天然胶乳热稳定性测定方法的比较研究

比较研究了几种常用天然胶乳热稳定性测定方法的精密度及其相关性。     

天然胶乳/丁基胶乳并用胶乳的性能研究

采用完全随机化试验方法,研究天然胶乳/丁基胶乳并用比和硫化强化包用量（以干量计）对并用胶乳及其硫化胶膜性能的影响。结果表明：并用胶乳的粘度随着停放时间的延长而逐渐增大;并用胶乳硫化胶膜的气密性随着丁基胶乳占比的增大而呈提高趋势;当天然胶乳用量为100份、丁基胶乳用量为5.42份、硫化强化包用量为2.65份时,并用胶乳硫化胶膜的拉伸强度可达到24 MPa左右。     

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     

天然胶乳的化学改性

简要介绍了天然胶乳化学改性的有利条件，化学改性天然胶乳的主要品种、相关技术及其应用以及仍存在的主要问题。     

填料对预硫化天然胶乳胶膜性能的影响

把２０份的沉淀法白炭黑、陶土及重质碳酸钙加到配合胶乳中搅拌混合,在７０℃条件下预硫化２小时。采用浇注的方法准备试片。测定了水沥滤对胶膜机能产生的影响,同时对橡胶与填料的相互作用、耐老化、应力松弛及沥滤后胶膜的结构进行了研究。由于加了沉淀法白炭黑、陶土及重质碳酸钙,降低了拉伸强度及扯断伸长率,但增加了预硫化胶乳胶膜的定伸应力;沥滤增进了胶膜性能。加入沉淀白炭黑及陶土改进了胶膜的抗裂强度;沉淀法白炭黑     

氧化锌对硫化天然胶乳性能的影响

研究氧化锌对硫化天然胶乳胶膜和胶体性能的影响,考察在短期贮存中胶乳胶体的稳定性。结果表明,2种新型氧化锌与普通工业氧化锌的硫化胶膜和胶乳胶体性能相差不大,氧化锌用量在0.4～0.6份时胶膜性能最好。     

红外光谱法鉴别掺假天然胶乳

在天然胶乳中按不同比例掺入木薯粉或面粉,制备掺假天然胶乳,采用傅里叶转换红外光谱进行表征和分析。结果表明:在天然胶乳中掺入木薯粉或面粉,红外光谱在3 500~4 000 cm~(-1)波段出现指纹区,掺入量越高,指纹区的波动幅度越大;在木薯粉或面粉的特征谱带,随着掺入量的增大,吸收强度增强。     

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     

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     

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     

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。     

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     

三氯溴甲烷改性天然胶乳的研究

用三氯溴甲烷改性天然胶乳，研究了反应时间、反应温度、三氯溴甲烷的用量等对改性胶乳的硫化胶膜物理机械性能的影响，利用DSC对产物进行了分析。结果表明，反应时间为10h，反应温度在35℃时，所得胶膜物理机械性能较好；随着三氯溴甲烷用量的增加，改性天然胶乳的硫化胶膜物理机械性能下降：三氯溴甲烷改性天然胶乳的玻璃化温度高于未改性天然胶乳。     

用改性天然胶乳进行合成纤维橡胶基布浸胶处理的研究

介绍用环氧化改性天然胶乳进行涤纶、尼龙及维棉、涤棉等橡胶基布表面浸胶处理,并对处理布在制品中与橡胶的层间附着性能进行评价.