超细纤维用LDPE 1I60A的流变和加工应用性能

研究了低密度聚乙烯(LDPE)1I60A的流变性能,聚酰胺(PA)6/LDPE共混纤维的开纤剥离性能及其剥离前后形貌的变化。结果表明:LDPE 1I60A熔体黏度低,PA 6/LDPE熔体黏度比大,有利于提高PA 6/LDPE中PA 6的含量;LDPE 1I60A与PA 6共混后加工性能优良,"岛"相分布均匀,LDPE 1I60A更易从PA 6/LDPE共混纤维中被溶解抽出,有利于得到PA 6含量较高的超细纤维。     

PA6/LDPE/PE-g-MAH共混纳米纤维的制备及结构研究

采用共混海岛纺丝法制备聚酰胺6/低密度聚乙烯/聚乙烯接枝马来酸酐(PA6/LDPE/PE-g-MAH)共混纤维,溶解剥离出LDPE基体相,可制备出PA6纳米纤维;研究了共混物的组成和纺丝条件对共混纤维的相结构、结晶、力学性能及PA6纳米纤维直径的影响。结果表明:随着共混物中PA6分散相含量增加,PA6纳米纤维的直径逐渐增大;PA6质量分数从30%增加至60%时,PA6纳米纤维平均直径由107 nm增至149nm;PA6质量分数为70%时,由于相逆转无法得到PA6纳米纤维;在PA6质量分数为55%条件下,提高拉伸倍数,PA6纳米纤维的直径进一步降低,且结晶度、力学性能增加。     

PA6/LDPE共混物流变性能的研究

研究了聚酰胺6/低密度聚乙烯(PA6/LDPE)共混体系的结构和流变性能。结果表明:共混体系呈现以PA6为分散相,LDPE为连续相的海岛结构;在实验范围内共混体系为非牛顿流体,满足幂律方程;LDPE对温度比较敏感,LDPE的流变行为占主导地位,PA6的粘度主要受剪切力的影响;在剪切速度一定时,PA6与LDPE的粘度比随着温度的升高而增加;在温度一定时,粘度比随着剪切速率的增加而下降;改变温度及剪切力可以调节两组分粘度比。     

高流动性PA 6超细纤维的制备及其性能研究

采用自制的高流动性聚己内酰胺(HPA 6)、普通聚己内酰胺(PA 6)、低密度聚乙烯(LDPE)为原料,通过共混纺丝法分别制备HPA 6/LDPE定岛纤维和HPA 6/PA 6/LDPE不定岛纤维,溶解去除LDPE,得到一系列HPA 6超细纤维;研究了HPA 6的可纺性及其超细纤维的线密度、力学性能、染色性能等。结果表明:由于HPA 6在纺丝温度下较好的流动性和高支化结构及大量末端基团,HPA 6可纺性良好;HPA 6/LDPE质量比为70/30时,157.4 dtex/36 fHPA 6超细纤维断裂强度为3.85 c N/dtex,断裂伸长率为14%,染色深度为1.809,色牢度达5级;HPA 6超细纤维的力学性能和染色性能优异,与PA 6超细纤维性能相当,可拓展其在纤维领域的应用。     

共混工艺对SMAH增容ABS/PA6共混物形态和力学性能的影响

以(苯乙烯/马来酸酐)共聚物(SMAH)为增容剂,研究了共混工艺对(丙烯腈/丁二烯/苯乙烯)共聚物/尼龙6(ABS/PA6)共混物聚集态结构和力学性能的影响。结果表明,ABS与PA6直接共混时相容性差;加入增容剂SMAH后,分散相尺寸变小且易均匀分散,显著改善了ABS/PA6共混物的力学性能。当ABS为连续相、PA6为分散相时,共混物的聚集态结构强烈地受共混工艺的影响,(ABS/SMAH)/PA6共混物的分散相尺寸最小、力学性能最优;当PA6为连续相、ABS为分散相时,共混物的聚集态结构基本不受共混工艺的影响。     

LDPE/PA6海岛复合超细纤维的可纺性及性能研究

采用熔融复合纺丝法制备了低密度聚乙烯(LDPE)/聚己内酰胺(PA6)海岛复合超细纤维,讨论了纺丝温度、海岛比例和纺丝速度对纤维的可纺性、结构和性能的影响。结果表明:在纺丝温度为278℃,LDPE/PA6质量比为50/50,45/55,40/60,35/65,30/70,冷却长度为140 mm,纺丝速度为1 000 m/min时,海岛复合纤维具有良好的可纺性和海岛结构,其超细纤维线密度为0.077~0.110 dtex;在PA6质量分数为55%条件下,提高纺丝速度,PA6超细纤维的直径进一步降低,力学性能增加,但不匀率上升。     

尼龙6/低密度聚乙烯不定岛型海岛纤维生产技术

以尼龙6(PA6)和低密度聚乙烯(LDPE)为原料,采用共混熔融纺丝技术,制得单纤为5~6dtex的不定岛型海岛纤维,该纤维在后加工过程中通过苯减量可得到0.001~0.01dtex的超细纤维。介绍了这种纤维的制造工艺,讨论了对纤维生产影响较大的工艺参数。     

聚酰胺6/低密度聚乙烯海岛型纤维萃取分离的研究

利用低密度聚乙烯(LDPE)溶于热甲苯的原理,用甲苯对聚酰胺6/低密度聚乙烯(PA6/LDPE)海岛型纤维中的LDPE进行萃取,得到聚酰胺6超细纤维。用DSC、SEM研究了海岛纤维在萃取过程中的变化及影响因素。结果表明:萃取过程是甲苯向海岛纤维渗透、溶解LDPE以及LDPE向甲苯中扩散的动态平衡。萃取温度与时间是其主要影响因素,在85～90℃下萃取60～70 min,可充分萃取LDPE。由于不同时间段甲苯对LDPE的萃取速率不同,因此可采用甲苯对流、多段连续的萃取方式进行萃取。     

接枝LDPE与PET共混物的热力学性能和相形态研究

通过红外光谱对合成的三种极性单体接技LDPE进行了确证,采用热分析仪和扫描电镜研究了接枝LDPE/PET共混物的热力学性能和相形态结构。结果表明,接枝LDPE与PET共混,对PET结晶过程有一定的加速促进作用;由缺口冲击断面观察发现,接枝LDPE以分散相分布在PET连续相中,但相界面之间有丝状物相连,说明接枝LDPE与PET有较好的相容性。     

丁苯橡胶与高压聚乙烯共混物的微观相结构形态

采用冷冻超薄切片,四氧化锇染色制备样品,用透射电子显微镜观察,研究了丁苯橡胶/高压聚乙烯(SBR/LDPE)共混物的微观相结构形态。当 LDPE用量为 5—35％时,LDPE为分散相,SBR为连续相,并随 LDPE用量的增加,分散相的区域尺寸由 0.5 μm增大到 3.0 μm,而其形态则由近似圆球形变成不规则的长条形。当 LDPB用量增大到50％时,LDPE 呈网状结构,在网络区包藏有小于0.2μm的SBR颗粒,即发生了相转变。共混温度以110±5℃为宜。二段共混与一段共混相比,共混均匀,分散相的最大区域尺寸可由 5 μm下降到小于 1μm,且相分布较密。加入助剂,能使相结构更为精细。     

Rheological and Mechanical Properties of LDPE/HDPE Blends

Melt rheology and mechanical properties of binary blend of low-density polyethylene (LDPE) and high-density polyethylene (HDPE) have been investigated. Four different wt fractions of blends containing LDPE/HDPE (20/80, 40/60, 60/40, and 80/20) were prepared. Cole-Cole plots [storage melt viscosity (η′) vs. loss melt viscosity (η″)] and relation between storage melt viscosity (η′) with frequency (ω) and blend composition were constructed. Miscibility of blends was established from rheological data. Impact strength of the blends increased with increasing LDPE concentration, whereas tensile strength shows the opposite trends. Percentages of the crystallinity of the blends were calculated by both the differential scanning calorimetry and wide-angle X-ray scattering methods, which show that the percentage of crystallinity decreased with increasing LDPE concentration, but the rate of crystallization of HDPE phase was unaffected.     

茂金属聚乙烯（mPE）／高压聚乙烯（LDPE）共混熔体的流变学

研究了不同比例共混的茂金属聚乙烯（mPE)和高压聚乙烯（LDPE）熔体的流变行为,讨论了共混物组成、剪切速率和剪切应力以及温度对熔体流变曲线、熔体粘度和膨胀比的影响,mPE的加工提供了理论依据。不同共混比的熔体均为假塑性流体,且熔体假塑性随LDPE含量增大而增强。熔体流动活化能随LDPE组成的增加逐渐增大,粘度对温度的敏感性增强,共混物的非牛顿指数随LDPE的增加而降低,改善了mPE的加工性能。     

Basic and applied rheology of m-LLDPE/LDPE blends: Miscibility and processing features

The linear viscosity of m-LLDPE/LDPE blends is adjusted to a free volume model, conceived for miscible blends. A deviation from the model is observed at 47.5% m-LLDPE/52.5% LDPE blend, suggesting immiscibility in the molten state at this composition. Time-temperature superposition method is used to confirm miscible and immiscible cases. The effect of miscibility on practical rheological features is analysed using extrusion rheometry. The results indicate a core-sheet morphology in the immiscible blend, as the less viscous LDPE encircles the m-LLDPE phase. Miscible blends with a high LDPE content and immiscible 47.5% m-LLDPE/52.5% LDPE blend, show ‘melt fracture’, but not ‘sharkskin’. The latter is observed in miscible blends of a high m-LLDPE content. ‘Sharkskin’ is postponed in 87.5% m-LLDPE/12.5% LDPE blend, a result which is associated to the elongational viscosity enhancement, due to the presence of long chain branches. The correlation between melt spinning and blown film extrusion results is investigated, showing evidences of the technical limitations caused by immiscibilty.     

Investigation of the melting behavior and morphology development of polymer blends in the melting zone of twin‐screw extruders

The melting behavior and the morphology development that runs parallel to it play central roles in the processing of polymer blends. We studied the impact of speed, melt throughput, continuous‐phase viscosity, screw configuration, and disperse‐phase content on the melting behavior and morphology development in the melting zone of a twin‐screw extruder. The polymer blend used incorporated polyamide‐6 (PA6) as its disperse phase and a high‐viscosity or low‐viscosity polypropylene as the matrix phase. The melting behavior of the polymer blend was investigated with press plates. A qualitative assessment was made of the processes, on basis of the optical impression gained from the transilluminated press plates. One key result was that the PA6 granules melted very rapidly in the polypropylene melt. We took samples over the length of the melting section to permit a quantitative assessment of the morphology. The results show a finely dispersed morphology already at the start of the melting section. This did not undergo any essential change as the blend passed through the extruder, and only a limited correlation was evident with the process parameters. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1986–2002, 2001     

PETA熔融接枝PP/LDPE共混物的研究

研究了季戊四醇三丙烯酸酯熔融接枝PP／LDPE共混物体系中，各因素对产物熔体质量流动速率和熔体强度的影响，并对产物拉伸粘度和化学接枝情况等进行了测试及表征，实验结果表明，引发剂用量较低，单体用量较高时，产物的熔体质量流动速率小,熔体强度较高，拉伸粘度较大，且在拉伸过程中，产生了应变硬化效应；随着单体用量的增加，接枝率会有所上升。     

Effects of varying melt flow rates on laser melt-electrospinning of low-density polyethylene nanofibers

The ultimate functionality and applicability of polymeric nanofibers are mainly to subject on its diameter. This study explores the influence of melt flow rates (MFRs) of low-density polyethylene (LDPE) on the diameter of laser melt electrospun nanofibers. Ethylene-vinyl alcohol (EVOH) copolymer was added to the nonpolar LDPE as a spinning aid. After electrospinning, the EVOH was removed from LDPE/EVOH blend fiber by treating with isopropanol/water solution and LDPE nanofiber was obtained with a diameter of only 190 ± 85 nm for the highest MFR. A linear diameter reduction was observed for pure LDPE and EVOH removed LDPE fiber with the increase of MFR. However, a slight diameter increment was reported for the LDPE/EVOH blend fiber with higher MFR due to the improved melt viscosity of the component. A massive diameter decrement was found after EVOH removal from the blended fiber, resulting in the renovation of microfiber to a stable nanoscale dimension.     

Studies on binary and ternary blends of polypropylene with ABS and LDPE. I. Melt rheological behavior

Studies are presented on melt rheological properties of binary blend of polypropylene (PP) and acrylonitrile–butadiene–styrene terpolymer (ABS), and ternary blend of PP, ABS, and low-den-sity polyethylene (LDPE). Data obtained in capillary rheometer are presented to describe the effect of blending ratio, shear stress, and shear rate on flow properties, melt viscosity, and melt elasticity. At a blend composition corresponding to 10 wt % ABS content, both binary and ternary blends show maximum in melt viscosity accompanied by minimum in melt elasticity. Pseudoplasticity of the melt decreases with increasing ABS content. In ternary blends, LDPE facilitates the flow at low LDPE contents and obstructs the flow at high LDPE contents. Scanning electron microscopic studies are also presented to illustrate the state of dispersion and its variation with blend composition.