玻纤增强尼龙66产品性能差异原因分析

通过用差示扫描量热仪(DSC)和扫描电镜(SEM)对2种性能存在较大差异的尼龙66(PA66)产品进行测量和观察，测试结果表明2种产品性能差异是由于基体的结晶度、增强玻纤(玻璃纤维)在PA66中的分布均匀性以及基体和玻纤之间的相容性造成的。     

傅立叶红外光谱(ATR)法鉴别尼龙6和尼龙66

研究使用傅立叶红外光谱(ATR)法对尼龙6和尼龙66两种材质快速鉴别的方法。本文利用傅立叶红外光谱(ATR)法对两件尼龙样品进行鉴别。结果表明,傅立叶红外光谱(ATR)法具有分析时间短、样品需求量小、几乎不破坏样品、不消耗检材、快速简便、分析结果满意等优点。     

尼龙66与尼龙6及其共混物的熔融与结晶行为

分别将尼龙66(PA66)、尼龙6(PA6)以及不同比例的PA66/PA6共混物,经双螺杆挤出机挤出造粒,得到不同类型的PA粒料。使用自动黏度测定仪测试了挤出加工前后PA66和PA6的相对黏度,其中PA66和PA6的相对黏度分别下降了10.1%和2.5%。结果表明,PA66与PA6经过双螺杆挤出加工后都产生了降解现象,且在相同的加工条件下,PA66比PA6降解得更快。采用衰减全反射傅里叶变换红外光谱(ATR–FTIR)与差示扫描量热(DSC)法研究了PA66、PA6及其不同比例共混物的熔融与结晶行为。结果表明,加工历史对PA66与PA6的熔融与结晶行为影响很大,当两者共混时,PA6质量分数超过40%时共混物才开始出现PA6的熔融峰与结晶峰。     

尼龙6/66/1010三聚体的静电纺丝

研究了尼龙6／66／1010三氟乙醇溶液的静电纺丝。结果表明,尼龙6／66／1010的溶液纺丝质量分数为6％-14％。随着尼龙溶液质量分数的增加,纤维上的珠串缺陷由圆形向纺锤形转变,并随着质量分数的进一步增大,珠串缺陷消失。溶液质量分数从6％增加至10％,纤维平均直径从230nm增加到487nm,质量分数为6％的尼龙溶液纺出的纤维直径分布最宽。     

尼龙612/6共聚物的表征与非等温结晶动力学研究

以尼龙612盐和己内酰胺为原料,采用熔融聚合的方法合成了尼龙612/6共聚物,采用傅里叶红外光谱仪(FTIR)、核磁共振氢谱仪(1HNMR)、偏光显微镜(PLM)对其相关结构进行表征,并分别用Jeziorny修正的Avrami方程、Ozawa方程、莫志深法进行非等温结晶动力学分析。结果表明:尼龙612结晶过程为二次成核,成核后沿着晶核二维盘状生长;而尼龙612/6共聚物的结晶过程为一次均相成核,晶核形成后沿晶核二维盘状与三维球状生长;莫志深法分析结果对应参数a基本保持一致,说明Avrami指数n与Ozawa指数m之间确实存在一定的数量关系,F(T)的变化表明,要在单位时间内达到更高的结晶度需提高降温速率,同时相同结晶度下尼龙612的结晶速率远大于尼龙612/6共聚物;采用Kissinger方程计算得出尼龙612及其共聚物的非等温结晶活化能ΔE分别为-433.29 kJ/mol、-94.12 kJ/mol。     

尼龙6/尼龙66合金的性能研究

研究了相容剂、增韧剂对改性尼龙6／尼龙66合金性能的影响。研究结果表明，以EVA／PE－g－MAH为相容剂、以PA6和PA66为基料、以EAA及PE为得合增韧剂改性的PA6／PA66合金，其吸水率有较大降低，且综合性能较好。     

氯化钙对尼龙6/硫酸钙晶须增强材料结构与力学性能的影响研究

本文用熔融共混法成功制备氯化钙/(尼龙6/硫酸钙晶须)复合力学增强材料,采用DSC、FTIR、XRD研究氯化钙对尼龙6/硫酸钙晶须复合材料结构性能的影响。结果表明:与硫酸钙晶须对尼龙6起异相成核作用的机理不同,引入少量的氯化钙对尼龙6的结晶性能、分子链间作用力产生很大影响;且当CaCl2含量3%时,PA6拉伸强度能提高至33%左右,缺口冲击强度有小幅度降低。     

尼龙6/聚酯(PET)共混体系结晶相分离的研究

用差示扫描量热（ＤＳＣ）考察尼龙６／聚酯（ＰＥＴ）共混体系的结晶行为,表明是结晶相分离的。不同条件下,结晶相分离的过程和形成的结晶态不同,反映在热行为上,如熔融过程和相应特征参数值,便随着处理的条件、组成比等而改变。研究结果还表明,当尼龙６组分的质量分数Ｗ ＰＡ－６＜ ０．１ 时,它被ＰＥＴ 阻隔而不再结晶,因两者形成部分氢键,酯基对尼龙６ 结晶影响的结果,尼龙６／聚酯（ＰＥＴ）共混体系中尼龙６ 的熔融峰温,随组成比的变化呈现波浪形曲线。     

国内尼龙6、尼龙66产业的发展现状

介绍了国内尼龙产业的整体情况,同时着重介绍了尼龙6和尼龙66上下游产业的技术情况.目前国内尼龙6技术基本成熟,而尼龙66的技术还不成熟,主要原因是原材料己二腈未国产化,长期受到国外制约.介绍了现阶段国内正在积极开展的相关研究和中试进展,最后提出今后国内尼龙产业的需求和发展建议.     

Toughened nylon66/nylon6 ternary nanocomposites by elastomers

The elastomer toughening of PA66/PA6 nanocomposites prepared from the organic modified montmorillonite (OMMT) was examined as a means of balancing stiffness/strength versus toughness/ductility. Several different formulations varying in OMMT content were made by mixing of PA6 and OMMT as a master‐batch and then blending it with PA66 and different elastomers in a twin screw extruder. In this sequence, the OMMT layers were well exfoliated in the nylon alloy matrix. The introduction of silicate layers with PA6 induced the appearance of the γ crystal phase in the nanocomposites, which is unstable and seldom appears in PA66 at room temperature and it further affected the morphology and dispersion of rubber phase resulting in much smaller rubber particles. The incorporation of POE‐g‐MA particles toughened the nanocomposites markedly, but the tensile modulus and strength were both reduced. Conversely, the use of OMMT increased the modulus but decreased the fracture toughness. The nanocomposites exhibited balanced stiffness and toughness. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Aggregation structure and molecular motion of (glass-fiber/matrix nylon 66) interface in short glass-fiber reinforced nylon 66 composites

Aggregation structure and thermal molecular motion of an adhered polymer layer on a glass-fiber (GF) surface after a removal of nylon 66 from a short glass-fiber reinforced nylon 66 were studied on the basis of photoacoustic spectroscopy-infrared spectroscopy (PAS-IR), pyrolysis-gas chromatography (Py-GC), X-ray photoelectron spectroscopy (XPS) and scanning viscoelasticity microscopy (SVM). PAS-IR, Py-GC and XPS measurements of the GF surface showed the presence of strongly adhered nylon 66 layer on the surface of aminosilane-treated GF. The glass transition temperature, T_g, of the adhered nylon 66 layer on the glass-fiber surface was directly evaluated on the basis of SVM measurement. In the case of the GF treated with an aminosilane coupling agent and a sizing agent, the magnitude of T_g at the (GF/nylon 66) interfacial layer was higher than that of the matrix nylon 66 due to the effective restriction of thermal molecular motion of nylon 66 at the (GF/nylon 66) interfacial layer. It is reasonable to consider that the sizing agent affects the strong interfacial interaction between a glass-fiber surface and matrix nylon 66 with covalent bond formation accompanying the network structure formation.     

Synthesis and properties of nylon 6/66/510 used as hot melt adhesives for metal plate with low-surface-energy coating

In this work, nylon 6/66 and nylon 6/66/510 containing 5?～?20?mol % nylon-510 were synthesized to be used as hot melt adhesive for metal plate with low-surface-energy coating. The effects of mole fraction of nylon-510 (X_m) on the thermal and mechanical properties of nylon 6/66/510 were systematically studied. The results demonstrated that: (1) the melting point of the copolyamide decreases and the glass transition temperature decreases when the X_m value increases; (2) the tensile strength of nylon 6/66/510 remains almost unchanged and is almost equal to that of nylon 6/66; (3) the elongation at break of nylon 6/66/510 is significantly higher than that of nylon 6/66. The crystal structure of the copolyamide was also investigated by wide-angle X-ray diffraction (WAXD). The hot-melt adhesives (HMAs) were prepared from nylon 6/66/510, and the adhesive experiments of HMAs to aluminum sheet with low-surface-energy coating were carried out. The results showed that the peeling strength of HMAs based on nylon 6/66/510 reaches a maximum value when X_m = 15?mol %.     

Nanoindentation and morphological studies on nylon 66/organoclay nanocomposites. II. Effect of strain rate

Strain rate effects on surface deformation behavior of exfoliated nylon 66 (PA66)/organoclay nanocomposites have been explored by nanoindentation in present study. Sharp indenter (Berkovich) has been used to indent on the surfaces of polymer/clay nanocomposite with different strain rates. Significant strain-rate hardening has been found consistently existing in both neat PA66 and its nanocomposite systems from surface to subsurface (a few micron deep into the bulk). However, strain rate shows almost no effect on the elastic moduli of the neat system and the nanocomposites. The elastic modulus and hardness increase with the indentation depth due to inhomogeneous distributions of the crystalline morphology as well as clay concentration for the case of the nanocomposites along the indentation direction. The mechanical properties observed are correlated with the inhomogeneous microstructures of the studied systems. The plastic index of PA66 and the nanocomposites have been evaluated as a function of strain rate.     

Effect of organoclay structure on nylon 6 nanocomposite morphology and properties

A carefully selected series of organic amine salts were ion exchanged with sodium montmorillonite to form organoclays varying in amine structure or exchange level relative to the clay. Each organoclay was melt-mixed with a high molecular grade of nylon 6 (HMW) using a twin screw extruder; some organoclays were also mixed with a low molecular grade of nylon 6 (LMW). Wide angle X-ray scattering, transmission electron microscopy, and stress-strain behavior were used to evaluate the effect of amine structure on nanocomposite morphology and physical properties. Three surfactant structural issues were found to significantly affect nanocomposite morphology and properties in the case of the HMW nylon 6: decreasing the number of long alkyl tails from two to one tallows, use of methyl rather than hydroxy-ethyl groups, and use of an equivalent amount of surfactant with the montmorillonite, as opposed to adding excess, lead to greater extents of silicate platelet exfoliation, increased moduli, higher yield strengths, and lower elongation at break. LMW nanocomposites exhibited similar surfactant structure-nanocomposite behavior. Overall, nanocomposites based on HMW nylon 6 exhibited higher extents of platelet exfoliation and better mechanical properties than nanocomposites formed from the LMW polyamide, regardless of the organoclay used. This trend is attributed to the higher melt viscosity and consequently the higher shear stresses generated during melt processing.     

Nanoindentation and morphological studies on nylon 66 nanocomposites. I. Effect of clay loading

Nanoindentation technique has been used to investigate the mechanical properties of exfoliated nylon 66 (PA66)/clay nanocomposites in present study. The hardness, elastic modulus and creep behavior of the nanocomposites have been evaluated as a function of clay concentration. It indicates that incorporation of clay nanofiller enhances the hardness and elastic modulus of the matrix. The elastic modulus data calculated from indentation load-displacement experiments are comparable with those obtained from dynamic mechanical analysis and the tensile tests. However, the creep behavior of the nanocomposites shows an unexpected increasing trend as the clay loading increases (up to 5 wt%). The lowered creep resistance with increasing clay content is mainly due to the decrease of crystal size and degree of crystallinity as a result of clay addition into PA66 matrix, as evidenced by optical microscopy and X-ray diffraction. At lower clay concentration (here ≤5 wt%), morphological changes due to addition of clay plays the dominant role in creep behavior compared with the reinforcement effect from nanoclay.     

High temperature behaviour of the crystalline phases in unfilled and clay-filled nylon 6 fibers

Temperature-induced crystalline phase transitions in neat nylon 6 fibers as well as nylon 6/montmorillonite nanocomposite fibers have been studied by means of wide-angle X-ray scattering. Both types of melt spun fibers only consist of the γ crystalline phase that does not display any transition during heating up to the melt. In contrast, fibers drawn up to the maximum draw ratio at 140 °C display the single α phase with a high degree of chain orientation. During the temperature increase, the α phase undergoes a gradual structural disordering but preserves its monoclinic character up to melting. The structural evolution of the α form turned out sensitive to the thermal and mechanical treatment of the fibers. Annealing the unfilled drawn fibers at 150 °C prior to the WAXS experiment improves the thermal stability of the α form due to healing of the processing-induced crystalline defects. The montmorillonite-filled fibers display both the α and the γ crystals, which readily turn into α crystal form only upon drawing. Due to the matrix shearing between the MMT platelets, the H-bonded sheets display a higher thermal stability as compared with unfilled drawn fibers. Upon cooling from the melt, the first signs of crystallization are of γ form in the MMT-PA6 fibers, but the α form rapidly turns predominant. Crystallization kinetics considerations are put forward to account for this finding.     

Effect of blend ratio on bulk properties and matrix-fibril morphology of polypropylene/nylon 6 polyblend fibers

Ternary blends of polypropylene (PP), nylon 6 (N6) and polypropylene grafted with maleic anhydride (PP/N6/PP-g-MAH) as compatibilizer with up to 50 wt% of N6 were investigated. PP-g-MAH content was varied from 2.5 to 10%. Blends of the two polymers PP/N6 (80/20) without the compatibilizer were also prepared using an internal batch mixer and studied. The ternary blends showed different rheological properties at low and high shear rates. The difference depended on the amount of N6 dispersed phase. Co-continuous morphology was observed for the blend containing 50% N6. This blend also exhibited higher viscosity at low shear rate and lower viscosity at high shear rates than the value calculated by the simple rule of mixture. At higher shear rates, viscosity was lower than that given by the rule of mixture for all blend ratios. An increase in viscosity was observed in the 80/20 PP/N6 blend after the concentration of the interfacial agent (PP-g-MAH) was increased. Polyblends containing up to 30% N6 could be successfully melt spun into fibers. DSC results showed that dispersed and matrix phases in the fiber maintained crystallinity comparable to or better than the corresponding values found in the neat fibers. The dispersed phase was found to contain fibrils. By using SEM and LSCM analyses we were able to show that the N6 droplets coalesced during melt spinning which led to the development of fibrillar morphology.     

氯化锂对尼龙6结构与性能影响的研究

用熔融共混法制备了尼龙6与氯化锂的共混物,采用DSC、XRD、测定熔体流动速率等方法研究了样品的结构与性能。结果表明加入氯化锂能够明显地改变尼龙6的结晶性能,使分子间作用力增强,玻璃化转变温度升高和熔体黏度增大。     

Phase transition in nylon 6/clay nanocomposites on annealing

The γ→α crystalline phase transition in nylon 6/clay nanocomposite prior to melting was investigated by X-ray diffraction. The phase transition in the nanocomposite took place at 160 °C, 40 °C higher than that of nylon 6 at 120 °C. The transition extent in the nanocomposite was lower than that in nylon 6. This could be caused by the strongly confined spaces between layers, and the favorable environment for the formation of the γ phase in the existence of clay. Besides, the less grown crystallites of the α phase transformed from the γ phase in the nanocomposite began to melt at much lower temperature than its normal melting temperature.