微孔螺旋中空涤纶短纤维研究

研究了微孔螺旋中空涤纶短纤维的生产工艺,并就喷丝孔的尺寸,微孔溶出工艺、成孔剂在涤纶切片中的共混比及纺丝工艺进行了探讨。结果表明:在常规涤纶切片中添加15%共聚酯-Y成孔剂,纺丝吹风速度0.4--0.6m/s、风温20-25℃等条件下所纺制的异形纤维成孔良好,纤维手感、吸水率等物理机械性能优于常规涤纶,是一种新型的仿毛差别化纤维。     

Walls in liquid crystalline polymers: an electron microscopy study

Walls between domains in an annealed liquid crystal polymer are examined in the transmission electron microscope. The associated contrast in bright field and for various positions of aperture in dark field has been interpreted in terms of the chain reorientation routes across the walls. In addition, the possible wall orientations for a given pair of adjacent domains have been analysed in the light of the necessity of constant chain flux normal to the wall. This condition is also shown to limit the available reorientation routes and simplify the experimental determination of wall structure. Specimens of a thermotropic copolyester annealed for 5 s at 300°C show walls which tend to lie parallel to the original shear direction. The chain orientation in the wall is locally more closely confined to the specimen plane than in the domains, and the distortion type is twist. After longer anneals the walls change contrast in bright field and appear as dark veins. Detailed analysis of micrographs obtained under different imaging conditions shows that the change in character of the walls is associated with a change in reorientation route. The chain axes within the walls that appear as dark veins rotate through the orientation where they are nearly perpendicular to the specimen plane. The stereographic projection is used throughout to illustrate the orientation relationships between the adjacent domains, the chain axes within the wall and the orientation of the wall itself.     

Mechanical properties of miscible polycarbonate-copolyester blends

Miscible blends of polycarbonate and the copolyester based on 1,4-cyclohexane-dimethanol and a mixture of terephthalic and isophthalic acids were melt processed into film and injection moulded into test bars. Wholly amorphous specimens of each type were mechanically tested directly after fabrication and after a variety of annealing conditions. As processed blends exhibited nearly additive responses versus blend composition for modulus, strength, elongation at failure, and notched lzod impact strength. Various annealing protocols caused maxima to appear in plots of modulus versus composition. Similar responses were observed for blend density, and good correlations were noted between density and modulus as both composition andhistory were varied. Sub-T_g annealing of injection moulded specimens was demonstrated to involve simultaneous relaxations of volume and molecular orientation. The individual effects of this combined process were separated by sequential super-T_g (or T_m) and sub-T_g annealing steps.     

用液晶PET(40)/PHB(60)共聚酯对PET共混改性的研究

用热致性液晶高分子材料对塑料进行共混改性,借助液晶的在位复合制取自增强塑料是近年来许多人感兴趣的课题,我们合成了质量比为４０／６０的ＰＥＴ／ＰＨＢ共聚酯,用它对ＰＥＴ进行共混改性,用差示扫描量热（ＤＳＣ）、动态力学粘弹谱,以及小角激光光散射（ＳＡＬＳ）进行结构和性能的考察,表明ＰＥＴ／ＰＨＢ共聚酯对ＰＥＴ有增塑和促进结晶的作用。     

Interchange reactions between poly(ethylene terephthalate) and its copolyesters

Poly(ethylene terephthalate) (PET) was blended with two kinds of co[poly-(ethylene terephthalate-p-oxybenzoate)] (POB-PET) copolyester, designated P46 and P64. The PET and POB-PET copolyester were combined in the ratios of 85/15, 70/30, and 50/50. The blends were melt-mixed in a Brabender Plasticorder at 275, 285, and 293°C for different times. The interchange reactions detected by proton nuclear magnetic resonance analysis occur during the processing at a greater level if the blending time increases. The interchange reactions are as a function of temperature, blending times, and composition of blends. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1591–1595, 1998     

Effect of orientation on the biodegradability of uniaxially stretched aliphatic copolyester films

The effects of uniaxial drawing conditions on the orientation of aliphatic copolyester films were investigated by using both Fourier transform infrared-attenuated total reflection (FTIR-ATR) dichroism and wide angle X-ray diffraction (WAXD) methods. The results showed that orientation in uniaxially drawn films was determined by the drawing rate and drawing temperature. At higher drawing rates and higher drawing temperatures, higher orientation was obtained due to a large deformation of spherulites. The WAXD patterns of drawn films exhibited the preferential orientation of lamellar crystallites. The results of microbial degradation indicated that development of crystalline orientation evidently depressed biodegradability of samples. Video microscopy observations revealed that the degree of orientation played a dominant role in determining the rate of surface erosion. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1999–2006, 1997     

Microstructural characterization of aromatic copolyesters made by step reactions,by gradient polymer elution chromatography

The potentials of Gradient Polymer Elution Chromatography (GPEC) in both the Reversed‐Phase (RP) and Normal‐Phase (NP) mode, for the characterization of aromatic copolyesters made by step reactions, according to their chemical microstructure, were studied. Hereto, a number of copolyesters, varying in molar mass and chemical composition (CC) were synthesized, which allowed a systematic study on the effects of those parameters in GPEC. By RP‐GPEC, highly detailed separations were obtained. Information on chemical composition differences could, however, only be obtained for the lower molar masses. From these results, qualitative evidence for differences in the chemical microstructure of two strongly resembling copolyesters was found that could not be obtained by other methods such as SEC and NMR. Nevertheless, it was found difficult to unambiguously assign observed differences in the high molar mass parts of RP‐GPEC chromatograms. Therefore, RP‐GPEC must mainly be considered as a versatile, qualitative fingerprinting tool. In contrast, NP‐GPEC provides more and quantitative information on microstructural differences. By a combination of SEC and NP‐GPEC the Molar‐Mass‐Functionality‐Type‐Distribution (MMFTD) of the (co)polyesters, and the Molar‐Mass‐Chemical‐Composition‐Distribution (MMCCD) of the fraction containing two alcoholic end groups of the copolyesters could be studied. Significant differences between strongly resembling copolyesters were found which, for the MMCCDs, can only be the cause of the relative importance of reaction kinetics in step reaction copolymers. This makes the assumption that a predictable, theoretical statistically determined CCD is formed in all cases, questionable. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 183–201, 1999     

Thermogravimetric kinetics of thermotropic copolyesters containing p‐oxybenzoate unit by multiple heating‐rate methods

Two series of thermotropic liquid crystalline copolyesters containing mainly the p‐oxybenzoate unit were studied by thermogravimetry to ascertain the kinetic parameters of their thermal degradation by six multiple heating‐rate techniques for the first time. The two copolyesters are (1) poly(p‐oxybenzoate‐co‐ethylene terephthalate‐co‐vanillate) and (2) poly(p‐oxybenzoate‐co‐2,6‐oxynaphthoate). The effect of copolymer composition, degradation stage, and test atmosphere on the three kinetic parameters of the thermal degradation in the weight loss range from 5 to 70% is discussed. Comparison of the multiple heating‐rate techniques with single heating‐rate techniques for calculating the kinetic parameters of thermal degradation was made. The respective activation energy, order, and natural logarithm of the frequency factor of the thermal degradation in nitrogen for the poly(p‐oxybenzoate‐co‐ethylene terephthalate‐co‐vanillate)s are between 180 and 230 kJ/mol, between 2.0 and 5.0, and between 28 and 38 min⁻¹ for the first degradation step and between 250 and 390 kJ/mol, between 6.4 and 7.6, and between 38 and 64 min⁻¹ for the second degradation step of the poly(p‐oxybenzoate‐co‐ethylene terephthalate‐co‐vanillate)s with the unit‐B content in the range of 70–75 mol %. The respective activation energy, order, and natural logarithm of frequency factor of the first degradation stage for the poly(p‐oxybenzoate‐co‐2,6‐oxynaphthoate) (Vectra) are between 380 and 570 kJ/mol, between 2.0 and 3.1, and between 55 and 68 min⁻¹ in nitrogen and between 160 and 210 kJ/mol, between 0.8 and 1.8, and between 25 and 32 min⁻¹ in air. The best methods of calculating the kinetic parameters of the thermal degradation for the copolymers are suggested. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2016–2028, 1999     

可生物降解脂肪-芳香族共聚酯的材料性能研究

采用稀土-钛催化剂,以1,4-丁二醇、己二酸和对苯二甲酸二甲酯为原料制备了含己二酸丁二醇酯(BA)和对苯二甲酸丁二醇酯(BT)单元的系列共聚酯(BA-co-BT)。采用GPC、DSC、流变仪等方法表征了BA-co-BT的相对分子质量、力学性能、热性能和流变性能。表征结果显示,对于含40%～60%(x)BT的BA-co-BT,在相对分子质量及其分布相近时,随BT含量的增加,BA-co-BT的热性能和韧性得到改善,玻璃化转变温度和熔点升高。BA-co-BT熔体的表观黏度随剪切速率的增加而降低,属剪切变稀的假塑性流体,且在低剪切速率下熔体表观黏度对温度更敏感。通过堆肥降解实验研究了BA-co-BT的生物降解性能。实验结果表明,含40%(x)BT的BA-co-BT具有良好的生物降解性。     

High Compatibility and Improved Barrier Performance in Blends Based on a Copolyester Modified with a Poly(amino ether) Resin

Summary: The structure and properties of blends of a PCTG and a PAE resin obtained by direct injection molding have been studied. The blends were almost immiscible, and were composed of a nearly pure PAE phase and a mixed PCTG‐rich phase containing minor PAE amounts. Electron microscopy observations showed a high intermixing level between both components. The permeability data indicated an improved barrier protection of PCTG upon PAE addition. The Young's modulus and the yield stress of the blends followed a linear behavior with respect to composition, while values close or slightly below linearity were observed for the break properties. The combined effects of the small dispersed particle size and the proposed good interfacial adhesion are stated as the main factors responsible for the positive mechanical behavior. The impact strength showed an unexpected variability for PCTG‐rich blends, which is attributed to a ductile‐brittle transition of PCTG.

Ductility of PCTG/PAE blends vs. composition.