Journal of Rubber Research最新文献

Filler hybridisation in elastomers has become a subject of both scientific and industrial interest. Consequently, the use of nanofillers has attracted researchers looking to enhance the performance of elastomers. Therefore, carboxyl graphene (CG) and silicon dioxide (SiO₂) nanofillers have been hybridised for the combined effect study of composite NBR (acrylonitrile butadiene rubber) elastomers in various accelerated environmental ageing conditions (high temperature, low temperature, and QUV). The inorganic filler (SiO₂) had enhanced dispersion upon hybridising with CG on the surface of a composite NBR elastomer. To evaluate the mechanical and dynamic mechanical properties, unfilled and filled (CG/SiO₂) composite NBR elastomer samples were prepared by mixing and rolling methods. Furthermore, the prepared samples were kept in various ageing chambers. The results of mechanical testing exhibited that tensile strength improvement was greater for filled elastomers than unfilled elastomers after ageing. Moreover, the filled elastomers were also able to retain the reduction in elongation at break after ageing. However, after ageing, the hardness of composite NBR elastomers increased marginally with the addition of CG/SiO₂. Moreover, the loss factor (tan δ) of a composite NBR elastomer (CG/SiO₂: 15/7.5), compared to that of the unfilled NBR elastomer before and after ageing, decreased but was still much higher than that of the aged unfilled NBR elastomer. The reason behind that was that CG/SiO₂ dispersion in the composite NBR elastomer matrix acted as a barrier against ageing. CG/SiO₂ hybridising is an effective way to develop high-performance composite NBR elastomers with good potential in industrial applications.

Graphical abstract

The slip casting of ceramics uses synthetically prepared water-soluble polymers and polymer emulsions as binder to achieve adequate yield stress of the consolidated body and high green strength. Substitution of synthetically prepared binders with a naturally renewable one is highly recommended for environmental friendliness and sustainability. Herein, slip casting of aqueous alumina slurries using natural rubber latex (NRL) binder is studied for the first time. Slurries of high alumina loading (40–55 vol%) at rubber concentrations in the range of 2–8 wt% obtained by mixing a concentrated aqueous alumina powder dispersion and a concentrated NRL exhibit viscosity and yield stress suitable for slip casting. The thickness of the body produced in 1 h from the slurries containing the NRL binder by slip casting in a plaster of Paris mold is three times higher than that produced from a slurry prepared using 2 wt% polyvinyl alcohol (PVA) binder. The slip-cast green bodies after annealing at 200 °C show high strength (3–9.68 MPa) due to cross-linking of rubber. Sintered ceramics prepared from the slip-cast bodies exhibit ~ 97% theoretical density (T.D) with an average grain size of 1.8 μm. NRL binder-based slip casting is capable of producing sintered alumina crucibles of wall thickness as low as 1.2 mm. NRL can be an eco-friendly and sustainable candidate binder for the slip casting of ceramic materials.

When cashew nutshell oil (CNSO), a well-known non-edible natural oil, is utilised as a blocking agent with diphenylmethane diisocyanate (MDI), this material displayed several advantages over commonly used petroleum-based phenolic compounds, including favourable deblocking conditions and decreased viscosity and better storage stability. When natural rubber (NR) is exposed to sunlight, ozone, UV radiation, and air, especially at high temperatures, the presence of unsaturated carbon–carbon double bonds in the backbone causes quick breakdown. In this work, the multiple bonds present in NR main chain were utilised and made saturated by the way of green emulsion polymerisation using CNSO-blocked MDI using a simple redox initiator. The polymerisation reaction was carried out at different monomer ratios to analyse the thermal stability of natural rubber. The deblocking temperature for CNSO-blocked MDI was determined using CO₂ evolution and the thermo-gravimetric (TGA) methods. Gel time analysis was also conducted and found suitable for heat-curable polyurethane systems. FT-IR and NMR spectroscopic methods were used to examine structural properties. The TGA analysis of copolymer synthesised using NR and CNSO-blocked MDI at an equivalent weight ratio shows higher thermal stability. From this observation, CNSO-blocked MDI greatly improves the thermal stability of natural rubber.

In this research, a new type of flexible cushioning material was fabricated from silicone rubber reinforced with different lengths and contents of flax short fibres and warp-knitted spacer fabric (FSR-WSF). The pressure reduction property and energy absorption capability of the FSR-WSF were thoroughly studied based on the plane compressive test. Furthermore, the obliquity model was utilized to characterize the dispersion of WSFs with different structures. The results demonstrated that a larger modulus and a smaller fracture strain were obtained for silicone rubber reinforced with 1.26% short flax staple fibres that were 2.5 mm in length. Additionally, a remarkable pressure reduction property was exhibited by an FSR-WSF containing 2.16% 3.5 mm short flax fibres, where the values of (mathrm{csc}alpha) and (mathrm{csc}beta) were 1.05 and 1.57, respectively. The results illustrated that the pressure reduction property of the FSR-WSF was the result of coupling between its internal components. These findings could contribute significantly to the development of composites reinforced by warp-knitted spacer fabrics.