Search Results (55)

Two series of environmentally friendly polymer blends of bio-based poly(ethylene 2,5 furanoate) (PEF) and poly(butylene 2,5 furanoate) (PBF) with epoxidized natural rubber (epNR) have been prepared. Both bio-based polyesters were synthesized from dimethyl furan-2,5-dicarboxylate (DMFDC) and 1,2-ethylene glycol (EG) or 1,4-butylene glycol (BG) by a two-stage melt polycondensation process. The miscibility of the components in the blend was assessed using calculations based on Hoy’s method. The chemical interactions, presence of functional groups, miscibility, and possible reactions or cross-linking between polyesters and epNR were analyzed by Fourier Transform Infrared Spectroscopy (FTIR). A significant influence of epNR addition on the melt flow index (MFI), limited viscosity number (LVN), and apparent cross-link density values was also demonstrated. Phase transition temperatures and associated thermal phenomena in polyester/epNR blends were evaluated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Oxidation onset temperature (OOT) tests were performed to obtain valuable information about the thermal-oxidative stability of the blends. Tensile tests revealed that the addition of epNR to PEF increases flexibility but at the same time reduces stiffness and tensile strength, especially at higher contents of epNR. In the case of PBF, a gradual decrease in tensile strength and elastic modulus is observed with increasing epNR content. Additionally, hardness tests showed that the addition of epNR leads to a decrease in hardness for both PEF- and PBF-based compositions. Full article

This study investigated the development of biocomposites for use as packaging and film in everyday applications. The utilization of rice flour (RF) as a cheap natural filler in the production of polybutylene succinate (PBS) biocomposites has been shown to reduce environmental issues caused by non-biodegradable plastic waste. The effect of rice flour content on the morphology and properties of PBS and RF biocomposites was comprehensively evaluated. Different amounts of rice flour were considered (0, 10, 20, 30, 40, and 50 phr), and a silane coupling agent and epoxidized natural rubber (ENR-50: 1 phr) were used as interfacial agents to improve compatibility between the matrix (PBS) and filler (RF). The PBS/RF biocomposites were prepared using a two-roll mill and shaped into test specimens and films using a compression molding machine. Batches of the composites containing different amounts of RF were prepared in accordance with the standards, and their morphology and properties, including mechanical properties, density, water absorption, and soil burial degradation, were evaluated. The results revealed that the incorporation of silane-treated RF filler and ENR-50 compatibilizer led to notable improvements in mechanical properties, particularly in tensile modulus, flexural strength, flexural modulus, and hardness. A significant improvement in mechanical performance was observed as the RF content increased, with the highest value recorded at the 50 phr loading. The enhancements observed in the composite properties are due to the inherent rigidity of the RF filler and its improved compatibility with the PBS matrix, which together contribute to a stronger and more efficient material. Additionally, the percentage of water absorption in the PBS/RF biocomposites increased with higher RF content. The results from the soil burial test demonstrated that increasing the RF content positively influenced the biodegradability of the PBS/RF biocomposite materials. Full article

Nanocomposites were synthesized from epoxidized natural rubber (ENR-50) and magnetite (Fe₃O₄) at 1, 5, and 9 wt.%, respectively. Various analyses were conducted to gain comprehensive insight into the properties of the nanocomposites. It was found that the ring epoxide units can be opened and bonded with the Fe moieties of the magnetite to form an Fe-O-C structure, as shown in FTIR spectra at 690 and 700 cm⁻¹. Peaks in UV-vis spectra at the wavelength of 297 nm shifted to 299, 303, and 309 nm for the nanocomposite samples with 1, 5, and 9 wt.% Fe₃O₄, respectively. XRD showed a decrease in the amorphous peak intensity, while new diffraction peaks emerged at 33° and 43°, indicative of the crystalline structure of the Fe₃O₄ in the nanocomposites. Based on TEM micrographs, it was found that the average size of Fe₃O₄ particles in the rubber matrix with 1 wt.% Fe₃O₄ was around 20 and 33 nm. SEM micrographs proved that nanoparticles with 1 wt.% Fe₃O₄ were regularly dispersed in the rubber matrix, and that magnetite nanoparticles were spherical in shape, as well as having strong interactions and bonding with the rubber matrix. A TGA thermogram showed three thermal steps of degradation across a wide temperature range, from 81 °C to 592 °C, and resistance to thermal degradation of the nanocomposite samples as compared to the rubber sample could be clearly observed. Furthermore, DCS showed higher Tg for nanocomposites at 24.4, 25.1, and 26.3 °C, respectively, compared to purified ENR-50 at −18.6 °C. Full article

Natural rubber (NR) possesses excellent comprehensive properties and plays an irreplaceable role in both national defense and people’s livelihood. In recent years, lignin, as a new development trend, has emerged as a reinforcing filler in natural rubber, partially replacing traditional carbon black, or serving as an antioxidant in rubber. However, lignin, a polar biomass filler, exhibits poor compatibility with non-polar natural rubber. To address the compatibility issue between the two, this paper adopts an in situ method, utilizing formic acid and hydrogen peroxide to modify natural rubber into two types of epoxidized natural rubber (ENR) with different degrees of epoxidation (E-25% and E-45%). Subsequently, through wet mixing, it is combined with a lignin aqueous solution (20 parts), and ethanol is used as a flocculant to prepare lignin/ENR composite rubber materials. Comprehensive characterization of the composite rubber materials reveals that after epoxidation modification, the interfacial compatibility between lignin and natural rubber has been significantly improved. Wet mixing also effectively enhances the dispersibility of lignin in the rubber matrix. Compared to natural rubber, the composite material with an epoxidation degree of 25% exhibits significantly superior mechanical properties and thermal stability. The tensile properties of the composite rubber increase from 29.4 MPa to 36.2 MPa, indicating the significant reinforcing effect of lignin. This study aims to investigate the effects of the epoxidation degree (25% and 45%) of epoxidized natural rubber (ENR) and the mixing method on the compatibility and reinforcement performance of composite rubber, providing a new method for preparing high-performance lignin/ENR composites. Full article

The inherent brittleness of bio-based poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) significantly restricts its industrial applications despite its industrial compostability. Blending with elastomeric polymers addresses mechanical limitations; however, interfacial incompatibility compromises miscibility as our previous work established. Herein, we investigate coffee oil epoxide (COE) as a bio-based plasticizer for PHBV/natural rubber (NR) blends in sustainable packaging applications. COE, derived from spent coffee grounds, was incorporated into PHBV/NR/peroxide/coagent composites via twin-screw extrusion. FTIR spectroscopy with chemometric analysis confirmed successful COE incorporation (intensified CH₂ stretching: 2847, 2920 cm⁻¹; reduced crystallinity), with PCA and PLS-DA accounting for 67.9% and 54.4% of spectral variance. COE incorporation improved optical properties (7.73% increased lightness; 21.9% reduced yellowness). Rheological characterization through Cole–Cole and Han plots demonstrated enhanced phase compatibility in the PHBV/NR/COE blends. Mechanical testing showed characteristic reductions in flexural properties: strength decreased by 16.5% and modulus by 36.8%. Dynamic mechanical analysis revealed PHBV/NR/COE blends exhibited a single relaxation transition at 32 °C versus distinct glass transition temperatures in PHBV/NR blends. Tan δ deconvolution confirmed the transformation from bimodal distribution to a single broadened peak, indicating enhanced interfacial interactions and improved miscibility. These findings demonstrated COE’s potential as a sustainable additive for biodegradable PHBV-based packaging while valorizing food waste. Full article

This study investigates the synergistic effects of incorporating modified zinc oxide–silica (ZnO-SiO₂) into tire waste (TW) and epoxidized natural rubber (ENR) blends, with a focus on crosslinking dynamics, mechanical reinforcement, and antibacterial activity. The addition of ZnO-SiO₂ significantly enhanced crosslink density, as evidenced by increased torque and accelerated cure rates. An optimal concentration of 10 phr was found to yield the highest performance. This optimal balance between chemical activation and mechanical reinforcement resulted in exceptional tensile properties, including notable improvements in Young’s modulus, tensile strength, and strain-induced crystallization (SIC). These enhancements were attributed to the strong interactions between ENR molecular chains and SiO₂ surfaces. However, excessive ZnO-SiO₂ concentrations caused filler agglomeration, which reduced both mechanical and antibacterial performances. An antibacterial analysis revealed a remarkable 99.9% bacterial reduction at 10 phr ZnO-SiO₂, attributed to the Zn²⁺ ion release and reactive oxygen species (ROS) generation, with sustained activity even after thermal aging. This durability underscores the composites’ potential for long-term applications. The findings establish ZnO-SiO₂ as a dual-functional filler that optimizes crosslinking, enhances mechanical properties, and provides durable antibacterial efficiency. These results highlight the potential of TW/ENR blends while offering critical insights into mitigating filler agglomeration to improve overall material performance. Full article

Thermally conductive composites were prepared based on epoxidized natural rubber (ENR) filled with alumina, silica, and hybrid alumina and silica. The thermal conductivity and mechanical properties were assessed. It was observed that the interactions of polar functional groups in the fillers and epoxy group in ENR supported a fine dispersion of filler in the ENR matrix. The mechanical properties were improved with alumina, silica, and hybrid alumina/silica loadings. The ENR/Silica composite at 50 phr of silica provided the highest 60 shore A hardness, a maximum 100% modulus up to 0.37 MPa, and the highest tensile strength of 27.3 MPa, while ENR/Alumina with 50 phr alumina gave the best thermal conductivity. The hybrid alumina/silica filler at 25/25 phr significantly improved the mechanical properties and thermal conductivity in an ENR composite. That is, the thermal conductivity of the ENR/Hybrid filler was 2.23 W/mK, much higher than that of gum ENR (1.16 W/mK). The experimental results were further analyzed using ANOVA and it was found that the ENR/Hybrid filler showed significant increases in mechanical and thermal properties compared to gum ENR. Moreover, silica in the hybrid composites contributed to higher strength when compared to both gum ENR and ENR/Alumina composites. The hybrid filler system also favors process ability with energy savings. As a result, ENR filled with hybrid alumina/silica is an alternative thermally conductive elastomeric material to expensive silicone rubber, and it could have commercial applications in the fabrication of electronic devices, solar energy conversion, rechargeable batteries, and sensors. Full article

In this study, epoxidized natural rubber (ENR) was mixed using a two-roller mixer. Water hyacinth fiber (WHF) acted as a reinforcing agent in the preparation of the rubber composite at 10 phr (ENRC/WHF). Chlorhexidine gluconate (CHG) was added at different concentrations (1, 5, 10, and 20 phr) as an antimicrobial and coupling agent. The tensile strength increased with a CHG content of 1 phr (4.59 MPa). The ENRC/WHF/CHG20 blend offered high hardness (38) and good morphology owing to the reduction in cavities and fiber pull-out from the rubber matrix. The swelling of the sample blends in oil and toluene decreased as the CHG content increased. Reactions of –NH₂/epoxy groups and –NH₂/–OH groups occurred during the preparation of the ENRC/WHF/CHG blend. The FTIR spectroscopy peak at 1730 cm⁻¹ confirmed the reaction between the −NH₂ groups of CHG and epoxy groups of ENR. The ENRC/WHF/CHG blend at 10 phr and 20 phr exhibited zones of inhibition against three bacterial species (Staphylococcus aureus, Escherichia coli, and Bacillus cereus). CHG simultaneously acted as a crosslinking agent between ENR and WHF and as an antimicrobial additive for the blends. CHG also improved the tensile strength, hardness, swelling, and antimicrobial properties of ENR composites. Full article

Silica, as a high-quality reinforcing filler, can satisfy the requirements of high-performance green tread rubber with high wet-skid resistance, low rolling resistance, and low heat generation. However, the silica surface contains abundant silicon hydroxyl groups, resulting in a severe aggregation of silica particles in non-polar rubber matrix. Herein, we explored a carbon black (CB)/silica hybrid reinforcing strategy to prepare epoxidized natural rubber (ENR)-based vulcanizates. Benefiting from the reaction and interaction between the epoxy groups on ENR chains and the silicon hydroxyl groups on silica surfaces, the dispersion uniformity of silica in the ENR matrix was significantly enhanced. Meanwhile, the silica can facilitate the dispersity and reinforcing effect of CB particles in the ENR matrix. By optimizing the CB/silica blending ratios, we realized high-performance ENR vulcanizates with simultaneously improved mechanical strength, wear resistance, resilience, anti-aging, and damping properties, as well as reduced heat generation and rolling resistance. For example, compared with ENR vulcanizates with only CB fillers, those with CB/silica hybrid fillers showed ~10% increase in tensile strength, ~20% increase in elongation at break, and ~20% increase in tensile retention rate. These results indicated that the ENR compounds reinforced with CB/silica hybrid fillers are a promising candidate for high-performance green tread rubber materials. Full article

The Nd-mediated coordinative chain transfer polymerization (CCTP) of dienes represents one of the state-of-the-art techniques in the current synthetic rubber field. Besides having well-controlled polymerization behaviors as well as high atom economies, it also allows for the generation of highly reactive Al-capped polydienyl chain-ends, which hold great potential, yet much less explored up to date, in achieving end functionalization to mimic the structure of natural rubber. In this study, we demonstrate an efficient in situ method to realize end-functionalizing polyisoprene by introducing epoxide compounds into a CCTP system. The end functionalization efficiency was 92.7%, and the obtained polymers were systematically characterized by ¹H NMR, ¹H,¹H-COSY NMR, DOSY NMR, and MALDI TOF. NMR studies revealed that a maximum of two EO units were introduced to the chain ends, and based on density functional theory (DFT) studies, an energy barrier of 33.3 kcal/mol was required to be overcome to open the ring of the EO monomer. Increasing the ratio of [Ip]/[Nd] resulted in gradually increased viscosities for the reaction medium and therefore gave rise to an end functionalization efficiency that decreased from 92.7% to 74.2%. The end hydroxyl group can also be readily converted to other functionalities, as confirmed by NMR spectroscopy. Full article

This study aimed to develop a value-added bio-based polymer product for food packaging. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a promising bioplastic with limitations in processability and brittleness, which our group previously addressed by incorporating high-molecular-weight natural rubber (NR) compatibilized with peroxide and coagent. Yet, processability in an industrial setting proved difficult. Coffee oil epoxide (COE), a waste-derived plasticizer, was incorporated into the PHBV/NR/peroxide/coagent matrix via extrusion, and properties of resulting sheets were evaluated. COE incorporation significantly decreased the oxygen and water permeability of the PHBV/NR sheets. Maximum degradation temperature T_peak (°C) increased by ~4.6 °C, and degree of crystallinity decreased by ~15.5% relative to pristine PHBV, indicating good thermal stability. Melting (T_m) and glass transition temperatures (T_g) of the PHBV/NR blend remained unchanged with COE incorporation. X-ray diffraction (XRD) revealed ~10.36% decrease in crystal size for the plasticized blend. Energy-dispersive X-ray analysis (EDAX) and scanning electron microscopy (SEM) confirmed good dispersion with no phase separation. The water uptake capacity of the plasticized blend was reduced by 61.02%, while surface contact angle measurements showed improved water resistance. The plasticized PHBV sheet shows promise for environmentally friendly packaging films due to its high thermal stability, effective barrier properties, and industrial scalability. Full article

In the present research, a plant-based leather substitute material or leather alternative was developed from natural rubber (NR) and pineapple leaf fiber (PALF) using a simple process. Pineapple leaf fiber was extracted from waste pineapple leaves using a mechanical method. Untreated PALF (UPALF) and sodium hydroxide-treated PALF (TPALF) were then formed into non-woven sheets using a paper making process. PALF non-woven sheets were then coated with compounded natural rubber latex at three different NR/PALF ratios, i.e., 60/40, 50/50, and 40/60. Epoxidized natural rubber with an epoxidation level of 10% (ENR) was used as an adhesion promoter, and its content was varied at 5, 10, and 15% by weight of the total rubber. The obtained leathers were characterized in terms of tensile properties, tear strength, and hardness. The internal structure of the leathers was observed with a scanning electron microscope. Comparison of these properties was made against those reported in the literature. It was found that the leather with NR/PALF equal to 50/50 was the most satisfactory; that prepared from TPALF was softer and had greater extension at break. With the addition of ENR at 5%, the stress-strain curve of each respective leather increased significantly, and as the amount of ENR was increased to 10 and 15%, the stresses at corresponding strains dropped to lower values but remained higher than that without ENR. PALF leather prepared in this study has comparable or better properties than other alternative leathers reported in the literature and is much stronger than that made from mushrooms. Thus, this type of leather alternative offers unique characteristics of being bio-based and having a lower carbon footprint. Full article

The photochemical degradation of natural rubber (NR) is a prevalent method used to modify its inherent properties. Natural rubber, predominantly derived from the Hevea Brasiliensis tree, exhibits an exceptionally high molecular weight (MW), often reaching a million daltons (Da). This high MW restricts its solubility in various solvents and its reactivity with polar compounds, thereby constraining its versatile applications. In our previous work, we employed TiO₂ in its powdered form as a photocatalyst for the functionalization of NR latex. However, the post-process separation and reuse of this powder present substantial challenges. In this present study, we aimed to functionalize deproteinized NR (DPNR) latex. We systematically reduced its MW via photochemical degradation under UVA irradiation facilitated by H₂O₂. To enhance the efficiency of the degradation process, we introduced TiO₂-coated hollow glass beads (TiO₂-HGBs) as photocatalysts. This approach offers the advantage of easy collection and repeated reuse. The modified DPNR showed a reduction in its number-average MW from 9.48 × 10⁵ to 0.28 × 10⁵ Da and incorporated functional groups, including hydroxyl, carbonyl, and epoxide. Remarkably, the TiO₂-HGBs maintained their performance over seven cycles of reuse. Due to their superior efficacy, TiO₂-HGBs stand out as promising photocatalysts for the advanced functionalization of NR across various practical applications. Full article

The textile industry is suffering a great challenge regarding wastewater management, primarily due to the implementation of improper systems, specifically for dye wastewater treatment. Photocatalysis is one of approaches that have been used to treat wastewater. Titanium dioxide (TiO₂) was immobilized by using the dip-coating technique in this research. Epoxidized natural rubber (ENR) and polyvinyl chloride (PVC) were used as a polymer to bind the TiO₂ on the glass substrate. This immobilized TiO₂/ENR/PVC underwent a photoetching process at various times to study the crosslink and porosity formations. Reactive red 4 dye was used as a model pollutant for photocatalytic performance. All immobilized TiO₂/ENR/PVC samples under 12, 24 and 30 h of photoetching process (TEP12, TEP24 and TEP30 samples, respectively) showed higher photocatalytic activity compared to those without photoetching process (TEP0 sample) due to the intermediate charge in crosslinking reaction after the photoetching process. The TEP24 sample showed the highest photocatalytic degradation; light harvesting; photocatalytic degradation. Full article

Flexible self-healing composite was fabricated based on blending the bromobutyl rubber (BIIR) and epoxide natural rubber (ENR) filled with hybrid fillers of carbon nanotubes (CNT) and carbon black (CB). To achieve self-recoverability, modification of BIIR was carried out through butyl imidazole (IM), and the healing capability was then activated by the addition of bis(triethoxysilylpropyl)tetrasulfide (TESPT), which resulted in good dispersion of CNT/CB in BIIR/ENR blends. The silanization of TESPT and CNT/CB hybrid filler surfaces was confirmed by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. Adding CNT/CB and incorporating TESPT into the composites effectively improved the curing and mechanical properties of the blends in terms of estimated crosslink density and tensile modulus. Further, the self-healing propagation rate was enhanced by the thermal conductivity of fillers and the ion–dipole intermolecular forces between the rubber chains, leading to the highest abrasion resistance and electrical conductivity. Using an environmentally friendly process, the recyclability of the self-healing composites was improved by the re-compression of the samples. With this, the constant conductivity relating to the rearrangement of the CNT/CB network is examined related to the usability of the composites at 0 and 60 °C. The conductive composites filled with a TESPT silane coupling agent present an opportunity for vehicle tires and other self-repairing applications. Full article