorcinol and 1,5-dihydroxy naphthalene, respectively with formaldehyde and urea in presence of acid catalyst. The resulting oligomers were characterized by elemental analysis, spectral studies (IR & NMR), number average molecular weight $(\overline{M}n)$ estimated by non-aqueous conductometric titration and thermal stability by thermogravimetric analysis (TGA). Each of these oligomers was used in resin matrix as a blending component for the modification of commercial epoxy resin for fabricating glass fiber reinforced laminates. Finally these laminates were evaluated for their synergetic thermal stability, mechanical properties and chemical resistance to different reagents.     

釜内聚合法制备间规聚苯乙烯与聚丙烯共混复合材料

采用MgCl2 TiCl4 β 二酮 MAO催化体系合成间规聚苯乙烯 (sPS)与等规聚丙烯 (iPP)共混复合材料 .对催化剂的活性和共混复合材料的组成随Al∶Ti和聚合温度的变化进行了表征 ,催化剂的活性可达 1.5× 10 5gB[molTi·h]- 1 ,sPS的含量可控制在 5 5 %～ 82 % .采用示差量热扫描仪 (DSC)和扫描电镜 (SEM)对共混复合材料的热性能和微观结构进行了研究     

茂金属聚乙烯和低密度聚乙烯共混物的流变行为

研究了茂金属催化乙烯丁烯1共聚物mPE和LDPE共混物的流变行为.测定了一系列共混物的稳态剪切粘度和动态粘弹性,用改进Cross模型拟合实验数据.mPE的零切粘度η₀较小,从牛顿型转变为非牛顿型所需的剪切速率较大,转变应力较高,在挤出加工剪切速率范围内熔体粘度高,对剪切敏感性差,这是由于它有较低的重均分子量、窄的分子量分布(M_w/M_n=21)所致.对于对数加和规律,共混物η₀在mPE/LDPE为50/50和25/75时有强烈的正偏差,这是由于共混物自由体积减小所致.共混物的转变应力τ^*和非牛顿指数n随LDPE加入量增大而降低,表明共混物对剪切的敏感性提高,加工性得到改善.G'和G”的一致性说明mPE和LDPE共混是相容的.     

Small Molecule: Polymer Blends for N-type Organic Thin Film Transistors via Bar-coating in Air

Fabricating n-type organic thin film transistors(OTFTs)based on small molecules via solution processing under atmospheric conditions remains challenging.Blending small molecules with polymer is an effective strategy to improve the solution processibility and air stability of the resulted devices.In this study,polystyrene was chosen to blend with n-type small molecule DPP1012-4F to enhance the continuity of the semiconductor layer and maintain a favorable edge-on stacking of semiconductors.The introduction of high-boiling point 1-chloronaphthalene as a solvent additive in the blending system can reduce the grain boundary defects in the microscopic morphology.These changes in aggregation behavior are confirmed by X-ray diffraction,atomic force microscopy and polarized optical microscopy analyses.Via bar-coating of the semiconductor layers in air,the electron mobility of the resulted OTFTs under the optimal condition is 0.73 cm2·V–1·s–1,which is amongst the highest n-type small molecule-based OTFTs with active layers prepared in air up to now.These results show a great potential of the blending strategy in industrial roll-to-roll manufacture of high-mobility n-type OTFTs.     

HDPE/PP共混物在振动剪切作用下的力学性能与形态控制

采用高剪切引起的相容与振动剪切保压方式控制共混物的形态,结果表明,当共混体系中HDPE/PP为92/8时的试样拉伸强度为97.1MPa,而80/20试样的缺口冲击强度为45.5kJ/m₂,较静态试样分别提高4.3倍和9.5倍.采用振动剪切注射技术可以针对某一组分获得高强度、高韧性的HDPE/PP共混制件.     

Study of morphological hysteresis in <Emphasis Type="Italic">partially immiscible</Emphasis> polymers

The morphology evolution of two systems of partially immiscible polymers, differing in miscibility, is investigated by means of rheological experiments and optical microscopy. For each system, two concentrations, 10% and 20%, are used. For immiscible systems, a hysteresis zone, defined by coalescence and breakup, exists where the average drop radius is not a unique function of the shear rate. We investigate whether the findings also apply to partially immiscible polymers. The average radii at different shear rates, measured with rheology, are compared to model predictions. The hysteresis zone, if present, is indeed affected by the polymeric system, the concentration and the flow history applied. Coalescence evolution is measured for three different step-downs in shear rate. For both 10% systems, the resulting average radii show a rather high scattering and do not match the theoretical predictions. For the 20% concentrations, the average experimental drop sizes seem independent of the magnitude of the step-down, at least during a certain period of time. Thereafter, it experiences a sudden, in the time scale of the experiments unbounded, increase in size that is more pronounced for the higher step-downs. Deviations of the experimental data from theoretical predictions are attributed to the partially immiscible character of the systems, yielding enhanced coalescence which, in turn, can induce confinement effects.     

Miscibility and Crystallization in Binary Crystalline Blends of Poly(butylene terephthalate) with Poly(butylene terephthalate-e-caprolactone)

Poly(butylene terephthalate)/poly(butylene terephthalate-e-caprolactone) is a new A/AxB1-x binary crystalline blend with intra-molecular repulsion interaction. Using the mean-field binary interaction model, the value of interaction parameter between the butylene terephthalate and caprolactone structural unit was first reported to be 0.305. This blend exhibited different crystallization behavior from a typical homopolymer/copolymer blend, which was carefully investigated by di?erential scanning calorimetry. It was found that poly(butylene terephthalate-e-caprolactone) copolymers have a great effect on the pure poly(butylene terephthalate) chain mobility and poly(butylene terephthalate) crystalline lattice packing. In the meantime, the crystallization of butylene terephthalate segments in copolymers was restricted by the previously formed poly(butylene terephthalate) crystallites. The two constituents for blending can not form a co-crystal in the range of composition even if they have the same butylene terephthalate unit. It can be concluded that longersegments in a copolymer would be beneficial for the formation of a co-crystal in blends.     

一种三级自动复叠制冷系统的试验研究

本文提出一种三级自动复叠的制冷系统,搭建了相应的研究装置,采用R134 a/R23/R14混合制冷剂,对试验装置和混合制冷剂组分的优化试验。并对降温过程中制冷系统中混合制冷剂合流特性进行了分析。     

聚对苯二甲酸丙二醇酯(PTT)的研究

新型聚酯材料聚对苯二甲酸丙二醇酯(PTT)是一种极有应用潜力的聚合物，但在非纤维领域的研究与应用才刚开始。本文简要概述了其发展状况；详述其结构、性能特点；重点介绍PTT目前在非纤维领域的应用与研究进展。     

Ring-opening copolymerization of epoxy-terminated polystyrene macromer with epichlorohydrin and study on properties of the copolymers

The synthesis and ring-opening copolymerization of epoxy-terminated polystyrene (PS-ep) macromer with epichlorohydrin (ECH) as well as some properties of the graft copolymers, were studied. The results showed that content of the epoxy-terminated macromer in the crude macromer can be increased by anionic polymerization of styrene in cyclohexane, and capping with propylene sulfide, followed by termination with ECH at 0 °C. The ring-opening copolymerization of ECH with the macromer can be performed by using a quaternary catalyst system which was composed of triisobutyl aluminium-phosphoric acid-water-amine in the molar ratio of 1:0.25:0.25:0.1-0.15. When the charging weight percentage of PS-ep/ECH=25-65% and M_n of PS-ep was 2.6-10×10³, the conversion of ECH was greater than 95% and the conversion of the macromer or grafting efficiency was 35-65%. The purified copolymer was characterized by IR, ¹H NMR and dynamic viscoelastometer to be a copolymer of ECH with polystyrene (PS) grafts. Transmission electron microscope showed the existence of PS domains in the continuous phase of polyepichlorohydrin (PECH). In a certain range of compositions the graft copolymer behaves like a thermoplastic elastomer. The graft copolymer can be melted and processed repeatedly. Its oil and solvent resistance were better than PS and similar to PECH rubber. The graft copolymer can be used as a compatibilizer for blending PECH with PS to form thermoplastic elastomer blends. Only 2% of it based on the blend is needed to raise the tensile strength of the blends obviously.