Preparation of zinc‐oxide‐free natural rubber nanocomposites using nanostructured magnesium oxide as cure activator

The effect of sol–gel synthesized magnesium oxide (MgO) nanoparticles as cure activator is studied for the first time in the vulcanization of natural rubber (NR) and compared with conventional zinc oxide (ZnO) in terms of cure, mechanical, and thermal properties. The NR vulcanizate with 1 phr (Parts per hundred parts of rubber) nano MgO shows an excellent improvement in the curing characteristics and the value of cure rate index is about 400% greater for NR vulcanizate containing 1 phr nano MgO in comparison to the NR vulcanizate with 5 phr conventional ZnO. Both mechanical and thermal properties of NR vulcanizate are found to be satisfactory in the presence of 1 phr nano MgO as cure activator in comparison to conventional NR vulcanizate. This study shows that only 1 phr nano MgO can successfully replace 5 phr conventional ZnO with better resulting properties in the sulfur vulcanization of NR. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42705.     

Preparation and Use of Nano Zinc Oxide in Neoprene Rubber

Zinc oxide (ZnO) of nanometer particle size was prepared by solid-state pyrolytic method. TEM, XRD, and surface area studies showed that the prepared zinc oxide had particle size in the range of 15–30 nm and surface area in the range of 12–30 m²/g. This nano zinc oxide was used as a curing agent in neoprene rubber. The optimum dosage of ZnO was found to be low compared to commercial ZnO. The cure characteristic and mechanical properties were compared with those containing conventional ZnO. It was found that a low dosage of zinc oxide was enough to give equivalent curing and mechanical properties compared to one containing a higher dosage (5 phr) of commercial zinc oxide in neoprene rubber.     

低溴化天然橡胶的研究

对自制的低溴化天然橡胶(BNR)的溴含量、红外谱图、在甲苯中溶解性能、不饱和度及综合力学性能进行研究分析。结果表明:随着反应过程中溴化液用量的增加,制得的低溴BNR的溴含量也增大,且溴含量不与溴化液用量成线性正比关系;溴化天然胶乳的红外光谱分析表明,溴已经接到天然橡胶分子链上,其C-Br键对应的红外光谱位置分别为956 cm-19、08 cm-1;在常温下,低溴BNR在甲苯中溶解性较差,在水浴加热70℃情况下,对低溴BNR在甲苯中的溶解性略有改善,同时随溴含量的增加,溶解性也越差。经塑炼后的低溴BNR在水浴加热70℃的情况下,对低溴BNR能完全溶于甲苯溶剂中;制得的低溴BNR的不饱和度略有降低,不饱和度随溴化液用量的增加变化不大;低溴BNR的加工性能总体较好,经溴化后的天然橡胶较纯胶的综合力学性能都有所下降,其中当硫磺用量为2.7份时,综合力学性能相对较好。     

A study of curative interactions in cis-1,4-polyisoprene. X. The cis-1,4-polyisoprene/sulfur/zinc dimethyldithiocarbamate and cis-1,4-polyisoprene/sulfur/zinc dimethyldithiocarbamate/ZnO systems

Aspects of the mechanism of zinc dimethyldithiocarbamate (ZDMC)-accelerated sulfur vulcanization were discussed. The trends in the efficiency parameter E, confirmed that crosslinking is preceded by the formation of pendent groups RS_xSX [R = polyisoprenyl, X = Me₂NC(S)] in ZDMC-based systems. The index x in RS_xX was calculated as 5.82 in the cis-1,4-polyisoprene (IR)/sulfur/ZDMC/ZnO compound at the initial stages of curing, compared to 3.23 in the absence of ZnO. The high value of x supports the postulation that elemental sulfur and ZDMC react at the early stages of vulcanization, to form the active sulphurating agent XS_xSZnSSX. Crosslinks form by either a disproportionation reaction between two α-methylic or α-methylenic pendent groups RS_xX, or a reaction between a pendent group RS_xX and the rubber chain—these routes are the same as that suggested for the IR/tetramethylthiuram disulfide (TMTD)/ZnO compound. The beneficial role of ZnO and zinc stearate is shown, as in the case of ZnO in the IR/TMTD/ZnO system, to be related to their ability to trap dimethyldithiocarbamic acid, which formed in the generation of pendent groups and crosslinks. ZnS is inactive in this regard. The formation of ZnS is characteristic of natural rubber/sulfur/ZDMC/ZnO systems, as opposed to IR/TMTD/ZnO mixtures where little ZnS forms.     

双金属稀土促进剂对丁苯橡胶/天然橡胶胎面胶的影响

通过配位反应制备得到双金属硫化促进剂二乙基二硫代氨基甲酸锌镧配合物(ZnLaDC),在不添加传统活化体系氧化锌(ZnO)/硬脂酸(SA)的情况下,考察了ZnLaDC用量对丁苯橡胶(SBR)/天然橡胶(NR)胎面胶复合材料硫化特性及物理机械性能的影响,并与传统硫化体系二乙基二硫代氨基甲酸锌(ZnDC)/ZnO/SA制备的硫化胶性能进行了对比。结果表明,随着ZnLaDC用量的增加,SBR/NR胎面胶复合材料的硫化特性、压缩疲劳生热性能及耐磨性得到有效提高,当ZnLaDC用量为5份时,复合材料的综合性能最佳。与传统硫化体系ZnDC/ZnO/SA制备的硫化胶相比,采用ZnLaDC制备的硫化胶具有更优异的静态力学性能及耐切割性。     

Effect of nano zinc oxide on the cure characteristics and mechanical properties of the silica‐filled natural rubber/butadiene rubber compounds

With the increasing interest in environmental and health issues, legal restrictions, such as European Union (EU) End of Life Vehicle Directives, were strengthened. This led us to incorporate nano zinc oxide (nano‐ZnO), with particle sizes of 30–40 nm and specific surface areas of 25.0–50.0 m²/g, instead of conventional ZnO into natural rubber (NR)/butadiene rubber (BR) compounds to decrease the content of zinc in the formulation. In the unfilled system, only a 20 wt % nano‐ZnO content, compared to conventional zinc oxide content, showed the cure characteristics and mechanical properties of the same level. This was because the increase in the specific surface area of the nano‐ZnO led to an increase in the degree of crosslinking. The effect of nano‐ZnO on the cure characteristics and mechanical properties was more pronounced in the silica‐filled system than in the unfilled system. This was mainly because of the dispersing agent used in the silica‐filled system, which also improved the dispersion of nano‐ZnO. The silica‐filled NR/BR compounds containing 0.3–3.0 phr of nano‐ZnO showed improved curing characteristics and mechanical properties, such as optimum cure time, 100 and 300% modulus, tensile strength, and tear strength compared to the compound with 5 phr of conventional ZnO. The optimum amounts of nano‐ZnO and stearic acid were only 1.0 and 0.1 phr, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

原位生成甲基丙烯酸锌对AEM补强的研究

研究了过氧化物硫化体系下的氧化锌(ZnO)、甲基丙烯酸(MAA)原位生成的甲基丙烯酸锌(ZDMA)对乙烯-丙烯酸酯橡胶(AEM)的补强作用。结果表明,原位生成的甲基丙烯酸锌对AEM具有较明显的补强作用。随甲基丙烯酸锌生成量的增加,体系的硫化速率加快,交联密度提高。当甲基丙烯酸锌的生成量为40份、ZnO/MAA摩尔比为0.75时,硫化胶具有较好的综合力学性能。     

Nano ZnO as cure activator and reinforcing filler in natural rubber

Zinc oxide (ZnO) nanoparticles of size 20–90 nm and surface area 9.56 m²/g were synthesized from ZnCl₂ and Chitosan and characterized by X‐ray diffraction, high resolution transmission electron microscopy (HRTEM), and scanning electron microscopy (SEM). Natural rubber (NR) vulcanizates containing nano ZnO was prepared by mill mixing and characterized by SEM, energy dispersive X‐ray analysis (EDAX), and HRTEM. Cure characteristics, free volume studies, bound rubber, crosslink density, and dynamic mechanical properties were evaluated and compared with that of NR vulcanizate containing conventional micro ZnO. Considering the cure characteristics, it was found that NR vulcanizate with 0.5 phr (parts per 100 g rubber) of nano ZnO showed low values of optimum cure time (t₉₀) and very high cure rate index compared with 5 phr of conventional micro ZnO. The study shows that micro ZnO can be successfully replaced with nano ZnO for accelerated sulfur vulcanization process in NR, and preparation of vulcanizate containing nano ZnO with better properties as that of micro ZnO. The optimum dosage of nano ZnO as a cure activator in NR vulcanization was found to be 0.5 phr compared with conventional grade micro ZnO. This will lead to substantial cost reduction in the manufacture of rubber products and alleviate environmental pollution due to excess ZnO in rubber compounds. POLYM. ENG. SCI., 2013 © 2013 Society of Plastics Engineers     

导电丁腈橡胶制备的研究

通过力学试验和电学试验确定了性能最佳的导电丁腈橡胶（NBR）配方,即：丁腈橡胶100份,氧化锌5份,硬脂酸1份,防老剂4010 1.5份,硫化剂DCP2份,硫磺0.3份,促进剂DM 1.5份,炭黑2004份。     

四针状氧化锌晶须改性硅橡胶的性能

制备了四针状氧化锌晶须（ZnOw）/硅橡胶复合材料;详尽地研究了晶须改性硅橡胶复合材料的力学性能、热稳定性及阻尼性能;通过扫描电镜观察了材料的断面以及晶须在基体中的分散性。结果表明：随氧化锌晶须填充量的增加,硅橡胶的力学性能降低,热稳定性和阻尼性能有明显的提高。当填充量为20份时,与纯硅橡胶相比,复合材料的热分解温度提高了近10 ℃,最大损耗因子提高了21%,有效阻尼温域向高温偏移了约15 ℃。     

巯基聚醚聚氨酯橡胶的制备及温敏性谱学研究

以过量甲苯二异氰酸酯和聚乙二醇为主要原料制备预聚物;以三乙烯二胺为催化剂,聚乙二醇二丙烯酸酯为交联剂,预聚物和巯基乙醇反应制备巯基聚醚聚氨酯橡胶。考察了催化剂用量和交联剂用量对产物性能的影响,采用变温红外光谱和拉曼光谱对其温敏性进行了研究。结果表明:催化剂用量0. 8%,交联剂用量1. 0%,产物性能最佳;200℃以下样品的红外吸收峰受温度变化影响不大;200℃时,样品在2 273 cm-1处出现-N==C==O特征吸收峰,同时2 583 cm-1处的―SH特征伸缩振动吸收峰消失。     

Understanding the role of ZnO as activator in SBR vulcanizates: Performance evaluation with active,nano, and functionalized ZnO

This study investigates (ZnO)s with different surface features as vulcanization activators in unfilled SBR vulcanizates. ZnO is termed the best activator due to its fast reaction kinetics. A high release of ZnO into the environment harms marine ecosystems, and most ZnO production goes to the rubber sector; therefore, reducing ZnO amount is essential. Active, nano and functionalized ZnO compared to conventional ZnO in SBR matrix; concentration optimized based on curing, mechanical, physical, and dispersion analyses. The Arrhenius equation approximated the cure curve's kinetic constant and activation energy. Crosslink density measured by swelling experiment and solvent freezing point depression. Nano ZnO was used from 0.5 to 2phr, active ZnO from 1 to 4phr, and functionalized ZnO from 1 to 3phr compared to 5phr of conventional ZnO. The tensile strength of N1.5, F1.5, and A2 SBR increased by 5%, 26%, and 18% compared to C5SBR, whose elongation at break improved by 30%, 7%, and 23%. The data were analyzed using tukey HSD post hoc test. Regarding mechanical properties and curing characteristics, 2phr active, functionalized, and 1.5phr nano ZnO is analogous to 5phr conventional ZnO in an unfilled SBR matrix. The quantity of ZnO in rubber vulcanizates decreased successively by 60%, 60%, and 70%.     

Effect of silica filler on aluminum-aluminum bonding by a self-vulcanizable blend based on chlorobutyl rubber and carboxylated nitrile rubber

Silica filler improves the aluminum-aluminum bonding by a self-vulcanizable rubber blend based on chlorobutyl rubber and carboxylated nitrile rubber. The joint peel strength depends on the filler loading, the state of cure, the molding temperature, and the adhesive film thickness. The higher peel strength in the filled adhesive system is due to filler reinforcement resulting in tear path deviation and the formation of Si—O—Al linkage at the aluminum-adhesive interface. Maximum peel strength was obtained at 10 phr filler loading, when the molding temperature was 180°C and the molding pressure was 0.35 MPa.     

硫化体系对氯化丁基橡胶/尼龙12动态硫化胶性能的影响

研究了氧化锌、N,N’-间苯撑双马来酰亚胺(HVA-2)/氧化锌和1,3-双柠糠酰亚胺甲基苯(PK 900)/氧化锌3种硫化体系下氯化丁基橡胶(CIIR)/尼龙(PA)12混炼胶的硫化特性及CIIR/PA 12动态硫化胶(TPV)的物理机械性能和微观相结构,并考察了PK 900与氧化锌不同配比对CIIR/PA 12TPV物理机械性能、流变性能及微观相结构的影响。结果表明,PK 900/氧化锌的硫化速率介于氧化锌和HVA-2/氧化锌两者之间,由其制备的TPV橡胶相粒径为1～2μm,均匀分布在树脂相中,物理机械性能最优;固定PK 900用量为3份时,随着氧化锌用量的减少,CIIR/PA 12 TPV的拉伸强度、扯断伸长率和100%定伸应力均呈现先增大后减小的趋势;当PK 900/氧化锌(质量比)为3/5时,CIIR/PA 12TPV的物理机械性能最佳,且呈现低剪切速率高黏度、高剪切速率低黏度的特性。     

Effects of zinc borate loading on thermal stability,flammability, crystallization properties of magnesium oxide/(90/10) mLLDPE/(NR/ENR-50) blends

Effects of different zinc borate (ZB) loadings on thermal, flammability and crystallinity properties of blends of 10 % rubber (9/1) natural rubber (NR)/epoxidised natural rubber (ENR)/metallocene linear low density polyethylene/N,N-m-phenylenebismaleimide/MgO were investigated. Fourier transform infrared spectroscopy revealed that –C=O and –OH groups appeared while C–O–C and C=C groups disappeared in all blend samples. ZB increased the activation of HVA-2 by changing the reaction mechanism and increasing the concentration of the –C=O groups in the blends due to the peak at 1,714–1,718 cm^?1. The crystallinity of all blends was increased by ZB loading increase; therefore, it played the heterogeneous nucleation center and maximum crystallinity was observed at 6 phr ZB blend. The thermal stability of NR improved with increase of zinc borate loading and the highest thermal stability was determined for 8 phr ZB blend. Good compatibilization between the two rubbers (NR/ENR-50) was achieved in the presence of ZB, which was revealed by the presence of only one peak for their decomposition. The limiting oxygen index value of mLLDPE was decreased by two rubbers loading increase, while it was increased by ZB loading increase to provide fire barriers to protect flammable materials from thermal damage. It was concluded that ZB has a synergistic effect on the LOI values of flame retardant mLLDPE/rubber containing MgO.     

A new route of cross-linking of carboxylated acrylonitrile-butadiene rubber via zinc oxide-amino acid network formation

Herein, we present a strategy that leads to the formation of a high-performance elastomeric material based on the carboxylated acrylonitrile-butadiene rubber (XNBR). A unique cross-linking route for XNBR has been designed, which does not involve typical cross-linking agents such as sulfur. In this study, the show cause-effect of zwitterionic compounds as the secondary cross-linking agent for ionic elastomer has been investigated. Naturally occurring lysine (Ly) and tryptophan (Trp) amino acid are the zwitterionic compounds, which have been explored here. This approach results in the formation of a cross-linked ionic elastomer that houses a dual ionic network structure formed by zinc oxide (ZnO) and amino acid. XNBR cross-linked by ZnO and different amino acid compounds exhibit superior physical properties as compared to the conventional cross-linking system. Fourier transform infrared spectroscopy, transmission electron microscope, and swelling study analyzes confirm the existence of zinc-carboxylate and zwitterionic network in XNBR after the cross-linking process. The dynamic mechanical analysis, differential scanning calorimetry, and oscillating disk rheometer analyzes show various thermal relaxations and transitions present in the dual cross-linked XNBR. The ZnO and amino acid cross-linked XNBR rubber with 2.5 phr of Ly and 5 phr of Trp show the highest tensile strength of 42.4 and 39.7 MPa, respectively, which is mostly higher than the previously reported values for ionic cross-linked elastomers.     

各向同性与各向异性天然橡胶磁流变弹性体的导热性能及磁流变性能（英文）

采用羰基铁粉粒子填充天然橡胶磁流变弹性体(MRE),研究了各向同性与各向异性MRE的磁流变性能及导热性能。结果表明,各向异性MRE的热扩散系数和导热系数比各向同性MRE分别提高了30. 1%和41. 9%。同时,随着应变的增大,MRE的相对磁流变效应呈下降趋势,而在相同应变下,各向异性MRE的储能模量以及相对磁流变效应均高于各向同性MRE。     

注射交联发泡成型超轻材料的研究

通过共混乙烯一乙酸乙烯酯共聚物(EVA)与马来酸酐接枝乙烯一丙烯酸酯的共聚物(Fusabond)，得到注射超轻发泡材料；考察了过氧化二异丙苯(DCP)、发泡剂(ACH)、氧化锌(ZnO)、硬脂酸(St)、硬脂酸锌(ZnSt)和填充剂(TA)对材料力学性能的影响。结果表明，当EVA用量为92份、Fusabond 8份、DCP 0．75份、ACH2．50份、St 0．40份、ZnSt 0．50份、ZnO 1．80份，且硫化温度为448K、交联发泡时间为320s时，材料的力学性能符合Adidas的标准，可用于生产Adidas运动鞋的中底。’     

苯并噁嗪树脂/丁腈橡胶复合材料双网络结构及其耐烧蚀和绝热性能

考察了苯并噁嗪树脂（PBR）对丁腈橡胶（NBR）耐烧蚀和绝热性能的影响。结果表明,随着PBR用量的增加,PBR/NBR复合材料的线性烧蚀率和热导率下降,这主要是由于燃烧表面的炭化物和基质之间的强烈相互作用及PBR在整个NBR基体中形成的树脂网络结构阻止了外部热流的侵入,此外PBR还能生成不可燃气体阻止了基质的进一步燃烧。当PBR用量为60份（质量）时,PBR/NBR复合材料的线性烧蚀率和热导率分别达到0.023 mm/s和0.169 W/（m·K）。     

硫化体系对再生胶性能影响的实验研究

考察了硫化体系中硫磺、促进剂M,促进剂TMTD,活性剂硬脂酸用量对再生胶制品拉伸强度以及断裂伸长率的影响.结果表明:适当提高硫化温度能减少硫磺的用量;在硫化温度为140℃,硫化时间为5min的条件下,当硫磺,促进剂M,促进剂TMTD和硬脂酸用量分别为1.5份,0.5份,0.5份,1.5份以及再生胶为100份时,再生胶硫...