Cure characteristics and mechanical properties of short nylon fiber‐reinforced nitrile rubber composites

Acrylonitrile butadiene rubber (NBR)‐based composites were prepared by incorporating short nylon fibers of different lengths and concentration into the matrix using a two‐roll mixing mill according to a base formulation. The curing characteristics of the samples were studied. The influence of fiber length, loading, and rubber crosslinking systems on the properties of the composites was analyzed. Surface morphology of the composites has been studied using Scanning Electron Microscopy (SEM). Addition of nylon fiber to NBR offers good reinforcement, and causes improvement in mechanical properties. A fiber length of 6 mm was found to be optimum for the best balance of properties. It has been found that at higher fiber loadings, composites show brittle‐type behavior. Composites vulcanized by the dicumyl peroxide (DCP) system were found to have better mechanical properties than that by the sulfur system. The swelling behavior of the composites in N,N‐dimethyl formamide has been analyzed for the swelling coefficient values. Composites vulcanized in the DCP system were found to have higher rubber volume fraction than that in the sulfur system, which indicates better rubber–fiber interaction in the former. The crosslink densities of various composites were also compared. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1023–1030, 2004     

双酯基季铵盐表面活性剂的合成及性能研究

以尼龙酸、环氧氯丙烷为原料合成二元酸酯中间体,再与十二烷基二甲基胺进一步反应合成双酯基阳离子表面活性剂。研究了反应时间、温度及催化剂用量对产物收率的影响,得到了最佳反应条件。终产物结构通过红外光谱分析得到证实,并对其表面性能进行了测试,临界胶束浓度0．34mmol／L,表面张力29．9mN／m。     

氨基硅油与蒙脱土协同阻燃尼龙6

通过熔融共混法制得尼龙6/纳米蒙脱土/氨基硅油复合材料,研究氨基硅油和蒙脱土的含量对共混物的力学性能和阻燃性能的影响.通过研究表明:蒙脱土的少量加入在很大程度上改善了尼龙6的力学性能和抗熔滴性能;纳米蒙脱土与氨基硅油(ASO)具有阻燃协同效应,使其极限氧指数(LOI)进一步提高.     

尼龙6/碳纳米管浇铸成型的反应动力学

将改性的多壁羟基碳纳米管分散在熔融的己内酰胺中,一步原位聚合制备MC(单体浇铸)尼龙6/碳纳米管复合材料;采用非等温反应动力学分析方法对尼龙6/多壁碳纳米管浇铸成型的反应过程进行研究.结果表明:随着改性碳纳米管含量的增加,反应活化能及指前因子增加;MC尼龙6及其碳纳米管复合材料成型过程的反应级数都在0.9 ～1之间,可以认为是准一级反应.     

PA6/LiC1复合材料结构分析与性能研究

采用熔融共混挤出的方法,制备了尼龙(PA)6/LiCl复合材料,研究了不同含量的LiC1对PA6的结晶结构及性能的影响.傅立叶变换红外光谱、差示扫描量热、X射线衍射分析及力学性能测试结果表明,LiC1中“+和PA6间产生了络合作用,破坏了PA6中原有的氢键,降低了PA6的分子链的规整排列,但该络合作用使PA6分子链间产...     

塑料摩擦试验方法的研究

以尼龙和超高分子量聚乙烯为研究对象,寻求一种理想的摩擦试验用试样预处理方法;并研究塑料在钢上滑动和钢在塑料上滑动的两种摩擦类型的摩擦系数区别及关系。通过反复性试验发现,采用砂纸预处理螺纹状试样,并与螺纹状摩擦副配套使用,摩擦面积和稳定性都大幅度增加;两种不同的滑动方式所得到的摩擦系数相差很大,具有不可比性。     

Effect of temperature and thermodynamic quality of solvent over unperturbed chain dimensions of nylon 6

A nylon 6 sample having average molecular mass 4.825 × 10⁵ g mol^?1 was fractionated into five different fractions with respect to molecular mass, which ranged from 3691 to 999,000 g mol^?1. The light scattering and intrinsic viscosity measurements were made in m‐cresol and its mixture with 1,4‐dioxane. The second virial coefficient, radius of gyration and Mark Houwink's constant and unperturbed chain dimensions were determined by light scattering and viscosity measurement. It has been observed that all these parameters are composition of solvent and temperature dependent. The solvent having composition of 97% m‐cresol and 3% dioxane, was best and it deteriorated with the increase/decrease in percentage of 1,4‐dioxane in m‐cresol. However, its thermodynamic quality was enhanced with the temperature. Such variation in quality of solvent was reflected in all the estimated parameters and showed maxima at this composition of solvent. The unperturbed dimensions obtained by different methods though, differed in values but showed same trend and NA‐MKB method gave close results to the one obtained through [η_o]. A new expression has also been proposed relating k_o to solvent quality and temperature and the data obtained by us for nylon‐6 and the one obtained from the literature for dextran obeyed this expression up to large extent irrespective of the solvent composition and temperature. The proposed equations have also been applied to dextran/methoxy ethylene and dextran/ethylene glycol systems and worked well. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Modification of nylon 66 by electron beam irradiation for improved properties and superior performances

Nylon 66 has been transformed into a material with significantly improved properties like hardness, tensile strength, and flexural modulus by processing it under the optimized dose rate of electron beam in the presence of suitable crosslinkers. Furthermore, percent water absorption of nylon 66 was reduced substantially on irradiation. Thermogravimetric analysis revealed that thermal stability of nylon 66 improved with increasing dose of radiation. Improvement of mechanical and thermal properties and reduction of water absorption of nylon 66 were due to the crosslinking of polyamide molecules made possible by the high energy radiation. Increase of crosslinking with increasing radiation dose was verified by the increase of gel content at higher doses. Differential scanning calorimetry showed that both melting and crystallization temperatures along with percent crystallinity of nylon 66 were decreased with the increasing dose of radiation leading to the development of more amorphous character in this semicrystalline polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Facile preparation of nylon 6 nanocomposites based on clay reinforcement and core‐shell latex toughening: Morphology,properties, and impact fracture behavior

This work is focused on a facile route to prepare a new type of nylon 6‐based nanocomposites with both high fracture toughness and high strength. A series of nylon 6‐matrix blends were prepared via melting extrusion by compounding with poly (methyl methacrylate‐co‐butadiene‐co‐styrene) (MBS) or poly(methyl methacrylate‐co‐methylphenyl siloxane‐co‐styrene) (MSIS) latices as impact modifier and diglycidyl ether of bisphenol‐A (DGEBA) as compatibilizer. Layered organic clay was also incorporated into above nylon 6 blends for the reinforcement of materials. Morphology study suggests that the MBS or MSIS latex particles could achieve a mono‐dispersion in nylon 6 matrix with the aid of DGEBA, which improves the compatibilization and an interfacial adhesion between the matrix and the shell of MBS or MSIS. High impact toughness was also obtained but with a corresponding reduction in tensile strength and stiffness. A moderate amount of organic clay as reinforcing agent could gain a desirable balance between the strength, stiffness and toughness of the materials, and tensile strength and stiffness could achieve an improvement. This suggests that the combination of organic clay and core‐shell latex particles is a useful strategy to optimize and enhance the properties of nylon 6. Morphology observation indicates that the layered organic clay was completely exfoliated within nylon 6 matrix. It is found that the core‐shell latex particles and the clay platelets were dispersed individually in nylon 6 matrix, and no clay platelets were present in MBS or MSIS latex particles. So the presence of the clay in nylon 6 matrix does not disturb the latex particles to promote high fracture toughness via particle cavitation and subsequent matrix shear yielding, and therefore, provides maximum reinforcement to the polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Morphology and properties of nylon6 and high density polyethylene blends in absence and presence of nanoclay

The morphology and properties of nylon6/HDPE blends without and with nanoclay has been reported. Scanning electron microscopy study of the (70/30 w/w) nylon6/HDPE blends with small amount (0.1 phr) of nanoclay indicated a reduction in the average domain sizes (D) of dispersed HDPE phase and hence better extent of mixing compared to the blend without any nanoclay. X‐ray diffraction study and transmission electron microscopy revealed that nanoclay layers were mostly located in nylon6 matrix of the (70/30 w/w) nylon6/HDPE blend. However, the same effect of nanoclay on the morphology was not observed in (30/70 w/w) nylon6/HDPE blend where HDPE became the matrix. In (30/70 w/w) nylon6/HDPE blend, addition of nanoclay increased the D of dispersed nylon6 domains by preferential location of the clays in side the nylon6 domains. Thus, the clay platelets in the matrix phase acted as barrier that restricted the coalescence of dispersed domains during melt‐mixing. Addition of PE‐g‐MA in both the compositions of nylon6/HDPE blend effectively reduced the D of dispersed phases. Storage modulus and thermal stability of the blend were improved in presence of small amount of clay, whereas addition of PE‐g‐MA lowered the mechanical and thermal properties of the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011