交联聚乙烯开发应用与发展建议

综述了各种交联聚乙烯的生产技术，包括辐射交联、过氧化物交联、硅烷交联、紫外光交联、盐交联等交联方法。同时对交联聚乙烯在电线电缆、管材等领域的应用提出了我国发展交联聚乙烯的建议。     

有机硅密封胶的结构和性能(Ⅰ)

研究了有机硅密封胶在不同条件下的固化行为,探讨了温度和湿度、胶层厚度对周化行为的影响;采用正己烷抽提法测定PDMS的交联程度,用甲苯溶胀法测定PDMS的交联密度,通过对比两类催化剂的作用,研究了四种不同结构的交联剂对交联反应的影响,结果表明交联剂和催化剂对同化速度起重要作用,交联剂的活性对固化胶的交联密度起决定性作用。     

国外聚氯乙烯交联技术的研究进展

概述了近年来国外聚氯乙烯交联方法、交联机理以及交联效果的研究成果,讨论了这些新技术的应用范围与发展前景。     

自交联型聚氨酯-丙烯酸酯复合乳液的合成研究

采用原位乳液聚合法,引入分子间交联的交联结构,制备了酮肼、环氧羧基双重自交联型聚氨酯-丙烯酸酯复合乳液,研究了交联基团对乳液及涂膜性能的影响。研究发现交联度的提高对于涂膜的硬度、耐水性、耐化学品性等有明显改进。     

乙烯-四氟乙烯共聚物的辐照交联及辐照敏化剂研究

简述了高分子辐照加工及其影响因素,详细综述了乙烯-四氟乙烯共聚物(F40)辐照交联研究,同时归类分析了F40辐照交联的辐照敏化剂合成及开发研究,并对F40的辐照交联开发做了相应的展望.     

提高丁腈手套交联密度的研究

一次性丁腈手套是医疗消耗品,由于其不易致过敏,良好耐溶剂性以及穿戴舒适性越来越受市场欢迎.本文以交联密度作为主要评价指标,研究了二正丁基二硫代氨基甲酸锌(BZ)和二乙基二硫代氨基甲酸锌(EZ)单独使用以及并用时对硫化胶的交联密度的影响;探讨了硫化温度以及硫化时间对交联密度的影响.结果表明在硫化工艺不变的条件增加促进剂的...     

交联聚乙烯的生产应用及发展前景

介绍了交联聚乙烯的用途以及发展前景，概述了交联聚乙烯的生产技术，包括辐射交联、过氧化物交联、硅烷交联、紫外光交联、盐交联等交联方法，提出了发展我国交联聚乙烯生产的一些建议。     

交联聚乙烯的生产应用及发展前景

介绍了交联聚乙烯的性能、用途以及发展前景,概述了交联聚乙烯的几种生产技术,包括辐射交联、过氧化物交联、硅烷交联、紫外光交联、盐交联等交联方法,提出了发展我国交联聚乙烯生产的一些建议。     

几种常用橡胶的辐射交联研究进展

介绍天然橡胶、聚异戊二烯橡胶、聚丁二烯橡胶、丁苯橡胶和三元乙丙橡胶等常用橡胶的辐射交联研究进展,分析分子结构、辐射温度及辐射剂量等因素对橡胶辐射交联效应的影响。     

氮丙啶化合物抑制Lyocell纤维原纤化

针对Lyocell纤维出现的原纤化问题,尝试用氮丙啶基化合物作为Lyocell纤维的交联剂抑制原纤化趋势,试验证明有比较好的抗原纤化能力,并适合在线交联。经过摩擦试验等证明氮丙啶化合物能起到较好的交联作用,提高湿摩擦时间,并且对Lyocell纤维原有的力学性能影响不大。     

Effect of crosslinking on polyamide 11/butadiene-acrylonitrile copolymer blends

The effect of crosslinking of polyamide 11 and butadiene-acrylonitrile copolymer (nitrile rubber) was studied. The effect of static and dynamic crosslinking on blending are described. Static and dynamic crosslinking do not significantly improve impact strength of low-rubber-content PA11/NBR blends. For blends with dynamic crosslinking and high rubber contents, mechanical properties including impact strength improve. Thermal behavior of crosslinked PA11/NBR blends were studied by DSC and DMA. SEM was used for investigation of the effect of crosslinking on particle size and particle size distribution, phase morphology, and fracture surface morphology. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1605–1611, 1997     

Preparation and characterization of gelatin gel with a gradient structure

Gelatin gel with a gradient structure was produced by a vapour crosslinking procedure. The crosslinking degree at various depths (distance from plate surface) and its gradient are dependent on the crosslinking time and vapour temperature. The experimental data indicate that the gelatin gel with a gradient structure does not follow a second‐order swelling kinetics. The dissolution rate can also be regulated by crosslinking time and vapour temperature. © 2000 Society of Chemical Industry     

Effect of molecular structure and topology on network formation in peroxide crosslinked polyethylene

The present study compared the crosslinking performance of single site linear low density polyethylenes (LLDPE) with high pressure, free radical polymerised, low density polyethylenes (LDPE). The difference in crosslinking performance is not fully explained by different structural parameters such as molar mass distribution (MMD), M_n, MFR₂ value and vinyl groups but is related more to the phenomenon of a long chain branched LDPE macromolecule being smaller in size in the molten state than a macromolecule of a linear LLDPE sample of the same molar mass. The result of the difference in size is that the LDPE will contain a larger number of intramolecular crosslinking points than the LLDPE, which, on the other hand, will contain a larger fraction of intermolecular crosslinking points. The crosslinking points mentioned are of either a physical or chemical nature. From the perspective of the network build-up, the intermolecular crosslinking points are the most efficient. To compensate for the larger fraction of intramolecular crosslinking points in LDPE, more peroxide can be added or vinyl groups can be introduced.     

An investigation of water crosslinking reactions of silane‐grafted LDPE

Factors—including time, temperature, morphology, and thickness of sample, the extent of silane grafting, and water concentration—that affect the rate and degree of water crosslinking reactions of the silane‐grafted LDPE are investigated. The gel content of the water‐crosslinked sample increases with increasing time, temperature, and water concentration, but with decreasing content of the crystalline component in the sample and thickness of the sample. The relationship between the gel content and the crosslinking time is dependent on thickness and morphology of the sample, and the extent of silane grafting in the sample. The crosslinking rates and the resultant gel content are inversely proportional to the content of crystalline component of the sample, suggesting that the crosslinking reactions occur mainly in the amorphous domain of the sample. For those samples with high resultant gel contents, the crystallizations of the samples are significantly enhanced by crosslinking when the gel contents are higher than about 40%, leading to a dual relationship between the gel contents of the samples and the crosslinking times. For low temperatures, the rate‐determining step of the crosslinking reactions is the diffusion of water, rather than the hydrolysis and the subsequent condensation reactions of the silyl trimethoxy groups. For high temperatures and high extents of silane grafting in the samples, however, the chemical reactions dominate the crosslinking process. The overall activation energy of the crosslinking reactions is dependent on thickness of the sample. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 186–196, 2001     

Preparation and properties of metallocene ethylene copolymer crosslinked by vinyltrimethoxysilane

Silane‐grafting and water‐crosslinking of ethylene–octene copolymer (EOR) was carried out. The influences of grafting formulation, comonomer content in EOR and time of the crosslinking process on grafting efficiency, degree and rate of crosslinking were investigated. The mechanical properties of various crosslinked samples are reported together with correlations with their gel contents. The results show that the extent of grafting increased with an increase in the amounts of dicumyl peroxide (DCP) and vinyltrimethoxysilane (VTMS) used in the reaction. The degree of crosslinking depended mainly on the extent of grafting, while the rate of the crosslinking process depended on the amount of amorphous phase in the samples. In this study, the variation of gel contents in the samples (0–77 %) had no significant influence on tensile properties. A large number of uncrosslinked regions are believed to exist inhomogeneously within the crosslinked polymers even after the sample has reached maximum gel content. The content of gel did not increase further when the crosslinking time was increased beyond that of reaching maximum gel, but the polymer network became denser, resulting in changes in polymer behaviour. Copyright © 2005 Society of Chemical Industry     

Study of iPP crosslinking by means of dynamic and steady rheology measurements

The crosslinking of isotactic polypropylene (iPP) using crosslinking agents (CAs) based on a peroxide/sulfur/accelerator system is a very attractive new method that has been reported recently. The present work deals with the study of the dynamic rheological behavior of iPP during and after the crosslinking process. The influence of the CA concentration and the processing temperature T on the rheological behavior of the iPP was analyzed. The kinetics of the crosslinking reaction was established using the technique described by G. A. Harpell and D. H. Walrod. This reaction is found to be of order one. At T = 180°C, the crosslinking reaction was faster. By varying the crosslinking agent content, different crosslinking degrees of iPP, expressed by the corresponding gel content, are achieved. On the other hand, the modified polypropylene exhibits an unexpected viscosity‐shear rate pattern, which describes the reverse crosslinking reaction mainly occurring by the opening of the bridges of the new interpenetrating network (IPN) formed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

交联型水性丙烯酸酯涂料的研究进展

对水性聚丙烯酸酯体系的交联类型、交联机理、交联反应的研究方法以及交联对涂膜性能的影响分别作了较详细的综述。     

Intercrystalline crosslinking of polyethylene

The heat distortion temperature (British Standards Method 102C) and DTA nominal melting point of high density polyethylene have been raised to 140°C by nonrandom crosslinking in which the crosslinks are superimposed on the existing semicrystalline structure. The crosslinking agent was a mixture of dicumyl peroxide and allyl methacrylate, and the crosslinking temperature was 120°C, just below the crystal melting range. In contrast, random crosslinking by the same system above the melting range at 160°C lowered the HDT (heat distortion temperature). Conventional peroxide crosslinking also lowered the HDT. The gel swelling of randomly crosslinked polyethylene was higher than that of nonrandomly crosslinked polyethylene having the same gel content. This dependence of the gel swelling on the crosslink distribution can be correlated with the HDT. The effect of γ-radiation and carbon black loading on the HDT has also been studied.     

Phthalonitrile end‐capped polyarylene ether nitrile: crystals embedded in matrix through crosslinking reaction

A novel single‐component composite based on phthalonitrile end‐capped polyarylene ether nitrile (PEN‐Ph) which undergoes a crosslinking reaction combined with crystallization behavior has been prepared successfully by hot compressing. The project focuses on studying the influence of the processing temperature and curing time on the crosslinking reaction and crystallization behavior. Differential scanning calorimetry analysis indicates that the crosslinking degree increases with an increase of processing temperature and curing time. In contrast, the crystallinity increases first and then decreases as the curing time increases, owing to the effect of the restriction of the crosslinking reaction on the crystallization behavior. Thermal polarizing microscope images provide direct evidence for crystal formation as a result of crosslinking reaction. Moreover, through comparative analysis of amorphous and crystallized PEN‐Ph sheets, the conclusion is drawn that the glass transition temperature and mechanical properties are affected by not only the degree of crosslinking but also by the crystallinity. © 2015 Society of Chemical Industry     

共聚原甲基丙烯酸酯系吸附功能树脂合成及其性能研究

采用悬浮聚合法合成了LMA(甲基丙烯酸十二酯)均聚树脂、BMA(甲基丙烯酸正丁酯)/LMA共聚树脂、BMA/HEMA(甲基丙烯酸( 羟乙酯)共聚树脂、BMA/DVB(二乙烯基苯)共聚树脂以及BMA/HEMA/LMA共聚树脂.研究了单体种类、交联剂种类以及用量与树脂吸附性能、交联密度间的关系,利用FT-IR对树脂试样的化学结构进行了表征.结果表明,与LMA均聚物相比,BMA被引入大分子主链后,BMA/LMA共聚树脂对煤油的吸附量大大降低,对甲苯和三氯乙烯的吸附量增大,而BMA/LMA/HEMA共聚树脂对煤油、甲苯和三氯乙烯的吸附量均有所下降;化学交联型树脂的吸附量随时间变化较小,物理交联型树脂其吸附量随时间变化较为明显;物理交联剂HEMA的质量分数影响树脂的三维网状结构,进而影响树脂的吸附性能;树脂大分子间存在氢键作用,有利于物理交联结构的形成,长侧链LMA结构单元的引入,促使侧链间发生缠结甚至结晶,进一步增强了物理交联结构.