Effects of Posttreatments on the Storage Stability of Reclaimed Rubber

Reclaimed rubber should be considered a source of new material with an economic impact, so the recycling of waste rubber is especially important. In this paper, sulfur-cured waste tire rubber powder is successfully devulcanized in a normal-pressure continuous regeneration system under the application of an activator and aromatic oil. Then, the reclaimed rubber was subjected to further mechanical shearing using a two-roll mill, rubber extruder, and rubber strainer. The effects of the storage time at room temperature on the properties and structure of reclaimed rubber were examined by sol fraction measurement, Mooney viscosity measurement, crosslink density measurement, tensile property testing, and Rubber Process Analyzer (RPA) measurement. The results under the test conditions indicated that different postprocessing operations were not making much difference to the properties of the reclaimed rubber. But the effect of storage time is more significant; the Mooney viscosity value increased from 65 to 90 when the storage period increases to 60 days, the sol fraction decreased, and the crosslink and density storage modulus also increased with increasing storage time due to the slow recombination and aggregation of the molecular fragments with free radicals happening in the reclaimed rubber during the storage.

Effects of Molecular Weight of Functionalized Liquid Butadiene Rubber as a Processing Aid on the Properties of SSBR/Silica Compounds

Liquid butadiene rubber (LqBR) which used as a processing aid play a vital role in the manufacturing of high-performance tire tread compounds. However, the studies on the effect of molecular weight, microstructure, and functionalization of LqBR on the properties of compounds are still insufficient. In this study, non-functionalized and center-functionalized liquid butadiene rubbers (N-LqBR and C-LqBR modified with ethoxysilyl group, respectively) were synthesized with low vinyl content and different molecular weights using anionic polymerization. In addition, LqBR was added to the silica-filled SSBR compounds as an alternative to treated distillate aromatic extract (TDAE) oil, and the effect of molecular weight and functionalization on the properties of the silica-filled SSBR compound was examined. C-LqBR showed a low Payne effect and Mooney viscosity because of improved silica dispersion due to the ethoxysilyl functional group. Furthermore, C-LqBR showed an increased crosslink density, improved mechanical properties, and reduced organic matter extraction compared to the N-LqBR compound. LqBR reduced the glass transition temperature (Tg) of the compound significantly, thereby improving snow traction and abrasion resistance compared to TDAE oil. Furthermore, the energy loss characteristics revealed that the hysteresis loss attributable to the free chain ends of LqBR was dominant.

Mooney Viscosity Determination Of Rubber With A Charm Filler

Research on the Determination of Viscosity Mooney From Rubber by Fillers Charcoal has been done. Each latex was added into the coconut shell charcoal ( particle size 80 mesh ) were 36 , 38 , 40 , 42, and 44 gram. Then the latex is coagulated with formic acid in pH 4.7. Formic acid is used as a control for the rubber crumple without the addition of coconut shell. Research carried out by measuring the quality of rubber Money Viscosity. From the results of research it turns out that the value of the viscosity of the money obtained by the addition of charcoal to the rubber in the latex is 72.5 ; 74 ; 75.5 ; 77 ; and 75. It can be seen that the value of the best rubber Mooney viscosity of 75 , so the rubber with medium Mooney viscosity value able to provide a meeting point between the energy efficient with superior physical properties .

Combined mechanistic and genetic programming approach to modeling pilot NBR production: influence of feed compositions on rubber Mooney viscosity

The process model comprised of a mechanistic model based on emulsion polymerization kinetics and a data-driven model derived from genetic programming is developed to correlate the feed compositions and process conditions to NBR Mooney viscosity.

Correction: Combined mechanistic and genetic programming approach to modeling pilot NBR production: influence of feed compositions on rubber Mooney viscosity

Correction for ‘Combined mechanistic and genetic programming approach to modeling pilot NBR production: influence of feed compositions on rubber Mooney viscosity’ by Ge He et al., RSC Adv., 2021, 11, 817–829, DOI: 10.1039/D0RA07257E.

Performance of Nano- and Microcalcium Carbonate in Uncrosslinked Natural Rubber Composites: New Results of Structure–Properties Relationship

Calcium carbonate (CaCO3) is one of the most important inorganic powders and is widely used as filler in order to reduce costs in the rubber industry. Nanocalcium carbonate reduces costs and acts as a semireinforcing filler that improves the mechanical properties of rubber composites. The objective of this study was to investigate the effect of nano-CaCO3 (NCC) and micro-CaCO3 (MCC) on the properties of natural rubber composites, in particular, new results of structure–properties relationship. The effects of NCC/MCC on the properties of rubber composites, such as Mooney viscosity, bound rubber, Mullins effect, and Payne effect, were investigated. The result of the Mullins effect of rubber composites filled with NCC was in good agreement with the results of Mooney viscosity and bound rubber, with higher Mooney viscosity and bound rubber leading to higher stress to pull the rubber composites. The Payne effect showed that the value of different storage moduli (ΔG’) of rubber composites filled with 25 parts per hundred rubber (phr) NCC was the lowest due to weaker filler network, while the rubber supplemented with 100 phr NCC had more significant ΔG’ values with increase in strain. The results of rubber composites filled with MCC showed the same tendency as those of rubber composites filled with NCC. However, the effect of specific surface area of NCC on the properties of rubber composites was more pronounced than those of rubber composites filled with MCC. Finite element analysis of the mechanical property of rubber composites was in good agreement with the result from the experiment. The master curves of time–temperature superposition presented lower free volume in the composites for higher loading of filler, which would require more relaxation time of rubber molecules. This type of nanocalcium carbonate material can be applied to tailor the properties and processability of rubber products.

Influence of filler system on the cure characteristics and mechanical properties of butyl reclaimed rubber

This research aimed to elucidate the effect of black and non-black filler systems on the cure characteristics and mechanical properties of butyl reclaimed rubber (BRR). In this study, BRR800 was the BRR investigated. Since reclaimed rubber is not entirely 100% rubber, actually being a mixture of rubber, carbon black, oil, zinc oxide, stearic acid and other compounding ingredients used in the original compounds, the reclaimed rubber content in each system was fixed at 161 parts per hundred (pphr). Each mixture was mixed using a two-roll mill. The fillers used in this study were carbon black and calcium carbonate. The Mooney viscosity, cure characteristics, crosslink density, and mechanical properties, such as hardness, abrasion resistance, compression set, tear strength, rebound resilience, and the tensile properties of the vulcanizates were investigated. The results showed that the Mooney viscosity of BRR800 filled with carbon black was increased effectively and had a faster curing time and higher crosslink density than BRR filled with calcium carbonate. In addition, except for compression set and elongation at break, the mechanical properties of BRR800 with a black filler system were higher than those of BRR800 with a non-black filler system.

The effect of mastication time on the physical properties and structure of natural rubber

The effect of mastication time in an internal mixer on the physical properties and microstructure of natural rubber (NR) was studied. The Mooney viscosity, plasticity, and complex viscosity reduced with increases in the mastication time due to the molecular breakdown of the rubber. The microstructural changes in the NR were studied using small-angle X-ray scattering. The results revealed that a reduction in the physical properties correlated with the structural changes, which occurred due to mastication. Increases in mastication time affected the distribution and size of the nonrubber component aggregations and the uniformity of the molecular structure of the NR.