尼龙6／马来酸酐接枝聚丙烯合金力学性能和流变行为的研究

本研究利用单螺杆挤出机通过熔融共混制备了尼龙6/接枝聚丙烯塑料合金,并测定了其吸水性、力学性能和流变行为。结果表明:接枝聚丙烯可以改善尼龙6与聚丙烯之间的相容性,合金的吸水率明显降低,在保持较高刚性的同时冲击性能优于尼龙6。流变测定表明:尼龙6/接枝聚丙烯合金的假塑性增加、熔体粘度上升、成型加工性较尼龙6有所改善。     

尼龙6/环氧树脂共混物流变性能的研究

用毛细管流变仪研究了尼龙6／环氧树脂共混物的流变性能。结果表明,在实验范围内共混物熔体为假塑性流体;随着环氧树脂用量的增加,表观粘度（ηa）增大,非牛顿指数（n）减小,熔体稠度（K）增大,粘流活化能降低。     

尼龙6/环氧树脂共混体系化学流变行为研究

利用转矩流变仪和应力流变仪对尼龙6/环氧树脂体系的化学流变行为进行了研究。结果表明:在热和剪切力的作用下,环氧树脂与PA6发生了化学微交联反应,使共混体系的转矩和熔体温度上升。研究了环氧树脂含量、转速和温度对共混体系的影响。反应共混物熔体呈假塑性流体特征。随着环氧树脂含量的增加,共混物熔体的复数粘度和储能模量上升。     

尼龙6共混增韧改性的研究

利用双螺杆挤出机通过熔融共混制备了尼龙6/三元乙丙橡胶(EPDM)/接枝三元乙丙橡胶(EPDM g MAH)和尼龙6/接枝三元乙丙橡胶(EPDM g MAH)塑料合金,并研究测定了其吸水性、力学性能和流变行为。结果表明:接枝三元乙丙橡胶明显改善尼龙6与三元乙丙橡胶之间的相容性,合金的吸水率明显降低,在保持较高强度的同时冲击性能远远优于尼龙6,接近或超过韧性尼龙;熔体指数明显下降、成型加工性较尼龙6明显改善。     

高流动性尼龙6的增强增韧改性研究

采用熔融共混方法,制备了高流动性尼龙6和尼龙6的增强增韧改性材料,考察了增韧剂添加量对改性材料的加工流变和力学性能的影响。结果表明,高流动性尼龙6的增强增韧改性材料的熔体流动性优于尼龙6的增强增韧改性材料,当增韧剂质量分数为10%~15%时,高流动性尼龙6的增强增韧改性材料力学强度和冲击韧性均优于尼龙6的增强增韧改性材料,实现了材料高刚度性能和高抗冲击性能的完美平衡。     

尼龙6/MYC共混物的熔融纺丝性能研究

用NYC对尼龙6进行改性,通过双螺杆挤出机共混造粒后再熔融纺丝,研究了改性尼龙6的性能。结果表明随着NYC含量增加尼龙6的结晶温度增加,而熔融温度和熔体流动速率降低;尼龙6纤维的最大可延伸比和不同倍率时的比强度都呈现先增加后减小的趋势,分别在NYC含量为0．5％时达到其最高值。     

尼尼6／环氧树脂共混体系化学流变行为研究

利用转矩流变仪和应力流变仪对尼龙6/环氧树脂体系的化学流变行为进行了研究。结果表明：在热和剪切力的作用下，环氧树脂与PA6发生了化学微交联反应。使共混体系的转矩和熔体温度上升。研究了环氧树脂含量．转速和温度对共混体系的影响。反应共混物熔体量呈假塑性流体特征。随着环氧树脂含量的增加，共混物熔体的复数粘度和储能模量上升。     

PS/PA6共混体系的研究进展

综述了国内外聚苯乙烯与尼龙6共混的研究进展,分析了共混物的相容性、相形态、结晶性能和流变性能。重点介绍了增容剂对聚苯乙烯与尼龙6共混的增容作用和共混物相形态的变化。     

尼龙共混物拉伸流动行为的研究

以Oldroyd共旋转B模型为基础,从理论上推导了尼龙拉伸流动模型,建立了针对尼龙熔体的拉伸流动本构方程,研究了尼龙6及其尼龙610共混物的熔体拉伸流动行为.结果表明,尼龙共混物的拉伸黏度与剪切速率的平方和拉伸速率之比呈现拟合关系,根据试验数据拟合得到了拉伸黏度对剪切速率的平方和拉伸速率之比的经验公式.并且通过数据拟合发现,尼龙6和尼龙610共混物的拉伸应力与参数t存在较好的幂律拟合关系.     

PP/PA6/POE-g-MAH三元共混对聚丙烯熔体强度的影响

将尼龙6(PA6)、普通聚丙烯(PP)以及POE-g-MAH三元共混,改善聚丙烯的熔体强度。应用熔体强度测试仪直接测量了改性PP的熔体强度值,并对改性PP的动态流变特性、红外光谱以及微观形貌特点进行了研究。研究结果表明,该方法可以提高聚丙烯熔体强度。     

Nylon 6 nanocomposites prepared by a melt mixing masterbatch process

A melt mixing masterbatch process for preparing nylon 6 nanocomposites that provides good exfoliation and low melt viscosities has been investigated. It is known that high molecular weight (HMW) grades of nylon 6 lead to higher levels of exfoliation of organoclays than do low molecular weight (LMW) grades of nylon 6. However, LMW grades of nylon 6 have lower melt viscosities, which are favorable for certain commercial applications like injection molding. To resolve this, a two-step process to prepare nanocomposites based on nylon 6 is explored here. In the first step, a masterbatch of organoclay in HMW nylon 6 is prepared by melt processing to give exfoliation. In the second step, the masterbatch is diluted with LMW nylon 6 to the desired montmorillonite (MMT) content to reduce melt viscosity. Wide angle X-ray scattering, transmission electron microscopy, and stress-strain analysis were used to evaluate the effect of the clay content in the masterbatch on the morphology and physical properties of the final nanocomposite. The melt viscosity was characterized by Brabender Torque Rheometry. The physical properties of the nanocomposites prepared by the masterbatch approach lie between those of the corresponding composites prepared directly from HMW nylon 6 and LMW nylon 6. A clear trade-off was observed between the modulus and melt processability. Masterbatches that have lower MMT content offer a significant decrease in melt viscosity and a small reduction in modulus compared to nanocomposites prepared directly from HMW nylon 6. Higher MMT concentrations in the masterbatch lead to a less favorable trade-off.     

Investigation on the interaction between polyamide and lithium salts

FTIR spectroscopy and thermal analysis were applied to study the nylon 6–lithium salt systems. The DTA results show that lithium ions cause a significant reduction of the melting point of nylon–lithium salt samples. In addition, lithium salts can also prevent the crystallization of molten nylon in the cooling process. Temperature‐variable FTIR spectroscopy demonstrates that stronger hydrogen bonds form when nylon–lithium halide is molten. Such stronger hydrogen bonds in molten nylon lithium systems may account for the reduction of the melting point and delaying the crystallization of the amorphous nylon. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2685–2690, 2000     

The influence of melt processing on the spatial organization of polymer chains in a crystallizable diblock copolymer of nylon 6 and PDMS

Crystallized chains of nylon 6 lie parallel to the interfaces of the microphase-separated morphology of a nylon 6/PDMS diblock copolymer. Orienting the morphology in the melt using plane strain compression enabled the nylon chain direction to be determined through a combination of transmission electron microscopy, small-angle X-ray scattering and wide-angle X-ray scattering pole figure analysis. Processing at temperatures above the nylon 6 melting point serves to orient the microphase-separated morphology of the melt; the nylon 6 chain orientations are then largely dictated by thermodynamic considerations that apply to chains crystallizing within the confines of a microphase separated melt. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1985–1990, 1998     

氯化锂对聚乙烯醇材料性能的影响

通过熔融共混挤出的方式,采用氯化锂(LiCl)对聚乙烯醇(PVA)进行改性,制备了PVA/LiCl复合材料,并运用傅里叶红外光谱法、差示扫描量热法和X射线衍射法等分析方法,研究了不同含量的LiCl对PVA的结晶行为和力学性能的影响。结果表明:LiCl中的Li+与PVA中的羟基产生络合作用,破坏了PVA中原有的氢键,降低了PVA分子链排列的规整性。随着LiCl含量的增加,复合材料的熔点、拉伸强度降低,断裂伸长率略微上升。     

Interaction of anhydrous ferric chloride with nylon 6

The interaction of anhydrous ferric chloride with nylon 6 has been inferred from Fourier transform infrared spectroscopy (FTIR), wide-angle x-ray diffraction (WAXD), thermal (DSC and TGA), and rheological (Rheometrics) measurements. At very low additive concentration of ～0.25 wt %, an about 50-fold melt viscosity increase of nylon 6 was observed. However, progressive decrease in melt viscosity was also observed with increasing additive concentrations indicative of degradation as confirmed by the enhancement of weight loss with TGA at a lower temperature. Decrease in crystallinity content of the filled nylon samples is inferred from the reduction of the melting endotherms with DSC, pronounced reduction in diffraction intensity with WAXD, an increase in amorphous CH₂ bending band (1400 cm^?1) with FTIR. The above results can be attributed to the strong complex formation between the FeCl₃ and the N? H groups as suggested by the subtraction spectra of FTIR where decreased intensities of the 690, 1200, and 1265 cm^?1 bands were observed.     

Miscibility and Mechanical Properties of Poly(4,4′-diaminobenzanilide- 2,6-naphthalamide)/Nylon 6 Molecular Composites

Poly(4,4′-diaminobenzanilide-2,6-naphthalamide) (DBNA) was synthe-sized by reaction of 2,6-naphthalene dicarboxylic acid with 4,4′-diamino-benzanilide. A new family of molecular composites based on the synthesized DBNA and nylon 6 has been discovered. Exploratory studies were con-ducted with polymers that are soluble in a common organic solvent, N-methylpyrrolidone containing lithium chloride, so that a blend could be prepared by precipitating blended materials in solution into a non-solvent such as water. The miscibility of blends of DBNA with nylon 6 was studied using a differential scanning calorimeter, dynamic mechanical analyser and Fourier transform infrared spectrometer. The blends were found to have at least partial miscibility between DBNA and nylon 6. The morphology and mechanical properties of the molecular composites were evaluated using a scanning electron microscope, transmission electron microscope and tensile tester. The etched specimen showed microfibrils with a diameter of a few nanometres. It has been found that improvement in DBNA dispersion and mechanical properties can be obtained by blending small amounts of DBNA in nylon 6. © of SCI.     

New developments in the melt rheology of nylons. I: Effect of moisture and molecular weight

Peculiar observations on the melt rheology of ultra-dry nylon resins, nylon 6 in particular, are reported. One aspect of this study deals with a sharp increase in zero shear melt viscosity (e.g. 2 to 5 times) as the nylon 6 resin moisture is taken from 0.10 down to 0.00%; the effect being reversible. Changes of such magnitude are unexpected considering that there are no detectable variations of the chemical/compositional/molecular weight type in the starting resin, when subjected to the imposed drying conditions. Another aspect of this study deals with a deviation of nylons (6, 6,6, and 12) from the Bueche (1952) relationship, well accepted for polymers to date. Under moderate drying conditions (e.g. 50°C/17 h/110 millitorr), the molecular weight exponent is found to be 3.8, which is within the range of 3.4 to 3.8 reported for nylon 6. However, under more severe drying conditions (e.g. 110°C/17 h/110 millitorr), the molecular weight exponents for nylon 6, nylon 66, and nylon 12 are 4.8, 5.4, and 4.6, respectively. We are proposing that a sharp increase in melt viscosity of ultra-dry nylon 6 is partly due to an increase in the molecular weight of the melt (extrudate) which then, has a more pronounced impact on melt viscosity in view of the 4.8 exponent. Such unique results, in contrast to polyethylene (free radical polymer) and poly(ethylene terephthalate) (condensation polymer) are tentatively attributed to H-bonding in nylon melts. Yet another aspect of this study deals with the rheology of supercooled molten polymers that can offer advantages for analytical characterization.     

胺类改性剂对尼龙6树脂可纺性能的影响

在己内酰胺水解聚合时加入一定量的可反应型复合胺类改性剂,合成出含有胺类改性剂的尼龙6树脂。研究了该改性剂对改善尼龙6树脂可纺性的作用。结果表明:在实验的添加量范围内,改性尼龙6树脂熔体黏度对切变速率的依赖敏感性下降,纺丝过程可以处于相对稳定的状态;与空白试样相比,当改性剂用量为0.1份时,尼龙6树脂中的低聚物含量明显减少,相对分子质量分布由1.7677降低到1.6093,表明在尼龙6熔体的纺丝成形过程中,胺类改性剂可以有效地改善其可纺性。     

Polymorphic behavior of nylon 6/saponite and nylon 6/montmorillonite nanocomposites

X‐ray diffraction methods and DSC thermal analysis have been used to investigate the structural change of nylon 6/clay nanocomposites. Nylon 6/clay has prepared by the intercalation of ε‐caprolactam and then exfoliaton of the layered saponite or montmorillonite by subsequent polymerization. Both X‐ray diffraction data and DSC results indicate the presence of polymorphism in nylon 6 and in nylon 6/clay nanocomposites. This polymorphic behavior is dependent on the cooling rate of nylon 6/clay nanocomposites from melt and the content of saponite or montmorillonite in nylon 6/clay nanocomposites. The quenching from the melt induces the crystallization into the γ crystalline form. The addition of clay increases the crystallization rate of the α crystalline form at lower saponite content and promotes the heterophase nucleation of γ crystalline form at higher saponite or montmorillonite content. The effect of thermal treatment on the crystalline structure of nylon 6/clay nanocomposites in the range between Tg and Tm is also discussed.