影响发泡剂H热分解的因素探讨

测试了发泡剂Ｈ在橡胶介质中的分解特性，发现影响发泡剂分解的主要因素有橡胶介质、发泡助剂和温度。发泡剂Ｈ在天然橡胶和乳液聚合的橡胶中的起始分解温度（Ｔｄ）较低，而在溶液聚合的橡胶中Ｔｄ较高；尿素能大大降低发泡剂Ｈ的分解温度，季戊四醇和硬脂酸锌也使发泡剂Ｈ的分解温度明显降低；温度越高，发泡剂Ｈ的分解越快。研究了发泡剂Ｈ的分解动力学，求出了发泡剂Ｈ的分解活化能。     

发泡剂AC分解动力学研究

采用正交试验法进行发泡剂AC分解动力学研究。结果表明，发泡剂AC分解速率随温度升高而增大，分解活化能随发泡剂AC含量的增大而增大;橡胶体系中发泡剂AC在160℃分解速率最低，体系中发泡剂AC含量较小导致其分解活化能小于发泡剂AC／发泡助剂混合体系的分解活化能。     

新型吸—放热平衡型发泡剂EXOCEROL232的特性研究

用ＤＳＣ 差示扫描量热仪测定了ＥＸＯＣＥＲＯＬ２３２（ 以下简称２３２） 的动态分解温度和热效应及发泡助剂对分解热力学的影响;用自行设计的发泡剂发气量测量装置测定了体系在不同温度下的分解动力学及其发泡助剂的影响;用偏光显微镜研究分析了不同发泡剂发泡片材的泡体结构。实验结果表明,发泡剂２３２ 属吸、放热平衡型发泡剂,分解反应中吸放、热基本平衡,发气过程诱导期短,分解无突变;发泡剂２３２ 的分解温度、分解焓值、分解速度受发泡活化剂及树脂配方中助剂的影响较小,发泡过程易控制;使用此发泡剂的挤出片材具有较好的泡孔结构,较低的密度,较高的拉伸强度,使用这类新型发泡剂不仅可降低成本,而且生产的发泡制品综合性能好,符合使用要求。     

促进剂在SBR海绵胶中的应用

利用EK-2000P型硫化仪研究了促进剂（噻唑类、次磺酰胺类、秋兰姆类）在SBR发泡硫化过程中对发泡剂OT分解速度的影响.结果表明：本研究中所使用的促进剂都可以一定程度的降低发泡剂OBSH的分解温度;促进剂DM可降低发泡剂OBSH的分解速度,促进剂M、CZ、DZ、NS、TMTD、TETD能提高发泡剂OBSH的分解速度.     

影响发泡剂ADC分解温度的因素

通过正交试验,研究了发泡剂ADC分解温度的影响因素,结果表明:活化剂种类对ADC分解温度影响最大,活化剂与发泡剂用量比次之;DSC法和目视法测定分解温度,发现发泡剂粒径小有利于活化剂活化。     

塑料·橡胶用发泡剂的动向与问题

1.发泡剂的分类 发泡剂粗分为物理发泡剂与化学发泡剂两类。物理发泡剂有空气、氮气、二氧化碳、碳氢化合物、氟里昂等,发泡时必须有特殊的成型机;化学发泡剂则是由于热分解或反应生成气体,在一般的成型机与特殊的成型机中均可使用。它又可再分为无机与有机两类。在160℃以下分解的称为低温分解发     

塑料发泡剂ダイフロ一系列

大日精化工业公司改善了原CO_2类发泡剂,又开发了N_2类发泡剂,实现了塑料发泡剂系列化。这一系列是该公司热分解型化学发泡剂的总称,根据分解温度、分解时间和粒度分布不同而有6大品种:     

TGA和DSC分析发泡剂对NBR橡胶发泡性能的影响

采用热重分析仪和示差扫描量热分析仪研究了偶氮二甲酰胺(AC)、N,N′-二亚硝基五次甲基四胺(H)、4,4′-氧代双苯磺酰肼(OBSH)、NaHCO34种发泡剂的分解特性。发现发泡剂AC与H的分解具有较强的突发性,发泡剂OBSH的突发性较弱,NaHCO3分解的突发性最弱。发泡助剂可以明显地降低发泡剂的分解温度,但是对发泡剂分解的突发性影响不大。发泡剂单独使用时以OBSH为最佳;复配使用时,当AC和H以2∶1的质量比使用时,效果最佳。以添加质量比为2∶1的AC和H复配发泡剂A为研究对象时,丁腈橡胶(NBR)发泡制品密度随发泡剂量的增加而逐渐减小,且当其用量超过12质量份时,密度减小的幅度变小。     

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     

AC发泡剂发生分解的原因和预防措施

近年来随着塑料工业的发展,泡沫塑料和高分子发泡剂品种很多,其中聚氯乙烯发泡剂以偶氮二甲酰胺(即AC发泡剂)为主。但是很多厂家反映.AC发泡剂在干燥工序易发生分解,甚至起火爆炸,造成人员伤亡和经济损失。1 分解温度及分解产物AC发泡刺是一种桔黄色或淡黄色的固体粉末,相对密度1.65,在空气中分解温     

聚氯乙烯人造革压延发泡工艺探讨

分析了纯放热性发泡剂AC与吸—放热复合发泡剂DDL-l05、DDL—107的分解特性和发泡特性。通过改变工艺条件和基础配方，探讨PVC相对分子质量、发泡剂分解特性、DOP用量、CaCO3用量对人造革发泡倍率、泡孔结构的影响，发现DDL-l05、DDL-107、AC三种发泡剂的发泡特性与其分解特性对应，选择PVC S700为基料，及适量DOP和CaCO3，发泡倍率与泡孔结构较理想。     

Cross-linking and foaming behavior of elastomers with water based blowing agents

Physiologically hazardous chemical blowing agents are state of the art for the foaming of extruded rubber profiles. Water is a potential alternative to these blowing agents and is incorporated into rubber compounds in the form of water-loaded hygroscopic substances such silica or hydrates. To achieve an optimum foaming result, the water desorption and cross-linking reaction has to be coordinated. Studies of the foaming behavior in the salt bath of the Sponge Rubber Analyzer show, that the density of an ethylene propylene diene monomer (EPDM) rubber compound is reduced to about 60% and a nitrile butadiene rubber (NBR) compound to approximately 70%. The low reference densities of chemically foamed EPDM of 30% and NBR of 45% are not achieved. This is attributed to the premature foaming when using water-loaded silica as blowing agent. Due to the low resistance of the rubber matrix, large cells are formed by coalescence, which collapse at low cross-linking densities. Investigations of the cross-linking behavior of EPDM and NBR with water-loaded silica as blowing agent state, that the cross-linking density is reduced to about 65% for EPDM and 50% for NBR when water is present. Furthermore, the incubation time is shortened by inhibition of the CBS retarder in the cross-linking system of the NBR. However, this is not sufficient to fix the foamed cells.     

Vulcanization of EPDM rubber compounds with and without blowing agents: Identification of reaction events and TTT‐diagram using DSC data

Vulcanization of industrial‐like ethylene propylene diene termonomer rubber compound is studied using a differential scanning calorimetry (DSC). The analysis starts with DSC information to obtain the total transformation heat, followed by an isothermal‐dynamic temperature ramp that captures diffusion‐controlled reaction kinetics. The vulcanization is modeled by an auto‐catalytic Kamal–Sourour model, complemented with a Kissinger model for the prediction of one energy of activation, DiBenedetto's equation for the glass transition temperature, and adjusted reaction constants to include diffusion mechanisms. Two rubber formulations, with and without blowing agents, containing crosslinking agents, primary and secondary accelerators, activators, promoters, and processing aids are studied. The identification and separation of multiple reaction events, occurring during crosslinking of the compound without a blowing agent, is done through a 2^k design of experiments. Time–temperature–transformation (TTT) diagrams are calculated, integrating the kinetic model, thereby delineating processability windows, providing avenues for optimization, design, and online processing control. According to the kinetics and the TTT diagrams, the blowing agent induces several differences to the vulcanization reaction: decreases reaction temperatures while increasing reaction heats. It eliminates the exothermic peak before vulcanization and decreases the fully cured resin's glass transition temperature. Therefore, the presence of the blowing agent drives a shift in the vitrification line, resulting in a reduced operational window. POLYM. ENG. SCI., 55:2073–2088, 2015. © 2014 Society of Plastics Engineers     

泡沫塑料发泡剂的研究进展

介绍了泡沫塑料常用的发泡剂,比较了各种发泡剂,如AC发泡剂及多种物理发泡剂的优缺点,并提出水发泡是今后发泡剂的发展方向。     

塑料用化学发泡剂

介绍了发泡剂的发展、分类以及国内外产品概况,重点从化学发泡剂、吸热性泡剂、复合型发泡剂、发泡剂母料等方面概述了发泡剂的进展。     

Rheological behaviour of copoly(ethylene/octene) elastomer compunds: Effect of blowing agent and precipitated CaCO3 filler

Abstract

An experimental study of the rheological behaviour of ethylene/octene copolymer compounds in extrusion containing blowing agent has been carried out. The cell morphology development was studied using scanning electron microscopy. Rheological properties of unfilled and precipitated CaCO₃ filled systems with various blowing agents, extrusion temperatures, and shear rates were studied using a capillary rheometer. The total extrusion pressure, apparent shear stress, apparent viscosity, and die swell of the unfilled and CaCO₃ filled compounds were also determined and the effect of blowing agent on the rheological properties of the compounds studied. It was observed that there is reduction of stress and viscosity with blowing agent loading. Incorporation of blowing agent led to decreased shear thinning behaviour resulting in an increase in the power law index. The viscosity reduction factor of the unfilled compound was found to be dependent on the concentration of blowing agent, the shear rate, and the temperature.     

浅谈太阳能热水器行业用聚氨酯发泡剂的发展方向

对太阳能热水器聚氨酯保温材料所用发泡剂的替代方向作了详细介绍,并对各类发泡剂的性能及其在太阳能热水器发泡体系中的应用进行了对比分析.     

Chemical and physical blowing agents in structural polyurethane foams: Simulation and characterization

Physical blowing agents such as n‐pentane and methyl formate and, for comparison, chemical blowing agents such as water were used to prepare structural polyurethane rigid foams of different densities by reaction injection molding. Experimental runs were carried out with formulations based on oligomeric isocyanate and a mixture of polyether polyols. The constitutive equations for the vaporization rate of the two blowing agents and the polymerization kinetics data are reported. Experimental results were compared with the prediction of a simplified theoretical model, and they showed a satisfactory agreement in terms of temperatures and density profile. All the specimens were characterized by physical‐mechanical properties such as hardness, impact strength, flexural strength and elastic modulus and the results were reported in function of the densities. The best mechanical performance were obtained with the physical blowing agents, due to a better density distribution profile and a thicker skin layer.     

发泡剂对软质PVC发泡材料性能的影响

对发泡剂偶氮二甲酰胺(AC)及其共混物、碳酸氢钠(NaHCO3)进行了DSC分析,讨论了几种AC共混物对软质PVC发泡材料性能的影响。结果表明:当AC/NaHCO3/稳定剂的质量比为4/0.8/6.2时,材料的密度可以降至0.3g/cm3以下,但材料的泡孔直径增大,力学性能有所降低;当AC/NaHCO3/L/稳定剂为4/0.8/0.6/6.2时,材料的密度继续降低,泡孔直径减小,其强度、回弹性增大,但断裂伸长率减小;当AC/NaHCO3/L/Na-L/稳定剂为4/0.8/0.6/1.0/6.2时,复合发泡剂受热时分解平缓、放热适中,制得的材料性能最佳,泡孔均匀细密。     

进口发泡异型材粉料的组分剖析

本文采用仪器分析和化学分析，对进口发泡异型材料进行了较全面的剖析，初步确定了该粉料的组成及含量，它们为：ＰＶＣ（７０％），稳定剂（４％），ＣａＣＯ３（５％），发泡剂（２％），增塑剂、润滑剂、颜料适量。此剖析结果为发泡异型材粉料的配方研究提供了重要依据。