天然橡胶胶乳热稳定性测定方法

论述了几种天然橡胶胶乳热稳定性测定方法的特点及其在应用上存在的问题,指出了进一步研究胶乳热稳定性测定方法的必要性     

增稠剂对天然胶乳热稳定性的影响

介绍了增稠剂在天然胶乳工艺中的应用，试验表明在胶乳中加入0．5－2．0份阿拉伯树胶粉，不仅对胶乳的粘度有影响，而且对胶乳的热稳定性也有明显的作用。     

天然胶乳的电子束辐照硫化

使用低能量电子加速器电子束有利于降低天然胶乳的辐照硫化成本,但存在射线穿透力低的缺点,而采用转鼓方式,其电子束能量利用率要高于容器型辐照方式,且具有实用价值。     

用天然胶乳制备氯化橡胶工艺

天然胶乳制备氯化橡胶，反应条件较温和，克服了传统方法的缺点，解决环保问题。     

纤维状海泡石/天然胶乳复合胶膜的力学及热稳定性能

采用乳液共混法制备了纤维状海泡石/天然胶乳复合胶膜,研究了海泡石的结构及复合胶乳的胶体性能,考察了纤维状海泡石用量对硫化复合胶膜力学性能、断裂形态及热稳定性的影响。结果表明,随着纤维状海泡石用量的增加,天然胶乳的黏度增大,机械稳定性下降。复合胶膜的拉伸强度和撕裂强度先增大后减小,500%定伸应力增大,扯断伸长率降低;当纤维状海泡石用量为3份时复合胶膜表现出良好的力学性能。与天然胶乳薄膜相比,纤维状海泡石/天然胶乳复合胶膜的热稳定性有所提高。     

天然胶乳制品的耐老化性能和防老剂的选择

本文介绍了天然胶乳制品的老化性能。并介绍了一些天然胶乳制品中用的防老剂品种的选择和用量。     

可替代天然胶乳的丁腈胶乳

印度《印度橡胶杂志》2006年98期48页报道： 天然胶乳是许多年来手套行业应用最广泛的胶乳，在未来一些年内，它仍将在这一行业起主导作用。现在形势已经有一些微妙的变化，丁腈胶乳的应用在不断扩大。经济性在此起着重要的作用。过去14个月内，天然胶乳的价格上涨了85％。与之相比，丁腈胶乳的价格比较稳定，导致越来越多的手套厂转向使用丁腈胶乳。     

马来西亚成为最大天然胶乳消费国

英国《欧洲橡胶杂志》2005年187卷3期13页报道：马来西亚已成为世界第10大橡胶消耗国、第5大NR消耗国和第1大胶乳消耗国。目前马来西亚的天然胶乳年消耗量已超过50万t。     

Study on preparation of chlorinated natural rubber from latex and its thermal stability

The effects of pH value of reaction system, reaction time, and reaction temperature on the chlorination reaction in the preparation of chlorinated natural rubber (CNR) from natural rubber latex were discussed. It has been found from the thermal analysis that the thermal degradation of CNR in nitrogen is a one-step reaction, and 30% carbonide with a stable structure remained at 360 to 700°C; whereas the thermo-oxidative degradation of CNR in air is a multistep reaction, and the thermal degradation ratio reaches to 100% at 560°C. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2863–2867, 1999     

磷脂对浓缩天然胶乳机械稳定性的影响

在天然胶乳中添加磷脂,研究磷脂对天然胶乳机械稳定性的影响,结果表明,随着磷脂用量和氨含量的增加,天然胶乳的机械稳定度逐渐升高。气相色谱-质谱联用仪(GC-MS)分析表明,磷脂在碱性条件下水解产生亚油酸、棕榈酸、油酸、反油酸、硬脂酸、α-亚麻酸等长链脂肪酸,进一步与氨水反应形成脂肪酸铵,并吸附在橡胶烃粒子表面,提高了天然胶乳的机械稳定性。随着碱度的升高和水解时间的延长,磷脂水解产物的化学组成和含量存在一定差异。     

Preparation and thermal stability of brominated natural rubber from latex

The effects of pH value of reaction system, reaction time, reaction temperature, bromine concentration, and amount of potassium persulfate on the bromination reaction in the preparation of brominated natural rubber (BNR) from natural rubber latex were discussed. It has been found from the thermal analysis, that is, the thermal degradation of BNR in nitrogen is a two‐step reaction, and 16% carbonide with a stable structure remained at 470–650°C. The thermo‐oxidative degradation of BNR in air is also a two‐step reaction, and the percentage of degraded BNR reaches to nearly 100% at 600°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of temperature on sulfur prevulcanization of natural rubber latex

Sulfur prevulcanization of natural rubber latex was conducted at 60, 70, 80, and 90°C for different periods. The extent of crosslinking was assessed. Tensile properties, water absorption, leaching, and stress-relaxation characteristics of the films were also evaluated. The volume fraction of rubber (Vr), which is a measure of crosslink density of the films, showed a maximum when prevulcanization was conducted at 80°C for 2 h or at 90°C for 1 h. At lower temperatures, the rate of reaction was slow. At each temperature, tensile strength and elongation at break decreased when the prevulcanization time increased, whereas the modulus increased up to a maximum crosslinking and thereafter decreased. Water absorption and leaching were more rapid in prevulcanized film than in postvulcanized film. The rate of stress relaxation slightly increased as the extent of prevulcanization increased. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1913–1920, 1997     

热裂解气相色谱法测定天然胶乳中的干胶含量

研究热裂解气相色谱法测定天然胶乳中的干胶含量。试验结果表明,干胶含量与裂解主要产物峰面积呈现良好的线性关系,采用标准曲线法测定天然胶乳中的干胶含量,重复测定的相对标准偏差为0.14%,与国标法的平均相对误差为1.51%,定量分析结果准确,操作简便。     

Novel method for toughening of polystyrene based on natural rubber latex

γ‐Radiation vulcanized natural rubber latex/phase transfer/bulk polymerization is a novel process for the preparation of toughened polystyrene based on natural rubber latex. The negatively charged γ‐radiation vulcanized natural rubber latex was first titrated with benzyldimethylhexadecylammonium chloride in the presence of a styrene monomer. At a critical transfer concentration, the crosslinked rubber particles transferred from the aqueous phase into the styrene phase in which they swelled, depending on the irradiation dose used. By bulk polymerization of the styrene phase containing transferred particles, the polymer blends exhibited two‐phase morphology similar to that of commercial high‐impact polystyrene that was microscopically obtained. The final product showed an increase in the unnotched Izod impact energy over the unmodified polystyrene. The effect of irradiation dose, rubber content, and initiator concentration on the impact property and morphology of toughened polystyrene prepared was investigated. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1333–1345, 1999     

Noncatalytic hydrogenation of natural rubber latex

Hydrogenation is an important method of chemical modification, which improves the physical, chemical, and thermal properties of diene‐based elastomers. Natural rubber latex (NRL) could be hydrogenated to a strictly alternating ethylene–propylene copolymer using diimide generated in an in situ system. The diimide generated using the in situ technique for hydrogenation of NRL was accomplished by thermolysis of p‐toluenesulfonyl hydrazide (TSH). A molar ratio of TSH to double bonds equal to 2 : 1 was found to be the optimum ratio to provide a high percentage of hydrogenation. 95% Degree of saturation of NRL was achieved in o‐xylene. Hydrogenated products are characterized by FTIR and NMR spectroscopy. The thermal stability of hydrogenated rubber was improved as shown from the results of thermogravimetric analysis. From the differential scanning calorimetry measurement, the glass transition temperature of the hydrogenated product did not appear to change. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2885–2895, 2007     

淀粉纳米晶对天然胶乳性能的影响

将淀粉纳米晶作为天然胶乳的补强剂,研究其对天然胶乳的胶体性能及硫化胶膜的物机性能、耐水性和耐溶剂的影响。研究结果表明:将淀粉纳米晶加入天然胶乳后,胶乳的粘度变化不大,机械稳定度提高;硫化胶膜的物机性能明显提高,耐溶剂性提高,而耐水性降低。