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Carbon nanofibers (CNFs) as new materials have been the focus of materials research, while being widely used in the processing of rubber composites. To solve the problem that CNFs are easy to agglomerate, the existing methods are mainly chemical modification of CNFs (complicated processing process), blending with fillers such as carbon nanotube (expensive material and high production cost ratio). In this study, we integrated the economics and processing methods, and used pyrolysis carbon black (CBp) and CNFs for blending to prepare rubber composites to solve the filler agglomeration problem. It was found that CBp and CNFs produce a synergistic effect, and the two are isolated from each other and in contact with each other, forming a more complete filler network inside the composite. Through the synergistic effect, the filler dispersion in the rubber becomes better and the performance of the composite is greatly improved. Compared with traditional filler blending, it is more economical and can save production costs to a great extent; compared with chemical modification, the process is simple and saves production time. The recycling of rubber products can be promoted through the mass use of CBp, which has a certain environmental protection effect. This study provides new ideas for polymer composite processing, and more experiments are needed later to verify the feasibility of this method. [ABSTRACT FROM AUTHOR]

Carbon based materials with excellent conductivity such as conductive carbon black, graphene, and carbon nanotubes (CNTs) are often used in the preparation of conductive polymer composites. Pyrolysis carbon black, as a recycled material of waste rubber, can be used as a substitute for other carbon black in some fields, which can greatly reduce the production cost and promote reuse of used rubber. In this article, pyrolysis carbon black is mixed with CNT and added to natural rubber by mechanical blending method to get the composite material. The synergistic effect of pyrolysis carbon black and CNT, 3D network structure and formation of conductive network are investigated, and the properties of composites are analyzed. The results show that the 3D "grape cluster" network structure formed by the synergistic action of the pyrolysis carbon black and CNT, which led to the improvement of the curing properties and mechanical properties of the composites, increase the Payne effect, decrease the dispersion of the filler, and significant reduction the volume resistivity of the composites. With the increasing of CNT content, the variation of the properties of the composites changed and stabilized. In general, when 40 phr pyrolysis carbon black and 4 phr CNT are mixed into rubber matrix, the composite has the best comprehensive performance, and the volume resistivity is 9.25E5. Our results provide new thoughts in preparing natural rubber conductive composites. By adding highly CNT and inexpensive pyrolysis carbon black, the problem of easy aggregation of a single filler is overcome, which is more economical than adding two highly conductive fillers, and the process is simpler and time‐saving compared to the modified solution. More studies need to be done in order to reveal the effects of pyrolysis carbon black in practical conductive composites. [ABSTRACT FROM AUTHOR]

Studies show that long‐term operation of the rubber mixer results in wear at the end face of the mixer. End face wear increases the gap between the mixing chamber and the end face, which results in leakage and reduces the mixing performance, thereby affecting the quality of the final product. Therefore, it is of significant importance to investigate the wear of metal face during the mixing process. In the present study, calcium powder was added to the rubber compound using a mechanical blender to obtain a composite material. Then the influence of the calcium powder on metal friction and wear of the end face of the mixer was analyzed. The obtained results show that the calcium powder has anti‐friction properties, which can greatly reduce the compound wear on the metal. The lowest corrosion and wear of the compound on the metal was achieved with 5 phr of calcium powder. Meanwhile, it is found that the tensile and tear‐resistance properties of the compound with 5 phr of calcium powder are slightly lower than those without calcium powder. However, the compound with 5 phr of calcium powder has higher friction, cold resistance, wet slip resistance, and lower rolling resistance. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Internal mixer is an important mixing equipment. After working for a long time, the end face of the internal mixer will be worn. The abrasion of the end face can increase the gap between the mixing chamber and the end face, and then material leakage occurs, which reduces the mixing effect and affects the performance of rubber compound. Therefore, it is very necessary to study the wear of the end face in the mixing process. As one‐dimensional nanomaterial, carbon nanotubes (CNTs) have a perfect hexagonal structure and many unusual mechanical, electrical and chemical properties. In recent years, with the deepening of the research of CNTs and nanomaterial's, their broad application prospects have also been continuously revealed. This paper analyzes the influence of rubber compounds with different CNTs content on the friction and wear of the end face from the perspective of formulation, and the correlation between corrosive wear and abrasive wear is studied. In the present study, it is found that as CNTs increase, the proportion of abrasive wear increases, the proportion of corrosive wear decreases, and the amount of the metal wear decreases. With the increase of CNTs, the hindering effect of CNTs on SiO2 molecules is strengthened, the degree of silanization reaction is reduced, the output of high‐temperature water vapor is reduced, and the corrosive wear of the metal is reduced. The spatial structure of CNTs is a cylinder with hexagonal plane, and it has extremely high toughness and softness, so it has slight wear on the metal. On the one hand, CNTs hinder the movement of SiO2 molecules. On the other hand, because CNTs have the wrapping effect on SiO2 molecules, some silica aggregates have no direct contact with the metal, CNTs become the medium for silica aggregates to contact with the metal. Therefore, with the increase of CNTs, the proportion of abrasive wear gradually increases, but the total amount of the metal wear gradually decreases. [ABSTRACT FROM AUTHOR]

Internal mixer is one the most commonly used rubber‐mixing equipment, which has been applied for decades. This device can operate continuously for a long time. Accordingly, it is quite probable to have wear of the end face of the mixer. Studies show that the end face wear increases the gap between the mixing chamber and the end face, resulting in material leakage, reducing the mixing effect and ultimately affecting the properties of the compound. Therefore, it is of significant importance to study the friction and wear of the mixing compound to the metal in the mixing process. Considering the superior characteristics of graphene (GE), it is considered a revolutionary material and has been widely applied in numerous applications. In the present study, the influence of the mixing compound with different amounts of GE on the friction and wear of the metal end face was analyzed and the ratio of the corrosion wear to abrasive wear was calculated for the first time. It was found that as the amount of GE increases, the proportion of abrasive wear on the metal increases, the proportion of corrosive wear on the metal decreases, and the metal wear decreases first and then increases. Moreover, the lowest metal wear can be achieved when the amount of GE is 3 phr. [ABSTRACT FROM AUTHOR]

Prolonged operations of mixers cause wear of mixer rotors and chamber walls and affect the clearances between the rotors and chamber walls, which reduce the mixing effect, weaken the dispersion of the packing, and affect the quality of rubber products. In this study, the effects of traditional mixing and wet mixing on the friction and wear of the chamber, and the properties of rubber were compared by using 60 phr of a silica natural rubber formulation system. The results show that a silanization reaction occurs between silica and the silane coupling agent during the mixing process and that the reaction rate is fastest when the temperature of the mixing chamber is maintained between 145 and 155°C for 1 min during the mixing process. The products of silanization reaction are ethanol and water; the water vapor that forms at high temperatures corrodes the mixing chamber of the internal mixer and aggravates wear and tear. Due to the high dispersion of silica during wet mixing, the silanization reaction is more complete and water vapor is produced at a high temperature. Hence, the rubber compound obtained by wet mixing has more significant wear on the mixing chamber. [ABSTRACT FROM AUTHOR]