基于橡胶加工分析仪对膜浓缩胶清橡胶性能研究

胶清橡胶为浓缩天然胶乳制备过程中的副产物,性能相对较差。通过中空纤维微滤膜浓缩工艺对胶清乳液浓缩,可去除部分蛋白质、铜离子、锰离子等物质以提高胶清橡胶的品质。本研究利用橡胶加工分析仪(RPA)对微滤膜浓缩胶清橡胶(NR-m)和传统酸凝固胶清橡胶(NR-s)的加工特性和耐老化性能进行研究,由实验结果可知：NR-m的流变指数为0.2758,低于NR-s的流变指数0.2862;而随应变变化,NR-m的弹性模量一直高于NR-s的弹性模量。这说明NR-m的加工性能相对较差。NR-m在应变下的损耗因子较小,说明内耗生热较小,同时,NR-m老化前后的损耗因子差值的最大值和最小值分别是0.0780和0.0265,其值均小于NR-m老化前后的损耗因子差值。说明NR-m的耐老化性能更佳。     

超滤法浓缩胶清橡胶性能的研究

采用中空纤维柱浓缩法制备天然橡胶胶清橡胶,并对其性能进行研究。结果表明:与未处理胶清橡胶相比,处理后胶清橡胶的丙酮溶物质量分数、塑性初值和塑性保持率均有所增大,挥发分质量分数、杂质质量分数、灰分质量分数和氮质量分数减小。与未处理胶清硫化胶相比,处理后胶清硫化胶的物理性能明显提高;随着处理孔径的增大,硫化胶的物理性能呈下降趋势。与未处理胶清橡胶相比,随着温度的升高,处理后胶清橡胶的损耗因子较小,剪切储能模量较大,表现出较好的加工性能。     

一种提高胶清橡胶性能的方法

正由海南大学申请的专利(公开号CN104693321A,公开日期2015-06-10)"一种提高胶清橡胶性能的方法",提供了一种提高胶清橡胶性能的方法:离心机分离得到的胶清乳液中加入0.1~10份胶乳稳定剂熟化后,经中空纤维柱(相对分子质量为1万~20万)滤除相对分子质量小的非橡胶组分,浓缩得到干胶质量分数为0.1~0.5     

金属离子钝化剂添加工艺对胶清橡胶性能的影响研究

通过不同的添加工艺将乙二胺四乙酸二钠(EDTA-2Na)、柠檬酸钠(NaCA)、三聚磷酸钠(STPP)三种金属离子钝化剂加入胶清橡胶,研究金属离子钝化剂对胶清橡胶硫化性能,物理机械性能及热氧老化性能的影响。结果表明,加入金属离子钝化剂,对胶清橡胶的硫化性能和物理机械性能的影响较小,但是能够明显提高胶清橡胶的热氧老化性能。NaCA和EDTA-2Na在凝固前加入胶清对提高胶清橡胶的热氧老化性能和热稳定性效果更好,而STPP则是在混炼过程中添加效果更好。     

凝固方法对胶清橡胶力学性能的影响

研究了3种不凝固方法对胶清橡胶性能和碳黑或CaCO3/胶清橡胶硫化胶力学性能的影响.结果表明,采用十二烷基硫酸钠和CaCl2凝固胶清制得胶清橡胶具有较好的性能.     

舰船用高性能密封橡胶研究(Ⅰ)硫化剂对氟橡胶硫化胶物理性能的影响

研究了硫化剂种类、用量对氟橡胶硫化胶的物理性能的影响。结果表明，硫化剂用量增加，硫化胶的硬度增大，扯断伸长率降低，拉伸强度先增大后降低，出现一个极大值，硫化胶的压缩永久变形先减少后增大，存在一极小值。     

高级胶清橡胶的制备及性能研究

采用正交试验法研究高级胶清橡胶的制备工艺条件.结果表明,高级胶清橡胶的最佳制备工艺条件为:硫脲质量分数 0.015.草酸质量分数 0.010.浸泡时间 15 h;制备的高级胶清橡胶性质相当于10#标准胶.高级胶清橡胶/5#标准胶并用胶和硫化胶性能基本达到5#标准胶指标要求.     

高级胶清与新鲜胶乳并用制备复合橡胶的研究

胶清经中空纤维柱过滤浓缩后,与木瓜蛋白酶反应制备高级胶清,将高级胶清与新鲜胶乳按一定干基质量比混合、共凝制备复合橡胶,研究高级胶清与新鲜胶乳并用比对复合橡胶性能的影响。结果表明:当高级胶清用量为10~40份时,复合橡胶的理化性质可达到国产5#标准胶的要求;高级胶清能促进复合橡胶的硫化并提高其物理性能。     

最新橡胶工艺原理(十七)

8．2 配方与橡胶物理性能的关系。8．2．1 硬度。硬度是硫化胶的重要物理性能之一，其测定方法比较简单。硫化胶的硬度随制品种类的不同而各异，但其一大特点是可以直接由橡胶成品测得。决定橡胶制品硬度的主要因素是补强填充剂和软化剂的种类及配合量、生胶、交联密度等。炭黑对硬度的影响程度随生胶种类的不同而各异，非结晶橡胶大于结晶橡胶，见表8—10．     

丁腈橡胶和丁腈酯橡胶性能对比

对丁腈橡胶(NBR)和丁腈酯橡胶(BNBR)热氧老化前后的物理机械性能和动态力学性能进行对比研究,并分析了分子结构对材料热氧老化和动态力学性能的影响。结果表明,NBR和BNBR的物理机械性能相当,热氧老化后BNBR的力学性能更优异,其原因可能是BNBR中酯基热稳定性好。NBR的腈基极性强于BNBR的酯基,侧基极性愈强,其相互作用力愈大,单键内旋转愈困难,链的柔顺性愈差,同时,BNBR的柔性酯基可起到增塑剂的作用,这2个因素导致BNBR在低温下的动态力学性能优于NBR。     

无氨保存胶清及胶清胶性能的研究

采用水溶性、不挥发性的广谱抗菌剂——三嗪衍生物(HY)作为鲜胶乳的新型无氨保存剂,研究了HY对胶清凝固总用酸量、胶清胶及胶清胶硫化胶片性能的影响。结果表明,HY保存胶清凝固总用酸量大大减少,除氮含量略微超标外,胶清胶的各项指标均达到1级胶清胶的标准,胶清胶的塑性保持率(PRI)明显提高。HY胶清胶硫化胶片的拉伸强度和耐热氧老化能力均优于氨胶清胶硫化胶片。热解重量分析(TGA)结果表明,HY和氨胶清胶硫化胶片热氧降解均为2步反应,耐热氧降解能力基本相同。     

Performance of fractal membranes in the ultrafiltration of skim natural rubber latex

Analytical Electron Microscopy reveals the possible existence of ceramic particulates as the active surface of fractal membranes, obtained from deposition of a colloidal suspension of inorganic-organic materials on polypropylene hollow fibres. These membranes exhibit high ultrafiltration flux with no obvious fouling. Ultrafiltration flux of skim natural rubber latex, at a specified concentration, was maintained constant for a period of at least 2 hours. On the contrary, the flux of unfractalized polypropylene hollow fibres dropped drastically within 40 minutes with severe irreversible fouling.

Familiar characteristic curves of flux proportional to pressure gradient in the low pressure region, followed by a transition zone and a region of pressure independent flux, were also observed for the case of fractal membranes, but with a more pronounced effect of shear rate. In the non gel polarized region, flux was found proportional to shear rate to the power of 0.88, which is somewhat higher than that expected by the Blatt equation. As expected, solute concentration affected the flux in accordance with the gel polarized model whereby flux is a linear function of the retained solute concentration. Flux was also found to increase by 1.9% for every degree centigrade increment in the temperature range of 30° to 65°C. This is lower than the theoretical expectation based on the viscosity changes, which indicates some degree of solute-solvent interaction.     

Characterization of enzyme‐deproteinized skim rubber

Skim natural rubber latex is a protein‐rich byproduct obtained during the centrifugal concentration of natural rubber latex. Skim latex has a very low dry rubber content (4–8%), and the rubber particles are smaller in size. It has a higher proportion of nonrubber solids, which are mostly proteinaceous in nature. It is difficult to coagulate, and it takes more processing time. The proteins in skim latex can be decomposed by proteolytic enzymes. This article discusses the use of stabilized liquid papain from the papaya plant (Carica papaya) for deproteinization followed by creaming for quick and easy coagulation of skim latex. The technological properties and aging characteristics of the deproteinized skim rubber are compared with those of conventionally prepared skim rubber and block rubber. The deproteinized skim rubber showed enhanced quality parameters. Particle size analysis revealed that deproteinization and creaming of the skim latex did not markedly change the particle size. Gel permeation chromatography showed a reduction in the quantity of fatty acids after deproteinization and creaming, which was reflected in the improvement of the aging characteristics in comparison with the control sample. Vulcanizates prepared with the deproteinized skim rubber had higher resilience, lower heat buildup, lower compression set, and good tensile strength and elongation at break in comparison with conventionally prepared skim rubber, and the properties were almost comparable to those of block rubber. The improvement in the mechanical properties and aging characteristics could be attributed to the reduction of the protein content, the partial removal of unsaturated fatty acids, and the removal of metal ions that were pro‐oxidants during the deproteinization and creaming process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

改性胶清橡胶及其复合材料的性能研究

采用有机改性钠基蒙脱土对胶清橡胶进行复合改性,制备改性胶清橡胶,并与杂胶、喇叭口胶、泡沫胶和废水胶复合,研究改性胶清橡胶及其复合材料的各项性能.结果表明,改性胶清橡胶塑性初值(P0)和塑性保持率(PRI值)与胶清橡胶相比大幅度提高,物理性能和热性能也明显改善;改性胶清橡胶/杂胶等复合材料的物理性能与杂胶等相比显著提高,P0和PRI值也有不同程度的增大.     

Creaming of skim natural rubber latex with chitosan derivatives

To recover residual rubber from skim natural rubber (SNR) latex, a novel method was developed on the basis of the use of water‐soluble chitosan derivatives. An anionic chitosan derivative, N,O‐carboxymethyl chitosan (CMCh), and a cationic chitosan derivative, N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (HTACh), were prepared. It was found that the creaming process could be achieved with both chitosan derivatives. By the addition of 7.34–10.3‐g/L CMCh, SNR latex was almost completely creamed, and no coagulation of SNR particles in the cream phase occurred. In the case of HTACh, the creaming process was achieved with a lower concentration (<3.70 g/L) than in the case of CMCh, but the size of SNR particles in the cream phase was larger. Solid‐state ¹³C‐NMR, thermogravimetric analysis, and ζ potential measurement results provided evidence that the creaming of SNR latex with CMCh and HTACh was controlled by the depletion flocculation and adsorption mechanisms, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Compatibility enhancement of silica and natural rubber compound using UVA-induced silane-grafted saponified skim natural rubber

Silane coupling agents are potential reagents widely used to improve the compatibility between silica and less polar rubber, especially natural rubber (NR). Nevertheless, high temperature is generally required to generate the interaction between the components during the mixing process. Accordingly, an alternative method by grafting the silane coupling agent onto the rubber molecules would be a desirable approach to develop a compatibilizer for the silica-filled NR compound. In this work, skim NR was used as a starting material due to its linear structure. The optimal conditions of the grafting reaction were found to be 1 phr of an alkoxy silane and 5 phr of benzoyl peroxide under 8 min of UVA irradiation time. These conditions were applied for producing the rubber material used in the mixing process of STR 5L and silica. The cure characteristics, silica dispersion and mechanical properties of the rubber compounds were improved, suggesting that the modified rubber was an efficient material for increasing the compatibility between silica and NR.     

Creaming skim natural rubber latex for encapsulation of urea fertiliser

Abstract

Skim natural rubber latex has been characterised before crosslinking with γ-radiation. Micrographs of γ-vulcanised skim particles embedded in polystyrene revealed a semi-interpenetrating polymer network morphology of fine rubber–polystyrene particles surrounded by membrane layer. Creamed skim latex was prepared by addition of 15–45 phr sodium alginate and further used for encapsulation of urea fertiliser. Non-spherical capsules containing an homogeneous urea dispersion were obtained.     

典型发用定型树脂的性能比较及研究

结合毛发的构造，通过单因素对比测试考察了各类定型树脂性能与构造的关系。结果表明：两性定型树脂的构造与毛发的构造非常相似，在涂层强度．耐湿性等方面具有明显的优势。另外．通过对比两性树脂与其它类型树脂复配后的性能．指出不同类型树脂的复配使用是今后定发产品配方设计的发展方向。     

Preparation and characterization of organoclay‐rubber nanocomposites via a new route with skim natural rubber latex

Skim natural rubber latex (SNRL) is a protein rich by‐product obtained during the centrifugal concentration of natural rubber (NR) latex. A new method to recover rubber hydrocarbon and to obtain nanocomposites with organoclay (OC) was investigated. The approach involved treatment of SNRL with alkali and surfactant, leading to creaming of skim latex and removal of clear aqueous phase before addition of OC dispersion. Clay mixed latex was then coagulated to a consolidated mass by formic acid, followed by drying and vulcanization like a conventional rubber vulcanizate. X‐ray diffraction (XRD) studies revealed that NR nanocomposites exhibited a highly intercalated structure up to a loading of 15 phr (parts per hundred rubber) of OC. Transmission electron microscopy studies showed a highly exfoliated and intercalated structure for the NR nanocomposites at loadings of 3–5 phr organically modified montmorillonite (OMMT). The presence of clay resulted in a faster onset of cure and higher rheometric torque. The rubber recovered from skim latex had a high gum strength, and a low amount of OC (5 phr) improved the modulus and tensile strength of NR. The high tensile strength was supported by the tensile fractography from scanning electron microscopy. Thermal ageing at 70°C for 6 days resulted in an improvement in the modulus of the samples; the effect was greater for unfilled NR vulcanizate. The maximum degradation temperature was found to be independent of the presence and concentration of OC. The increased restriction to swelling with the loading of OC suggested a higher level of crosslinking and reinforcement in its presence. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3277–3285, 2006