The relationship between the microstructure developed during injection molding of liquid crystalline polymers (LCPs) containing blends and their mechanical properties, was studied. A wholly aromatic copolyester LCP was melt blended in various levels with polycarbonate (PC), poly(butylene terephthalate) (PBT), Nylon 6 (N-6), and amorphous nylon (AN). In all cases the LCP was the minor component. The resulting injection molded structure had a distinct skin core morphology, where elongated fibrous LCP particles comprised the skin layer and spherical and ellipsoidal ones composed the core section. The highest elongation and the finest diameter LCP fibrils were obtained with AN/LCP system, followed by PC/LCP. PBT/LCP blends showed a coarser morphology, while N-6/LCP system did not correlate with the tensile moduli of the injection molded specimens. AN/LCP blends demonstrated the highest moduli values, consistent with the highest orientations observed using electron microscopy, followed by PC/LCP, PBT/LCP, and N-6/LCP. Finally, tensile strength levels were correlated with both orientation levels and interfacial adhesion between the polyblend components. AN/LCP that exhibited the highest orientation and good adhesion appearance gave the highest tensile strength values followed by PC/LCP, PBT/LCP, and N-6/LCP polyblends. 相似文献
The Izod impact strength of poly(vinyl chloride)/methyl methacrylate/butadiene/styrene(PVC/MBS)polymer blends can be changed significantly with different levels of MBS and/or MBS particle size. The following results were obtained by investigating the fracture of PVC/MBS test specimens: (1) The dependence of the Izod impact strength of PVC/MBS blend on MBS particle size confirms a maximum around a MBS particle size of 2000 Å. When MBS particle size is smaller than 2000 Å, the Izod impact strength increases with MBS particle size, and crazing occurs mainly in this region. When MBS particle size is larger than 2000 Å, then the Izod impact strength, in contrast, decreases with increasing MBS particle size, and both crazing and shear yielding occur, mainly in this region. (2) Tensile experiments of PVC/MBS blends carried out under various conditions showed that the amount of energy absorption increases with decreasing MBS inter-particle distance and with increasing MBS particle size when crazing is the main energy absorbing mode. The MBS inter-particle distance dominates the energy absorption when shear yielding is the main energy absorbing mode. (3) Therefore, the Izod impact strength of PVC/MBS blends and the maximum around a MBS particle size of 2000 Å can be explained as follows: Below 2000 Å, the energy absorption by crazing dominates the total energy absorption, and the energy absorption by crazing increases with MBS particle size. Above 2000 Å, the energy absorption by shear yielding is dominant, and the energy absorption by shear yielding increases with decreasing inter-particle distance, that is to say, decreasing MBS particle size. 相似文献
Vibration welding is used to assess the weldability of poly(butylene terephthalate) (PBT) and a polycarbonate/poly(butylene terephthalate) blend (PC/PBT) to each other and to other resins and blends: PBT to PC/PBT, PBT to modified poly(phenylene oxide) (M-PPO), PBT to polyetherimide (PEI) and PEI to a 65 wt% mineral-filled polyester blend (65-PF-PEB), PBT to a poly(phenylene oxide)/polyamide blend (PPO/PA), PC/PBT to M-PPO, and PC/PBT to PPO/PA. Based on the tensile strength of the weaker of the two materials in each pair, the following relative weld strengths have been demonstrated: PBT to PC/PBT,98%; PBT to PEI, 95%; 65-PF-PEB to PEI, 92%; and PC/PBT to M-PPO, 73%. PBT neither welds to M-PPO nor to PPO/PA, and PC/PBT does not weld to PPO/PA. 相似文献
Summary: To obtain a balance between toughness (as measured by notched impact strength) and elastic stiffness of poly(butylene terephthalate) (PBT), a small amount of tetra‐functional epoxy monomer was incorporated into PBT/[ethylene/methyl acrylate/glycidyl methacrylate terpolymer (E‐MA‐GMA)] blends during the reactive extrusion process. The effectiveness of toughening by E‐MA‐GMA and the effect of the epoxy monomer were investigated. It was found that E‐MA‐GMA was finely dispersed in PBT matrix, whose toughness was significantly enhanced, but the stiffness decreased linearly, with increasing E‐MA‐GMA content. Addition of 0.2 phr epoxy monomer was noted to further improve the dispersion of E‐MA‐GMA particles by increasing the viscosity of the PBT matrix. While use of epoxy monomer had little influence on the notched impact strength of the blends, there was a distinct increase in the elastic stiffness. SEM micrographs of impact‐fracture surfaces indicated that extensive matrix shear yielding was the main impact energy dissipation mechanism in both types of blends, with or without epoxy monomer, and containing 20 wt.‐% or more elastomer.
SEM micrographs of freeze‐fractured surfaces of PBT/E‐MA‐GMA blend illustrating the finer dispersion of E‐MA‐GMA in the presence of epoxy monomer. 相似文献
The object of this study was to investigate the physical properties and morphology of melt-mixed blends containing poly(butylene terephthalate) (PBT) with several functionalized polyolefins such as ethylene/vinyl acetate copolymer (EVA), EVA-g-maleic anhydride (EVA-g-MAH), EVA-g-ACID, EVA-g-ACID/ACRYLATE, ethylene methacrylate-g-MAH (EMA-g-MAH), ethylene/ethyl acrylate copolymer (EEA) and an ethylene ionomer. Special focus was made on PBT/EVA-g-MAH and PBT/EMA-g-MAH blends compared with PBT/EVA and PBT/EMA blends. Blends were prepared in a counter-rotating twin-screw extruder. Mechanical and thermal properties, glass transition temperature and morphology were examined using a tensile testing machine, differential scanning calorimeter (DSC), dynamic mechanical analysis and Scanning Electron Microscope (SEM). PBT/EVA-g-MAH and PBT/EMA-g-MAH blends exhibited better impact strength than PBT/EVA and PBT/EMA blends because of the larger interfacial adhesion of EVA-g-MAH and EMA-g-MAH with PBT than EVA and EMA. 相似文献
将乙烯–辛烯共聚物接枝马来酸酐(POE-g-MAH)和乙烯–辛烯共聚物接枝甲基丙烯酸缩水甘油酯(POEg-GMA)复配作为增容剂,采用熔融共混的方法制备尼龙(PA)6/聚对苯二甲酸丁二酯(PBT)合金。通过扫描电子显微镜、力学性能和吸湿性研究了PA6/PBT配比和增容剂用量对合金性能的影响。研究表明,增容剂的加入能改善PA6/PBT合金的相容性,PBT和增容剂的加入能有效地抑制PA6的吸水率。添加15份增容剂可使合金的缺口冲击强度达到15.5 k J/m~2,相比未加入增容剂提高385.9%。 相似文献