Journal of Rubber Research最新文献

This study investigates the complex dynamics of filler-filler interactions within rubber compounds, utilising advanced characterisation techniques. Effective dispersion of fillers within the rubber matrix is crucial for achieving optimal performance in vulcanised products. The absence of effective filler-rubber interaction can significantly impact the performance, reliability and lifespan of rubber products across diverse industries and applications. Hence, it is necessary to attain optimal filler dispersion and interaction within the rubber matrix to secure the desired properties and quality of the product. In this study, various industrial tools such as the Dynamic Mechanical Analyser (DMA) and Rubber Process Analyser (RPA) were employed to thoroughly examine the filler-filler interplay. Notably, a strong correlation coefficient exceeding 0.9 was observed, indicating a high degree of consistency between these two techniques. While RPA offers valuable insights into the processing behaviour of rubber compounds, DMA provides more detailed information on the structural and mechanical changes occurring in the rubber-filler matrix during and after vulcanisation. The investigation focuses on two rubber matrices: Natural Rubber (NR) and Styrene Butadiene Rubber (SBR). Three series of carbon black with varying particle sizes (N134, N339, N774), as well as silica, either individually or in combination, were utilised as fillers. Additionally, the effects of annealing before and after vulcanisation, along with the resulting mechanical properties, were analysed in depth. The deeper insights afforded by DMA can contribute to a more comprehensive understanding of the underlying mechanisms responsible for performance limitations and product failures, such as insufficient filler dispersion or flocculation during vulcanisation.

Establishing strong interfacial interactions between fillers and the polymer matrix is crucial for producing high-performance polymer nanocomposites. This study explores the development of ethylene-propylene diene monomer/acrylonitrile butadiene rubber (EPDM/NBR) nanocomposites using multiwalled carbon nanotubes (CNTs) modified with imidazolium-type ionic liquids (IL-CNTs). The mole percent uptake (MPU) of various solvents by EPDM/NBR nanocomposite membranes was examined to assess filler-polymer interactions. Cure properties were analysed using a moving die rheometer. Mechanical performance was evaluated through tensile, tear and hardness tests. Swelling resistance, compression set and crosslinking density were assessed to determine the impact of IL-CNT incorporation on the nanocomposite properties. Results showed that increasing CNT content led to higher torque and shorter cure times. The tensile strength and stress at 100% elongation of CNT- and IL-CNT-filled EPDM/NBR nanocomposites improved with increasing nanofiller content up to 5 phr, after which they began to decrease. The tensile strength and stress at 100% elongation for IL-CNT-filled composites saw improvements of 155% and 70%, respectively, compared to the base vulcanisates. Other properties, including tear strength, hardness, abrasion resistance, swelling resistance, compression set and crosslinking density, also increased with higher nanofiller content in IL-CNT-filled EPDM/NBR composites.

This study investigates the enhancement of the mechanical and physical properties of a 50/50 chloroprene rubber (CR) and natural rubber (NR) blend by incorporating halloysite nanotubes (HNTs) as a nanofiller. HNTs, a member of the nanoclay family, were added in varying concentrations up to 10 parts per hundred rubber (phr). Cure properties, including torques and cure times, were measured and analysed to understand the effects of HNT incorporation. The innovative aspect of this work lies in the exploration of HNTs’ potential to enhance mechanical properties such as tensile strength, hardness, tear strength and elongation at break, as well as swelling resistance across different solvent environments. The swelling resistance was quantified through mole percent solvent uptake in aromatic, aliphatic and chlorinated solvents, revealing the influence of HNT loading and penetrant size. The study also employed field-emission scanning electron microscopy to examine the morphology of fractured composites. The findings demonstrated that the mechanical properties and swelling resistance of the CR/NR blend improved with increasing HNTs loading, with optimal enhancements observed at 6 phr of HNTs. This work offers valuable insights into the use of HNTs as a reinforcing agent for rubber blends, providing a pathway for developing materials with improved performance across multiple properties.

A comprehensive analysis of crosslink density is crucial for understanding the functional characteristics of rubber vulcanisates. This study discusses a quantitative methodology for assessing crosslink density through the application of a Dynamic Mechanical Analyser (DMA), in which the storage modulus is evaluated during a temperature sweep on cured vulcanisate samples. To confirm the DMA findings, the Molecular Weight Between Crosslinks (Mw) and crosslink density derived from DMA were compared with results obtained from the solvent method, utilising the Flory-Rehner approach. The solvent method involved refining the swelling and drying periods for natural rubber (NR) matrices. The investigation covered the diverse vulcanisation systems, including conventional, semi-efficient, and efficient systems, and altering the dosage of the Zinc oxide activator. Additionally, the study delved into the influence of crosslink density on mechanical properties such as hardness and stress-strain characteristics. This was accomplished by manipulating the cure time of rubber vulcanisates, systematically adjusting it both below and above the tC90 determined through rheometric studies, covering a broad spectrum of intervals. Significantly, the research established a correlation between crosslink density determined by DMA and the widely accepted solvent approach. This comprehensive study establishes the utilisation of the Dynamic Mechanical Analyser to study the crosslink density and enriches our understanding of rubber vulcanisates, providing valuable insights into the intricate relationship between crosslink density and mechanical properties across various vulcanisation systems.

This study investigates the reinforcing effect of modified nanosilica (mNS) on natural rubber (NR) and acrylonitrile butadiene rubber (NBR) composites, with epoxidized natural rubber (ENR) used as a compatibilizer. Nanosilica (NS)-filled nanocomposites were developed and systematically analyzed for their morphological, rheological, and mechanical properties. Key findings indicate that increasing the mNS content from 0 to 10 phr enhances mechanical performance, including hardness, tear resistance, and abrasion resistance. Notably, the 70/30 NR/NBR blend with 6 phr of mNS exhibited a 128% increase in tensile strength and a 58% rise in stress at 100% elongation compared to unfilled NR/NBR. These improvements are attributed to the high surface area and uniform dispersion of mNS, which enhance interfacial interactions within the polymer matrix. Furthermore, higher mNS concentrations improved swelling resistance, reinforcing the nanofiller’s effectiveness in enhancing overall composite performance. These findings highlight the potential of mNS-reinforced NR/NBR composites for advanced elastomer applications.

Plastic waste is a major global issue because it takes a long time to decompose using current waste management techniques. This increasing concern about the breakdown of plastic waste has led to much interest in developing biopolymers. This study aims to investigate how adding ground tyre rubber (GTR) to high-density polyethylene (HDPE), low-density polyethylene (LDPE) and polyethylene terephthalate (PET) can accelerate the biodegradation process of these plastic materials. Composite materials made from a plastic or polymer-GTR matrix are created by blending 90% to 50% polymer with GTR using a twin-screw extruder known as thermal blending method. Polymer-GTR composite materials are tested in a laboratory using a CIS 24 PLUS incubator at temperatures of 37 °C, 30 °C and 20 °C. The experiments included a combination of air, moisture and other factors that could affect the rate of biodegradation. After being exposed to the environment for 30, 60 and 90 days, samples are collected and analysed. Adding GTR to plastic can make it more porous, making it easier for bacteria to break down the material. Moreover, GTR helps microbes to attach and provide carbon source for their metabolism within the polymer matrices. The thermal stability of waste plastic-GTR biocomposite materials are indicated by a decrease in activation energy (HDPE = 20.63 to 17.93 kJmol⁻¹, PET = 18.8 to 15.95 kJmol⁻¹ and LDPE = 25.71 to 23.39 kJmol⁻¹). Estimated values for enthalpy decrease from 23.19 to 5.15 kJmol⁻¹, 25.77 to 5.15 kJmol⁻¹ and 48.96 to 43.81 kJmol⁻¹, whereas the entropy increases from − 335.38 to − 310.02 Jmol⁻¹ K⁻¹, − 333.22 to − 306.03 Jmol⁻¹ K⁻¹ and − 378.53 to − 370.38 Jmol⁻¹ K⁻¹ for HDPE, PET and LDPE respectively. In summary, the study discovered that adding GTR through thermal blending can boost the biodegradation of plastic waste. This environmentally friendly approach could help reduce pollution caused by plastic waste.

Shape memory rubber (SMR) is a type of smart rubber capable of undergoing reversible transformations when exposed to external factors such as temperature. Lightly crosslinked natural rubber (NR) exhibits shape memory behaviour without requiring preliminary heat treatment making it a unique smart material. This study aims to develop rubber nanocomposite films reinforced with starch nanocrystals (SNC) for improvement of mechanical properties. To this end, the focus is on evaluating the shape memory effect (SME) and quantifying the energy storage potential of the SNC reinforced rubber composite films. Natural rubber latex (NRL) and SNC synthesized by acid hydrolysis were used as raw materials to fabricate the green shape memory natural rubber latex (SMNRL) films. It was found that the incorporation of SNC into NRL effectively enhanced the mechanical properties and SME of the rubber nanocomposite films. The tensile strength of the rubber nanocomposite film was increased by up to 206% upon addition of SNC while having no detrimental effect on the elasticity of the material. The excellent SME is demonstrated through high shape fixity (S_f) and shape recovery (S_r) achieving 93.3% and 100%, respectively. As a result of its shape fixing capability, the SMNRL film can store part of the applied energy showcasing its energy storage potential. The calculated stored energy is 20.6 MJ/m³ with a storage efficiency of 61.5%. In summary, SNC is an effective reinforcing filler showed through the increase in tensile strength. Moreover, addition of 8% SNC improved the S_f by 35% while having a positive impact on the energy storage potential of the rubber nanocomposite films.

Natural rubber (NR), valued for its high toughness and elongation, was incorporated into digital light processing (DLP) 3D printing resins to enhance mechanical performance using epoxidised Philippine NR (EPNR), optimised by statistical and machine learning methods. EPNR blends (0–10%) with cationic photo-initiator (CPI) and photo-curable commercial resin (PCR) were formulated using a solvent blending technique. Fourier transform infrared spectroscopy and simultaneous differential scanning calorimetry-thermogravimetry have confirmed successful epoxidation and improve thermal stability. The optimal formulation (6.36% EPNR, 2.10% CPI, and 91.54% PCR) achieved a toughness of 16,406.8 J/m³ and an elongation at break of 39.41%, marking a 78.1% improvement over unmodified PCR. Mixture design (MD) and artificial neural network (ANN) modelling yielded high predictive accuracy (R² ∼0.986), with ANN outperforming MD in minimising error. Guided by the trained ANN model, 3D printed structures exhibited improved chemical resistance and thermal stability, rivalling commercial resins. This work highlights the potential of EPNR as a reinforcement additive to enhance DLP resin performance, paving the way for innovative applications in additive manufacturing.

In this research paper, a comprehensive parameter manipulation study was conducted to investigate the challenges and opportunities involved in producing thinner natural rubber films. Employing the design of the experiment (DOE) method and response surface methodology (RSM) allowed tuning and manipulating various dipping protocols in exploring critical factors such as total solid content of the compounded latex, coagulant concentration, and dipping time. As such, the aim is to discern their individual and collective influence on film thickness and subsequently physical properties such as tensile strength and thermal ageing. In this study, the response surface refinement was conducted via central composite design (CCD) using these three factors: total solid content of the compounded latex, coagulant concentration, and dipping time. Based on the regression analysis, the optimum condition for thinner NR films with good tensile strength and ageing properties was achieved with final dipping protocols comprising 20% TSC, 5% coagulant concentration, and 5 s dipping time. The resulting responses from the validation experiments for thickness, tensile strength, and ageing were 0.073 mm, 18.11 MPa and 20.82 MPa, respectively. The implications of these findings are significant for the latex-dipped product sector, particularly in glove manufacturing. They facilitate the creation of cost-effective, thinner gloves while maintaining essential mechanical and ageing properties, which is vital for both medical and industrial uses. The result also shows that, perhaps with extra caution, RSM can be applied effectively in optimising the properties of the dipped film.

With the depletion of petrochemical resources, natural rubber (NR) shows its application potential. On the basis of deproteinised natural rubber (DPNR), a hydrophilic and water-absorbent polymer network composed of a deproteinised natural rubber-grafted-poly(acrylic acid) (DPNR-g-PAA) system and linear polyethylene glycol (PEG) was designed and fabricated. The graft copolymerisation of DPNR with acrylic acid (AA) was initiated by a redox initiator system consisting of potassium persulfate (KPS) and sodium hydrogen sulfite (NaHSO₃) under nitrogen, followed by the addition of PEG to the system. The key factors influencing the grafting efficiency of DPNR-g-PAA were investigated, including reaction temperature, mixing time and AA content. The grafting system was finally attached to the hydrophilic polymer PEG. Water adsorption behaviour tests and water contact angle experiments indicated that grafting PAA and linking PEG in DPNR latex increased hydrophilicity. The results indicated that the maximum water absorption of DPNR-g-PAA was 78.24 ± 5.06% and the minimum of water contact angle of DPNR-g-PAA@PEG was 9.58 ± 1.37°. Through the modification of PAA and PEG, the DPNR-g-PAA@PEG product improves the hydrophilicity of DPNR, which has the potential for application in water retention agents and slow-release fertilizers.