涂料树脂交联技术的最新进展

通过专利文献和研究报告的调查，评论了溶剂型和水性涂料交闻技术的最新进展，（１）降低挥发性有机化合物（ＶＯＣ）含量：（２）用无毒交联剂替换有毒的多异氰酸酯；（３）汽车面漆防酸雨；防擦伤；（４）节能的低温化；（５）更高的性能。各种新交联体系已开发出来以代替现行体系．诸如氨基树脂固化，多异氰酸酯固化和封闭型多异氰酸酯固化。一些采用新体系的商业产品已投放市场。     

交联结构的表征及其对硫化胶性能的影响

主要介绍硫黄硫化橡胶交联键类型和交联密度的表征方法以及交联结构对硫化胶性能的影响。表征交联键类型的方法主要有化学探测剂法、固体核磁共振法、校准曲线法和光谱分析法等,其中化学探测剂法比较成熟,而固体核磁共振法作为新技术具有很大的潜力。表征交联密度的方法主要有化学测定法、平衡溶胀法、力学测定法、核磁共振法和透射电子显微镜法等,其中平衡溶胀法是一种经典方法,核磁共振法也得到了广泛应用。     

应用溶剂刻蚀法研究聚乙烯的交联结构

应用四氯化碳溶液和三氯甲苯溶液为溶剂对交联聚乙烯表面结构及断面结构进行刻蚀处理，利用扫描电镜对聚乙烯的交联结构进行观察。结果表明，聚乙烯断面结构用三氯甲苯溶液刻蚀50h处理后，可清晰地观察到其交联结构。     

热氧老化对特种氟橡胶交联结构及力学性能的影响

采用加速老化实验方法对特种氟橡胶密封材料的热氧老化性能进行了研究,获得了不同老化温度及老化时间对特种氟橡胶力学性能和交联结构的影响规律。研究结果表明,氟橡胶在热空气中老化时随老化温度的升高和老化时间的延长,材料的拉伸强度、硬度降低,100%定伸应力先增加后减小,拉断伸长率先减小后增大,回弹性和压缩永久变形增大。材料的交联密度先增加后减少,表明氟橡胶在热氧老化初期以交联为主,在老化后期以降解为主。     

硬质橡胶的结构与性能

硬质橡胶作为特种橡胶制品的一种,因其优异的耐化性和绝缘性,目前仍广泛应用于防腐衬里等耐化学品材料以及绝缘材料中.国内研究较少且对其结构的认识还不完善,本文通过大量文献,系统地总结了硬质橡胶在交联结构、不饱和度以及聚集态结构上的特点,以期对国内的相关理论及应用研究有所帮助;还简述了硬质橡胶性能,指出通过改性使其高功能化是这类硬质橡胶材料的发展方向.     

表面交联后处理对高吸水性树脂性能的影响

将硫酸铝、丙三醇和乙二醇二缩水甘油醚溶于水配制成表面交联液,对水溶液聚合法合成的高吸水性树脂(SAP)进行表面交联后处理,研究了硫酸铝、丙三醇和乙二醇二缩水甘油醚用量,表面交联温度和表面交联液用量对SAP吸液性能和加压吸收量(AUL)的影响。运用FTIR和SEM对SAP进行了表征。结果表明,随着硫酸铝用量的增加,SAP的吸液倍率增大,AUL减小。而SAP吸液倍率随着乙二醇二缩水甘油醚用量和表面交联温度的增大而降低,AUL则随之升高。当w(丙三醇)=9%时,SAP吸水倍率和吸盐水倍率有最大值685 g/g和79g/g,当w(丙三醇)=12.7%时,AUL达到最大值33 g/g。当交联液用量为7.7 g时,SAP的综合性能最好。     

交联剂对合成高吸油性树脂的影响

采用水分散相悬浮聚合法，以甲基丙烯酸长链烷基酯为单体，二甲基丙烯酸乙二醇酯为交联剂合成高吸油性树脂；并且探讨了交联剂对聚合过程和树脂吸油性能的影响。实验证明，交联剂用量越大，体系凝胶化现象到来得越早，转化率随反应时间增长得较快，但是最终转化率相差不大。交联剂用量越大，树脂对各种油品的吸油倍率越小；交联剂的用量大于0.4mL时，吸油倍率变化不明显。     

不同高吸水性树脂吸附金属离子的研究

本文共制备两种吸水树脂:一种以丙烯酸(AA)为单体,采用过硫酸钾(KSP),硝酸铈铵(CAN)为复合引发剂,N-N′-亚甲基双丙烯酰胺(MBA)为交联剂,加入羧甲基纤维素(CMC)接枝共聚制备纤维素类吸水树脂;另一种则用相同浓度的单体,引发剂,交联剂,反应条件下制备聚丙烯酸类吸水树脂。通过对两种吸水树脂吸附重金属离子如Na+、Li+、Ca2+、Zn2+、Co2+、Fe3+溶液,以及对尿素的吸附能力,吸水速率,保水能力的测试比较,结果表明:在相同的反应条件下纤维素类吸水树脂对离子的吸附能力强于聚丙烯酸类吸水树脂。     

Synthesis and properties of oil absorption resins filled with polybutadiene

Polybutadiene (PB) is used to fill an oil absorption resin as a physical crosslinker to construct a kind of 3‐dimensional network with a high degree crosslinking and low crosslink density. A series of acrylic resin particles with various compositions are prepared by suspension polymerization, using benzoyl peroxide (BPO) as an initiator and ethylene glycol dimethacrylate (EGDMA) as a chemical crosslinker. The effects of the polymerization temperature, initiator concentration, monomer feed ratio, and chemical and physical crosslinker concentrations on the oil absorbency and gel fraction (degree of crosslinking) are studied. The recipe and operation conditions are optimized as follows: a mass ratio of 3:1 for styrene (St)/dodecyl methacrylate or St/butyl acrylate, 0.5 wt % BPO, and 80°C for 7–8 h. The effect of the physical crosslinker (PB) concentration is complex. The oil absorbency increases with increasing PB at lower EGDMA concentrations. However, under this same condition, particles cannot be formed if the PB concentration is higher than a certain value. By contrast, there is an optimum PB concentration when the EGDMA concentration is higher. The oil absorption speed is also investigated. The presence of PB can speed up absorption. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3309–3314, 2003     

Preparation and properties of modified bismaleimide resins based on phthalide‐containing monomer

A series of bismaleimide resins based on phthalide‐containing monomer have been prepared by the copolymerization reaction of 3,3‐bis[4‐(4‐maleimidophenoxy)phenyl] ‐phthalide (PPBMI), 4, 4'‐dimaleimido diphenylmethane (MBMI) and 2, 2'‐diallyl bisphenol A (DABPA) in different feed ratios. The curing behavior, thermal, mechanical and physical properties and compatibility of all resultant resins were carefully characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), notched Izod impact test, water absorption test and scanning electron microscopy (SEM). DSC investigations showed that with an increase of the weight ratio of PPBMI, the dominating exothermic polymerization temperature (T_p) increased. The glass transitions were observed from DMA thermograms for the cured BMI resins in the temperature range from 277°C to 311°C and decreased with increasing PPBMI content. The TGA results indicated the thermal stability was improved as PPBMI content increased. The investigations of the mechanical properties showed a complicated trend with an increase in PPBMI content. In addition, the equilibrium water uptake of the modified resins was reduced as PPBMI content increased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1084‐1091, 2013     

不同方法制备高吸水性树脂性能的研究

以玉米秸秆为主要原料,除杂改性得羧甲基纤维素。然后以N,N’-亚甲基双丙烯酰胺为交联剂,分别采用传统加热聚合、微波辐照聚合和超声辐照法合成高吸水性树脂,并对吸水树脂的吸水倍率、吸盐水(质量分数为0.9%NaC l水溶液)倍率及保水能力进行测试。结果表明,同一比例下,超声辐照法制得的吸水性树脂的吸水倍率及保水能力均高于其它两种方法;超声功率为60%的条件下,吸水倍率可达635 g/g。微波辐照法制得的吸水性树脂的吸盐水倍率较高,微波功率为320 W时制得的吸水树脂吸盐水倍率可达65 g/g。     

高吸水性复合树脂的制备及性能

使用新的交联剂合成一种新型可自降解的高吸水性复合树脂.以过硫酸铵为引发剂,柱撑膨润土层间的多羟基聚合铝阳离子为交联剂,膨润土、丙烯酸和丙烯酰胺为主要原料,采用水溶液共聚法合成高吸水性复合树脂.采用XRD测试法研究了膨润土的柱撑效果;通过研究高吸水性复合树脂吸去离子水和0.9%NaCl溶液的倍数探讨了柱撑膨润土和引发剂的最佳用量;通过观察高吸水性复合树脂吸水凝胶的状态初步探讨了复合树脂凝胶的自降解情况.结果表明：多羟基聚合铝阳离子被引入膨润土的层间,柱撑效果很好;柱撑膨润土和引发剂的最佳用量分别为单体总质量的2.4%,0.34%;所制备的高吸水性复合树脂比其他的高吸水树脂的自降解性好,在65℃下25天就已完全降解.     

Effect of crosslinking structure on sorption of CO2 in photocrosslinked PVCA film

The sorption behavior of CO₂ gas in photocrosslinked poly(vinyl cinnamate) film was examined under atmospheric pressure. The sorption isotherm was well described by the Langmuir equation, suggesting that sorption of CO₂ is mainly governed by adsorption in the microvoids. The amount of sorbed CO₂ was significantly affected by the degree of crosslinking. The CO₂ sorption was enhanced at a lower degree of crosslinking but was decreased at a higher degree of crosslinking. The unexpected increase in the amount of adsorbed CO₂ correlated with the increase in the number of microvoids that occurred as a result of the crosslinking reaction. However, further crosslinking led to a decrease in the mean size of the microvoids. The smaller microvoids, in comparison to CO₂ molecules, did not act as adsorption sites, so that the amount of sorbed CO₂ decreased. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1744–1750, 2000     

Probing molecular mobility during crosslinking process of commercial resins by NMR multiexponential relaxation data analysis

In this study, we present the experimental results for the crosslinking process of a commercial polyester resin based on measurements of the spin lattice relaxation time T₁ of protons, as function of the crosslinking time evolution. Multiexponential decomposition of the evolution of magnetization measured in inversion‐recovery experiments is performed. The population of “rigid” and “mobile” nuclear spin sites was estimated as function of time evolution. In analogy to the usual monomer conversion u, site conversion from “mobile” to “rigid” sites u_M were also estimated as a function of time evolution and initial concentrations of the reagents. The multiexponential decomposition approach of T₁ relaxation data allows one to follow crosslinking processes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of crosslinking on the properties of sodium caseinate films

Protein films are used as effective lipid, oxygen, and aroma barriers at moderate relative humidity conditions. However, they perform poorly as moisture barriers. The introduction of crosslinks within or between protein chains by enzymatic or chemical modification has been proposed as an alternative means to achieving a stronger polymeric matrix structure, which would result in better functional film properties. In this article, we report the preparation and characterization of sodium caseinate (SC) films crosslinked by glutaraldehyde (GTA) or heat. The crosslinking density increased with GTA content. The thermal stability and tensile modulus and strength increased with GTA content, although films with a low crosslinking density exhibited lower properties than the uncrosslinked sample. Unexpectedly, water vapor permeability and absorption also increased with crosslinking density. The crosslinking of SC was also induced by simple heating. The resulting films showed enhanced thermal, mechanical, and barrier properties compared to the unmodified SC films and even the GTA‐crosslinked samples. GTA crosslinking was unable to reduce the high hydrophilicity of the SC films. Thermally induced crosslinking was revealed to be a valid alternative for improving the properties of SC films, without the inherent complications associated with the use of a chemical crosslinking agent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010