尼龙11、尼龙12的发展及应用

介绍了尼龙11、尼龙12的特性，应用范围和发展动态。     

用中低粘度尼龙生产玻纤增强型挤出级尼龙

介绍了将工业品中、低粘度的尼龙通过共混改性制成玻纤增强型挤出级尼龙专用料。已将玻纤增强型挤出级尼龙制作列车异型密封条 ,使用效果良好     

尼龙12的合成与应用

本文重点介绍了尼龙１２的合成及其物化性质，用途。     

尼龙结构对尼龙/聚乙烯共混物织构形态的影响

比较了尼龙６／线型低密度聚乙烯（ＰＡ６／ＬＤＰＥ）和尼龙１０１０／线型低密度聚乙烯（ＰＡ１０１０／ＬＬＤＰＥ）共混和的织构形态,共混物的织构形态除与织构调节剂、组分比有关外,还与尼龙物结构有很大关系。在尼龙／聚乙烯二元共混物中,分散相粒子以球状（或椭球状）形式存在,粒子较大,两相界面清晰,加入织构调节剂后,分散相粒子明显变小,分布均匀,在尼龙６共混物中,除仍有表面光滑的球状粒子外,出现了莲藕断面状粒子,但两相之间仍有缝隙,而在尼龙１０１０共混物中,出现了辐（车）轮状粒子,两相间相互作用强,分散相粒子与连续相之间紧紧地连接在一起,表明高碳数的尼龙１０１０与聚乙烯的链段间的相容性更好。     

新型阻燃尼龙

四种阻燃级别达型到94V一0的新型阻燃尼龙用于注塑成刑电子／电器部件。Chem聚合物公司出品的这些混合物既包括了含卤、玻纤增强材料，也包括无卤非增强材料。尼龙6品级包括Chemlon233GVH。     

碳纤维增强MC 尼龙的研究

利用树脂传递模塑成型的原理, 通过阴离子聚合制得了碳纤维增强MC 尼龙。研究了不同纤维含量对复合材料性能的影响。研究结果表明, 用这种方法制得的碳纤维增强MC 尼龙的机械性能较普通MC 尼龙有较大幅度的提高, 纤维在基体中的分散性好, 同基体的粘接性也相当好。      

耐高温尼龙的研究进展

回顾了尼龙(PA)的发展历程,介绍了几种传统耐高温尼龙的性能特点及主要生产厂商,同时阐述了几种最新的耐高温尼龙进展.提出了发展建议,认为对半芳香尼龙的共聚改性以及新型的半芳香尼龙的合成,是目前高温尼龙的研究热点.     

Polymorphism in nylon 66

The molecular structure of room temperature (RT) nylon 66 and its transition to the high temperature (HT) form have been examined by X-ray crystallographic techniques. An initial literature survey on the RT form revealed a number of anomalies in the spatial relationships of the molecules within the unit cell, namely, poor ethylenic segment packing, distortion of the amide group from a planar configuration and lack of similarity on the projected cell base between RT nylon 66 and RT nylon 6. These anomalies have been resolved, and models proposed which give a better fit between calculated and observed data. The remainder of the paper describes the examination of the HT form with the object of determining whether or not a three-dimensional hydrogen bonded network could exist beyond 180° C. By determining unit cell dimensions and measuring intermolecular hydrogen bond distances it was possible to eliminate certain directions for hydrogen bonded planes. On the basis that any such distance must not exceed about 0.31 nm, which is the maximum hydrogen bond distance reported in the literature, it was concluded that a three-dimensional network could not exist. The cause of the structural transition is attributed to progressive changes in ethylenic segment torsion angles.     

Fatigue fracture of nylon polymers

The purpose of this study was to determine the effect of frequency on fatigue crack propagation rates in unfilled nylon polymers. Specifically it was of interest to investigate the frequency dependence under conditions where hysteretic heat generation did not occur. For dry injection-moulded nylon the results demonstrate that a strong frequency dependence exists with higher crack propagation rates at lower frequencies. This indicates that the mechanism of fatigue crack growth at room temperature is primarily one of creep crack growth, especially at frequencies below 1.0 Hz. It is also noted that hysteretic heating causes fracture mode transitions to occur during stable fatigue crack propagation in injection-moulded nylons, even at relatively low cyclic frequencies (5.0 Hz).     

Effect of water content on the piezoelectric properties of nylon 11 and nylon 7

A study of the effect of absorbed water on the piezoelectric properties of Nylon 11 and Nylon 7 films has been carried out. Films were prepared by slow cooling from the melt or by quenching rapidly into ice water. Poled films were soaked in distilledde-ionized water and the piezoelectric strain coefficientd ₃₁, piezoelectric stress coefficiente ₃₁, dielectric constant, and elastic modulusc measured continuously as the films dried out in a stream of dry nitrogen gas. The results obtained show that the piezoelectric response of poled Nylon 11 and Nylon 7 films is sensitive to adsorbed water, the sensitivity being greater for Nylon 7 than for Nylon 11. These observations are discussed in terms of the effect of water on molecular relaxation of these polymers.     

Structural studies of nylon 13,13

A structural study of nylon 13,13 has been carried out by means of X-rays and electron microscopy. Both X-ray and electron diffraction data, obtained from oriented films as well as from lamellar crystals prepared in solution, evidenced that nylon 13,13 adopts a structure in a monoclinic lattice of parameters a _o=0.488 nm, b _o=0.473 nm, c _o=3.40 nm, ==90°, =121°. As expected from the constitution of the nylon, no trace of structure with chains in fully extended conformation (-form) was observed throughout this study.     

Fatigue fracture of nylon polymers

The influence of glass fibres on the fatigue crack propagation rates of injection-moulded nylons has been determined. In contrast to previous results for unreinforced nylons, the cracking kinetics are independent of the oscillating load frequency. The fact that the crack growth rate per cycle is constant, when expressed in terms of the time under load, demonstrates that the contribution of creep crack extension is minimized by the glass fibres. Thus a true fatigue process is suggested for the fatigue fracture of the reinforced system, even when the glass fibres are preferentially aligned parallel to the crack growth direction. A complicating factor in characterizing the fatigue resistance of the glass-reinforced nylons is the tremendous influence of fibre orientation on crack growth rate. It is shown that the anisotropy problem can be handled by simply expressing the crack growth rate data in terms of the strain energy release rate rather than the usual stress intensity factor representation. Results for four different glass-filled nylons show that the diverse crack growth rates for cracking parallel versus perpendicular to the glass-fibre axes collapse on to individual strain energy release rate curves. Each single relationship therefore characterizes the fatigue fracture of the filled material and furthermore permits a prediction of the cracking rates for any glass-fibre orientation based upon the expected change in modulus. Finally it is demonstrated that the increased stress dependence of fatigue crack propagation (slope of the Paris plot) in filled nylons can be duplicated in unfilled samples under certain conditions. It is concluded that the fatigue fracture mechanism is matrix dominated in these chopped glass-fibre reinforced materials.     

Twinning modes in nylon 6.6

The possible twinning modes of nylon 6.6 are predicted on the basis of the crystal structure using Mallard's Law for pseudo-hexagonal lattices. Three conjugate pairs of twin modes are expected. On compression of samples oriented by drawing and strong rolling the main twin mode operative is shown to be (1¯10) and evidence is found for at least two other twin modes, probably (010) and (100). These results are used to explain the texture of lightly rolled sheet as a superposition of a twinned component on an untwinned component, and can be further generalized to explain the previously observed texture produced by slight extension of randomly oriented material.     

Stress-relaxation hardening of nylon 66 filaments

It was observed that an additional increment in stress was necessary to continue deformation in nylon 66 filaments, which had been relaxed, but not unloaded, before fracture. This stress increment consisted of a small permanent increase in stress, in addition to a larger temporary increase in stress to yield. Both the temporary and permanent increments increased as the strain, strain rate, temperature and humidity increased. Similar effects were observed in other polymers, but not in metals or ceramics.