RIM-pultrusion of nylon-6 and rubber-toughened nylon-6 composites

Unidirectionally reinforced thermoplastic composites of Nylon-6 and polypropylene oxide-Nylon-6 block copolymers have been prepared by the reaction injection molding (RIM)-pultrusion process. This process takes advantage of both the RIM and the pultrusion techniques, while avoiding their inherent shortcomings. It also represents a novel way of incorporating toughening rubber domains into a thermoplastic composite. The composites produced exhibit excellent mechanical integrity with essentially zero void content. The chemical and physical states of the composites produced by the process were probed in terms of mechanical relaxation behavior using a dynamic mechanical spectrometer. Due to the simultaneous occurrence of both polymerization and crystallization processes in the reacting system, the resulting material is in a thermodynamically nonequilibrium state. An annealing effect is shown to correspond structurally to an increase in matrix crystallinity and the degree of phase separation, Izod impact tests were used to compare Nylon-6 and rubber-toughened Nylon-6 RIM-pultruded composites. The potential of secondary processing was, demonstrated by compression molding of the RIM-pultruded composite rods.     

抗静电增强尼龙6的研制

以非离子和阴离子型抗静电剂组成复合抗静电体系，用玻璃纤维为增强剂，研制成具有良好的抗静电和机械性能的抗静电增强尼龙６，研究了抗静电复合体系构成，玻璃纤维含量对抗静电增强尼龙６性能的影响，并对其流变性能进行了考察。     

Evaluation of degradation on Nylon-6 and Nylon-6/montmorillonite nanocomposite by color measurement

An evaluation of degraded level is an important subject for industrial products. Ordinarily, many kinds of polymer material changes its color through the degrading process by altering its chemical structure, and IR and UV are applicable to ensure the production of the functional groups. However, these methods are hardly applicable to measurements of product on site without the sample collection. A spectrophotometer is sufficiently lightweight, compact, and capable of measurements on site without the sample collection. With these backgrounds, the correlation of the color with the tensile strength and the molecular weight was studied by using the spectrophotometer. Through the thermal aging test at various temperatures, specimens became yellowish and the increase rate of color change was different between neat Nylon-6 and Nylon-6 nanocomposite. Such changes were closely related to the tensile strength and the molecular weight. As a method to evaluate the polymer degradation, the correlation of the difference of yellowness index (ΔYI) with the tensile strength and the molecular weight was sufficiently high and the ΔYI indicated a difference between neat Nylon-6 and Nylon-6 nanocomposite. From these results, it is found that the color measurement with the spectrophotometer is a practical method for evaluation of polymer degradation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

尼龙6超韧化研究进展

介绍了超韧尼龙6的最新研究进展.主要介绍了几种超韧尼龙6的制备方法,其中马来酸酐接枝聚烯烃弹性体与尼龙6-无机纳米复合材料共混,能得到刚性、强度和韧性综合性能较好的超韧尼龙.     

Modification of nylon-6 with semi-or wholly-aromatic polyamides

In this study, flexible Nylon-6 was reinforced by semi-or wholly-aromatic polyamides; poly(m-phenylene isophthalamide) (PmIA), poly(4,4′-diphenylmethane terephthalamide) (PMA), and poly(4,4′-diphenylsulfone terephthalamide) (PSA). Various high molecular weight block copolyamides were synthesized by solution polymerization using p-aminophenylacetic acid (p-APA) as a coupling agent. Their thermal properties have shown that the block copolyamides exhibit higher T_g and T_m, and better thermal stability than those of Nylon-6, especially PmIA modified Nylon-6. The order of their thermal properties of aromatic modified Nylon-6 copolyamides is PmIA > PMA > PSA. Moreover, the T_g and T_m of multiblock copolyamides are higher than those of triblock copolyamides. From the wide-angle X-ray diffraction pattern, it is found that the triblock copolyamides have two diffraction peaks, i.e., 2θ = 20.5° and 24°. However, the multiblock has only one peak at 2θ = 20°, indicating a different crystal structure for multiblock copolyamides. For the mechanical properties, it is found that the multiblock copolyamides have a more significant reinforcing effect than the triblock copolyamides. Also, the order of the physical properties of aromatic modified Nylon-6 copolyamides, such as tensile strength, is PmIA > PMA > PSA, but for the elongation PSA > PMA > PmIA.     

Orientation and structure development in melt-spun Nylon-6 fibres

A network model is applied to describe the deformation behaviour of melt-spun Nylon-6 fibres obtained at different spinning and drawing conditions. The network draw ratio is determined from analysis of true stress-strain curves and correlated with fibre orientation. From this analysis it appears that the deformation behaviour of Nylon-6 fibres adheres to a pseudo-affine mechanism. The results are discussed in terms of the semicrystalline nature of Nylon-6 fibres. By means of on-line birefringence measurements, wide angle X-ray scattering (WAXS) and solid-state NMR, it is shown that the crystalline and amorphous phases in Nylon-6 respond in a different way to network deformation. In the spin line, an affine (rubber-like) deformation mechanism is observed and this rubber-like network behaviour is transferred to the amorphous phase. After winding and conditioning of the spun fibres, a crystalline phase with relatively high orientation is formed which deforms according to a pseudo-affine mechanism upon further stretching.     

尼龙6纤维的粘弹性及微细结构

本实验采用动态力学方法研究了不同拉伸倍数尼龙6纤维的动态粘弹性,并应用密度梯度法,双折射法和X光衍射法等测定了拉伸尼龙6纤维的结构参数,如△n,ρ,R。实验结果表明:随着拉伸倍数的增加,尼龙6纤维的弹性模量逐步增加,α损耗峰的温度移向较高的温度。而α损耗峰的强度在拉伸2.5倍时达最大值,以后又随拉伸倍数的增加而下降。拉伸尼龙的粘弹性与结构参数之间也有很好的相关性。     

Nylon-6/liquid natural rubber blends prepared via emulsion dispersion

Nylon-6 is widely used as engineering plastic because it is easy to process, high tensile properties, resistant to chemical and abrasion. However, poor impact strength at low temperature makes it limitedly used in some applications. Nylon-6/liquid natural rubber (LNR) blends were prepared via emulsion dispersion with composition of 100nylon-6/0LNR, 95nylon-6/5LNR, 90nylon-6/10LNR, 85nylon-6/15LNR, 80nylon-6/20LNR and 75nylon-6/25LNR. Nylon-6 was dissolved in a 2,2,2-trifluoroethanol and chloroform mixture (1:1 TFE/CHCl₃) and emulsified with hexadecyltrimethylammonium bromide (HTAB). LNR was dispersed into the nylon-6 emulsion to form homogeneous nylon-6/LNR emulsions and the emulsions were de-emulsified with methanol, filtered and dried. High impact behaviour was achieved at 85nylon-6/15LNR composition. DSC thermogram indicated a single glass transition temperature, T _g and SEM images showed no phase separation between blend components implying homogeneous blends were obtained.     

Continuous electrospinning of polymer nanofibers of Nylon-6 using an atomic force microscope tip

An atomic force microscopy (AFM) probe is successfully utilized as an electrospinning tip for fabricating Nylon-6 nanofibers. The nanometre-size tip enabled controlled deposition of uniform polymeric nanofibers within a 1 cm diameter area. Nylon-6 nanofibers were continuously electrospun at a solution concentration as low as 1 wt% Nylon-6 in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). Wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) results of the AFM electrospun fibers indicated that the nanofibers predominantly display the meta-stable γ crystalline form suggesting rapid crystallization rate during the process. In addition to precise control over fiber deposition and diameter, some of the drawbacks of conventional electrospinning such as large volume of solutions and clogging of needles can be overcome using this AFM based electrospinning technique. Lastly, a comparison of electrospun fibers from syringe-needle based electrospinning and AFM probe-tip based electrospinning indicated significant morphological and microstructural differences in the case of AFM based electrospinning.     

Synthesis and characterization of polyesteramides having short Nylon-6 segments in the main chains through polycondensation and chain extension

A Nylon-6 oligomer (PrePA) was synthesized by ring-opening polymerization from ε-caprolactam with 2-amino-ethanol under the catalysis of H₃PO₃. Polyesteramide prepolymers (PrePEAs) having amide content from 10 to 60 mol% were prepared through melt polycondensation from adipic acid, 1,4-butanediol and the PrePA. Chain extension of PrePEAs was carried out at 200 °C using 2,2′-(1,4-phenylene)-bis(2-oxazoline) and carbonylbiscaprolactamate as combined chain extenders. The chain-extended polyesteramides (ExtPEAs) with intrinsic viscosity up to 0.61 dL/g were synthesized. The ExtPEAs were characterized by FT-IR and ¹H NMR spectra, differential scanning calorimetry, wide angle X-ray scattering, thermogravimetric analysis and tensile test. The results showed that the ExtPEAs mainly crystallized in the Nylon-6 crystallites. ExtPEAs had T_g from −46.71 to 4.28 °C, T_m from 106.69 to 139.92 °C, thermal stability with initial decomposition temperature over 339 °C, tensile strength up to 30.89 MPa and stain at break higher than 797.1%. These ExtPEAs were strong, thermally stable and tough thermoplastic polymers.     

Studies on Impact Toughening and Thermal Properties of Nylon-6/LDPE-g-MAH Blends

Polyamide (PA)-6 is an engineering thermoplastic. It finds its application in electrical, mechanical, and automotive parts due to its very high processing and excellent barrier properties to oils. Unfortunately, Nylon-6 (Ny6) is relatively high priced, has poor impact strength, particularly when notched, and poor dimensional stability as well as poor barrier properties to moisture, which limits its applicability. On the other hand, due to low cost, low coefficient of friction, lightweight, high strength, high barrier properties to moisture, good optical properties, and ease of processing, low density polyethylene (LDPE) is an ideal material to incorporate with Polyamide-6 for film, container, and many engineering applications. The present study deals with the preparation of Nylon-6 and modified LDPE (MLDPE) blends, varying the MLDPE concentration from 0 to 50 wt%. The objective of this study is to find the effect of maleic-anhydride grafted low-density polyethylaene on various mechanical properties such as tensile, impact, and flexural properties of Nylon-6. There is a decrease in tensile and flexural properties, the notched Izod impact strength increased greatly when the MLDPE content was 20%. It includes the study the effect of MLDPE on thermal properties and morphological properties of Nylon-6. The morphology of PA/MLDPE blends showed dispersed particle in the polymeric matrix.     

Preparation of Monomer Casting Nylon-6-b-Polydimethylsiloxane Copolymers with Enhanced Mechanical and Surface Properties

Nylon-6-b-polydimethylsiloxane copolymer was synthesized with macroinitiator through in situ polymerization. The macroinitiator with two chain-growing centers per molecule is based on hydroxyl terminated polydimethylsiloxane (PDMS) functionalized with diisocyanate. The influence of PDMS contents on the properties of copolymers was studied. Differential scanning calorimetry and X-ray diffraction were used to investigate the melting temperature, crystallization temperature and crystal form of samples, and the results showed that the crystallinity of polymers decreased. The mechanical properties of samples were studied by notched-impact testing and tension test. The notched impact strength was improved by 200% with PDMS concentration up to 4?wt%. The form of scaly was seen by scanning electron microscope proved the improvements of the impact strength of the copolymer. The water contact angles test showed that the surface tension of copolymers decreased with the PDMS content increasing and the surface of copolymer changed from hydrophilic to hydrophobic.     

尼龙6超韧化

介绍了国外在尼龙６超韧化改性研究领域中的最新进展。主要介绍几经龙６共混物及其增韧的机理。     

消除尼龙-6黄粒子

黄粒子严重影响了尼龙-6切片质量,分析了黄粒子产生的原因及解决措施.     

Model compounds of cellulose: Trityl ethers substituted exclusively at C-6 primary hydroxyls

Triphenylmethylcellulose (trityl cellulose) in which substitution of only the primary hydroxyls at C-6 on the cellulose chain occurs has been prepared using superdry cellulose derived from gel cellophane. The diacetate and dicarbanilate derivatives substituted exclusively at C-2 and C-3 secondary hydroxyls could then be prepared. Detritylation afforded the cellulose dicarbanilate or diacetate. Proof that no secondary substitution occurred was afforded by elemental analysis and by tosylation followed by replacement of the tosyl group with iodine. Because of the low D.P. of the cellulose and the ease with which the cellulose polymers can be cast into films, these cellulose model compounds might find utility for studying the effect of reactions at either the primary or the secondary hydroxyls of cellulose.     

尼龙6自润滑材料的物理改性

采用烧结成型方法，在较好烧结工艺条件下研究了尼龙６自润滑材料的物理、软科学性能与组成间的关系，并得到了最好的自润滑材料配方。     

Evaluation of adhesion characteristics of nylon-6 tire cord to natural rubber

The adhesion characteristics of Nylon-6 cords to rubber matrix, using Resorcinol Formaldehyde Latex (RFL) solution, were evaluated at various conditions. The heat-setting studies of RFL dipped cords in the temperature range of 180–210°C showed a loss in tensile properties. However, a minimum in the loss was observed when a pretension load was given to the cords. Percent shrinkage of RFL-dipped cords increased with the increase in temperature of heat setting. Adhesion behavior of Nylon-6 cords to rubber matrix showed some improvement under relaxed conditions in the entire temperature range studied. With the application of suitable tension to cord, adhesion behavior can be made constant. This has been attributed to the higher extent of shrinkage of cords under relaxed conditions providing greater cord surface area. This in turn, leads to increased cord to rubber matrix.     

己内酰胺发展前景广阔

介绍了己内酰胺和尼龙-6的用途，通过大量的统计数据，论述了世界、亚洲及我国己内酰胺和尼龙-6的生产、消费、价格、发展的情况，对我国目前己内酰胺、尼龙-6以及尼龙-6工程塑料的发展前景作了比较详实的介绍。     

马来酸酐(MAH)接枝SEBS及其对PPO/PA6合金性能的影响

利用红外光谱测定了接枝样品,用其中马来酸酐(MAH)的特征峰与苯乙烯/乙烯/丁烯/苯乙烯嵌段共聚物(SEBS)的特征峰之比值来表达接枝率,探索了接枝时MAH和助剂的量对接枝率的影响,同时探讨了不同接枝率的相容剂及不同比值的聚苯醚(PPO)/尼龙6(PA6)对PPO/PA6合金的增容作用及其对合金的综合性能影响.结果表明:(1)加入合适的助剂有利于SEBS体系的接枝,而当MAH的加入量为3%时得到的接枝率最高;(2)接枝率提高,合金的综合性能稍有改善;(3)PPO/PA6 = 70/30时性能指标达到最优.而接枝的SEBS加入量10%时PPO/PA6合金的综合性能最优.     

尼龙6/纳米钛合金复合材料的制备及结构

将经过有机化处理的纳米钛合金粉体与尼龙6通过熔融共混制备成了尼龙6/纳米钛合金复合材料。X-射线衍射和透射电镜显示,在钛合金粉体含量低时,钛合金粉体在尼龙6基体中实现了纳米尺度的分散,但随钛合金粉体含量增加,团聚现象明显增加;红外光谱(IR)分析和Molau试验表明,复合材料中钛合金粉体与周围尼龙6分子间存在某种键合;实验结果还表明,钛合金粉体对尼龙6基体的化学结构和结晶形态没有产生明显的影响。