Journal of Rubber Research最新文献

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.

Rubber (Hevea brasiliensis Müll. Arg.) is a major economic crop grown in tropical areas. However, the various service functions of rubber plantations and their benefit to society, the economy and the environment are still unclear. Data on rubber planting areas, dry rubber and wood yields, carbon sequestration and oxygen release capacities, biodiversity, employment, and market prices for natural rubber and rubber wood were collected. Observations of land use patterns and functions were carried out. The results showed that the capacity of average annual carbon stock capacity of rubber plantations in China was 36.51 million tonnes. The accumulation values of carbon sequestration and oxygen release, 416.89 million tonnes and 304.42 million tonnes, respectively. A total of 849 plant species, 60 bird species, 5 species of ground beetle, 25 species of wild bees, 27 ant species, 10 termite species, 87 spider species and 38 hemipterous species were found in rubber plantations. The average annual dry rubber and rubber wood yields were 676,300 tonnes and 1.29 million m³. From 2000 to 2020, 14.20 million tonnes of dry rubber were produced and 27.02 million m³ of wood were harvested. The average annual output of dry rubber and rubber wood was US$1.86 billion, while total output value summed to US$ 39.08 billion from 2000 to 2020. Rubber cultivation and plantation operation activities employed an average of 1.11 million people annually. Land use management and natural disasters may affect the service functions of rubber plantations, which are carbon sequestration and oxygen release, maintaining biodiversity, providing dry rubber and rubber wood, maintaining water and conserving water sources, absorbing employment, changing unsustainable agricultural practices and habits of smallholders and ethnic minorities, and promoting transfer of technologies. In the future, on the basis of recognising and rationally weighing the various functions of rubber plantations and their main driving factors, smallholders are expected to maximise the social, economic and ecological functions of rubber plantations through effective crop management and utilisation of resources.

Dialysed C-serum precipitate (DCP), a sub-fraction of latex C-serum originating from Hevea brasiliensis, has shown specific in vitro antiproliferative properties towards cancer-origin cell lines. As a potential agent to be used in cancer treatment, preclinical safety assessment tests are crucial. This study focused on investigating the mutagenicity of DCP via bacterial reverse mutation assay (Ames test), Mouse lymphoma assay (MLA), and micronucleus assay according to OECD guidelines. No mutagenicity was exhibited by DCP at concentrations lower than 1 mg/mL for the five different auxotroph strains of Salmonella typhimurium (TA 98, TA 100, TA 1535, and TA 1537) and Escherichia coli WP2uvrA pKM101 in the absence and presence of metabolic activation system (S9-mix). Nonetheless, it has been found that DCP was able to induce negligible mutation in MLA and micronucleus assay. Overall, DCP does express dose-dependant mutagenicity according to the assays conducted and thus, it is crucial to take this into consideration should DCP be used in the development of therapeutic agent.

Determining the partitioning of carbon black [CB] in miscible rubber–rubber blends [RRB’s] is a demanding problem in the rubber industry, testing one’s ability (especially tyre industry); hence, this research work aims to investigate the partitioning of CB in miscible styrene butadiene rubber [SBR]/butadiene rubber [BR] blends. SBR:BR with blend ratios of 70:30/50:50 and 30:70 with 50 phr CB were prepared on two-roll mill. Nanoscale partitioning of CB within the nanoscale phase-separated SBR/BR blends was quantitatively determined using dynamic mechanical analysis [DMA]. DMA confirmed 63%, 93%, and 45% of CB partitioning towards BR phases of 70:30, 50:50, and 30:70 in CB-filled SBR/BR blends. An attempt to determine the partitioning of CB was also made by making use of solid-state nuclear magnetic resonance spectroscopy [SS-NMR spectroscopy] to interrelate the partitioning of CB determined using DMA. TEM images were helpful in observing CB's dispersion and network ability in CB-filled SBR/BR blends. The results of CB partitioning confirm maximum partitioning of CB towards the nano-dispersed phase in CB-filled SBR/BR blends and are in well agreement with the constrained regions of BR and mechanical properties of CB-filled SBR/BR blends. Attenuated total reflectance-Fourier transform infrared spectroscopy’s (ATR-FTIR spectroscopy) spectra were used as a tool to determine the interactions within CB-filled rubbers and RRB’s in comparison to their neat counterparts. To the best of our knowledge, partitioning of CB controlled by nanoscale phase-separated morphology and its effect on mechanical properties has not been studied so far; hence, this study would be significant to academics and industrial researchers working in the area of rubber composites.

To improve the biocompatibility of dipped films from natural rubber latex (NRL) without compromising physical strength, high ammoniated NRL (HA-NRL) compounding formulations were devised by manipulating the amount of compounding ingredients and additive materials. In this study, the compatibility of 3-aminoproplymethyldiethoxysilane (APMDS) with calcium carbonate (CaCO₃) filler in zinc diethyldithiocarbamate (ZDEC) accelerated HA-NRL formulas were explored. It was found that ZDEC residue detected using High-Performance Liquid Chromatography (HPLC) was less than 6 μ/g in all NRL-dipped films. Furthermore, the cytotoxicity response of the films showed a lower toxicity effect in the presence of APMDS. The occurrence of chemical interactions between APMDS, CaCO₃ and crosslinked NR was confirmed by the Attenuated Total Reflectance-Fourier Transmittance Infra-Red (ATR-FTIR) spectrometer. Interestingly, the physical strength of NRL-dipped film was greatly improved when APMDS was incorporated together with CaCO₃ at a low dosage of ZDEC. This may be due to the adequate physical interaction between the APMDS-surface-modified filler particles and APMDS-surface-modified rubber particles. Overall, a biocompatible NRL film with satisfactory physical strength, low ZDEC residue and low cytotoxicity was achieved by employing a low dosage of ZDEC in the presence of APMDS and CaCO₃.