Journal of Rubber Research最新文献

Rubber is the most important economic crop of Kerala, which plays a significant role in the agrarian economy of the state. The present study aimed to develop a forecasting model for the yield of rubber in Kerala, using the productivity data and meteorological data from the past 62 years, from the year 1960–1961 to 2022–2023. The study used both conventional approaches and advanced machine learning techniques for the model development. Different time series models have been developed based on ARIMA, ARIMAX, NNAR, and NNARX methods. Annual rainfall and annual maximum temperature were used as exogenous variables for this study. The models were compared for accuracy and goodness of fit using RMSE and MAPE values. The conventional models, ARIMA and ARIMAX, performed well in model model-building phase, but the prediction accuracy declined in the validation phase. The models NNAR (2,4) and NNAR (2,3) with exogenous variables have performed equally well in terms of accuracy and model fit across both development and testing phases. NNAR (2,4) has been identified as the best model considering its simplicity.

This study explores the influence of halloysite nanotubes (HNTs) on the performance characteristics of styrene-butadiene rubber (SBR) and carboxylated acrylonitrile butadiene rubber (XNBR) composites. HNTs were incorporated into the SBR/XNBR matrix at varying loadings (2, 4, 6, 8, and 10 parts per hundred rubber, phr) to assess their effects on curing behavior, mechanical strength, abrasion resistance, and solvent resistance. The incorporation of HNTs markedly accelerated the vulcanization process, as indicated by reduced scorch and optimum cure times, along with increased torque values during rheometric analysis. Among the tested formulations, the composite containing 6 phr HNTs demonstrated the most notable improvements, with tensile strength increasing by 160%, elongation at break by 24%, stress at 100% elongation by 97%, and tear strength by 91%, relative to the unfilled SBR/XNBR blend. In addition to enhanced mechanical performance, the inclusion of HNTs also improved the composites’ hardness, abrasion resistance, and compression set behavior, indicating increased crosslinking density and filler-matrix interaction. These findings suggest that HNTs serve as effective multifunctional nanofillers, capable of simultaneously reinforcing and optimizing the cure characteristics of SBR/XNBR rubber blends, with 6 phr identified as the optimal loading for balanced property enhancement.

The research focuses on the preparation of blending styrene-butadiene rubber (SBR) with Novolac and SBR: Novolac: Silica nanocomposites. The performance and properties of the nanocomposites were analysed using SEM, contact angle, FT-IR, DSC, XRD and peel adhesion tests after reinforcement with nano-silica. The results indicate that Novolac resin reduces scorch and optimises curing times. The viscosity, maximum torque and cure rate index were increased as the loading levels of Novolac increased up to 20 phr. Further, it enhances crystallisation, thermal stability and swelling resistance. Significant reduction in scorch and cure times was observed, while viscosity, maximum torque and cure rate index increased with silica loading up to 6 ppm due to improved homogeneity and dispersion. In addition, increasing the contact angle indicates improved crystallinity, while thermal stability exceeded that of the SBR: Novolac blend. The interaction between Si-OH groups on SiO₂ nanoparticles and carboxyl groups in phenolic resin increased crosslinking density by 5% and 47%, while the swelling rate decreased by 3% and 50% for SBR: Novolac and SBR: Novolac: Silica, correspondingly. According to the results, the adhesion strength between nanocomposites and the copper/iron wires increased by 495% and 900%, respectively, with nano silica loading up to 5 phr.

A recent study has shown that undergrowth yams can be integrated into mature rubber trees. However, the effect of this combination on the agronomic, health and physiological parameters of rubber tree needs to be assessed. To this end, two accessions of undergrowth yams were grown in the inter-rows of mature rubber trees of clone GT1. The experimental set-up was a Fisher block design with two factors, five treatments and three replications. The parameters measured were girth increment (Incr), rubber yield, tapping panel dryness rate (TPDR), leaf water potential, dry rubber content (DRC), sucrose content, inorganic phosphorus (iP) and thiol content (R-SH). The results showed that the treatments in which undergrowth yams were combined with rubber trees exhibited girth increments of 1.39 cm.yr^− 1, yield of 122.02 g per tree and per tapping (g.t.t^− 1), very low tapping panel dryness rates less than 0.30% and midday leaf water potential of 1.48 MPa statistically identical to those of the control rubber trees. Thus, at the end of the experiment, the associated rubber trees presented a balanced physiological profile similar to that of the control rubber trees, with very high dry matter content (DRC = 48.43%), reflecting high biosynthetic activity in the latex, sucrose availability of 7.09 mmol/l l-1, a high Pi content of 23.46 m.mol.l^− 1 and an average R-SH content of 0.66 m.mol.l^− 1. Undergrowth yam can be cultivated in mature rubber trees without adversely affecting their physiological or agronomic performance.

In this study, halloysite nanotubes (HNTs) were used to reinforce ethylene propylene diene monomer (EPDM) and chlorinated isobutylene-isoprene rubber (CIIR) blend composites. The effects of HNT loading on cure characteristics, mechanical properties, rebound resilience, swelling resistance, compression set, crosslinking density, and abrasion resistance were systematically evaluated. With increasing HNT content, minimum torque, maximum torque, delta torque, and cure rate index increased, while scorch time and optimum cure time decreased. Tensile strength and stress at 100% elongation increased up to 6 phr of HNTs, showing improvements of 76.7% and 49%, respectively, compared to the unfilled blend. Tear strength increased continuously with increasing HNT loading, reaching a 54.4% improvement at the highest concentration. However, elongation at break and rebound resilience declined by 10% and 31%, respectively, as HNT content increased. Crosslinking density increased up to 6 phr and then declined, showing a similar trend to the swelling resistance. Compression set values rose with increasing HNT loading. These results indicate that 6 phr of HNT provides optimal performance in balancing reinforcement and elasticity.

Fused Deposition Modelling (FDM) presents some challenges when printing with polypropylene (PP)-based materials because they shrink and warp, making it difficult for the materials to adhere to 3D printer build plate/platform. A combination of appropriate thermoplastic elastomers (TPEs), additives, and an optimised material formulation results in significantly improved warpage behaviour of PP-based 3D-printed parts. Two series of experiments were conducted in which PP/maleic anhydride-grafted ethylene vinyl acetate copolymer (EVA-M) with and without the addition of an external compatibiliser was tested. An evaluation of the mechanical and thermal behaviour and 3D printability of TPE based on PP/EVA blend compounds at various ratios was performed. Both compatibilised and non-compatibilised PP/EVA-M compounds were successfully prepared and demonstrated to be viable for 3D printing using the FDM method, except for a 30/70 blend ratio for PP/EVA-M and a 30/60/10 blend ratio for the PP/EVA-M/compatibiliser compound. Analysis of the thermal behaviour of selected PP/EVA-M compared to that of virgin PP was conducted to study the relationship between warping and the crystallinity of the blends. The differential scanning calorimeter results revealed that lower crystallisation in TPE blends than in PP compounds reduced warping issues. Furthermore, the 3D printer processing parameters were adjusted to improve adhesion to the 3D printer platform. In terms of enhancing the mechanical properties, the addition of an external compatibiliser improved the mechanical properties of TPE at a specific blend ratio. This paper also demonstrated the feasibility of reusing waste thermoplastic elastomer materials through multiple reprocessing cycles.

Malaysia is one of the world’s largest producers of natural rubber latex (NRL), making an important contribution to its gross domestic product (GDP). However, NRL is highly susceptible to microbial contamination. This leads to spontaneous coagulation once it leaves the rubber tree, reducing yield and necessitating the use of latex preservation systems. Ammonia is widely used as commercial preservatives for latex stabilisation. However, the incorporation of ammonia into latex has long been shown to negatively impact both the environment and the well-being of latex industry workers and consumers of latex products. The multiple disadvantages of ammonia in latex formulations, such as undesirable odour, toxicity, volatility, health and environmental issues, have therefore highlighted the need for the development of new and innovative latex preservative systems that are free of ammonia. This paper begins with a comprehensive overview of NRL production, preservation and its history. It then covers the production of ammonia, its main applications in latex, and the drawbacks associated with its synthesis and use in latex stabilisation. Additionally, the review explores alternative non-ammonia latex stabilisers in detail, highlighting their advantages compared to ammonia, the pros and cons of these stabilisers, and the sustainability of ammonia-free latex preservative systems for future industrial applications.

In recent years, there has been a growing emphasis on the development of lightweight composite materials, particularly for automotive and aerospace applications. This study focuses on the fabrication and comprehensive evaluation of multiple fibre (carbon/basalt) and waste rubber reinforced epoxy composites, with particular attention to their mechanical and thermal properties. The waste rubber, sourced from post consumer tyres, was ground into fine particles and subjected to a pre treatment process involving cleaning and drying to promote optimal adhesion to the epoxy matrix. Hybrid composites with varying stacking sequences, incorporating carbon fibre, basalt fibre, and waste rubber, were produced using the hand lay-up technique. Mechanical performance, including tensile strength, flexural properties, and impact resistance, was rigorously assessed for each configuration. Among the tested laminates, those with carbon fibres as exterior layers, basalt fibres as interior layers, and waste rubber as a toughening phase achieved the most balanced mechanical performance exhibiting superior impact resistance while maintaining high tensile and flexural moduli. The incorporation of waste rubber significantly improved the impact resistance of the composites without compromising their structural integrity, highlighting their strong potential for high-performance applications in the automotive and aerospace sectors.

In this study, multi-walled carbon nanotubes (MWCNTs) were incorporated into ethylene-propylene-diene monomer (EPDM) and styrene-butadiene rubber (SBR) blends to develop high-performance nanocomposites. The prepared materials were thoroughly characterized to evaluate their curing behavior and a wide range of mechanical and physical properties, including tensile strength, elongation at break, tear strength, stress at 100% elongation, rebound resilience, and Shore A hardness. Additional assessments encompassed abrasion resistance, swelling resistance, crosslink density, compression set, and morphological analysis. The incorporation of MWCNTs resulted in significant improvements in mechanical properties, with tensile strength increasing by up to 99% and stress at 100% elongation improving by 29% compared to the unfilled EPDM/SBR blend. Enhanced swelling resistance and crosslink density further confirmed the effective interaction between the nanotubes and the rubber matrix. Field Emission Scanning Electron Microscopy (FESEM) revealed uniform dispersion and strong interfacial adhesion of MWCNTs within the matrix. These results demonstrate the potential of MWCNTs in reinforcing EPDM/SBR nanocomposites for advanced rubber engineering applications.

The global demand for natural rubber emphasizes the need for increasing yield per hectare as the expansion of planting areas becomes difficult. To overcome some of the limitations related to the propagation of rubber trees through grafting, research has been carried out for years on Hevea clonal plants produced by in vitro tissue culture technology (vitroplants, VP). This study conducts a large-scale evaluation of VP across two rubber estates in Ivory Coast and Ghana. Using VP could significantly reduce the growth time of seedlings in the nursery and provide flexibility in planting schedules independent of seed availability. For 66 months, 14 ha of field trials were monitored to compare growth dynamics, stand uniformity, and trunk conicity of VP with trees from grafted plants (GP) of RRIM600 clone. The findings reveal that VP exhibited superior trunk girth at 66 months, suggesting an earlier readiness for tapping compared to GP with a more conical trunk shape, which may lead to increased latex yield. The differences in growth rates in the field between VP and GP were significantly affected by the developmental stage of the plants at planting, with VP being planted with fully developed leaves and self-rooted systems, while GP were planted with developed rootstocks but dormant buds. This enabled VP to establish more rapidly and thus reach readiness for latex tapping sooner than GP. The study underscores the importance of further research on clonal selection, acclimatization period, rootstock interactions and the yield performances of this novel planting material.