环氧化天然橡胶原位接枝SiO_2制备天然橡胶复合材料的力学性能和阻尼特性

采用环氧化天然橡胶(ENR)原位接枝SiO_2母胶制备NR/ENR/SiO_2复合材料,考察NR/ENR/SiO_2复合材料的力学性能和阻尼特性。结果显示,添加环氧化天然橡胶原位接枝SiO_2母胶的NR/ENR/SiO_2复合材料比单独添加环氧化天然橡胶和SiO_2的样品分散性更好、硫化速率更高、力学性能升高明显,且耐老化性能得到改善。添加ENR原位接枝SiO_2母胶的NR/ENR/SiO_2复合材料与对照样相比,玻璃化转变温度升高,有效阻尼温域扩宽,阻尼性能提高。     

非迁移型防老剂的制备及在天然橡胶中的应用

采用纳米白炭黑与硅烷偶联剂γ-环氧丙氧基丙基三甲氧基硅烷反应,再与对氨基二苯胺进行接枝反应,制备出一种非迁移型防老剂(SiO2-g-RT),用傅里叶变换红外光谱、热重分析对其进行了表征;用扫描电子显微镜和差示扫描量热法考察了SiO2-g-RT在天然橡胶(NR)硫化胶中的分散性及NR硫化胶的热氧老化性能。结果表明,防老基团成功地接枝到了白炭黑表面;SiO2-g-RT在NR中的分散性好于白炭黑,其抗热氧老化性能比小分子防老剂有明显提高。     

环氧化天然橡胶对白炭黑/天然橡胶硫化胶物理性能和减震性能的影响

研究不同环氧度环氧化天然橡胶(ENR)对白炭黑/天然橡胶(NR)硫化胶物理性能、减震性能及压缩疲劳生热性能的影响。结果表明:ENR可以提高白炭黑/NR硫化胶的物理性能和实用温度范围内的阻尼性能,降低硫化胶的压缩疲劳生热,其中环氧度为40%的ENR效果最优。     

天然橡胶环氧化改性工艺研究

研究中性环境制备环氧化天然橡胶(ENR)的工艺。本试验确定的天然橡胶(NR)环氧化改性体系反应条件如下:乳化剂异构十三碳醇聚氧乙烯醚1308,体系的NR固形物质量分数0. 25～0. 28,NR/丙酮/过氧硫酸氢钾的物质的量比1∶0. 435∶0. 190,温度4～8℃。在此反应条件下可制得环氧度为28%、反应效率为73. 68%的ENR。此方法制得的ENR性能稳定,副产物少。     

环氧化天然橡胶及其应用研究进展

介绍环氧化天然橡胶(ENR)的制备方法、性能及其对聚合物基复合材料的改性效果.ENR在保留天然橡胶(NR)的结构和性能的基础上,可进一步提高NR的气密性能和耐油性能等.不同硫化体系硫化ENR的性能不同,ENR的环氧度越高,其玻璃化温度越高,气密性能和耐溶剂性能越好.ENR可作为相容剂对NR和其他橡胶及白炭黑进行改性,提高胶料的性能和白炭黑在胶料中的分散性.     

氢化天然橡胶/氢氧化镁/环氧化天然橡胶复合材料的制备及性能研究

采用水合肼/双氧水/硫脲体系对天然胶乳进行氢化改性制备氢化天然橡胶(HNR),研究HNR/氢氧化镁[Mg(OH)_2]/环氧化天然橡胶(ENR)复合材料的微观结构和性能。结果表明:制备HNR的最佳氢化条件为水合肼/NR的C=C键物质的量比5.5/1,双氧水/水合肼物质的量比1.85/1,硫酸铜浓度3.5 mmol·kg~(-1),表面活性剂浓度20g·kg~(-1);HNR/Mg(OH)_2/ENR复合材料具有良好的界面相容性;HNR/Mg(OH)_2/ENR并用比为10/5/5的复合材料极限氧指数达到20.7%,阻燃性能良好。     

环氧化天然橡胶的研究与应用

环氧化天然橡胶（ENR）是由NR化学改性而成,笔者阐述了环氧化天然橡胶制备原理和方法、环氧化天然橡胶性能及应用研究、环氧化天然橡胶共混改性研究,其中包括ENR与PVC共混体系的研究、ENR其它共混体系的研究和ENR改性的研究.     

环氧化天然橡胶的硫化特性

用过醋酸法制得的系列环氧化天然橡胶(简称ENR。用硫化仪研究其硫化特性,焦烧性能,助剂影响。通过硫化主硫化期(稳态期)测定ENR有促进剂的硫黄硫化反应动力学级数,表观反应速度常数及表观活化能。     

环氧化天然橡胶的二元酸硫化

环氧化天然橡胶(ENR)是通过用过酸对天然胶乳进行部分环氧化反应而制成的。环氧化作用使天然橡胶具有较高的气密性、较低的油溶胀性和较高的湿牵引力。近来,使用加速硫黄硫化体系对这些性能的改进及其他特性如焦烧、老化、网状结构等都进行了研究。因为环氧基和不饱和键是ENR中的反应活性部位,所以它们容易进行交联和化学改性。当不饱和键可与硫黄过氧化物和其他交联剂发生交联时,环氧化物就成为与多官能化合物(如二元酸、多元胺等)发生交联的可能部位。     

环氧化天然橡胶复合材料性能研究

采用新方法制备环氧化天然橡胶(ENR)/白炭黑和天然橡胶(NR)/ENR/白炭黑复合材料,并对其性能进行研究。结果表明:ENR/白炭黑复合材料的热稳定性优于ENR;在NR/ENR并用胶中加入白炭黑和硅烷偶联剂KH-550,NR/ENR/白炭黑复合材料0℃时的损耗因子(tanδ)增大,65℃时的tanδ值减小,复合材料的抗湿滑性能提高,滚动阻力减小。     

Molecular-level dispersion of graphene into epoxidized natural rubber: Morphology,interfacial interaction and mechanical reinforcement

The interfacial interaction of composites dominates the properties of polymeric/inorganic nanocomposites. Herein, epoxy and hydroxyl groups are introduced into the natural rubber (NR) molecular chains to anchor oxygenous functional groups on the surface of graphene oxide (GO) sheets and therefore enhance the interfacial interaction between GO and rubber. From the morphological observation and interaction analysis, it is found that epoxidized natural rubber (ENR) latex particles are assembled onto the surfaces of GO sheets by employing hydrogen bonding interaction as driving force. This self-assembly depresses restacking and agglomeration of GO sheets and leads to homogenous dispersion of GO within ENR matrix. The formation of hydrogen bonding interface between ENR and GO demonstrates a significant reinforcement for the ENR host. Compared with those of pure ENR, the composite with 0.7 wt% GO loading receives 87% increase in tensile strength and 8.7 fold increase in modulus at 200% elongation after static in-situ vulcanization.     

Mechanical properties and blend compatibility of natural rubber –chlorosulfonated polyethylene blends

Natural rubber (NR) was blended with chlorosulfonated polyethylene (CSM) with various formulation and blend ratios (NR/CSM: 80/20 –20/80, wt/wt). Rubber blends were prepared by using a two‐roll mill and vulcanized in a compression mold to obtain the 2 mm‐thick sheets. Tensile properties, tear resistance, thermal aging resistance, ozone resistance, and oil resistance were determined according to ASTM. Compatible NR/CSM blends are derived from certain blends containing 20–30% CSM without adding any compatibilizing agent. Tensile and tear strength of NR‐rich blends for certain formulations show positive deviation from the rule of mixture. Thermal aging resistance depends on formulation and blend ratio, while ozone and oil resistance of the blends increase with CSM content. Homogenizing agents used were Stuktol®60NS and Epoxyprene®25. Stuktol®60NS tends to decrease the mechanical properties of the blends and shows no significant effect on blend morphology. Addition of 5–10 phr of epoxidized natural rubber (ENR, Epoxyprene® 25) increases tensile strength, thermal aging resistance, and ozone resistance of the blends. It is found that ENR acts as a compatibilizer of the NR/CSM blends by decreasing both CSM particle size diameter and α transition temperature of CSM. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 127–140, 2006     

环氧化天然橡胶硫化胶在不同气氛下的热降解行为？

利用热重-微商热重（ TG-DTG-DSC）研究了在氮气、空气氛围中ENR硫化胶的热降解动力学,根据不同升温速率下得到的热重数据,通过Ozawa-Flynn-Wall模型求取热降解过程的活化能E、指前因子A等参数,得到ENR硫化胶在不同气氛下降解反应过程中动力学参数方面的差异。 ENR在氮气气氛中降解时为一步反应,在空气中为复杂多步反应。另外,空气气氛中的活化能E和指前因子A均大于氮气中。     

Thermoplastic natural rubber based on polyamide‐12: Influence of blending technique and type of rubber on temperature scanning stress relaxation and other related properties

Thermoplastic natural rubber based on polyamide‐12 (PA‐12) blend was prepared by melt blending technique. Influence of blending techniques (i.e., simple blend and dynamic vulcanization) and types of natural rubber (i.e., unmodified natural rubber (NR) and epoxidized natural rubber (ENR)) on properties of the blends were investigated. It was found that the simple blends with the proportion of rubber ～ 60 wt % exhibited cocontinuous phase structure while the dynamically cured blends showed dispersed morphology. Furthermore, the blend of ENR exhibited superior mechanical properties, stress relaxation behavior, and fine grain morphology than those of the blend of the unmodified NR. This is attributed to chemical interaction between oxirane groups in ENR molecules and polar functional groups in PA‐12 molecules which caused higher interfacial adhesion. It was also found that the dynamic vulcanization caused enhancement of strength and hardness properties. Temperature scanning stress relaxation measurement revealed improvement of stress relaxation properties and thermal resistance of the dynamically cured ENR/PA‐12 blend. This is attributed to synergistic effects of dynamic vulcanization of ENR and chemical reaction of the ENR and PA‐12 molecules. Furthermore, the dynamically cured ENR/PA‐12 blend exhibited smaller rubber particles dispersed in the PA‐12 matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Curing Characteristics and Aging Properties of Natural Rubber/Epoxidized Natural Rubber and Cellulose II

In this work, natural rubber (NR) and regenerated cellulose (cel II) latexes were co-coagulated and to the mixture epoxidized natural rubber (ENR) was added on a two-roll mill. The cellulose content was fixed at 20 phr while ENR content varied from 0 to 75 phr. The influence of ENR was studied through the cure characteristics, aging and dynamic-mechanical properties. The aging provides nanocomposites with better solvent resistance and increased tensile strength at ENR content of 25 phr. The results suggest that a new type of light-colored nanocomposites were obtained, which presented high mechanical performance and resistance to solvents.     

Thiol Addition to Epoxidized Natural Rubber: Effect on the Tensile and Thermal Properties

Epoxidized natural rubber (ENR) samples of various epoxidation degrees were synthesized from natural rubber (NR) latex, and 25 mole% epoxide of ENR was used to prepare ENR room temperature-curable films for coating applications. The films were prepared from rubber solutions. Trimethylolpropane tris(2-mercaptoacetate) (TMP-SH) was used as a curing agent. The effect of the thiol additive on the tensile and thermal properties of epoxidized natural rubber (ENR) was investigated. For the sake of comparison, NR and TMP-SH-containing formulations were also prepared.

It was observed that the addition of TMP-SH improved the tensile, thermal and swelling properties of ENR, indicating the formation of crosslinks. On the other hand, the addition of TMP-SH didn't improve the properties of NR, indicating the absence of reaction with TMP-SH. On the basis of data on the properties of the ENR films of this work it is demonstrated that these are appropriate for coating applications.     

环氧化天然橡胶共交联改性EPDM/NR共混物的性能

将三元乙丙橡胶(EPDM)与环氧化天然橡胶(ENR)共交联改性后,再与天然橡胶(NR)共混,考察了ENR共交联改性EPDM/NR共混胶的硫化特性、硫化胶的物理机械性能、溶胀指数和耐热空气老化性能,并对该硫化胶进行了差示扫描量热分析。结果表明,EPDM经过ENR共交联改性后与NR共混,ENR共交联改性EPDM/NR共混胶的交联程度明显提高,各相达到了同步交联,硫化胶的综合性能得到了显著改善。     

The Curing Behavior and Adhesion Strength of the Epoxidized Natural Rubber Modified Epoxy/Dicyandiamide System

The curing properties and adhesive strengths of the epoxidized natural rubber (ENR, 25 mole percent epoxidation) modified epoxy systems are studied with differential thermal calorimetry (DSC), scanning electron microscopy (SEM), and lap shear strength (LSS) measurement. The results of DSC analyses indicate that the curing exotherm, the curing rate, the reaction order, and the glass transition temperature of the epoxy system are affected by the presence of reactive ENR. From SEM micrographs, it is obtained that a second spherical rubber phase is formed during cure and the particle size of the rubber phase is increased by increasing the curing temperature and the ENR content. The changes of the volume fraction of the rubber phase and the T_g of the cured systems indicate that the mutual dissolution between epoxy resin and ENR happens and which changes with the curing temperature and the ENR content. The LSS of adhesive joints prepared with the ENR modified adhesives are all lower than those of the unmodified epoxy system, and decrease with increasing the amount of ENR added because of the limited compatibility of the ENR with the epoxy matrix.     

Study on the thermal degradation of epoxidized natural rubber

The thermal degradation and thermooxidative degradation of epoxidized natural rubber (ENR) were studied by thermogravimetry (TG). In the thermal degradation of ENR, the initial temperature of weight loss T₀ = 1.20B + 348, the temperature of maximum weight loss rate T_p = 1.07B + 392, and the final temperature of weight loss T_f = 0.77B + 445. The C_p, which corresponds to the degradation rate at temperature T_p, increases along with the heating rate B and its mean value is 43%, but C_f, which corresponds to the degradation rate at temperature T_f, is not affected by the heating rate, and its average value is close to 100%. As in the thermooxidative degradation, T₀ = 1.84B + 246, T_p = 0.30B + 378, and T_f = 2.27B + 584. The value of C_p increases along with the heating rate B and its mean value is 36%, but C_f is not affected by the heating rate and the average value approximately equals 100%. The thermal degradation in nitrogen could be a one-step reaction, whereas the thermooxidative degradation has a multiple-step reaction. The reactive environment has a great effect on the thermal degradation of ENR and the difference of the mechanisms of the two reaction systems is obvious. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2207–2211, 1998