Latex Research Articles

Reinforcing Nitrogen Nutrition Through Partial Substitution with Organic Nitrogen Enhances the Properties of Natural Rubber

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 g·tree−1·year−1 of nitrogen. The medium-nitrogen treatment received 276 g·tree−1·year−1 of nitrogen, and the high-nitrogen treatment received 552 g·tree−1·year−1 of nitrogen. In addition, the low-organic-nitrogen substitution treatment and medium-organic-nitrogen substitution treatment were amended with 276 g·tree−1·year−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 g·tree−1. Additionally, this treatment exhibited superior soil total nitrogen (1067.69 mg·kg−1), available nitrogen (84.06 mg·kg−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 × 106 g·mol−1), number-average molecular weight (0.36 × 106 g·mol−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 N·mm−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.

Identification of the HbZAR1 Gene and Its Potential Role as a Minor Gene in Response to Powdery Mildew and Anthracnose of Hevea brasiliensis

Powdery mildew and anthracnose are the main diseases of rubber trees. In recent years, there have been large outbreaks in the rubber-planting areas of Asia, seriously affecting the yield and quality of rubber latex. ZAR1 is a conserved and distinctive coiled-coil nucleotide-binding leucine-rich (CNL) repeat in the plant kingdom, playing a crucial role in disease-resistance processes. To elucidate the function of the HbZAR1 gene in rubber trees (Hevea brasiliensis), three candidate HbZAR1 genes were identified using bioinformatics methods and comprehensively analyzed. The results indicate that the HbZAR1 protein is conserved in different plant species. Examination of cis-regulatory element sequences of HbZAR1genes reveals that the HbZAR1 gene promoter exhibits a remarkable enrichment of stress, light, and hormone elements. An expression analysis shows that the expression levels of the three HbZAR1 genes are highest in the bark and lowest in latex. Three HbZAR1 genes can respond to both rubber tree Erysiphe quercicola and Colletotrichum siamense infection; especially, HbZAR1.1 and HbZAR1.2 show significant upregulation in expression levels during the early stages of infection. These findings suggest that the three HbZAR1 genes may be involved in rubber tree susceptibility to E. quercicola and C. siamense through different immune mechanisms. Subcellular localization results indicate that the HbZAR1 genes are expressed in the nucleus and plasma membrane. This study also shows that the three HbZAR1 genes and activated mutant HbZAR1.1D481V do not induce stable ROS production and cell death, suggesting possible gene degradation, functional redundancy, or acting as minor genes in disease resistance. This research provides valuable insights for further studying the function of HbZAR1 genes in rubber trees and the mechanisms of immune molecules.

Diffusion Behavior of Organic Solvents in Graphene Oxide/Nano Silica Hybrid Natural Rubber Latex Nanocomposite: Experimental and Theoretical Approach

AbstractThis study explores the impact of a graphene oxide (GO)/nano silica (NS) hybrid (GO/NS) filler on the diffusion characteristics of natural rubber (NR) composites when exposed to toluene, xylene, and hexane solvents. The lowest solvent uptake is observed for NR GO/NS 3 (3 phr), which is attributed to forming a robust filler network within the composite. The calculation of crosslink density using the Flory‐Rehner equation reveals significantly higher values for NR GO/NS 3, indicating good crosslinking density in the presence of the hybrid filler. Furthermore, molecular mass between crosslinks (Mc) is calculated, demonstrating a favorable fit with the Affine model. The investigation extends to theoretical modeling, where the Korsemeyer–Peppas and Peppas–Sahlin models are employed to predict solvent uptake behavior. Strikingly, the experimental values exhibit a strong alignment with the Peppas–Sahlin model. This comprehensive analysis provides valuable insights into the diffusion behavior of graphene oxide/nano silica (GO/NS) hybrid‐reinforced natural rubber latex in organic solvents, highlighting potential applications in areas such as solvent‐resistant coatings, barrier materials for chemical storage, and enhanced performance in protective gloves and seals used in harsh chemical environments.

Effects of oil palm trunk biochar as filler on physical and mechanical properties of deproteinised and epoxidised natural rubber latex foam

Effects of oil palm trunk biochar as filler on physical and mechanical properties of deproteinised and epoxidised natural rubber latex foam

Second‐degree burns treatment: Preclinical in vivo approaches using natural latex rubber containing Aloe vera extract

AbstractNatural rubber latex (NRL) obtained from Hevea brasiliensis is emerging as a viable and economical alternative for biomedical treatments, particularly for dermal injuries. Its effectiveness is enhanced when combined with bioactive molecules, such as those found in Aloe vera (AV), known for their healing properties and are commonly used in low‐cost wound healing therapies. Thus, this study evaluated the physicochemical and biological properties of NRL incorporated with 25%, 35%, and 50% AV, both in vitro and in vivo. FTIR analyses revealed only physical interactions between NRL and AV, facilitating their release, as evidenced by the release profile. In vitro assays indicated improved biocompatibility in samples composed of 25% and 35% AV, while complete cell death occurred at 50% AV. Histological evaluations of second‐degree burn models in rats showed greater re‐epithelialization of the epidermis with 35% AV after 14 days of treatment. However, 50% AV highlighted the importance of avoiding overdosing to prevent tissue necrosis. Despite the differences observed between in vitro and in vivo results, NRL membranes containing AV are a promising approach for future clinical trials in skin wounds treatment, offering an effective and affordable solutions for skin regeneration in clinical settings.

Influence of Different Grafted Natural Rubbers on Electrical and Mechanical Properties of Natural Rubber/Carbon Nanotubes Composites

This study investigates the augmentation of electrical and mechanical characteristics of natural rubber (NR) film with different forms by integrating carbon nanotubes (CNTs). NR with different forms (i.e., natural rubber grafted with polystyrene (NR–g–PS) and polybutyl methacrylate (NR–g–PBMA)) were successfully synthesized. The success of these grafting was confirmed through Proton Nuclear Magnetic Resonance (1H–NMR) and Attenuated Total Reflectance–Fourier Transform Infrared (ATR–FTIR) analyses, which showed that the grafting efficiency exceeded 90%. The properties of ungrafted NR and grafted NRs with CNTs were compared and analyzed. It was found that the NR/CNTs composites with grafting displayed significantly improved electrical properties and mechanical strength when compared to the NR/CNTs composites without grafting. It was found that the NR–g–PBMA exhibited an 860% increase in electrical conductivity at 100 kHz compared to ungrafted NR. This might be attributed to the synergistic of the high specific surface of CNTs and the high polarization of functional groups, which gave a higher value for the CNTs filled grafted NR than the ungrafted NR. Moreover, the mechanical properties of NR–g–PS composites showed a 114% increase in 100% modulus, 127% in tensile strength, and 37% in hardness, while the NR–g–PBMA composites exhibited a 159% increase in 100% modulus, 95% in tensile strength, and 34% in hardness compared to ungrafted NR. This enhancement can be attributed to the formation of chemical linkages between the grafted NR matrix and CNTs through functional groups from both. Consequently, it can be concluded that introducing functional groups on grafted NR assists in establishing a crosslinking network, enhancing both the mechanical and electrical properties. Additionally, this research emphasizes the benefits of producing flexible conductive materials with high modulus and enhanced electrical properties. Keywords: Natural rubber latex, Graft copolymerization, Glutaraldehyde, Natural rubber composites, Electrical properties

Fully Atom-Efficient Solvent-Mediated Biopolymer Manufacturing: A Base Case Illustrated with Macromolecular Surfactants Tailored to Stable Polymer-Water Interfaces.

This work introduces a novel 1-pot, 0-waste, 0-VOC methodology for synthesizing polymeric surfactants using acrylated epoxidized soybean oil and acrylated glycerol as primary monomers. These macromolecular surfactants are synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, allowing for tunable hydrophilic-lipophilic balance (HLB) and ionic properties. We characterize the copolymers' chemical composition and surface-active properties, and evaluate their effectiveness in forming and stabilizing emulsions of semiepoxidized soybean oil and poly(acrylated epoxidized high oleic soybean oil). Comprehensive analyses, including gel permeation chromatography, nuclear magnetic resonance spectroscopy, dynamic light scattering, particle size distribution, zeta potential, and critical micelle concentration, provide detailed insights into the copolymers and the emulsions they form. The results demonstrate that the RAFT-polymerized surfactants offer long-lasting stability and effectively disperse both common oil-in-water emulsions and highly viscous and hydrophobic polymer latexes. These surfactants outperform traditional small molecule surfactants by reducing particle size and preventing phase separation, even over extended storage periods. Stable polymer-water interfaces are achieved through HLB control, tailored by monomer composition, and the final product requires no additional purification since polymerization occurs in liquid surfactants. While small molecules contribute to rapid micelle formation, the polymeric components enhance long-term stability through steric repulsion and slower dynamics. This method enables even the emulsification of polymers with submicron particle size, which ordinarily requires emulsion polymerization. Integrating biobased polymeric surfactants with advanced polymer processing techniques opens new possibilities for transforming highly hydrophobic polymers into latexes, facilitating downstream applications. This innovation enhances the environmental sustainability of surfactant production and broadens the potential for polymer emulsification technologies. Additionally, the integrated solution-processing approach demonstrated here can be applied to other emerging polymers, where judiciously selected nonvolatile solvents facilitate the polymerization and play a role in the final application.

Transcriptomic and Proteomic Integration Reveals Key Tapping-Responsive Factors for Natural Rubber Biosynthesis in the Rubber Tree Hevea brasiliensis

Natural rubber is a crucial industrial material, and it is primarily harvested from the latex of the rubber tree Hevea brasiliensis by tapping the tree trunk. During the regular tapping process, mechanical damage seriously affects latex reproduction and rubber yield, but the molecular mechanisms on tapping stimulation remain unclear. In this study, we firstly determined the changed physiological markers on latex regeneration, overall latex yield, and latex flow time during the tapping process. Then, we combined proteomics and transcriptomics analyses of latex during tapping and identified 3940 differentially expressed genes (DEGs) and 193 differentially expressed proteins (DEPs). Among them, 773 DEGs and 120 DEPs displayed a persistent upregulation trend upon tapping. It is interesting that, in the detected transcription factors, basic helix-loop-helix (bHLH) family members occupied the highest proportion among all DEGs, and this trend was similarly observed in DEPs. Notably, 48 genes and 34 proteins related to natural rubber biosynthesis were identified, and most members of small rubber particle protein (SRPP) and rubber elongation factor (REF) showed a positive response to tapping stimulation. Among them, SRPP6 and REF5 showed significant and sustained upregulation at the gene and protein levels following tapping, indicating their pivotal roles for post-tapping rubber biosynthesis. Our results deepen the comprehension of the regulation mechanism underlying tapping and provide candidate genes and proteins for improving latex production in the Hevea rubber tree in future.

Preparation and properties of silicone modified BA/MMA/VAc/VeoVa10 quaternary polymer latex

Preparation and properties of silicone modified BA/MMA/VAc/VeoVa10 quaternary polymer latex

Isolation, Development and Validation of Chromatographic Methods for the Estimation of Linoleic Acid from Different Parts of Euphorbia Neriifolia Linn.

Objectives: This is the first report on the development and validation of thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC)-densitometric methods for the identification of linoleic acid (LA) in petroleum ether extract (PEE) of Euphorbia neriifolia (EN) stem (ST), latex (LX), and bark (BA). Methodology: Chromatographic analyses were performed on silica gel-G and silica gel 60 F254 plates and the antioxidant activities of isolated compounds were investigated by 2,2-diphenyl-1- picrylhydrazyl (DPPH) spectrophotometric assay. Results: The chromatographic analyses revealed better spots and well-separated peaks of LA with retention factor (Rf) values at 0.54 (ST), 0.40 (LX), and 0.64 (BA), respectively. The linearity of the calibration curve ranges from 10-50 ng/spot (ST), 10-100 ng/spot (LX), and 50-200 ng/spot (BA). The proposed method was characterized by better accuracy, better robustness, and good precision, ranging from 0.173 to 0.372% (intra-day) and 0.185 to 0.205% (inter-day). The value of the limit of detection and quantification equal to 1.04 and 3.16 ng/spot in ST, 0.87 and 2.64 ng/spot in LX, and 0.177 and 0.53 ng/spot in BA determined the sensitivity of the method. In the obtained chromatogram, no peak was observed other than the LA which determined the specificity of the method. The % RSD of < 2% after periods of 12, 24, 36, 48, and 72 h determined the stability of standard LA. Conclusion: Thus, the fingerprinting method is valuable in determining the adulterants and in routine quality control of formulations and herbal drugs.

Study on the preparation and modification mechanism of GO/SBR composite modified emulsified asphalt

This paper employs graphene oxide (GO) and anionic styrene-butadiene rubber (SBR) latex as modifiers for road-emulsified asphalt. A silane coupling agent (KH550) is used to modify GO, resulting in the development of a novel GO/SBR composite-modified emulsified asphalt. A mathematical model was optimized to determine the optimal material ratio, which was verified through performance tests. Techniques such as Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were utilized to investigate the modification mechanism. The results indicated that both the median particle size and storage stability of the GO/SBR composite-modified asphalt were enhanced, with significant improvements in mechanical properties compared to ordinary emulsified asphalt. Microscopic analysis revealed enhanced dispersion of modified GO in asphalt, and the interaction between modified GO and emulsified asphalt was determined to be purely a physical reaction. This study provides valuable insights into the application of GO in road engineering.

Comparative Study of Interfacial and Conventional Techniques for Nanosilica Incorporation in Natural Rubber Latex-Based Composites with Varied TEOS Content

This study investigates the preparation of natural rubber latex (NRL) composites with varying nanosilica contents of 5, 15, 30, and 45 phr, using both interfacial and conventional mixing techniques. Analysis focused on viscosity, plasticity, morphology, and FTIR spectra to evaluate the impact of these methods on composite properties. The interfacial techniquemaintained lower viscosity values, indicating better latex stability, and achieved higher silica yields and conversion rates (94 - 99%) at elevated TEOS contents. Plasticity analysis revealed that the interfacial method produced more uniform and stable plasticity values, suggesting improved resistance to oxidation and enhanced mechanical properties. SEM and FTIR analyses confirmed superior dispersion with the interfacial technique, especially at higher silica contents. These findings highlight the efficacy of the interfacial technique in optimizing the properties of NRL composites, making it a promising approach for advanced material applications. HIGHLIGHTS Analysis of interfacial and conventional mixing techniques reveals their impact on NRL composite properties, demonstrating the interfacial method's superior stability, silica dispersion, and enhanced mechanical properties. The interfacial method maintains lower, stable viscosity, prevents latex destabilization, achieves higher silica yields, and ensures economic and sustainable production of high-quality composites. SEM and FTIR analyses confirm better silica dispersion and morphology with the interfacial method, enhancing composite performance, durability, and informing industrial applications and future research directions. GRAPHICAL ABSTRACT

Carica papaya L. Latex Mediated Green Synthesis of Zno Nanoparticles for its Antimicrobial Activity

Zinc oxide nanoparticles have gained potential recognition because of their distinctive characteristics and wide utilizatrion in various fields. Therefore, development of novel biological techniques is significant for the biosynthesis of ZnO nanoparticles using the latex of Carica papaya L. Plant latex is a natural product produced by a number of plant species which are used by different tribal communities in India as a folk medicinal treatment on natural wounds or cuts. Plant latex has a huge demand as herbal products in an aspect of clinical, therapeutical and also in agricultural sectors. Natural latex is composed of different important biomolecules like, tannins, flavonoids, glycosides, sterols, saponins etc. These different active chemical constituents have versatile medicinal activities against different pathogens such as bacteria, fungi, viruses and protozoans etc. This study reports on the biosynthesis of ZnO nanoparticles (Zn NPs)using latex of C. papaya as an effective reducing agent. Green synthesis of nanoparticles has advantageous over conventional methodsbecause it does not require the use of toxic chemicals and therefore environmentally sustainable. The elemental composition of C. papaya latex was also analysed using X-ray Fluorescence (XRF) technique. Properties of synthesized ZnO NPs were characterized using various methods such as ultra violet visible spectrophotometer (UV-Vis), scanning electron microscopy and Fourier transform infrared spectroscopy. Green synthesized ZnO nanoparticles also assessed for its antimicrobial activity against selected bacterial and fungal species.

Preparation and properties of fluorinated VAc-VeoVa10 latex emulsified with allyl nonyl phenoxy propyl alcohol polyoxyethylene ether ammonium sulphate

Purpose The traditional VeoVa10-VAc copolymer latex, which prepared via the emulsion polymerization of the mixed monomers of VAc and VeoVa10, has the poor water resistance and thermal stability because of the migration of the conventional emulsifier molecules and the low bond energy of C-C bond. The purpose of this work is that the fluorinated monomer is used to modify the latex. The film of the resultant latex has the C-F bond with high bond energy and low surface energy, which can effectively improve the heat resistance and water resistance of the resultant film. In addition, the reactive emulsifier is used to replace the conventional emulsifier. The drawbacks of the conventional emulsifier molecules migrate and desorb can be avoided when the polymer latex is stored, thereby also improving the water resistance. Design/methodology/approach The modified VAc-VeoVa10 latex has been successfully synthesized via the semi-continuous seeded emulsion polymerization, which VAc and VeoVa10 is used as the main monomers and HFMA was used as the functional monomer. KPS and reactive surfactants of SE-10 were used as the initiator and emulsifier, respectively. The structure of resultant latex film was characterized by Fourier transform infrared spectroscopy (FTIR). The latex films were tested by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and contact angle (CA). The particle size and its distribution of the latex were measured by the nano particle size analyzer. Findings The factors that had an influence on the properties of the latex and the film were investigated in detail. The stability of the resultant latex is good. The average particles of the latex and its distribution are small and uniform, respectively. In comparison with the conventional latex film, the thermal stability and hydrophobicity of the resultant latex film are improved obviously. Practical implications The resultant latex can be used in both the waterborne interior and exterior wall coatings, pickering stabilized waterborne polymer dispersions, polymer powders, environmentally friendly polymer-modified waterproof mortar and other fields, which can be satisfied with the high demand of thermal stability and hydrophobicity. Originality/value The modification of poly (VAc-VeoVa10) by reactive surfactant and fluorinated monomer is seldom reported. In this study, the fluorinated poly (VAC-VeoVa) latex is prepared via the reactive surfactants, which VAc and VeoVa10 is used as the main monomers and hexafluorobutyl methacrylate is used as the functional monomer. Potassium persulfate (KPS) and allyl nonyl phenoxy propyl alcohol polyoxyethylene ether ammonium sulfate are used as the initiator and emulsifier, respectively.

Bioderived Thiol-Ene Emulsion Polymerization for Hybrid Latex Particles.

The thiol-ene emulsion polymerization of three dienes synthesized from bioderived compounds, and subsequent preparation of core-shell polymer latexes, is reported. Levoglucosan (LGA), levogucosenone (LGO) and isosorbide were first modified with 4-pentenoic acid to install polymerizable groups. These monomers were used along with a dithiol to prepare poly(thioether) particles via ab initio emulsion polymerization using potassium persulfate as initiator and sodium dodecyl sulfate as surfactant. The structure of the diene significantly influenced the size of the resulting polymer latex particles. Given their low glass transition temperature, the LGA-derived poly(thioether) particles were used as a seed for the seeded emulsion polymerization of either styrene or methyl methacrylate. Core-shell latex particles with a high Tg core and a low Tg bioderived shell were formed, as verified by electron microscopy and in agreement with theoretical predictions of the equilibrium particle morphology based on the interfacial tensions of each particle phase.

The Far-ultraviolet Spectrum of FU Ori South

The eruptive young stellar object FU Ori is the eponym of its variable class. FU Ori stars are known to undergo outbursts with amplitudes of >4 mag in the V band and durations of several decades. Interaction with a binary companion is one proposed outburst trigger, so understanding both components of the FU Ori system is crucial. A recent Hubble Space Telescope/Space Telescope Imaging Spectrograph observation of the FU Ori system clearly resolves its North and South components. We report here on the spectrum of FU Ori South. We detect near-ultraviolet continuum emission but no far-ultraviolet continuum, although several bright emission lines consistent with those seen in T Tauri stars are present. The presence of the C ii] 2325 multiplet and many H2 lines indicate active accretion. We estimate the extinction to the source and find that the UV spectrum favors A V < 4, contrary to past estimates based on the near-infrared spectrum.

Enhanced mechanical properties of rubber/clay nanocomposite via compounding butadiene-styrene-vinyl pyridine rubber-contained clay gel with styrene butadiene rubber

An efficient and environmentally friendly strategy is demonstrated for improving the clay dispersion in non-polar rubbers and enhancing their interaction at the interface. In this work, we introduced butadiene-styrene-vinyl pyridine rubber (VPR) latex into clay gel to prepare VPR/clay gel, which was then incorporated into the styrene-butadiene rubber (SBR) to prepare SBR/VPR/clay nanocomposites (NCs), by gel compounding method. The results showed that the dispersion of the clay layer improved by the incorporation of VPR, and the interfacial strength between clay and rubber increased. As a result, the mechanical properties of SBR/VPR/clay NC significantly improved. The tensile strength of SBR/VPR/clay NC was up to 16.3 MPa, which was 930 % higher than that of the pure SBR and nearly 30 % higher than that of the SBR/organoclay nanocomposite (SBR/oclay NC) with the same filler loading.

Natural Rubber Latex Wastes from Balloon Production as Valuable Source of Raw Material: Processing, Physico-Mechanical Properties, and Structure

This study explores the potential for recycling natural rubber (NR) latex waste from balloon production through the devulcanization and revulcanization processes. The mechanical devulcanization of colored latex balloon waste was conducted, followed by revulcanization using a sulfur-based system. The reclaimed rubber’s properties, including crosslink density, tensile strength, and abrasion resistance, were compared with those of virgin NR. The results demonstrate that the reclaimed rubber maintains a crosslink density close to that of virgin NR. Hardness and abrasion resistance were comparable, indicating successful material recovery. Structural analyses, including FTIR and SEM microscopy, revealed that the devulcanization process effectively allowed for successful revulcanization. This study concludes that NR latex waste can be effectively recycled and reused in rubber composite formulations, offering a sustainable approach to waste management in the rubber industry and contributing to developing eco-friendly materials. In the context of this research, integrating advanced chemical and physical methods, such as solubility parameter calculations and enhanced devulcanization techniques, could further optimize the devulcanization process. These methods quantitatively enhance the efficiency of material recovery, offering a path to more sustainable recycling practices. The findings suggest that combining such advanced methodologies could significantly improve recycled NR latex’s overall performance and applicability in industrial applications.

High-value application of kaolin by wet mixing method in low heat generation and high wear-resistant natural rubber composites

In this study, a silane coupling agent and kaolin, a natural mineral resource, were introduced into the wet mixing process of natural rubber latex, the high wear-resistant and low-generation heat natural rubber composites were prepared. The sputtering, collision, and deposition of coupling agent/fillers/natural rubber latex mixed emulsion onto the roller effectively could break up the filler aggregates, enable fillers to be better infiltrated, distributed, and dispersed in the rubber. The effects of dry/wet mixing processes and the ratio of kaolin to silica on the crosslinking density, filler dispersion, extrusion rheological properties, gas barrier properties, dynamic mechanical properties and thermal stability of NR composites were investigated, and the silanization mechanism was summarized by FTIR and XRD. The experimental results showed that kaolin improved the crosslinking density and failure temperature, reduced the Payne effect, extrusion swell, and rolling resistance. Compared with 60 phr silica-filled natural rubber, the gas barrier property and wear resistance of 60 phr kaolin-filled natural rubber were improved by 64 % and 27 %, respectively, and the rolling resistance was reduced by 57 %. When the ratios of silica to kaolin were both 20:40, the crosslinking density, gas barrier property, and wear resistance of wet mixing were improved by 24 %, 45 %, and 9 %, respectively, compared with dry mixing. This study provided a new method for the high-value application of kaolin in wet mixing and green tires.

Characterization and application of composite resin of natural rubber latex and polystyrene waste as a binder for water-resistant emulsion paint formulation

Sustainable production of efficient and low-cost coating materials from recycled plastic wastes will have a significant impact on economic advancements in paints and coatings, as well as waste management. Polystyrene waste was reduced to a resin, which was further modified by blending with natural rubber latex (NRL). The recycled polystyrene resin (rPS) and NRL formed homogeneous composite resins (rPS-NRL) blends in various ratios, and the changes in some physicochemical properties of the resins were studied. The rPS-NRL blended in different ratios exhibited higher density (0.83–0.92 g/cm3), refractive index (1.401–1.438), viscosity (935–1287 cP), elongation (5–18 %), and melting point (184°C–217.5°C), as well as lower moisture uptake (1.1–0.88 %) and faster drying time (32–19 min), compared to the rPS resin. Changes in functional, structural, and morphological characteristics of the resins were studied using Fourier transformed infrared (FTIR) spectrometer, X-ray diffractometer (XRD), scanning electron microscope (SEM) and thermogravimetric analyzer (TGA-DTA). The results indicated molecular interactions between NRL and the rPS resin, which form the basis for the unique physicochemical properties of the composite resin compared with the pristine rPS and NRL resins. White (CaCO3) pigmented emulsion paint produced using the rPS-NRL composite resin as binder was tested in comparison with paint produced using the conventional polyvinyl acetate (PVA) binder, where the rPS-NRL paint exhibits superior properties, including outstanding resistance to water.