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。     

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。     

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。     

胶乳钙镁含量测定的改进

６０年代制订的“浓缩天然胶乳游离钙镁含量的测定方法”，为寻找当时浓缩胶乳易凝固、机械稳定性低的原因，调控浓缩胶乳有关指标，在提高浓缩胶乳的质量、指导胶乳制品的生产等方面发挥了重要作用。３０多年来，一直未能制订新的标准的测定方法，致使在生产，科研中出现很多混乱，特别是“克当量”这一单位不再使用后，有些同志在量的单位换算中出现了不应有的错误。因此，制订新的测定方法的统一标准就显得更加迫切。１９９３年华南热带农产品加工设计研究所向国家有关部门申请立项制订该项国家标准，１９９４年得到农业部的批复。我们…     

氮化硼对天然胶乳硫化胶膜力学性能的影响

研究氮化硼用量、不同改性氮化硼对天然胶乳胶膜力学性能的影响,通过热重分析仪分析其热稳定性。结果表明:随着氮化硼用量的增加,复合胶乳胶膜的力学性能先增加后降低,当氮化硼的用量为20份,天然胶乳胶膜的力学性能最好;使用KH570改性过的氮化硼制得天然胶乳胶膜的性能好,且KH570的最佳用量为2.5份时,复合胶膜的力学性能最好,热失重分析可知,改性的硫化胶膜的热稳定性有所提高。     

胶乳法氯化天然橡胶溶胶和凝胶的分析

采用化学分析方法、高分辨裂解气相色谱－质谱、傅立叶红外光谱结合热分析技术对胶乳法氯化天然橡胶（CNR）中所含的溶胶和凝胶成分进行了分析。结果表明：胶乳法CNR中所含的凝胶成分主要为CNR分子的分子间交联物，具有与溶胶成分相似的氯化结构，氯含量较同等氯化程度的线性CNR稍低；胶乳法CNR中的凝胶成分的热稳定性及热氧稳定性较溶胶成分差，对胶乳法CNR的热稳定性及热氧稳定性会产生不利的影响。     

不溶性硫磺总硫含量和热稳定性测定方法概述

介绍了不溶性硫磺总硫含量和热稳定性的测定方法,并对6种总硫含量测定方法和3种热稳定性测定方法进行分析比较.指出红外分光光度法是测定不溶性硫磺中总硫含量的最佳方法,在热稳定性的测定中推荐使用石蜡油-硅油二浴法.建议进一步完善测定方法,以适应今后对不溶性硫磺性能、质量的更高要求.     

胶乳的最低成膜温度测定及其成膜性

以浸渍用羧基丁腈胶乳为例论述了最低成膜温度的测定方法及其在成膜过程中随环境温度而发生的变化，并与其它类型胶乳相对比，试验证实了羧基丁腈胶乳所特有的优良成膜性。讨论了成膜性能与生产工艺的关系。     

LPNR胶乳和NR胶乳热降解性能的研究

采用热重分析法和导数热重分析法研究低蛋白NR(LPNR)胶乳和NR胶乳在氮气气氛中的热降解性能。结果表明，LPNR胶乳和NR胶乳的热降解过程相似，热降解反应级数相差不大，热降解率均随升温速率增大而略有增大；NR胶乳的平衡起始降解温度较高，LPNR胶乳的平衡最大降解速率温度和平衡终止降解温度与NR胶乳相近；LPNR胶乳的热稳定性比NR胶乳差。     

影响胶乳热稳定性测定结果的一些因素的探索

测定天然胶乳的化学稳定性目前尚无国际标准方法。在ISO/TC45中,曾讨论了天然胶乳的化学稳定度测定方法。结果认为所提出讨论的5个方法都缺乏重现性,均不适合国际标准要求。国内应用天然胶乳的单位,通常沿用橡胶工业手册第六分册第一章所规定的热稳定度测定法测量胶乳化学稳定性。在使用这     

制备工艺对NR性能的影响

采用新鲜天然胶乳分别制备乙酸凝固NR(NR-1)、微生物凝固NR(NR-2)、乙醇胺混合微生物凝固NR(NR-3)和蛋白酶混合自然凝固NR(NR-4),研究制备工艺对NR性能的影响。结果表明:NR-1和NR-2生胶的耐热老化性能和热稳定性好于NR-3和NR-4生胶;NR-4胶料的MH最大,t90最短,NR-3胶料的MH较小,t90最长;NR-4硫化胶的定伸应力和拉伸强度较大,拉断伸长率较小,NR-1硫化胶的定伸应力和拉伸强度较小;NR-4生胶、混炼胶和硫化胶的弹性转矩(S′)和剪切储能模量(G′)最大,损耗因子(tanδ)最小,NR-1生胶、混炼胶和硫化胶的S′和G′最小,tanδ值最大。     

Preparation,characterization and application of gamma irradiated some water soluble polymers/natural rubber latex blends

This work mainly depends on the assumption or hypothesis which exploits the tendency of natural rubber latex (NRL) to cross-link under irradiation in the presence of Alginate and CMC biopolymer and form (ALG/NRL and CMC/NRL) films containing polar/charged functional groups which offer them hydrophilicity, and consequently water absorption capacity. CMC/NRL and ALG/NRL (v/v) blend films prepared first by latex compounding followed by casting technique. The prepared ALG/NRL and CMC/NRL blend films characterized then, by various techniques such as IR, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Equilibrium swelling properties and gel percent GF% of prepared films also studied in details. GF% studies revealed that the GF% increased with increasing both NRL content and irradiation dose for both ALG/NRL and CMC/NRL. Thermal analysis shows the increased thermal stability of the irradiated samples due cross-linking effect of NRL. The improved gel content percentage obtained paved the way for the application of various films in the removal of toxic dyes such as acidic, direct, and basic dyes from waste water where in this study, the films exhibited high affinity toward basic blue dye.     

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。     

Enhancing the thermal stability of natural rubber/recycled ethylene propylene diene rubber blends through the use of bio‐compatibilizers

Recycling of rubber waste and searching for alternative routes to prolong the service life of rubber products are of significant concern. One of the ideas to reduce the rubber waste is to blend it with the virgin rubber to gain synergistic properties from its own advantages. In this study, natural rubber (NR) and recycled ethylene propylene diene rubber (R‐EPDM) were blended as a way to combine the mechanical properties and oxidative resistance given by NR and R‐EPDM, respectively. New approaches in enhancing the thermal stability were observed through the use of bio‐compatibilizers that is, alkanolamide (AKA)‐based refined, bleached, and deodorized palm stearin (RBDPS) and NR latex (NRL). The thermal stability of the blends was monitored through two techniques: thermo‐oxidative aging and thermogravimetric Analysis. Results indicated that the aging resistance of the blends was improved by addition of AKA and NRL as bio‐compatibilizers. This is confirmed by the enhancement of thermal decomposition temperature and the activation energies of the blends. The obtained TG profiles and the calculated kinetic parameters indicated that introducing AKA and NRL enhanced their thermal stability, especially at higher contents of AKA and NRL. J. VINYL ADDIT. TECHNOL., 25:E155–E165, 2019. © 2018 Society of Plastics Engineers     

Ammonium‐assisted green fabrication of graphene/natural rubber latex composite

Direct incorporation of nano reinforcement fillers has been a challenge for composite design because of strong aggregation. In this article, a stabilizer‐free method is developed to prepare new graphene/natural rubber latex (NRL) composite as the stabilizer ammonium was diffused completely in the final heat vulcanization. The as‐prepared composite was investigated by scanning electron microscopy, static mechanical analysis, dynamic thermal mechanical analysis, swelling analysis, and positron annihilation analysis. The results demonstrated that because of good dispersion and special two‐dimensional structure of the graphene, there is strong interfacial interaction originated from the π–π interactions and hydrogen bonds between graphene and NRL matrix even at a low loading. After the introduction of graphene, the glass transition temperature (T _g ) and the crosslink density are improved to 6°C and 7%, respectively, with a slight decrease in overall free‐volume number (3.5%) and fraction (1%). It is also surprising to notice that the tensile strength of NRL is improved to 8% without compromising the elongation at break, which actually increases 3%. Therefore, ammonium‐assisted dispersion of graphene is feasible for graphene/NRL fabrication. POLYM. COMPOS., 2013. © 2012 Society of Plastics Engineers     

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     

表面活性剂对天然胶乳蛋白质含量影响的研究

采用表面活性剂直接处理鲜胶乳离心浓缩法制备浓缩胶乳,先用尿素预处理新鲜胶乳后加入表面活性剂处理,再离心浓缩法制备浓缩胶乳。研究表面活性剂种类、尿素预处理时间和预处理温度及新鲜胶乳的pH值对处理所得浓缩胶乳蛋白质含量的影响。同时用傅立叶红外吸收光谱对2种处理方法制备的浓缩胶乳胶膜进行了表征。实验结果表明,鲜胶乳先经尿素预处理一定时间后加入阴离子表面活性剂处理,再离心浓缩制备浓缩胶乳,蛋白质含量显著降低。适宜条件下,浓缩胶乳的氮含量从质量分数0．430％下降至0．089％。红外光谱分析表明,先用尿素预处理新鲜胶乳,然后加入阴离子表面活性剂处理,再离心浓缩制备浓缩胶乳,胶膜在1546cm。处蛋白质的酰胺Ⅱ谱带几乎消失,在3295cm。处N—H的伸缩振动峰明显减弱。     

Application of natural rubber latex as scaffold for osteoblast to guided bone regeneration

Natural rubber latex (NRL) from Hevea brasiliensis is a colloidal system composed of cis ‐1,4‐polyisoprene. Its applications have grown due its angiogenic and wound healing activity. NRL has been used in guided bone regeneration as barrier, enhancing bone formation. However, there has been no study reported so far which shows its in vitro biocompatibility with osteoblasts. Thus, the aim of this work was to apply thermally induced phase separation under several temperatures to induce porosity in NRL; and test its mechanical properties, cytotoxicity, cell adhesion, and mineralization with MC3T3‐E1. Only biomembranes submitted at ?20 and ?10 °C presented porosity. Fourier transform infrared spectroscopy showed no change in cis ‐1,4‐isoprene spectra. Biomembranes were elastic (Young's modulus < 1 MPa). According to ISO10993–5, NRL showed no cytotoxicity. Cells adhered on the NRL and produced mineral matrix as analyzed by scanning electron microscopy–energy‐dispersive spectrometry, von kossa, and Fourier transform infrared spectroscopy. Cells on NRL presented higher alkaline phosphatase activity, however, mineralization showed no difference by alizarin red S dye extraction. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45321.     

Preparation of low‐allergen natural rubber latex by transglutaminase catalysis

The technique of enzyme treatment on the water‐soluble proteins and mechanical properties of natural rubber latex (NRL) films was studied. The main aim was to introduce an enzymic catalysis method to tackle the protein allergy problem in NRL product. The suitable pH value, the temperature, and the best proportion of transglutaminase to deal with NRL were found. The protein spillage of modified NRL films was greatly lower than that of unmodified NRL, and the tensile strength and the elongation at break of the modified NRL films almost had been scarcely changed. The compactness of the NRL films was improved simultaneously. These suggest that the modified NRL can be used as a kind of latex with low‐allergy personal barrier products such as surgical gloves. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

硫脲修饰交联壳聚糖对天然胶乳蛋白质含量影响的研究

以三聚氯氰为活化剂制备硫脲修饰戊二醛交联壳聚糖，用傅立叶红外吸收光谱对产物进行了初步表征；研究了壳聚糖及其衍生物处理对天然胶乳蛋白质含量的影响．以及处理时间、处理温度和鲜胶乳氨含量对硫脲修饰戊二醛交联壳聚糖处理鲜胶乳后所得浓缩天然胶乳蛋白质含量的影响。结果表明：硫脲修饰戊二醛交联壳聚糖处理鲜胶乳再经离心机浓缩处理可显著降低天然胶乳的蛋白质含量。在适宜的条件下，胶乳胶膜的氮质量分数从未处理的0．430％降至0．132％。鲜胶乳氨含量和处理时间对胶乳的蛋白质含量有较大影响．而处理温度则影响不显著。红外谱图分析表明．硫脲修饰戊二醛交联壳聚糖主要通过与蛋白质形成氢键的形式吸附胶乳中的蛋白质。