Natural rubber latex (NRL) is a biopolymer consisting of isoprene monomers in a cis configuration connected by double bonds that can degrade naturally. Most natural rubber (NR) based products are single-use items and its microbial degradation process is relatively slow. Hence, this review highlights the importance in the enhancement of biodegradation of NR, the methods applied to increase the biodegradation rate, and characterization of biodegradation of rubber. The biodegradability of NR-based products is enhanced via selective microorganism strains, suitable composting environment and the addition of biofillers. Rubber oxygenase enzymes and latex cleavage protein are major contributors in the biodegradation of NR-based products, while biofillers such as chitosan, cellulose whiskers and starch enhances biodegradation rate up to 60 %. Biodegradation of NR-based products is confirmed through characterization of physicochemical, thermal and mechanical properties using SEM, XRD, FTIR, GPC, TGA, UTM, physical appearance and weight loss. NR-based materials with enhanced biodegradability have many uses, thus its customizability should be studied further in terms of different product forms, fabrication method, orientation of biofiller used and incorporation of metal organic frameworks.

Electronic waste (e-waste) from nonbiodegradable products present a significant global problem due to its toxic nature and substantial environmental impact. In this study novel electrically conductive biodegradable films of uncured natural rubber (NR) incorporating graphite platelets and chitosan were developed via a latex aqueous microdispersion method. Chitosan was added as a dispersing and thickening agent to encourage the uniform distribution of graphite in the NR matrix at loadings of 20-60 parts per hundred rubbers (phr). FTIR confirmed interactions between NR, graphite, and chitosan. FE-SEM and Synchrotron XTM analyses demonstrated uniform graphite dispersion. The result of XRD revealed the greatest crystallinity at 86.9% with 60 phr graphite loading. Mechanical properties testing indicated a significant increase in Young's modulus to 58.2 MPa, or about 470-fold improvement over the pure NR film. The composite films demonstrated improved thermal and chemical resistance, and their electrical conductivity could rise dramatically to 1.22 x 10-5 S cm-1 at 60 phr graphite loading, or about six orders of magnitude higher than pure NR film. The composite films exhibit antibacterial activity against Staphylococcus aureus and some inhibition against Escherichia coli. In addition, the NR composite films exhibited biodegradability ranging from 16.7% to 25.1% after three months of soil burial, declining with increased graphite loading. These results demonstrate the potential of NR-graphite composites as conductive materials for flexible electronics, such as thin-film electrodes in energy storage devices and sensors.

BackgroundUrea-based fertilizers are essential for agricultural productivity but contribute to environmental degradation by releasing soil nitrogen (N) through N leaching and runoff. To address these issues, this study develops and characterizes slow-release composites of thermoplastic starch (TPS) and epoxidized natural rubber (ENR) that incorporate 46-0-0 fertilizer. TPS, recognized for its moisture sensitivity and biodegradability, was blended with ENR to enhance matrix compatibility and optimize nutrient release from the fertilizer. The blending process included different fertilizer concentrations (6.9, 10, 15, and 20 wt%) within various components of the composite.ResultsThe characterization included evaluation of mechanical properties, water absorbance, biodegradability in soil, ammonium release, and ammonium leaching. The TPS/ENR composites exhibited a two-stage decomposition, with TPS dissolving first to provide an initial nutrient boost, followed by the biodegradation of ENR to ensure sustained nutrient delivery. Ammonium release assays demonstrated that TPS/ENR composites delayed nutrient dissolution compared to conventional fertilizers, significantly reducing nitrogen loss through leaching. Notably, the TPS/ENR composite with 6.9 wt% of 46-0-0 fertilizer exhibited the highest efficiency, achieving sustained ammonium release and enhancing soil nitrogen retention while mitigating phytotoxicity in lettuce and maize germination assays.ConclusionsThese findings highlight the potential and environmental benefits of delivering fertilizer in TPS/ENR composites to improve nitrogen fertilizer efficiency in agricultural systems. The slow-release mechanism provides both initial and sustained nutrient supply, addressing the dual challenges of early crop nutritional needs and long-term environmental sustainability.

Natural rubber (NR) is a material with a wide range of industrial and commercial applications, including agriculture, defense, transportation, and domestic use. However, the mechanical properties of natural rubber treated by traditional acid coagulation are limited, which restricts its application in high-end products. Furthermore, the wastewater generated also causes soil acidification. Consequently, there is a necessity to investigate new coagulation methods to enhance the comprehensive performance of natural rubber and reduce environmental pollution. In this work, a novel method for the preparation of environmentally friendly high-performance natural rubber by alkaline protease/calcium chloride coagulation of natural rubber (AC-NR) is reported. The research demonstrates that the products of protein cleavage by alkaline protease together with calcium ions can greatly enhance the cross-linking between rubber particles, form the network structure of natural rubber well. Furthermore, increasing the pH at the isoelectric point of the discharged wastewater reduces the impact on soil acidification. In comparison with those from conventional acid coagulation of natural rubber (A-NR), the tensile strength of AC-NR was increased by 7.9 MPa, the tear strength was increased by 5.3 kN/m, the final temperature rise was lowered by 6.5 degrees C, and abrasion performance was improved. This study demonstrates that by utilizing the collaborative impact of alkaline protease and calcium chloride on the rubber molecular chain during the coagulation process of natural rubber, environmentally friendly high-performance natural rubber with excellent mechanical properties and reduced environmental pollution can be prepared without the necessity for chemical modification or cumbersome processes, which is conducive to the green development and high-quality pursuit of NR materials.

A few recent studies introduced natural rubber latex (NRL) as a stabilizer for improving the mechanical properties of soil such as ductility, compressive and tensile strengths, durability, etc. However, none of these studies addressed the effect of NRL treatment on swelling and compressibility of soil. The present study investigates the effect of NRL treatment on swelling and compressibility characteristics of three soils of different plasticities by conducting oedometer tests. Untreated and NRL-treated samples of the selected soils were prepared with the same soil dry density. For preparing treated samples, in place of water, NRL was added to soil. The results of one-dimensional swelling-compression tests demonstrated that in low and medium plastic soils, NRL treatment increased the swelling potential marginally, whereas it considerably reduced the swelling in the high plastic soil, which is expansive in nature. NRL did not cause any changes in the swelling pressure of medium plastic soil. At the same time, it brought about a considerable drop in the swelling pressure of high plastic soil. In the consolidation tests, a decrease in compressibility, quantified in terms of compression index, was observed in all soils after NRL treatment. The resilient nature of rubber content caused an increase in the recompression index in all treated samples. A reduction in the coefficient of consolidation was observed in NRL-treated soils. The study concludes that despite the high deformability of rubber, NRL treatment does not negatively affect the swell-compression behaviour of soils. Besides, the treatment effectively controls the swelling and compression of highly compressible soil.

This study explores the efficacy of Natural Rubber Latex (NRL) as an additive in enhancing the mechanical properties and durability of cement-stabilized Recycled Concrete Aggregate (RCA) and Lateritic Soil (LS) blends for pavement applications. The research focused on determining the optimal NRL content and evaluating the performance of the stabilized blends under environmental stress represented by wetting-drying (w-d) cycles. Unconfined Compressive Strength (UCS) and Indirect Tensile Strength (ITS) tests were conducted alongside Scanning Electron Microscopy (SEM) to assess the microstructural integrity of the materials. The results demonstrated that the inclusion of NRL at a 5% rubber-to-cement (r/c) ratio significantly improved the initial UCS, ITS, fatigue life, and durability performance of the RCA:LS blends. The 70:30 RCA:LS blend outperformed the 50:50 blend, indicating a composition-dependent response to NRL addition. The findings suggest NRL's potential in sustainable pavement construction, with implications for enhancing strength in stabilized pavement materials.

The partial substitution of chemical fertilizer with organic fertilizer is a crucial practice for enhancing crop production and quality, although its impact on natural rubber has rarely been explored. In this study, a two-year field experiment was conducted to investigate the impact of different nitrogen application rates and varying proportions of organic nitrogen substitution on dry rubber yield, nitrogen nutrition, and natural rubber properties. Regarding nitrogen application, the control treatment received no nitrogen amendment, while the low-nitrogen treatment was amended with 138 gtree-1year-1 of nitrogen. The medium-nitrogen treatment received 276 gtree-1year-1 of nitrogen, and the high-nitrogen treatment received 552 gtree-1year-1 of nitrogen. In addition, the low-organic-nitrogen substitution treatment and medium-organic-nitrogen substitution treatment were amended with 276 gtree-1year-1 of nitrogen each. The results demonstrated that the 50% organic nitrogen substitution treatment resulted in the highest dry rubber yield across all sampling periods, ranging from 46.43 to 94.65 gtree-1. Additionally, this treatment exhibited superior soil total nitrogen (1067.69 mgkg-1), available nitrogen (84.06 mgkg-1), and nitrogen content in roots (1.08%), leaves (3.25%), fresh rubber latex (0.27%), and raw natural rubber (0.44%) compared with other treatments. In terms of the physical properties of natural rubber, the 50% organic nitrogen substitution treatment resulted in advantages in the weight-average molecular weight (1.57 x 106 gmol-1), number-average molecular weight (0.36 x 106 gmol-1), plasticity retention index (97.35%), Wallace plasticity (40.25), and Mooney viscosity (81.40). For mechanical properties, natural rubber from the substitution treatment exhibited higher tensile strength (19.84 MPa), greater elongation at break (834.75%), and increased tear strength (31.07 Nmm-1). Overall, the substitution of 50% chemical nitrogen fertilizer with organic nitrogen fertilizer improved nitrogen nutrition in rubber trees by introducing organic nitrogen input, resulting in remarkable enhancements in natural rubber properties. Therefore, the incorporation of organic fertilizer as a substitution for 50% of chemical fertilizer is demonstrated as an effective strategy for improving both the yield and properties of natural rubber.

The physico-chemical and biological properties of natural rubber latex (NRL), entailing its biodegradability and biocompatibility, render it a promising material for various biomedical applications. This research explores the facile blending of NRL with dextrin in different compositions to investigate its potential as a prospective UV shielding transdermal patch for biomedical applications. The superior compatibility between the polymers after blending and the improved thermal stability have been established through FTIR, DSC, and TGA examinations, respectively. Optimization of blended polymers for compatibility, wettability, crystallinity, and static mechanical properties has been performed. Morphology characterization conducted via SEM and AFM techniques suggests a uniform morphology for the optimized blend system. The UV shielding ability of the blend has been confirmed by the evaluation of in-vitro UV shielding performance, UV protection factor (UPF), and the superior protection of the optimized system on living cells upon UV irradiation. The observed cell viability, swelling, erosion, porosity, hemocompatibility, and soil degradation properties suggest the NRL-DXT combination for the possible development of high-quality transdermal patches.

Developing novel formulations and processes to improve the fungal growth inhibition and biodegradability of NR products has become a major challenge for the scientific community, given the health risks associated with fungi in natural rubber (NR) products and the environmental concerns regarding NR waste. Consequently, this study comprehensively investigated the synergistic effects of chitosan and gamma irradiation on enhancing fungal growth inhibition and biodegradability in natural rubber latex (NRL) films. The research involved incorporating varying chitosan contents (0, 3, 6, or 9 phr) into NRL composites and exposing them to different gamma doses (0, 5, 10, or 15 kGy). The results showed that increasing the chitosan content and the gamma dose improved the ability of the NRL samples to inhibit fungal growth on their surfaces. This was evidenced by the absence of fungal colonies after 7 days of incubation on potato dextrose agar (PDA) plates for NRL samples irradiated at 5-15 kGy with 9 phr of chitosan. This determination was based on isolating fungi from the film surfaces, followed by serial dilution and a viable plate count. The biodegradability tests also revealed that the NRL films irradiated at 15 kGy with 9 phr of chitosan had the highest weight loss, reaching as high as 10.42 +/- 0.62 % after soil burial for 8 weeks. However, the results indicated that gamma irradiation on the pristine NRL and chitosan/NRL films did not substantially alter the thermal stabilities, density, morphology, and functional groups of the samples. Lastly, by comparing the tensile properties of all the NRL films to the ASTM D3578-01a standard for examination gloves, the optimum conditions for the NRL films were 5 kGy of gamma irradiation with 9 phr of chitosan. This combination resulted in gloves with sufficient tensile strength and complete fungal growth inhibition.

Agricultural activities contribute to numerous waste problems and have emerged as a significant environmental concern. Nondegradable plastic residues decompose, releasing microplastics and affecting ecosystems and the environment. Consequently, biodegradable bio-composite films consisting of polylactic acid (PLA), natural rubber (NR), and rice straw (RS) have been developed with the aim of using them in agricultural applications. In this study, the PLA/NR blend, at a fixed ratio of 60/40 wt%, was filled with 3 and 5 wt% RS powder and extruded through a slit die into films. The biodegradability of all films was examined after being buried for 90 days in soil with a moisture content of 30% by weight. The neat PLA film showed the lowest weight loss percentage, 3.33%, suggesting a comparatively slower degradation rate in comparison to the PLA/NR(60:40) blend and all bio-composite films. The presence of 40 wt% NR in the film helped accelerate the biodegradation process during soil burial. The film produced from PLA/NR 60:40 wt% matrix filled with RS at 5 wt% led to rapid degradation, leading to a weight loss of 8.30%. From SEM micrographs, the morphology of all polymers after burial in soil showed fractures, the formation of pores, and obvious surface indications of fungi growing. The content of carbon decreased after soil burial, while oxygen content increased, and nitrogen was detected. The XRD analysis revealed low crystallinity in the neat PLA, consistent with the DSC analysis. The addition of NR and RS to the composites led to an increase in the crystallinity of PLA phase. All investigated materials exhibited an increase in crystallinity after being buried in soil. This research demonstrates that bio-composite films manufactured from the PLA/NR(60:40) blend filled with RS degrade more easily than unmodified PLA film.