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。     

黄色沉淀物对胶乳质量的影响

将天然胶乳离心得到的黄色沉淀物按不同比例加入浓缩胶乳中,并研究不同浓缩胶乳的胶体性质及胶膜的物理机械性能,发现添加黄色沉淀物会促使浓缩胶乳残渣含量及挥发酸值升高,会促使干胶含量及机械稳定度降低,但也会在一定程度上提高硫化胶膜的物理机械性能。     

橡胶加工专利

12 5 :6 0 742 c 由胶乳制备橡胶薄膜Jpn.Kokai Tokkyo Koho JP0 881,5 0 3[96 81,5 0 3](cl.C0 8Cl/ 0 0 )将合成橡胶胶乳与 1.0～ 10 %的天然橡胶胶粉 (平均粒径为 0 .1～ 0 .5 μm)混合在一起 ,制成薄膜。用非离子 -阴离子表面活性剂混合物与碱性蛋白酶处理由胶园采集的胶乳 (30 %橡胶胶乳 ) ,用水稀释 ,缩合 ,再稀释 ,并进行离心 ,直至橡胶含量达 5 % ,然后将得到的溶液与 (NH4 ) 2 SO4 混合 ,进行离心、稀释 ,并进一步进行离心操作 ,直至得到胶乳粒子 (平均粒径为0 . 38μm)为 5 0 %的澄清的胶乳为止。然后 ,将 10 0 g L X- 5 2 …     

不同品系天然橡胶胶乳的性能研究

对同一割龄6个品系的鲜胶乳,将其浓缩后比较各品系浓缩胶乳的性能,浓缩胶乳硫化胶膜的物理机械性能进行研究.结果表明热研8-79鲜胶及浓乳的干胶和总固含量最高,热研88-13的钙镁含量最高,RRIM600的分子量最大,硫化胶膜物理机械性能最好.     

改善胶乳三腔双囊胃管质量的生产工艺研究

以浓缩天然胶乳并用20份MG49天甲胶乳作胃管基础管身胶料可有效提高管身硬度和撕裂强度,并解决纯天然胶乳管身硬度不足、临床不易插管的难题,而对产品工艺性能及其他性能无不良影响。用"硝酸钙+工业酒精+表面活性剂"代替"硝酸钙+生粉附型剂+表面活性剂"作凝固体系,可改善胃管球囊胶膜厚度的均匀性。对胃管球囊内表面做适度氯化处理,可克服球囊与胃管管身产生的粘连或粘伤。适当改变绑线位置可有效减少胃管球囊胶膜出现的龟裂纹;球囊绑线处涂覆氯仿值二中~三中(见表9注)、总固体25%~35%的胶料3~4次,可获得较好涂胶效果。     

天然胶乳手套蛋白质过敏问题及对策

介绍了天然胶乳手套中所含蛋白质的种类、胶乳蛋白质过敏的起因和流行情况,指出过敏反应与胶乳中的可抽提蛋白质含量有关,采用沥滤、超声波技术与沥滤结合、多次离心胶乳、手套表面氯化处理、酶处理和辐射工艺可降低胶乳手套中的可抽提蛋白质的含量。     

氨含量和贮存时间对原产天然胶乳和胶清胶乳凝聚物性能的影响

原产天然胶乳用质量分数分别为0.35%、0.60%和0.80%的氨进行处理,经离心处理后分离成为浓缩天然胶乳(干胶含量60%)和胶清胶乳(干胶含量约5%)。再通过加入质量分数0.65%～0.75%(以胶乳计)的NH;、月桂酸铵和水,将浓缩胶乳调节为高氨型胶乳,在室温下贮存30～120 d,考察了贮存时间和原产胶乳中的氨含量对胶乳碱度、力学性能稳定时间(MST)、挥发性脂肪酸(VFA)值、凝胶含量和磷酸盐含量的影响。结果表明,胶乳的MST、VFA值、凝胶含量和磷酸盐含量随着贮存时间的延长而增加。在原产天然胶乳中加入过量氨后,由于[Zn(NH_3)_n)^(2+)络合物的生成,使浓缩天然胶乳中的凝胶含量增加。当浓缩天然胶乳和胶清胶乳二者中的氨含量增加,且原产胶乳的贮存时间延长时,胶乳的稳定性得到提高,胶清胶乳中不易产生凝聚物。     

离心浓缩胶乳的防冻处理

由于我国天然橡胶的生产周期约为每年的 4月中、下旬开始至年底结束 ,在供应和使用上有 4个月处于低温季度 ,加上目前所生产的离心浓缩胶乳 ,在贮存和运输途中的温度一般只能适应 2～ 35℃ ,不但要注意防晒 ,必要时又要做好防冻 ,有时就满足不了寒冷地区用户生产的需要。现将有关提高浓缩胶乳防冻的处理简介于下。胶乳经过冷冻和融解 ,都会影响胶乳一定程度的稳定。如果胶乳受冻的温度较低 ,往往影响某些乳胶制品的生产和使用性能。要制备出有一定耐寒防冻的离心浓缩胶乳 ,可在浓缩胶乳中加入 0 .2 %的水杨酸钠与0 .2 5%的月桂酸铵作稳定剂 …     

蛋白酶解产物对天然橡胶硫化特性和物理机械性能的影响

采用离心法制备不同蛋白质含量的天然胶乳，再通过碱性蛋白酶酶解橡胶粒子表面蛋白质，研究了蛋白质酶解产物对天然橡胶硫化特性和动态行为的影响。结果表明，随着离心次数的增加，天然橡胶中氮质量分数由0.27%降至0.13%，生胶复数黏度降低，混炼胶硫化速率变慢，硫化胶交联密度降低，力学性能下降，储能模量在应变和频率扫描下不断降低；由于蛋白质分解产物的作用，天然胶乳经离心加酶处理后，复数黏度高于单纯离心处理的，而且硫化速率加快，力学性能、储能模量均得到提升，尤其是二次离心加酶天然橡胶的硫化速率可达17.8 min^-1，拉伸强度可达23.73 MPa，明显高于二次离心天然橡胶的9.59 min^-1和20.52 MPa。     

蒸发浓缩天然胶乳的制备工艺研究

采用真空旋转蒸发工艺制备浓缩天然胶乳(蒸浓胶乳),讨论了高温下胶乳的保存体系,研究了温度、压力、转速以及不同操作方式对真空旋转蒸发浓缩速率的影响,考察了蒸浓胶乳的总固含量、干胶含量、挥发性脂肪酸值等指标,并与离心浓缩胶乳的有关值进行对照。实验结果表明,真空度为0.075～0.080 MPa、中等转速、操作温度为70℃为较佳的制备工艺条件。     

Hyperdeproteinized natural rubber prepared with urea

Preparation of hyperdeproteinized natural rubber was made from fresh latex and preserved high‐ammonia latex by treatment with urea in the presence of sodium dodecyl sulfate. Concentration of urea, temperature, and time for the incubation were investigated to remove the proteins effectively. Under the best conditions, the total nitrogen content and amount of allergenic proteins for the deproteinized rubbers were 0.005 wt % and 1.0 μg/ml, respectively, which were less than those of natural rubber deproteinized with proteolytic enzyme. The hyper‐deproteinized natural rubber was proved through FT IR spectroscopy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 555–559, 2004     

Removal of proteins from natural rubber with urea and its application to continuous processes

The removal of proteins from natural rubber through a batch process was studied by the incubation of the rubber latex with urea in the presence of sodium dodecyl sulfate. Under suitable conditions, the total nitrogen content of deproteinized natural rubber (DPNR) decreased from 0.38 to 0.02 wt % after incubation for 10 min; this was similar to that of the rubber deproteinized with a proteolytic enzyme for 12 h. For applications, continuous incubation and centrifugation were individually investigated by the use of a semicircular channel and a continuous centrifuge, respectively, to scale up DPNR preparation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

生物酶法催化天然乳胶中过敏蛋白质交联的研究

利用谷氨酰胺转氨酶催化天然乳胶(NRL)水溶性蛋白质(WSP)发生交联,减少天然乳胶中水溶性蛋白质的含量.利用粒径分析、结构表征、十二烷基硫酸钠凝胶电泳实验证明了交联反应的发生.采用这一新技术可以降低天然乳胶制品的过敏性,拓展了其在医疗卫生领域、食品加工等领域的应用空间.     

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。     

Polymer electrolyte membrane with nanomatrix channel prepared by sulfonation of natural rubber grafted with polystyrene

High‐proton‐conductive polymer electrolyte with a nanomatrix channel was prepared by graft copolymerization of styrene onto deproteinized natural rubber followed by sulfonation with chlorosulfonic acid. First, natural rubber latex was purified with urea in the presence of surfactant to remove almost all proteins present in the rubber. Second, graft copolymerization of styrene onto deproteinized natural rubber was carried out with tert‐butyl hydroperoxide/tetraethylenepentamine as an initiator at 30°C in latex stage. The graft‐copolymerized natural rubber (DPNR‐graft‐PS) was sulfonated with chlorosulfonic acid in chloroform solution at an ambient temperature. The resulting sulfonated DPNR‐graft‐PS was characterized by FTIR spectroscopy, solid state ¹³C CP/MAS NMR spectroscopy, elemental analysis, and transmission electron microscopy. High proton conductivity of about 0.1 S/cm, less water uptake of 24 wt % and comparatively good stress at break of 9 MPa were accomplished at suitable contents of styrene units and sulfur, i.e., 32 wt % and 75 mol %, respectively. The high proton conductivity, excellent stability, and good mechanical properties were associated with not only the formation of the nanomatrix channel but also a specific concentration of sulfuric acid group. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Effect of surface modification of microcrystalline cellulose with ionic liquids on natural latex composites

As an environmentally friendly biomacromolecular material, microcrystalline cellulose (MCC) enhances the performance of natural rubber latex (NRL) composites. However, MCC has strong polarity, which weakens the interfacial interaction between MCC and the non-polar NRL matrix and reduces the reinforcing performance due to the many hydroxyl groups on its surface. In this paper, the ionic liquid (IL) modified MCC/IL material was prepared, and AIR-FTIR, x-ray diffraction, and XPS photoelectron spectroscopy were performed to detect it from the perspective of environmental protection. And natural latex/microcrystalline cellulose/ionic liquid (NRL/MCC/IL) composites with excellent properties were prepared by latex blending. The activation energy, vulcanization characteristics, basic mechanical properties, dynamic mechanical properties, and filler-rubber interfacial interactions of NRL/MCC/IL composites were investigated. The results showed that the vulcanization rate constant of NRL/MCC/IL composites increase, the activation energy decreases and the mechanical properties were significantly improved. At the same time, the matrix interface interaction of composites was quantitatively calculated using Ayala parameters. The results showed that the interfacial interaction force of the composite was stronger after an appropriate amount of IL pretreatment. The whole process is not only conformed to the concept of green development, but also broadens the application of MCC in rubber materials.     

HEMA接枝改性天然胶乳的制备及其粘接性能研究

以甲基丙烯酸羟乙酯(HEMA)作为天然胶乳(NRL)的接枝改性剂,采用乳液聚合法制备了NR-g-HEMA[HEMA接枝NR(天然橡胶)]胶乳;然后以此为基体,并以水溶性松香树脂为增黏树脂、邻苯二甲酸二丁酯(DBP)为增塑剂等,制备相应的NR-g-HEMA胶粘剂;最后,用该胶粘剂压制胶合板,并对胶合板的粘接性能进行了测定。结果表明:采用单因素试验法优选出制备NR-g-HEMA胶乳的最佳工艺条件为m(干态单体)∶m(NRL)∶m(引发剂)∶m(活化剂)∶m(交联剂)=20∶100∶0.2∶0.2∶0.1、反应时间为8 h和反应温度为16℃,此时相应胶合板的剪切强度(1.88 MPa)符合Ⅲ类胶合板的指标要求。     

不同割龄橡胶树RRIM600胶乳组份及性能的研究

本论文研究了割龄3年、割龄13年、割龄20年、割龄24年和割龄28年5种不同割龄的RRIM600天然胶乳的性能。主要研究了天然胶乳粒径,生胶性能,混炼胶的硫化特性以及硫化胶的力学性能。结果表明,割龄28年胶树所得天然胶乳平均粒径最小,胶粒的分布范围较窄,分散性较好;割龄20年橡胶树生胶的P₀和门尼黏度较大,割龄为20年和28年橡胶树所得天然橡胶拉伸强度和撕裂强度较大。     

Development of correlation between potassium hydroxide number and conductivity of concentrated natural rubber latex

Increase in the ion concentration in the medium was found to increase conductivity and potassium hydroxide number (KOH No) in natural rubber latex (NRL). Addition of long chain fatty acids can increase the ion concentration in the medium and stability of NRL. A series of concentrated natural rubber latex samples from three different areas with different soils and climatic conditions were tested for the parameters such as KOH No and conductivity. They have been measured over a period of 62 days, upon addition of soap to natural rubber latex concentrate. The result showed that there was a strong positive linear correlation between conductivity and KOH No. The regression equation to express the relationship between the variables has also been found. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008