Effect of adding different silane coupling agents on metal friction and wear in mixing process

The function of silane coupling agent in rubber mixing field is to combine inorganic matrix with rubber organic matrix. Silica is commonly used in the rubber mixing field to strengthen rubber. The size and amount of silica aggregates in the mixing process are important factors affecting the wear of the mixing chamber. The wear of the mixing chamber would lead to a increasing gap between the mixer chamber and the rotor, which caused the mixing efficiency reducing. It also affected the dispersion effect, then affected the mechanical and physical properties of the vulcanized rubber. In this paper, the effects of rubber compound on metal friction and wear were studied by using four silane coupling agents commonly used in rubber mixing field. The experiment was carried out at 15°C, and the attention should be paid to drying during sample preparation to avoid the deviation of the experiment caused by hydrolysis of silane coupling agent. The results showed that silanization reaction occured between silica and silane coupling agent in the mixing process. The mixing temperature was usually maintained at 145 to 155°C for 1 min in the mixer, and the silanization reaction rate was the fastest during this time. We took this rubber compound as the research object and studied the friction and wear of the rubber compound on the mixing chamber in the mixing process. The products of the silylation reaction are alcohol and water. This paper studies the corrosion and abrasion of the mixing chamber by water at high temperatures. In the mixing process, abrasive wear was the main wear form, but the corrosion wear caused by high temperature steam still occupied a large proportion.     

白炭黑/NR湿法混炼共沉胶加工和动态性能研究

本文通过扫描电镜观察了白炭黑在湿法和干法混炼硫化胶中的分散,显示白炭黑在湿法混炼胶中分散性更好。研究了白炭黑的用量对白炭黑/NR湿法混炼共沉胶的加工和动态性能影响,与传统干法混炼胶作对比,结果表明,湿法混炼共沉胶中增加白炭黑用量,会延长硫化时间,粘性转矩增大,拉伸性能提高,玻璃化温度升高;湿法炼胶比干法炼胶的焦烧时间长,混炼胶加工中能耗大、自身生热小,硫化胶有较好的物理机械性能和动态性能。     

生胶摩擦性能对密炼机工作的影响

由微观和唯象分析建立了橡胶粘附摩擦的理论模型。通过对模型的分析和试验验证,提出了提高密炼机混炼效果的新途径;（１）密炼机温度控制采用温水冷却,使密炼机处于最佳工作状态;（２）通过合理选择密炼室和转子表面材料以改变材料表面能来增大胶料与它们之间的摩擦力;（３）在压砣压力较大的条件下,在密炼室内壁沿与转子轴线同方向加工浅的光滑槽,可明显改善混炼效果。     

串联密炼机组的研发和应用概况

介绍串联密炼机组的研发和应用概况。串联密炼机组由带压砣的上位机与不带压砣的大容量下位机组成,上位机采用低温转子,下位机采用啮合型转子。串联密炼机组可以实现从原材料投入到终炼胶产出连续一步完成,尤其适用于白炭黑用量大的胶料混炼,可提高混炼质量和生产效率,降低混炼能耗。大连橡胶塑料机械股份有限公司串联密炼机组的结构设计重点:密炼室和转子、传动系统、液压式压砣、冷却系统和过渡翻板门等;系统控制要点:密炼室温度和冷却效果、转子无级调速和压砣位置无级调整等。     

Effects of silanization temperature and silica type on properties of silica‐filled solution styrene butadiene rubber (SSBR) for passenger car tire tread compounds

Influence of silanization temperature on properties of silica‐filled solution polymerized styrene butadiene rubber was investigated. Two types of silica, i.e., highly dispersible silica (HDSi) and conventional silica (CSi), were compared. Results show that the increased silanization temperature leads to the enhanced rubber–filler interaction, filler dispersion, and cross‐link density giving rise to the improvement in vulcanizate properties such as modulus, heat build‐up (HBU), and dynamic set, as well as tire performance, e.g., wet grip (WG), rolling resistance (RR), and abrasion resistance. Great care, however, must be taken to avoid the scorching phenomenon during the mixing process at too high temperature. Taken as a whole, the balanced properties are found at the silanization temperature of 140°C. Surprisingly, HDSi provides insignificant differences in degree of filler dispersion, WG, and RR, compared to CSi, despite its claimed greater dispersability. Probably, the relatively long mixing time used in this experiment may override the influence of silica type. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43342.     

Internal mixing: A practical investigation of the influence of intermeshing rotor configuration and operating variables on mixing characteristics and flow dynamics

This paper deals with the measurement and interpretation of pressures and temperatures produced by the mixing of a rubber compound in the chamber of an internal mixer equipped with interlocking rotors. Pressure transducers and infrared/fiber optic temperature sensors were sited flush with the inner surface of the mixing chamber of a Francis Shaw KO Intermix of 2 L chamber volume. The variation of pressure with transducer position In the chamber wall and with rotor position was measured for selected fill factors and rotor speeds at “equilibrium” conditions (quasi-static power requirement for the mixer) and at intervals during a complete mixing cycle. Two rotor designs were studied. Interpretation of the results was carried out with reference to biconical rotor rheometer measurements on the mixed rubber compounds and by reference to four regimes of viscoelastic behavior identified for two-roll mill mixing. A basic flow analysis was carried out by use of the lubrication approximation in conjunction with an isothermal power-law model.     

The effect of surface functionalization of carbon nanotubes on properties of natural rubber/carbon nanotube composites

The objective of this study was to prepare natural rubber composites filled with carbon nanotubes (CNTs) that show an electrical percolation threshold at very low CNT concentrations. Therefore, two methods of surface functionalization of CNTs were investigated to enable an improved dispersion of CNTs and chemical interaction between CNTs and rubber matrix. On one hand, the CNTs have been functionalized ex situ by acid treatment and silanization reaction with bis(triethoxysilylpropyl) tetrasulfide before mixing with the rubber and otherwise in situ functionalization was directly carried out during the processing of the composites in the internal mixer. The grafting of silane molecules onto CNT surface was established by Fourier transform infrared spectroscopy and scanning electron microscopy. Tensile tests revealed the outstanding properties of composites prepared by in situ silanization method. The in situ silanization led to a better dispersion of the CNTs and the formation of chemical linkages between CNT surface and rubber and this became manifest in higher reinforcement of the rubber, higher crosslink densities, and a lower electrical percolation threshold. It was also shown that the in situ silanization is retarding the vulcanization reaction. POLYM. COMPOS., 36:2113–2122, 2015. © 2014 Society of Plastics Engineer     

两种混合模式下PS-MAMA微量组分在聚合物熔体中的分散

通过苯乙烯(St) 和3-异丙烯基-α,α-二甲基苄基异氰酸酯(TMI) 共聚制备了共聚物P(St-co-TMI),然后与9-(N-甲氨基甲基)蒽(MAMA)反应合成了具有示踪特性的聚苯乙烯大分子示踪剂(PS-MAMA)。采用PS-MAMA作为微量组分,在自制的间歇混合器中考察了两种混合模式下其在聚苯乙烯(PS)和聚甲基丙烯酸甲酯(PMMA)中的分散行为。结果表明:对于左右两个转子同时异向转动的匀速混合模式,虽然可以在较短时间内使微量组分在转子壁面和混合腔体内壁之间形成稳定的层状分布,但是随着混合时间的延长,层与层之间的混合较慢;而对于交替异向转动的方波混合模式,尽管在混合初期,层内和层间的浓度分布都不均匀,但是流场的交替变化加快了微量组分PS-MAMA 在聚合物熔体中的分散。因此,方波混合模式的混合效果要优于匀速混合模式的。     

橡胶混炼质量的影响因素及改进方法

从混炼工艺和混炼设备两个方面分析橡胶混炼质量的影响因素及改进方法。改善混炼工艺如采用高速或变速混炼工艺、低温一次法混炼工艺等可以提高混炼胶性能的稳定性和生产效率;调整湿法混炼喷射压力,在白炭黑胶料混炼过程中加入干冰,外加适当功率及时间的超声波作用辅助混炼可以提高配合剂的分散性和混炼胶的综合性能;对混炼设备内表面进行良好的涂层点焊,可以延长混炼设备的使用寿命,提高生产效率。这些方法对于提高混炼胶性能及生产效率,降低能耗和污染等具有突出的作用。     

Engineering performance and material viscoelastic analyses along a compounding line for silica‐based compounds. I. Mixing line performance analysis

In the tire industry, the preparation of silica‐filled compounds requires relatively complicated compounding operations, which involve several dumping, cooling, and remixing steps, to eventually obtain quality final batches. The various and complex sets of events that take place along the mixing line remain, however, poorly understood. The objectives of this study, reported in two companion articles, were to deepen the understanding of silica–silane compounding operations. Two approaches were used in parallel: first, we performed a deep analysis of the engineering performance of an existing—and successful—mixing line by paying attention to the various curves that are nowadays recorded during internal mixing, and second, we studied the variations of the nonlinear viscoelastic properties along the mixing line using so‐called Fourier transform rheometry, implemented on a commercial torsional dynamic rheometer. The first article of the series is devoted to the performance analysis of the mixing line through mixing trials along an industrial line. Silica dispersion and the treatment with silane were initiated during a master‐batching process; then, two remixing steps were performed to achieve the right silanization degree. Curatives were added during a final mixing step. Mixing signatures, containing information such as mixing power, ram position, compound temperature, and rotor speed, gave some insight to the dispersion–silanization processes and, among other results, showed that the dumping, cooling, and remixing of the compound comprised a more efficient process than the maintenance of a very high batch temperature for an extended time, essentially because one could make use of stress‐induced dispersing effects. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

同步同向转子密炼机性能的研究

首次提出同步同向转子密炼机的混炼原理,并通过在Ｘ（ Ｓ） Ｍ－ １ ．７ 同步同向转子密炼机上的实验来研究和分析同步同向转子对混炼过程的影响。     

啮合式转子密炼机中转子的模拟和设计

对聚合物在啮合式转子密炼机中的流动进行了模拟分析,并分析了4种不同类型啮合式转子的混炼作用,还将模拟分析结果与分离式转子密炼机的实验结果进行了比较,结果表明,啮合式转子密炼机的填充因数比分离式转子密炼机大。     

Effects of mixing conditions on the reaction of 3‐octanoylthio‐1‐propyltriethoxysilane during mixing with silica filler and natural rubber

The effects of mixing temperature and mixing time on the reaction of 3‐octanoylthio‐1‐propyltriethoxysilane (NXT silane) during mixing with precipitated silica and natural rubber (NR) were investigated. Results showed that the reaction between NXT silane and precipitated silica can proceed at temperatures above 130°C. Because of the blocking group of NXT silane, the silane–NR coupling reactivity is low, so that the reaction of NXT silane with NR occurs only during the curing period. There is no reaction between NXT silane and NR during mixing, which showed that the mixing time of silica‐filled NR compound containing NXT silane must be longer than 10 min at 150°C to obtain the desired silane coupling efficiency. With increasing mill temperature, the coupling efficiency increases. A high mixing temperature promotes improvement of silane–silica coupling efficiency, although the tensile strength, 100% modulus, 300% modulus, and hardness of NR vulcanizates decrease. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2295–2301, 2004     

Graphene/carbon black/natural rubber composites prepared by a wet compounding and latex mixing process

The extensively used latex mixing approach to prepare graphene can improve the graphene dispersion but meets some challenges in the preparation of high content carbon black filled rubber system like a rubber tire. Owing to the high melt viscosity of the rubber/graphene masterbatch, the dispersion of carbon black is not perfect during twin-roll mixing and some aggregates will be formed. Here we proposed a wet compounding process, combined with ultrasonically assisted latex mixing, named as the WCL method to prepare reduced graphene oxide/carbon black/natural rubber (rGO/CB/NR) composites. The morphological observations confirmed that both graphene and carbon black can be evenly dispersed in the rubber composites. The incorporation of rGO also improves the hardness, thermal conductivity and anti-aging properties of the composites. The rGO/CB/NR composites prepared by the WCL method possess better mechanical properties compared to conventional latex mixing. The entanglement-bound rubber tube model was utilised to understand the reinforcing mechanism.     

采用新型变间隙转子混炼短纤维/橡胶复合材料

分析短纤维/橡胶复合材料的混炼机理,针对短纤维胶料混炼特点设计新型变间隙六棱同步转子。转子棱峰与密炼室内壁间隙影响短纤维在胶料中的混合和分散以及混炼胶中短纤维的长度。新型六棱同步转子采用变间隙设计,大间隙有助于短纤维的混合,小间隙有助于短纤维的分散。采用新型六棱同步转子可改善短纤维/橡胶复合材料的混炼质量和性能,并能够提高生产效率。     

白炭黑补强胶料的开炼机混炼工艺研究（Ⅱ）——溶聚丁苯橡胶

试验设计一种白炭黑补强溶聚丁苯橡胶的开炼机混炼工艺。相对于传统三段混炼工艺中的二段在高温开炼机上进行,将一段胶的热处理（硅烷化反应）放在老化箱中进行,重点考察热处理时间对胶料性能的影响。结果表明,该混炼工艺安全易行,二段热处理温度和时间控制精准,避免了高温混炼对胶料的剪切破坏,所得胶料的性能与密炼机混炼效果相当。     

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.     

白炭黑补强胶料的开炼机混炼工艺研究（Ⅰ）——天然橡胶

试验设计一种白炭黑补强天然橡胶的开炼机混炼工艺.相对于传统三段混炼工艺中的二段在高温开炼机上进行,将一段胶的热处理（硅烷化反应）放在老化箱中进行,重点考察热处理时间对胶料性能的影响.结果表明,该混炼工艺安全易行,二段热处理温度和时间控制精准,避免了高温混炼对胶料的剪切破坏,所得胶料的性能与密炼机混炼效果相当.     

密炼机的混炼时间对天然橡胶结构与性能的影响

研究了密炼机的混炼时间对天然橡胶结构与性能的影响。结果表明,随混炼时间延长,排胶温度升高且有加快的趋势,混炼胶的门尼黏度先变大后减小。混炼时间适度延长有利于炭黑的分散,但达到一定程度后影响变小。选择合适的混炼时间既能有利于炭黑的分散,又能保证较高的平均分子量,此时硫化胶综合物理机械性能最好。     

Silica-filled NR compounds prepared by dry and wet masterbatches with different mixing times

Silica-filled NR compounds are prepared by mixing rubber with organic-networked silica and additives such as curatives, processing and coupling agents, and stabilizer in a dried state (dry-mixed NR, DNR) and mixing a silica-NR wet masterbatch prepared in liquid phase with the additives (wet-mixed NR, WNR). The effects of mixing method and time of DNR and WNR compounds on their cure, process, tensile, and dynamic properties are investigated. The mixing of DNR crushes silica aggregates to smaller ones, but also forms occasionally large ones, while the mixing of WNR produces small aggregates without forming larger ones because silica aggregates are already covered with rubber. The high silica dispersion, suppressed silica aggregation, low Payne effect, and low-loss modulus of the WNR compounds prepared by mixing for a sufficient time result in their low viscosity, high scorch safety, and low rolling resistance without sacrificing other rubber properties.