对苯乙烯磺酸钠改性炭黑对天然橡胶胶乳力学性能的影响

在Haake转矩流变仪的热机械作用下,用对苯乙烯磺酸钠(NASS)对炭黑进行预处理,制备了在水介质中具有优异的分散稳定性的亲水性纳米炭黑粒子(PNASS-CB),并将其直接用于天然橡胶胶乳的补强研究.1HNMR和FT-IR结果表明NASS在炭黑表面成功聚合包覆,用热重分析方法计算其包覆率为8.1 wt%,接枝率为2.5 wt%.亲水性炭黑的表面自由能降低,同时,Payne效应和结合胶含量表明亲水性炭黑粒子与橡胶的相互作用强于亲水性炭黑粒子之间的相互作用.因此,亲水性炭黑/天然橡胶胶乳复合材料的硫化时间变短,转化速度加快,硫化胶的撕裂强度提高了85%,拉伸强度提高了30%,断裂伸长率提高了20%.     

亲水性炭黑-天然橡胶纳米复合材料的制备及性能

利用原位球磨法制备了聚苯乙烯磺酸钠表面修饰炭黑,粒径分析和离心沉降实验结果表明,改性炭黑在水中具有十分优异的分散稳定性。利用该改性炭黑通过胶乳混合法成功制备了亲水性炭黑-天然橡胶纳米复合材料。采用万能电子拉力机、扫描电子显微镜、结合橡胶含量分析和动态热机械分析等多种手段对该复合材料进行了测试和研究。结果表明,与未改性炭黑相比,改性炭黑在橡胶基体中的分散性明显改善,与基体的相互作用显著增强,材料的力学性能大幅提高,填料网络化程度明显减弱。     

稀土化合物处理高耐磨炭黑填充粉末丁腈橡胶

以经稀土化合物处理的高耐磨炭黑和丁腈胶乳为原料,以凝聚共沉法制备粉末丁腈橡胶.研究了分散剂和稀土化合物对粉末胶颗粒粒径及其硫化胶性能的影响.结果表明,粉末胶颗粒粒径随分散剂用量的增加而减小,随La3+用量的增加而增大.La3+改善了硫化胶的性能,特别是扯断伸长率和拉伸强度.进一步分析得出,硫化胶性能得以改善的根本原因是La3+改善了炭黑粒子在橡胶基体中的分散均匀性及其与橡胶基体的黏结牢固性.     

海泡石负载稀土/天然胶乳胶膜复合材料制备与表征

以La为负载活性组分,酸处理后的海泡石(SSep)为载体,采用沉淀-吸附法制备海泡石负载稀土复合(La-SSep)分散液,并与天然胶乳进行乳液共混,制备了海泡石负载稀土/天然胶乳复合胶膜。研究了海泡石负载稀土前后的微观形貌,考察了海泡石负载稀土量对复合胶膜的硫化特性和硫化胶膜的力学性能、热稳定性的影响。结果表明:当La负载量为2%时,海泡石剥离更为完全;复合胶膜的正硫化时间缩短,交联密度先增大后减小;随着稀土负载量的增加,硫化胶膜的拉伸强度、扯断伸长率、 300%定伸应力与500%定伸应力均先增大后减小。当稀土负载量为2份时,复合胶膜具有良好的热稳定性。     

改性低分子量聚异戊二烯橡胶的合成与应用

采用阴离子溶液聚合法合成了低分子量3,4-聚异戊二烯(LPI), 并对其进行改性, 制备了硅氧烷改性的低分子量3,4-聚异戊二烯(MLPI), 将其应用于白炭黑补强的溶聚丁苯橡胶(SSBR)复合材料, 探究了端基改性物LPI-丙基甲基二甲氧基硅烷(LPI-CMDS)、 LPI-丙基三甲氧基硅烷(LPI-CTMS)、 LPI-丙基三乙氧基硅烷(LPI-CTES)和接枝改性物3-巯丙基三乙氧基硅烷接枝改性LPI(LPI-g-MTS)对SSBR复合材料中白炭黑的分散以及硫化胶性能的影响. 混炼胶的应变扫描和结合胶含量分析结果表明, MLPI增强了填料与聚合物之间的相互作用, 改善了白炭黑在复合材料中的分散, 其中LPI-g-MTS因活性位点多, 效果最佳; 与填充LPI的复合材料相比, 硫化胶的物理机械性能, 尤其是填充LPI-g-MTS后硫化胶的300%定伸应力和拉伸强度分别提升了89.66%和27.15%, 这为改善白炭黑在非极性橡胶中的分散提供了一条新途径.     

炭黑填充顺丁橡胶(BR)复合材料中多重相互作用的研究

通过溶液浸泡及高速离心的方法分离了填料与聚合物间的强弱相互作用,研究了炭黑填充BR复合材料中多重相互作用与炭黑含量的关系,基于不同结合橡胶含量与储能模量的关系,提出了该多重相互作用随炭黑含量的演变模型.结果表明,存在于炭黑凝胶Ⅰ中的玻璃化转变温度和结晶熔融峰在炭黑凝胶Ⅱ中均完全消失,该现象意味着炭黑凝胶Ⅰ中测得的玻璃化转变及结晶行为只是与炭黑形成弱相互作用的那部分分子链段的贡献.在选用玻璃化转变温度考察炭黑-橡胶相互作用时应综合考虑样品特性以及测试方法.当炭黑含量不高于50 phr时,结合橡胶Ⅱ的含量随炭黑含量的增多呈线性增大,结合橡胶Ⅲ的含量则受炭黑含量的显著影响.炭黑填充橡胶复合材料中的多重相互作用可通过重叠模型进行描述,当炭黑含量分别为25~30phr,50~55 phr以及70~80 phr时,填充复合材料体系中分别存在结合橡胶Ⅲ的重叠层,结合橡胶Ⅲ和结合橡胶Ⅱ的重叠层,以及结合橡胶II的重叠层.     

离子液体对硫-超导炭黑复合材料电化学性能的影响

以热处理方法由单质硫与超导炭黑制备硫含量为59%的硫-超导炭黑复合材料.X射线衍射、扫描电镜测试表明,单质硫均匀地分散在高比表面积的超导炭黑中.如于电解液中添加室温离子液体,则可有效减弱复合材料中多硫化物在电解液的穿梭效应,提高硫复合材料的电化学性能.充放电测试表明,该硫-超导炭黑复合材料在含有离子液体的电解液中循环50周后,容量仍保持483.6mAh/g.     

TBIR改性BIIR/NR共混物的结构与性能

研究了新型合成橡胶——高反式-1,4-丁二烯-异戊二烯共聚橡胶(TBIR)对全钢轮胎气密层并用橡胶——溴化丁基橡胶(BIIR)/天然橡胶(NR)(质量比70/30)的改性作用,探讨了BIIR/NR/TBIR共混物的交联密度、填料分散性及力学性能,特别是并用硫化胶的气密性及屈挠疲劳性能等.结果表明,与无定型的BIIR和NR相比,结晶性TBIR的引入提高了炭黑填充的BIIR/NR/TBIR混炼胶的强度和模量,且随着TBIR用量的增大,混炼胶中TBIR的结晶熔融峰更明显,混炼胶的强度与模量显著提高.硫化特性结果表明,随着TBIR用量的增大,BIIR/NR/TBIR共混物的硫化速率略有提高,交联密度略有降低;TBIR用量为10~30份(生胶总质量的10%~30%)时,BIIR/NR/TBIR硫化胶在机械性能基本保持不变的情况下,耐热氧老化性能提高10%以上,耐一级屈挠疲劳性能提升2~5倍,气密性提高17%.炭黑分散结果表明,经过动态疲劳实验BIIR/NR硫化胶中炭黑聚集体的平均粒径增大至11.5μm,明显大于BIIR/NR/TBIR硫化胶中炭黑聚集体的平均粒径.对含TBIR硫化胶在周期性应力应变过程中的结构演变及对耐疲劳裂纹引发性能的影响机制进行了探讨,结果表明,TBIR可改性BIIR或者BIIR/NR制备高抗裂口引发的全钢轮胎气密层材料.     

橡胶胶乳的硫化——Ⅰ.胶乳硫化基本规律的初步探讨

本文系统地研究了胶乳种类、胶乳浓度、硫化温度、硫磺用量以及促进剂用量等五个主要因素对天然胶乳硫化过程的影响,并且阐明了在硫化过程中胶乳胶膜物理性能、结合硫量以及橡胶交联度之间的相互关系。 实验结果说明,胶乳中非橡胶成分在硫化初期不仅不促进硫化而且还阻碍硫化进程,在硫化的中期与后期它的促进效果才明显地显示出来。非橡胶成分含量愈高其硫化胶乳胶膜物理性能愈低。在一定范围内随着胶乳浓度的降低硫化速度稍有增加。随着硫化温度的升高胶乳硫化速度将相应加速,但在我们使用的硫化体系条件下温度过低与过高时其对硫化速度的影响减弱,最适宜的硫化温度是60—70℃。硫磺用量增加到一定程度后它对胶乳硫化速度即不再产生影响,在胶乳硫化过程中所能达到的结合硫量远远低于硫磺在橡胶中的溶解度。在通常用量下促进剂S.D.C.用量愈大其硫化促进效果亦愈大,在用量为0.125—0.25％之间其促进效果有一明显的转折。 硫化胶乳胶膜性能与橡胶交联度及结合硫量之间有一定的依赖关系。各种不同的影响胶乳硫化的因素都不改变这一依赖关系。在胶乳硫化过程中硫磺的交联效率是不恒定的,胶乳在硫化时主要是形成多硫键。在胶乳硫化时结合硫磺中的相当一部分并不对交联键的形成作出贡献。 胶乳硫化动力学基本     

炭黑N134在不同橡胶基体中的分散及其混炼工艺调控

以炭黑N134作为填料,对比了异戊橡胶、丁苯橡胶及仿生橡胶3种体系下混炼工艺对硫化胶性能的影响,并针对仿生橡胶体系炭黑分散度低的问题,对混炼工艺进一步优化,从而提高分散度和动静态性能.结果表明,在所研究的密炼时间范围内,随着密炼时间的延长,异戊橡胶体系和丁苯橡胶体系的分散等级由原本的1级左右提升至6级以上.但延长密炼时间并未明显提升仿生橡胶体系的炭黑分散度.针对该问题引入塑炼和包辊工艺,仿生橡胶炭黑分散性明显提高.随炭黑分散等级的增加, 3种橡胶体系的伸张疲劳性能均得到了较大改善.其中仿生橡胶生胶经塑炼后,门尼黏度和重均分子量均明显下降,表明塑炼对于增强胶料的加工性能有明显作用.相同炭黑混炼时间下,随着塑炼时间的延长,硫化胶佩恩效应也增强,这主要是由于炭黑分散程度的提高使得炭黑与橡胶基体的有效接触面积增加,进而在一定程度上增加了界面结合胶的含量.     

Preparation and mechanical properties of water-dispersible hyperbranched polymer grafted carbon black/natural rubber composites by latex blending method

In order to improve the mechanical properties of rubber-matrix composites, carboxyl-terminated hyperbranched poly (2-hydroxypropane-1,2,3-tricarboxylic acid) grafted carbon black (CB-g-CTHBP) was prepared, and it could be stably dispersed in water for up to 90 days. CB-g-CTHBP dispersion and natural rubber latex were blended to obtain NR/CB-g-CTHBP, and the effect of CB-g-CTHBP content on the mechanical properties of composites was discussed. The results show that the dispersibility and wettability of CB-g-CTHBP to composites are significantly improved after grafting hyperbranched polymer onto the surface. Compared with the composite filled with NR/CB, when the amount of filler is 30 phr, tensile strength, tear strength, and shore A hardness of NR/CB-g-CTHBP increase by 54.78%, 55.13%, and 20.96%, respectively. Moreover, CB-g-CTHBP could disperse more evenly in the natural rubber-matrix, and the interaction between CB-g-CTHBP and rubber-matrix could further enhance in the composite.     

In situ silica reinforcement of methyl methacrylate grafted natural rubber by sol–gel process

In situ silica reinforcement of natural rubber (NR) grafted with methyl methacrylate (MMA) (MMA-GNR) was achieved via the sol–gel reaction of tetraethoxysilane (TEOS) by the use of solid rubber and latex solutions. Silica contents within the MMA-GNR as high as 48 and 19 phr were obtained when using the solid rubber and latex solutions, respectively, under optimum conditions. The conversion efficiency of TEOS to silica was close to 95%. The in situ formed silica MMA-GNR/NR composite vulcanizates were prepared. MMA-GNR/NR composite vulcanizates reinforced with the in situ formed silica prepared by either method had similar mechanical properties to each other, but a shorter cure time and higher mechanical properties than those reinforced with the commercial silica at 9 phr. The TEM micrographs confirmed that the in situ formed silica particles were well dispersed within the MMA-GNR/NR composite matrix, whilst the commercial silica particles showed a significant level of agglomeration and a lower level of dispersion.     

Characterization of kaolinite/emulsion-polymerization styrene butadiene rubber (ESBR) nanocomposite prepared by latex blending method: Dynamic mechanic properties and mechanism

The latex blending method was chosen to prepare Kaolinite/emulsion-polymerization styrene butadiene rubber (ESBR) nanocomposite to improve the interaction between filler particles and rubber matrix chains. The influences of kaolinite particles size, filler contents, and flocculants types on dynamic mechanical properties and the relative reinforcement mechanism of the prepared composite were systematic investigated and proposed. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the kaolinite particles were finely dispersed into the rubber matrix and arranged in parallel orientation. The prepared nanocomposites by latex blending exhibited improved crosslinking characteristic and dynamic mechanical parameters. The KAl (SO₄)₂ flocculant presented obvious modification in dynamic properties and crosslinking characteristic. Both the decrease in kaolinite particle size and the increase in kaolinite content can greatly improve the storage modulus and reinforcing effect of kaolinite/ESBR nanocomposites. The dynamic reinforcement mechanism of kaolinite can be explained by filler network including a certain thickness of rubber shell on the surface of kaolinite lamellar structure and the aggregations network between kaolinite particles The optimum way to balance the dynamic properties of rubber nanocomposites at different temperatures is to reduce the surface difference between kaolinite and rubber matrix and the degree of filler-filler networking on the basis of kaolinite with nanoscale (nanometer effect).     

Effect of carbon-black treatment by radiation emulsion polymerization on temperature dependence of resistivity of carbon-black-filled polymer blends

High dispersibility and stability of carbon black particles in low-density-polyethylene (LDPE) matrix were obtained by radiation emulsion polymerization on carbon particles surface, and electrical resistivities of its simple were examined. First carbon particles treatment on radiation emulsion polymerization on surface were synthesized by the reaction with a polymer-emulsion systems containing reactive group in the molecular unit, carbon particles and emulsifier. Then, the carbon particles treatment on radiation emulsion polymerization on surface was dispersed into LDPE, and its composites were prepared for electrical measurements. The effect of radiation crosslinking of the composite on the Positive temperature coefficient (PTC) and negative temperature coefficient (NTC) phenomenon was investigated. The experimental results showed that PTC and NTC effects of the composites were obviously influenced by the irradiation dose. Various microstructure-exploring means were used to study the conductive composite, such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM).     

Curing and Physical Properties of Natural Rubber/Wood Flour Composites

Natural rubber based composites were prepared by incorporating Wood flour of two different particle size ranges (250–300 µm) and (300–425 µm) and concentrations (15 and 30 phr) into the matrix, using a Banbury® internal mixer according to a base formulation. Curing characteristics of the samples were studied. Influence of particle size and loading of filler on the properties of the composites was analyzed. Results obtained show that the addition of wood flour to natural rubber increased scorch time and curing time and caused improvement in modulus at 300% strain and in tear properties. However, it decreased tensile strength and elongation at break. The particle size range of 300–425 µm was found to offer the best overall balance of mechanical and dynamic properties (tan δ and viscous torque). Swelling behavior of the composites in toluene was also analyzed in order to determine the rubber volume fraction and crosslinking density. Composites with the bigger particle size wood flour were found to have greater crosslinking density than the ones with smaller particle size, fact that could possibly indicate a better rubber-filler interaction in the former. Major percentage of filler increased slightly this interaction. Water absorption behavior of the composites with wood flour reached a maximum of 12% w/w when 30 phr of filler were incorporated; nonetheless, particle size did not affect this property. The ageing study in presence of air at 70 °C revealed that natural rubber composites with wood flour maintained the same classification cell with temperature as the pure rubber. A compound with 30 phr of carbon black was prepared for comparative purposes. Results obtained were as expected. Scorch time decreased and higher values of modulus at 300% strain and tensile strength were achieved, due to strongest interaction between filler and elastomer.     

稻壳基二氧化硅/碳复合材料的表面改性及对天然橡胶的影响

以稻壳基二氧化硅/碳复合材料(SiCB)作为天然橡胶(NR)的补强填料, 采用表面化学改性的方法将天然乳胶(NRL)接枝到SiCB表面, 改善其与NR基体的相容性. 研究了不同处理方法对接枝NRL效率的影响, 以及填料填入NR后对硫化橡胶力学性能的影响. 结果表明, 经过硝酸和γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(γ-MPTMS)预处理, NRL能高效接枝在SiCB表面, 得到的样品SiCB_MR10比未处理的SiCB_P有更强的补强能力. 硫化胶NR/SiCB_MR10的拉伸强度、 300%定伸和撕裂强度较NR/SiCB_P分别提高了61.06%, 27.15%和15.90%, 与传统炭黑产品N774填充的硫化胶NR/N774的力学性能相近. 经过NRL接枝改性的SiCB_MR10具有替代商业炭黑的应用前景.     

Novel biphasic structured composite prepared by in situ silica filling in natural rubber latex

The sol‐gel reaction of tetraethoxysilane in natural rubber (NR) latex was conducted to produce in situ silica‐filled NR latex, followed by adding sulfur cross‐linking reagents to the latex in a liquid state. The latex was cast and subjected to sulfur curing to result in a unique morphology in the NR composite of a flexible film form. The contents of in situ silica filling were controlled up to 35 parts per one hundred rubber by weight. The silica was locally dispersed around rubber particles to give a filler network. This characteristic morphology brought about the composite of good dynamic mechanical properties. Synchrotron X‐ray absorption near‐edge structure spectroscopy suggested that the sulfidic linkages of the sulfur cross‐linked composites were polysulfidic, S_x (x ≥ 2), and a fraction of shorter polysulfidic linkages became larger with the increase of in situ silica. The present observations will be of use for developing a novel in situ silica‐filled NR composite prepared in NR latex via liquid‐phase soft processing. Copyright © 2011 John Wiley & Sons, Ltd.     

Evaluation of air permeability characteristics on the hybridization of carbon black with graphene nanoplatelets in bromobutyl rubber/epoxidized natural rubber composites for inner‐liner applications

Nanotechnology has been explored recently as a means of enhancing the properties of conventional elastomers for engineering applications. In the current study, the effect of nanofillers on air impermeability properties of Brominated isobutylene‐isoprene rubber (BIIR)/Epoxidized natural rubber (ENR) blend has analyzed for automotive applications. The ENR chosen is ENR 25 and ENR 50 (25 and 50% epoxidation) and prepared the blends in a ratio of 75:25 (BIIR:ENR), and from both blend based composites, a part of carbon black replaced with graphene nanoplatelets (GNP). The physical and thermal properties were compared for both binary blend nanocomposites to study the level of exfoliation and reinforcement behavior of GNP. Morphology studies were employed to reveal the level of interaction between GNP and carbon black in both blends. The influence of epoxidation in the formation of nanostructures in both blends have been evaluated, and the effect of nanostructures on air permeability properties was studied. The air impermeability of BIIR‐ENR 50 nanocomposites were improved with increasing platelet concentration, a 30% improvement in air permeability is obtained for BIIR‐ENR 50 composites over BIIR ‐ENR 25.     

Influence of the structural characteristic of pyrolysis products on thermal stability of styrene-butadiene rubber composites reinforced by different particle sized kaolinites

A series of rubber composites were prepared by blending styrene-butadiene rubber (SBR) latex and the different particle sized kaolinites. The thermal stabilities of the rubber composites were characterized using thermogravimetry, digital photography, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. Kaolinite SBR composites showed much greater thermal stability when compared with that of the pure SBR. With the increase of kaolinite particle size, the pyrolysis products became much looser; the char layer and crystalline carbon content gradually decreased in the pyrolysis residues. The pyrolysis residues of the SBR composites filled with the different particle sized kaolinites showed some remarkable changes in structural characteristics. The increase of kaolinite particle size was not beneficial to form the compact and stable crystalline carbon in the pyrolysis process, and resulted in a negative influence in improving the thermal stability of kaolinite/SBR composites.