单体浇铸尼龙的增韧改性研究

本论文论述了单体浇铸尼龙的增韧改性制备方法，在绝热条件下通过己内酰胺与十二内酰胺活化阴离子共聚制得冲击强度显著改善的浇铸尼龙制品。探讨了增韧改性单体浇铸尼龙的合成工艺、反应条件及聚合成型过程，研究了十二内酰胺共聚单体对制品试样球晶结构和机械性能的影响。     

浇铸尼龙6/超细滑石粉复合材料的性能研究

采用超细滑石粉对浇铸尼龙6材料进行改性,对改性后复合材料的性能进行了研究。结果表明：在一定的配方组成下,超细滑石粉改性浇铸尼龙6复合材料与未改性前相比,尺寸稳定性、耐热性和热分解温度均有所提高,且光泽度基本保持不变,对浇铸尼龙6的应用普及有较大的实际意义。     

MC共聚尼龙弹性体的性能表征研究

选用不同的单体与己内酰胺无规共聚，或添加六甲基磷酰三胺（ＨＰＴ）等进行复配改性制备ＭＣ共聚尼龙弹性体，用ＤＳＣ法研究ＭＣ共聚尼龙弹性体的热性能。结果表明，热性能的变化趋势与材料力学性能变化相吻合。己内酰胺／十二内酰胺阴离子共聚弹性体的ＤＳＣ分析结果表明，随着十二内酰胺用量的增加，Ｔｇ、Ｔｍ、Ｔｃ、△Ｈｍ及χｃ均呈线形下降。当十二内酰胺组份达４０％时，共聚物呈非晶形结构，具有典型的聚酰胺弹性体性能。ＨＰＴ增韧改性ＭＣ尼龙的ＤＳＣ分析结果表明，随着ＨＰＴ用量的增加，Ｔｇ、Ｔｍ、Ｔｃ、△Ｈｍ及χｃ均呈有规律的下降，添加２０ｐｈｒ时，结晶度从原样的５０．１％降为２５．８％，ＭＣ尼龙的热性能从典型的结晶型高聚物向增韧尼龙转化。采用共聚、增塑复配方法时，从冲击强度、冲击回弹值、２５％应变压缩强度等可见，ＭＣ尼龙共聚物已呈典型的聚酰胺弹性体性能，比单因素的共聚、增塑改性效果要好。     

基于新型增韧剂的浇铸尼龙工艺方法

浇铸尼龙机械强度大、韧性良好、化学稳定性强、刚度以及硬度高,是一种被广泛使用的重要工程塑料。然而,在高低温使用环境中浇铸尼龙的冲击强度差,韧性差并且易于脆性破坏。本文采用己内酰胺为单体,以内酰胺钠为引发剂,通过聚氧化亚甲基三胺对其增韧来改善浇铸尼龙的冲击强度和环境适用性。研究结果表明聚氧化亚甲基三胺增韧剂的加入有效提高了材料的塑性形变能力,其含量为60 g(CP5)的样品结晶能力强,结晶度高,热稳定性好,冲击韧性最优。     

超韧性增强尼龙66的研究

超韧性增强尼龙66是超韧性尼龙66用玻璃纤维增强改性的品种,是一种强度和韧性均十分优越的新型材料.介绍了用玻璃纤维增强超韧性尼龙66的生产工艺,讨论了生产工艺对材料物化性能的影响。同时还研究了超韧性高强度尼龙66的部分物化性能,说明超韧性高强度尼龙66是一种理想的工程塑料.     

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.     

国外动态

尼龙12新单体的制法作为尼龙12的单体,过去都是用十二碳内酰胺。意大利的斯尼亚维斯科沙公司和英国的BP化学公司新开发了一种比十二碳内酰胺更容易聚合的单体—12-胺基十二酸(ADA)。     

含油MC尼龙复合材料的摩擦磨损性能研究

制备了一种轴承润滑油填充浇铸尼龙(MC尼龙)复合材料,并对其力学性能和摩擦磨损性能进行了研究。结果表明:润滑油的加入明显改善了MC尼龙的力学性能和摩擦磨损性能,提高了MC尼龙的韧性和摩擦系数;当润滑油用量为5%时,MC尼龙复合材料具有较高的强度和韧性,同时具有较低的摩擦系数和磨损量。     

树状分子PAMAM接枝改性纳米SiO2与尼龙6的原位复合

将树状分子PAMAM接枝改性的纳米Si02与尼龙6进行原位复合，测试了复合材料的各项性能，对树状分子改性无机纳米粒子进行了初步的探索。结果表明：PAMAM接枝改性纳米SiO2可以提高尼龙6的强度、刚性和非等温结晶能力，但材料的韧性在接枝PAMAM代数较高的情况下趋于降低，同时，基体的摩尔质量显著下降。     

浇铸(MC)尼龙改性研究进展

介绍了目前国内外浇铸(MC)尼龙改性的研究现状。对MC尼龙改性后的性能进行综述,主要包括力学性能、耐磨与自润滑性能及抗静电性能的改性研究成果,并展望了未来MC尼龙改性研究的发展趋势。     

Anionic copolymers of octanelactam with laurolactam (nylon 8/12 copolymers)—v. Effect of annealing on thermal properties and crystalline structure

The effects of different annealing time/temperature regimes on the thermal and crystalline behaviour of a series of statistical copolyamides (nylon 8/nylon 12), prepared by activated anionic polymerization of octanelactam/laurolactam (OL/LL), were determined by DSC, X-ray (WAXS), density and viscosity measurements. The melting temperature and the heat of melting increased with annealing time and temperature. The results were correlated with the molar composition of the copolyamides and showed a gradual increase in percentage crystallinity with time.     

Acrylic acid γ-ray irradiation-grafted nylon 4 membranes

This study was to improve the performances of nylon 4 membranes for washing waste-water treatment of nuclear power plants, e.g., removal of detergent and salt by membranes. The effects of the degree of grafting and ionization on the reverse osmosis performances of acrylic acid (AA)-grafted nylon 4 membranes by γ-ray irradiation modification were investigated. The relationships of operating conditions, such as feed concentrations of salt and detergent, operating temperature, and pressure, and the performances of water flux and solute rejection of the prepared membranes were obtained. Water flux of the prepared membranes was highly sensitive with the operating temperature. It was found that an increase in the operating pressure could increase the water flux and the impaction effect directly. Water flux and salt rejection were significantly improved by both ionized and nonionized AA-grafted nylon 4 membranes compared to ungrafted nylon 4 membranes. Water flux increased rapidly and solute rejection dropped off slightly as the grafted membranes were ionized. The 100% detergent rejection could be obtained by the nonionized AA-grafted nylon 4 membranes with 38.6 and 69.6% degrees of grafting under various operating conditions. Results obtained showed that these modified nylon 4 membranes were usable for washing waste-water treatment of nuclear power plants. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of MC nylon/modified yttrium hydroxide nanocomposites

In this article, monomer casting (MC) nylon is synthesized. MC nylon could replace nonferrous metals in certain applications, including gears, wheels, and other moving parts. However, compared with metals, MC nylon products have poor strength and stiffness, and crack easily, especially at low temperatures. In addition, the dimensional stability of MC nylon is poor, especially in the large casting nylon products, causing significant internal stresses due to shrinkage. Thus, MC nylon cracks easily when cast and molded. The yttrium hydroxide particles are modified by stearic acid and dispersed in the caprolactam. The polymerization time is short due to fast anionic polymerization. Copolymerization with different ratios of yttrium hydroxide particles can be used to prepare the copolymer. The effects of different amounts of yttrium hydroxide on the performance of the monomer casting nylon are studied. The products are characterized using X‐ray diffraction, impact, and tensile testing. When the percentage of modified yttrium hydroxide is 0.3 wt %, the composite exhibits the maximum impact strength, thus the 0.3 wt % of modified yttrium hydroxide is the suitable percentage to enhance the impact strength of MC nylon. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43356.     

Melamine cyanurate surface treated by nylon of low molecular weight to prepare flame‐retardant polyamide 66 with high flowability

In the present research, a nitrogen‐based flame‐retardant, melamine cyanurate (MCA) was surface‐treated with low‐molecular‐weight nylon through a solvent process to further improve its flowability and dispersion. The surface energy and flow energy of the modified MCA were investigated. The properties of polyamide 66 (PA66) prepared with surface‐treated and with conventional MCA were evaluated and compared. Because of lower surface energy and flow energy for modified MCA, its agglomeration degree and flow resistance are obviously decreased compared with conventional MCA, thus achieving finer and more homogenous dispersion in the PA66 matrix. Moreover, the low‐molecular‐weight nylon resin encapsulating MCA surface will melt at lower temperature during compounding with PA66; hence, it serves as a lubricant and carrier to further improve the flowability and dispersion of the flame retardants. Based on these advantages, the modified MCA flame‐retardant PA66 achieves much better flame retardancy, flowability, and mechanical properties compared with conventional MCA/PA66 under the same loading level of flame retardant (10 wt%).     

The structure and physical properties of copolymers of lactams

Copolymers of caprolactam with caprylolactam and laurolactam were prepared by activated anionic copolymerization under adiabatic conditions, at an initial polymerization temperature of T₀ = 130°C. The drop of the crystalline phase content and changes of the copolymer morphological structure depending on the content of comonomers result in increasing toughness and deformability due to enhanced yielding ability. The dependences of the copolymer structure and properties on the concentration of comonomers are different for the two series of copolymers. This results from different courses of the polymerization and crystallization history as a consequence of a large difference between polymerization rates of caprylolactam and laurolactam.     

Mechanical and dynamic mechanical properties of nylon 66/montmorillonite nanocomposites fabricated by melt compounding

Nylon 66 nanocomposites were prepared by melt compounding of nylon 66 with organically modified montmorillonite (MMT). The organic MMT was pre‐modified with about 14 wt% of ammonium surfactant, much lower than the 35–46 wt% in most commercial organic MMT powders. Transmission electron microscope observation indicated that the MMT layers were well exfoliated in nylon 66 matrix. Dynamic mechanical analysis confirmed the constraint effect of exfoliated MMT layers on nylon 66 chains, which benefited the increased storage modulus, increased glass transition temperature and reduced magnitude of alpha relaxation peak. The effects of organic MMT loading levels on reinforcement and fracture behaviour of the nanocomposites were evaluated using tensile and three‐point bending tests. The addition of the organic MMT clearly increased Young's modulus and tensile strength but decreased ductility and fracture toughness of nylon 66. Copyright © 2004 Society of Chemical Industry     

Phase continuity in polystyrene–nylon 6,10 graft copolymers

Using a modified interfacial polymerization route, a graft copolymer of nylon 6,10 and polystyrene was prepared. First, an aqueous suspension of styrene monomer was encapsulated with nylon 6,10, followed by polymerization of the styrene to form the graft copolymer. When the material was subsequently molded below the crystalline melting point of nylon 6,10 (220°C), modulus–temperature behavior intermediate between polystyrene and nylon 6,10 was observed. However, when this graft copolymer was molded above the melting point of nylon 6,10, behavior more like pure polystyrene was observed. Phase contrast microscopy revealed that material molded below 220°C showed a continuous cellular-phase structure of about 30 microns in diameter, the interior of the cells being composed of polystyrene and the cell walls being composed of nylon 6,10. Phase inversion phenomenon was observed in the graft copolymer as the molding temperature was raised above 220°C. The nylon 6,10 phase became discontinuous, small globules being formed. This behavior is analogous to spheroidization in steel. It is thought that molten nylon 6,10 spheroidizes to attain a lower surface-energy state.     

改性MC尼龙在榨糖机轴瓦上的应用

介绍采用在MC尼龙聚合过程中添加纳米CaCO3和石墨制备改性MC尼龙的方法,比较了改性MC尼龙与普通MC尼龙的性能,并用改性MC尼龙制成糖厂榨糖机上的轴瓦,生产试用后可满足用户的使用要求。     

改性锦纶66与高模量低收缩聚酯帘线在半钢子午线轮胎中的应用对比

对改性锦纶66帘线和DSP帘线的性能及应用进行对比试验。试验结果表明，DSP帘线的耐热性和尺寸稳定性优于改性锦纶66帘线；聚酯帘线用作胎体骨架材料时，成品轮胎的高速性能和耐久性能均达到并超过设计要求，在高速和耐久试验中，轮胎表面温升高于改性锦纶66胎体轮胎。