AC发泡剂热分解研究及其预防

本文从ＡＣ发泡剂的热分解研究着手，研究了ＡＣ发泡剂在生产和储运过程中各种热分解现象及其原因，提出了预防措施和改进设想。     

AC发泡剂在RPVC体系中的分解动力学

本文主要研究了ＡＣ发泡剂在ＲＰＶＣ低发泡材料体系中受添加剂影响的分解动力学特征，利用ＤＳＣ差热扫描仪等仪器，对其分解热行为进行了测定和分析，获得了对工业生产应用有价值的数据，为工业化生产低发泡材料提供了理论根据。     

橡胶发泡剂热分解反应动力学研究方法

本文综合介绍了橡胶发泡剂分解过程动力学研究方法。包括升温和恒温下橡胶发泡剂分解放气量压力和体积测试方法,在橡胶介质中发泡剂分解特性的研究方法。并自行设计了一套较为简单实用的实验装置,这些测试方法的建立可为橡胶的实际生产提供一定的参考价值。     

AC发泡剂的分解活化机理及其突发性的表征

采用动力学与热力学相结合的方法,从ＺｎＯ２地ＡＣ次级反应的影响入手探讨了放热型发泡热分解特性及其分解活化机理。提出了表征发泡剂特性的动力学参数,热力学参数及其相关性。     

AC发泡剂分解动力学的研究—添加剂的影响

本文测定了AC发泡剂和添加剂不同配比下的AC分解温度和发气量,研究了AC分解动力学并讨论了分解机理及添加剂促进AC分解发泡的原因。结果表明,随三盐/AC配比中三盐量的增加,AC分解温度和发气量降低,当三盐/AC之比小于0.2时,分解活化能(Ed)随三盐用量的增加而减小;三盐/AC大于0.2而小于0.45时,Ed随三盐用量增加而增大;当大于0.45时,Ed趋于定值。不同的三盐/尿素配比都使分解温度从158℃降至135℃左右,但随三盐量增加,尿素的分解速率增加。在各种添加剂中,锌盐是比三盐更好的发泡促进剂。但三盐和ZnSt复配后效果并不好,使发气量有较大下降。配制好的三盐和AC存放一段时间后,分解温度和发气量均有下降和减少。     

乙烯-丁烯共聚物中发泡剂AC的分解特性研究

用傅里叶变换红外光谱分析、热重分析和差示扫描量热分析等方法对发泡剂偶氮二甲酰胺(AC)及其在乙烯-丁烯共聚物(ENR)基体中的分解特性进行了定性和定量表征。结果表明,等速升温条件下AC的热分解失重有3个阶段,产生63 %的气体产物;在ENR基体中,氧化锌和硬脂酸锌均能降低AC的起始分解温度,但后者还能使AC分解的峰值温度降低,硬脂酸锌是比氧化锌更有效的活化助剂;氧化锌/硬脂酸并用的活化效果应归功于形成的硬脂酸锌;交联剂DCP使AC的起始分解温度略有下降。     

AC发泡剂的改性

本文分四个主要方面来叙述AC发泡剂的改性。其改性目的在于扩大应用领域,增加新品种,优化发泡制品以及加速AC产品系列化。     

氟代烃类发泡剂的研究进展

氟代烃类具有沸程短、发泡效率高、与发泡基质溶解性好等特点,因其独特的保温性能广泛应用于聚氨酯材料。由于CFCs、HCFCs发泡剂破坏臭氧层,而HFCs类发泡剂温室效应显著,新型发泡剂的设计研发备受氟化工行业关注。本文通过对氟代烃制备方法及降解过程的介绍,综述了此类发泡剂分子结构的演变历程,指出新型发泡分子可能具有的结构特征：①碳链更长;②具有C—O、C=C等键;③分子内氟原子含量更多。设计时,通过计算化学精确预估化合物的物化性能,减少实验工作量;合成时,采用酯化、加氢等新工艺高效引入C—O、C=C等键;改进氟化催化体系,提高氟源转化率等方面研究,是含氟发泡剂设计合成研究的发展方向。     

发泡剂对三聚氰胺甲醛泡沫塑料性能的影响

用多聚甲醛代替部分甲醛溶液,与三聚氰胺在pH值为8.5～9.5、温度在85℃条件下发生羟甲基化反应,制备固含量≥65%的树脂,加入固化剂和乳化剂,用发泡剂进行发泡,讨论了不同种类的发泡剂对三聚氰胺甲醛树脂发泡理化性能的影响。结果表明,三聚氰胺甲醛树脂"泡孔"是开孔结构,MD I发泡剂能提高树脂的强度,NaH-CO3发泡剂可以提高树脂的阻燃性能,AIBN发泡剂能制备出高发泡材料。     

EPDM胶料中发泡剂H的分解特性研究

选用ＥＰＤＭ作橡胶介质,重点测试了发泡剂Ｈ在ＤＥＰＤＭ胶料中的分解温度、发气量及分解速度等参数。试验结果表明,有机发泡剂（ＡＣ,Ｈ和ＯＢＳＨ）在ＥＰＤＭ胶料中的分解温度低于它们的空气中的分解温度,而无机发泡剂（碳酸氯钠和碳酸氢铵）则刚好相反;不同牌号的ＥＰＤＭ胶料对发泡剂Ｈ的热分解影响并不显;发泡剂Ｈ的热分解主要受氧化锌和硬脂酸等配合剂的影响,分解温度降低至１３４℃;在较高温度下发泡剂Ｈ的起始分     

酮连氮法ADC发泡剂生产工艺的研究

介绍了酮连氮法ADC的生产原理、工艺、消耗及三废排放情况。     

环保聚氨酯泡沫塑料发泡剂研究进展

从环保的角度介绍了水、液态CO2、戊烷系列和HFC系列聚氨酯泡沫塑料发泡剂,综述了它们各自的性能和优缺点,以及改进缺陷的可能性和方法,并结合以往的研究和实验着重指出HFC-245 fa和HFC-365m fc是两种很有前途的替代发泡剂,预测了聚氨酯泡沫塑料发泡剂的发展趋势。     

ADC发泡剂生产装置节水措施

介绍了ADC发泡剂生产中为节约水资源所进行的工艺改进情况。改造后,水资源循环利用,大大降低了生产成本。     

PVC压延革专用ADC发泡剂的研制与工业应用

介绍了采用添加复合助剂的方法对常规ADC进行化学改性的情况。考察了抑制剂在低温段的抑制发泡效果和促进剂在高温段的促进发泡效果，确定了在常规ADC中加入2％～6％的草酸为抑制剂和加入适量促进剂的发泡剂配方，经筛选并在实际生产中应用，满足了PVC压延人造革工艺的新需求。     

发泡剂和硫化体系对NR/SBR并用海绵胶性能的影响

探讨发泡剂和硫黄硫化体系对NR/SBR并用海绵胶硫化 发泡特性和物理性能的影响。结果得出,应根据海绵胶的硫化 发泡工艺和物理性能要求选用发泡剂AC和DDL系列;采用发泡剂DDL105,硫化体系的硫黄用量为1～1 2份、促进剂CZ用量为0 5份,海绵胶的硫化与发泡速度匹配性好,拉断强度较高,回弹性较好。     

Investigation of thermoplastic elastomer (TPE) foaming process using blowing agent by rheological and morphological methods

The effects of a chemical blowing agent (CBA) or an encapsulated physical blowing agent (PBA) on morphological development in ethylene octene copolymer (EOC) matrix using dicumyl peroxide (DCP) as a curing agent were investigated by rheological, mechanical, and morphological methods. Temperature ramp tests were carried out to understand curing and foaming processes. Curing temperature (T_cure) was determined as the crossover temperature where storage modulus G′ coincided with loss modulus G′′ in the rheological point of view. For the CBA, T_cure increased with increasing CBA concentration, whereas for the PBA, T_cure decreased with increasing PBA concentration. Other critical temperatures T_1st, T_2nd by foaming process were determined using the axial normal force. With these critical temperatures (T_cure, T_1st, T_2nd), curing and foaming mechanisms can be estimated. Simultaneously, volume expansions of samples were observed with camera. Morphology and mechanical analysis were conducted on fully cured and foamed ECP (is defined as EOC with DCP) with blowing agent. ECP with the CBA exhibited an irregular open-cell structure, whereas when produced using the PBA, it formed a regular closed-cell structure. Specific tensile strength tended to increase with increasing PBA concentration but as blowing agent concentration increased elongation at break decreased. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47358.     

Rheological behavior of ethylene–octene copolymer vulcanizates: Effect of blowing agent and precipitated silica filler

An experimental study of the rheological behavior of ethylene–octene copolymer vulcanizates in extrusion containing blowing agent has been carried out. The cell morphology development has been studied through a scanning electron microscope. Rheological properties of unfilled and precipitated silica‐filled systems with variations of blowing agent, extrusion temperature, and shear rate have been studied by using a Monsanto processibility tester (MPT). The total extrusion pressure (P_T), apparent shear stress (τ_wa), apparent viscosity (η_a), and die swell (%) of the unfilled and silica‐filled compounds have been determined by using MPT. The effect of blowing agent (ADC) on the rheological properties of the vulcanizates has also been investigated. There is a reduction of stress and viscosity with blowing agent loading. It was observed that the incorporation of a blowing agent led to decreased shear thinning behavior resulting in an increase in power law index. The viscosity reduction factor (VRF) of unfilled vulcanizates is found to be dependent on the concentration of the blowing agent, shear rate, and temperature, whereas VRF of silica‐filled vulcanizates is found to be dependent on shear rate, temperature, and blowing agent concentration. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1132–1138, 2003