Search

Bagasse ash (BA) is an agricultural waste obtained from power plants using sugarcane bagasse as an energy source. Although BA is successfully used as a building material, its application in the polymer industry remains challenging due to the lack of surface reactivity. In this study, BA was purified and named PBA before being incorporated into acrylonitrile butadiene rubber (NBR). Tannic acid (TA), a naturally occurring plant polyphenol, was used as a surface‐modifying agent for improved interfacial interaction. The effect of TA content on the properties of PBA‐filled NBR was investigated. The results showed that the presence of TA resulted in cure retardation, i.e., the scorch time, cure time, and activation energy of the vulcanization reaction increased with increasing TA content. However, the increase in TA content enhanced a rubber‐filler interaction, as evidenced by the considerable increase in bound rubber content. Such an enhancement resulted in the improvement of certain mechanical properties, including hardness, modulus, tensile strength, and tear strength. This research showed that tannic acid can be used as a surface‐modifying agent in NBR/PBA composites. [ABSTRACT FROM AUTHOR]

The present study provides a state of the art on methods for evaluating active chain density of rubbers from swelling experiments. This review focuses more particularly on the effects of components that are known to limit the swelling, and which typically results in an overestimation of the active chain density. These components are commonly considered as insoluble. Different corrections dealing with the two principal insoluble components, namely zinc oxide (Zn0) and carbon black (CB) filler, are thoroughly investigated. A comparative study on the same natural rubber (NR), either filled and unfilled, vulcanized with three different vulcanization systems, is performed to evaluate the relevance of each predictive approach. The results obtained highlight their respective limitations. In particular, it is shown that the swelling ratio of unfilled and filled natural rubbers are linearly related, suggesting that fillers have no significant effect on the overall number of cross‐links formed during vulcanization. As a result, we propose a unified approach for correcting the ZnO content for unfilled NR and both the ZnO and CB contents for filled NR. By comparing with results issued from uniaxial tensile tests, it is shown that the use of a mechanical response is a relevant alternative for determining the active chain density. [ABSTRACT FROM AUTHOR]

Elemental sulfur has shown to be a promising alternative feedstock for development of novel polymeric materials with high sulfur content. However, the utilization of inverse vulcanized polymers is restricted by the limitation of functional comonomers suitable for an inverse vulcanization. Control over properties and structure of inverse vulcanized polymers still poses a challenge to current research due to the dynamic nature of sulfur‐sulfur bonds and high temperature of inverse vulcanization reactions. In here, we report for the first time the inverse vulcanization of norbornenyl pentafluorophenyl ester (NB‐PFPE), allowing for post‐modification of inverse vulcanized polymers via amidation of reactive PFP esters to yield high sulfur content polymers under mild conditions. Amidation of the precursor material with three functional primary amines (α‐amino‐ω‐methoxy polyethylene glycol, aminopropyl trimethoxy silane, allylamine) was investigated. The resulting materials were applicable as sulfur containing poly(ethylene glycol) nanoparticles in aqueous environment. Cross‐linked mercury adsorbents, sulfur surface coatings, and high‐sulfur content networks with predictable thermal properties were achievable using aminopropyl trimethoxy silane and allylamine for post‐polymerization modification, respectively. With the broad range of different amines available and applicable for post‐polymerization modification, the versatility of poly(sulfur‐random‐NB‐PFPE) as a platform precursor polymer for novel specialized sulfur containing materials was showcased. [ABSTRACT FROM AUTHOR]

Chloroprene rubber (CR) is an expensive and frequently used material in many industries. Thus, a blend of natural rubber (NR) and CR can be used to balance cost and product performance. In this research, the primary objective is to achieve the ideal blend of CR/NR rubber for automotive industry by simultaneously optimizing various response variables, including hardness, tensile strength (TS), vulcanization index (CRI), torque difference and Tan δ. This optimization process is carried out using response surface methodology (RSM) and desirability functions. The study delves into examining the influence of accelerators, retarders, curatives, and the ratio of NR in the final batch on both curing characteristics and mechanical properties. The investigation is conducted through the application of analysis of variance (ANOVA) and linear/nonlinear regression models with the assistance of Design Expert 11. When the quantities of the fillers, TMTM80, DP80, S80, and CTPI80, are at their optimum levels of 1.08, 1.78, 3.5, and 0.96 PHR, respectively, and the NR ratio in the final masterbatch is around 27%, the estimated values for Tan δ, hardness, and TS are approximately 0.144, 55.183 Shore A, and 21.085 MPa, respectively. The observations from the validation experiments align with the predicted outcomes, as all response variables fall within the 95% prediction interval. It is noteworthy to mention that prior research has not attempted simultaneous optimization for CR/NR blend, incorporating these fillers. [ABSTRACT FROM AUTHOR]

Highlights The valorization of plant wastes for developing environmentally friendly composites has garnered increasing attention over the past two decades. The management of a significant quantity of Nile rose plant waste presents a mounting challenge, particularly in light of escalating water demand. This study delves into the impact of Nile rose fiber (RF) loading and utilizing Vinyltrimethoxysilane (VTMS) as a coupling agent on the characteristics of a composite comprising RF and natural rubber (NR). The verification of the fiber structure treated with silane (TF) was accomplished via Fourier transform infrared (FTIR) spectroscopy. The crosslinking between the NR matrix and the fibers is promoted by the formation of siloxane (SiOSi) linkages in 1050–1100 cm−1. An extensive evaluation of the impact of RF on the characteristics of NR composite was conducted, encompassing morphological properties, mechanical characteristics, and water absorption resistance. The results of the morphological analysis revealed that the modification of RF with silane enhanced the interfacial adhesion between RF and NR. Furthermore, the tensile strength (TS) of NR increases to values of 7.31 and 8.5 MPa by an improvement of 61% and 88% when 10 and 15 phr of TF are added, respectively. Moreover, rubber composites with silane exhibited superior water resistance to those without it across various filler loadings. Specifically, the composite with 20 phr TF absorbed 7% water, whereas the counterpart with untreated fiber (RF) absorbed 12.5% water. The analysis of swelling validated that the interaction between the RF and NR is significantly impacted by the modification of fiber and its incorporation into the composite, as evidenced by the decreased swelling index values from 367% to 298% observing in composites incorporating TF as opposed to those containing RF. Silane treatment improves the interaction between RF and NR. The TF and NR matrix interacted more and developed an interfacial bonding. The rate of vulcanization is accelerated in the presence of treated RF. TF/NR composites have fewer voids and microcracks, inhibiting water diffusion. 15% TF content optimal for good physical and mechanical properties. [ABSTRACT FROM AUTHOR]

This research aims to investigate the effect of reduced graphene oxide (rGO) on the kinetics of addition vulcanization in polydimethylsiloxane (PDMS) elastomers. For this purpose, the synthesis of graphene oxide (GO) and silane‐grafted GO followed by chemical reduction of particles was conducted to prepare rGOs with different surface chemistry. Particles were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, x‐ray diffraction, scanning electron microscopy, and energy‐dispersive x‐ray analysis. Composites of PDMS containing these particles were prepared by solution mixing, and vulcanization of composites was investigated using differential scanning calorimetry. Results showed that the rate and degree of vulcanization reaction increase up to a critical concentration of particles and then decrease afterward. This behavior was attributed to the catalytic effect of chemical groups on the surface of rGOs, whereas the reverse behavior above the critical concentration was correlated to the immobilization of trapped rubber in the network of particles. Grafting graphene oxide by a long alkyl‐chain silane covered these chemical groups, suppressed the catalytic effect, improved the dispersion of particles, and shifted the critical concentration lower. The critical concentration was correlated to the electrical percolation threshold of particles and confirmed by the solvent swelling method. It was also shown that rGO can itself act as the catalyst for the vulcanization of PDMS with no need for platinum. As the dynamic‐mechanical‐thermal analysis showed, the PDMS composites containing 0.75 wt% of particles did not vulcanize properly. However, composites containing fewer particles were vulcanized. Highlights: Reduced graphene oxide affects additional vulcanization of PDMS.Below a critical loading, rGO accelerates vulcanization by a catalytic effect.Above critical loading, rGO decelerates vulcanization by a networking effect.Surface groups of rGO control catalytic and networking mechanisms.Silane modification of rGO affects interfacial behavior, thus critical loading. [ABSTRACT FROM AUTHOR]

In this study, composites obtained through low-temperature carbonization of elastomeric matrix highly filled with graphite, carbon black and short carbon fibers were studied for the purpose of determining residual stresses at different scales using a combination of several complementary methods. The state-of-the-art techniques included X-ray stress analysis using the sin2 ψ method, the micro-ringcore technique via Focused Ion Beam milling and Digital Image Correlation (FIB-DIC), the contour method, the strain gauge method, and the hole drilling technique with digital laser speckle pattern interferometry (DLSPI). It was found that the contour method could not be used implemented for residual stress evaluation due to the low electrical conductivity of composite. Moreover, the DLSPI hole drilling method did not reveal any fringes indicating significant residual stress level exceeding a few MPa. The strain gauge method also revealed a narrow residual stress distribution with an average value of approximately zero. In contrast, the X-ray sin2 ψ method as well as FIB-DIC technique both returned values of about 150-250 MPa. A hierarchical model of the composite is proposed based on the Davidenkov Type I-II-III stress classification that provides an explanation of these observations. [ABSTRACT FROM AUTHOR]

The goal of this work was to develop acrylonitrile–butadiene (NBR) elastomer composites filled with hydroxyapatite (HAP) characterized by improved cure characteristics and resistance to burning. Silane, i.e., (3-aminopropyl)-triethoxysilane, ionic liquid, i.e., 1-decyl-3-methylimidazolium bromide and surfactant, i.e., cetyltrimethylammonium bromide, were used to improve the filler's dispersibility in the elastomer matrix and to reduce the time and temperature of vulcanization. The effects of HAP and dispersants on the cure characteristics, crosslink density and physico–chemical properties of NBR composites were explored. The additives used, especially the ionic liquid and surfactant, effectively improved the dispersion of HAP in the NBR matrix. The amount of HAP and the dispersant used strongly affected the cure characteristics and crosslink density of NBR. The optimal vulcanization time significantly increased with HAP content and was pronouncedly reduced when ionic liquid and surfactant were applied. In addition, ionic liquid and surfactant significantly lowered the onset vulcanization temperature and improved the crosslink density and hardness of the vulcanizates while impairing their elasticity. HAP and dispersants did not significantly affect the damping properties or chemical resistance of NBR vulcanizates. Above all, application of HAP considerably enhanced the resistance of vulcanizates to thermo-oxidative aging and reduced their flammability compared with the unfilled NBR. [ABSTRACT FROM AUTHOR]

A novel accelerator, cerium cysteine (Ce-Cys) was synthesised by double replacement reaction. The complex was characterised by FT-IR analysis, thermal analysis, EDTA titration and elemental analysis, respectively, to determine that the molecular formula of the complex was Ce (Cys)3Cl3·3H2O. Cure characteristics, crosslink density, mechanical properties and thermo-oxidative ageing of NR compounds were investigated. The research revealed that the vulcanisates containing Ce-Cys manifested high scorch time, outstanding mechanical properties, and better thermo-oxidative ageing properties. Furthermore, based on kinetic calculations, it was concluded that as the amount of Ce-Cys increased, the reactivity of the crosslink precursor increased while the activation energy decreased. [ABSTRACT FROM AUTHOR]

Non-linear rheological behaviours of high fluorine content fluoroelastomer (HF-FKM) mixtures with varied carbon black (CB) filling amounts were investigated. Non-linear viscoelastic characteristics of HF-FKM mixture are characterised by large amplitude oscillatory shear (LAOS) tests, correlations between rheological behaviour and CB content were then discussed. Each non-linear viscoelastic parameter of HF-FKM mixture presents a three-stage characteristic with increasing CB content, corresponding to ranges of 0–20 phr, 25–30 phr, and 35–45 phr. Three stages of viscoelasticity characteristics for HF-FKM mixtures were considered to depend on the alteration of CB-elastomer network structure with increasing CB content, corresponding to the states where continuous phase of gum, CB-elastomer mesophase and excessive CB agglomerates predominate in mixture compound, respectively. After vulcanisation, samples with 30 phr CB content show the best resilience performance against thermal ageing, contributing to the existence of CB-elastomer mesophase. Samples with 25 phr CB content possess the second lowest compression sets at 225 and 250 °C ageing conditions but perform no better than those with 35 phr at 275 °C. The reason is presumed to be that the presence of excessive CB agglomerates in HF-FKM vulcanisate reduced irreversible deformation of the CB-elastomer network under compression at elevated temperatures. [ABSTRACT FROM AUTHOR]

Natural rubber latex (NRL) collected from various Hevea brasiliensis clones, namely RRIM600, RRIT251, and PB235, was used to prepare vulcanized natural rubber. The influence of protein content in various natural rubber clones on storage hardening, tensile properties, and thermal properties was investigated. It was found that the RRIM600 clone exhibited the highest protein content. The increased storage hardening is related to the higher protein content in the latex. The cure characteristic of vulcanized natural rubber depends on the proteins in NRL and acts as an activator in vulcanization system. Moreover, the RRIM600 clone exhibited the maximum of 300% modulus, 500% modulus, tensile strength, and thermal stability. This is attributed to the chemical interaction (H-bonding interaction), physical crosslink (entanglement), and also the presence of strain-induced crystallization in natural latex molecules. Thus, this study is aimed to understand the key role of non-rubber components from different clones on the networking structure. The concept utilized in this study holds great potential for a wide range of applications, leveraging the properties of natural rubber latex collected from diverse clones. [ABSTRACT FROM AUTHOR]

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accelerators are indispensable additives in rubber vulcanization reactions. Hypo‐sulfonamide accelerators are widely used due to their fast vulcanization speed. However, the short vulcanization induction period compromises the processing safety of rubber. In this paper, we incorporated experiments with molecular simulations to investigate the underlying reasons for the different effects of various hypo‐sulfonamide accelerators The vulcanization induction period of each accelerator was investigated according to the vulcanization curves. Furthermore, the corresponding reaction mechanism was explored from the molecular scale through quantum mechanical and molecular dynamics simulations. Subsequently, the research focus was discussed in depth. The compatibility relationship between the accelerators and the rubber materials was verified through the crosslinking density test, and a coincidence between the experimental and simulation results was found. This study guides the selection and improvement of hypo‐sulfonamide accelerators and corroborates the factors influencing the vulcanization induction period of natural rubber by accelerators. Highlights: Reactivity of accelerators calculated by quantum mechanical simulations.Difference in solubility parameter characterizes accelerator/NR compatibility.Mobility and diffusion coefficient reflect the diffusion ability of the promoter.Molecular simulation results are consistent with experimental results. [ABSTRACT FROM AUTHOR]

The solidification technology of natural rubber exerts a significant impact on the properties of natural rubber. The solidification technology of alkaline protease has been highly valued by researchers at home and abroad because of its good solidification effect, excellent vulcanization performance, and low pollution. In this study, the effects of alkaline protease solidification technology and enzyme dosage on the structure and properties of natural rubber were investigated and compared with those of formic acid solidification technology. The solid‐state NMR results showed that increasing the enzyme dosage increased the molecular chain entanglements in the raw rubber. The gel content test results showed that the natural network structures (i.e. gels) increased after the addition of alkaline protease. The test results of the vulcanization characteristics showed that the addition of alkaline protease significantly shortened the positive vulcanization time. The Mw was the largest at an enzyme dosage of 0.07%. The test results for mechanical properties showed that the mechanical properties were best when the enzyme dosage was 0.07%. In addition, as the alkaline protease dosage increased, the Akron abrasion volume of natural rubber decreased, and the Akron abrasion volume was the lowest at an enzyme dosage of 0.07%. [ABSTRACT FROM AUTHOR]

Selecting the optimal settings for the production of rubber goods can be a very time-consuming and resource-intensive process. A promising method for optimizing rubber processing in a short period of time is the use of simulation routines. However, process simulations have only recently enabled meaningful predictions of not only the part's state of cure but also its mechanical characteristics. As a first approach, second-order polynomials were considered suitable for describing the properties of compression-molded parts. However, more precision is required for injection molding due to the narrower distribution of mechanical characteristics of parts produced at different vulcanization temperatures. This became evident when the approximation of mechanical data with second order models partly revealed significant failures of part behavior prediction. To tackle this issue, a combined approach for approximation is proposed in this contribution by means of logistic growth function in addition to second order polynomials. To feed the model, an experimental plan was designed for producing injection-molded parts from an SBR compound at various temperatures and to different degrees of cure. The parts obtained were then characterized mechanically, and the results were opposed to varying degrees of cure and extents of reaction to calculate the model coefficients. Once available, a simulation-based calculation of the mechanical part quality is possible. The comparison of test results from the simulation and the real process has shown a reliable prediction, as simulation results were found within the natural deviation of the real measurements. [ABSTRACT FROM AUTHOR]

Rubber compounds based on acrylonitrile‐butadiene rubber were filled with biopolymer fillers, namely kraft lignin, and calcium lignosulfonate. For cross‐linking of rubber compounds, sulfur curing system, dicumyl peroxide, and combination of dicumyl peroxide with trimethylolpropane trimethacrylate were used. The main objective of the work was to investigate the influence of biopolymer fillers content and curing system composition on vulcanization process of rubber compounds, cross‐link density, morphology, and physical‐mechanical properties of vulcanizates. The results revealed that rubber compounds filled with calcium lignosulfonate can be efficiently cured with sulfur as well as peroxide curing systems. Modulus, hardness, and elongation at break were strongly dependent on cross‐link density. Vulcanizates filled with high content of lignosulfonate exhibited comparable values of tensile strength, regardless of the curing system applied. The application of kraft lignin into peroxide systems cured rubber compounds resulted in undesirable reactions between functional groups of the biopolymer and peroxide radicals. Depletion of peroxide radicals resulted in significant deceleration of curing process and decrease in cross‐link density of vulcanizates. This was reflected in typical change of physical‐mechanical characteristics, decrease in modulus and hardness, and increase in elongation at break. Very good adhesion and compatibility between the kraft lignin and the rubber matrix resulted in enhancement of tensile behavior of vulcanizates cured with sulfur system. [ABSTRACT FROM AUTHOR]

The combination of silicone rubber (SR) and ethylene‐propylene‐diene monomer (EPDM) could have an aggregate of their properties. High temperature vulcanized (HTV) is one of the most widely used SR type. This study explores the impact of montmorillonite Cloisite® layered silicate nanoclay on the vulcanization characteristics, mechanical‐dynamical behavior, and thermal properties of the HTV/EPDM blend. For this purpose, varying ratios of the HTV/EPDM compounds were prepared in the range of 100/0, 50/50, and 0/100, with 0, 3, and 5 wt% of Cloisite® using an internal mixer. The X‐ray diffraction results indicate that the mixing time, Cloisite® content and base polymer significantly influence the distance between Cloisite® layers. Cloisite® was found to accelerate the curing system and reduce the difference between minimum and maximum torque. The mechanical analysis of the prepared HTV/EPDM/clay nanocomposites revealed an increase in hardness, tensile strength, and modulus for samples with applied Cloisite® content. The degradation temperature was raised in HTV base samples by the presence of Cloisite®. On the other hand, the degradation temperature was dropped in the EPDM base samples as the amount of Cloisite® increased. In the HTV/EPDM/clay compounds, the degradation temperature was between the degradation temperatures of pure HTV and EPDM rubbers. [ABSTRACT FROM AUTHOR]

Immersed tube tunnel is the main structural form of cross-sea channel, the waterproof and tightness of immersed tube joints are crucial, which directly affects the safety and durability of the whole life of the project. OMEGA waterstop is the second waterproof device of the tube joint, its installation surface space is narrow, the working space is limited, and it has significant cross impact with other construction in the tunnel. Combined with the Shenzhen -Zhongshan Link immersed tube tunnel engineering, this paper introduces the OMEGA waterstop installation and construction technology in confined space of large steel shell immersed tunnel. This technology has the advantages of simple construction, flexible operation, high construction efficiency, and low impact on other processes. It can provide reference and experience for the installation of waterstops in pipe gallery structures such as immersed tunnels, underwater open-cut tunnels, and metro projects in the future. [ABSTRACT FROM AUTHOR]

Natural rubber (NR) composites have been widely applied in damping products to reduce harmful vibrations, while rubber with only a single composition barely meets performance requirements. In this study, rubber blend composites including various ratios of NR and styrene butadiene rubber (SBR) were prepared via the conventional mechanical blending method. The effects of the rubber components on the compression set, compression fatigue temperature rising and the thermal oxidative aging properties of the NR/SBR blend composites were investigated. Meanwhile, the dynamic mechanical thermal analyzer and rubber processing analyzer were used to characterize the dynamic viscoelasticity of the NR/SBR blend composites. It was shown that, with the increase in the SBR ratio, the vulcanization rate of the composites increased significantly, while the compression fatigue temperature rising of the composites decreased gradually from 47 °C (0% SBR ratio) to 31 °C (50% SBR ratio). The compression set of the composites remained at ~33% when the SBR ratio was no more than 20%, and increased gradually when the SBR ratio was more than 20%. [ABSTRACT FROM AUTHOR]

Purpose: One of the low-cost minerals that can be used as reinforcing filler in polymer industry is pumice powder. Pumice is a highly porous volcanic glass formed during explosive eruptions. This pumice has received significant interest because of its large surface area with various polar groups and can be processed easily. Design/methodology/approach: This study is carried out to investigate the effect of partial replacement of silica (as traditional filler) by naturally occurring pumice powder to improve the thermal and mechanical properties of nitrile butadiene rubber cured with electron beam radiation (doses from 25 to 150 kGy). Findings: The results indicated that the addition of pumice powder increase the tensile strength at lower doses up to 75 kGy (especially at concentration of 5 phr). Besides, an improvement in the thermal stability was attained with the addition of pumice powder. Originality/value: Pumice powder is volcanic-based alumina and silica which is mainly composed of SiO2. It has porous structure which is formed by dissolved gases precipitated during the cooling as the lava hurtles through air. Due to its porous structure, it has low density and high thermal insulation. It also has high temperature and chemical resistance, for these reasons it became preferable material to be used as filler in the plastic and rubber industry. [ABSTRACT FROM AUTHOR]

Background: Allergic contact dermatitis (ACD) from rubber glove usage is usually caused by rubber additives such as the accelerators. However, in analyses of the suspected gloves, ordinary rubber allergens are not always found. Accelerator‐free rubber gloves are available, but some patients with accelerator allergy do not tolerate them and might also be patch test positive to them. Objectives: To identify and chemically characterize a new allergen, 2‐cyanoethyl dimethyldithiocarbamate (CEDMC), in rubber gloves. We describe two patient cases: patient 1 that led us to the identification of CEDMC and patient 2 with occupational ACD caused by CEDMC. Methods: The patients were examined with patch testing including baseline and rubber series, and their own rubber gloves. High‐performance liquid chromatography (HPLC) was used for chemical analysis of rubber gloves. The allergen was synthesized and identified by nuclear magnetic resonance, mass spectrometry and infrared spectrometry, and tested on patient 2. Results: CEDMC was identified by HPLC in a nitrile glove associated with hand eczema in patient 1. Patient 2 whose nitrile gloves contained CEDMC was patch test positive to CEDMC. Conclusions: CEDMC is a new contact allergen in nitrile gloves and probably forms during vulcanization from residual monomer acrylonitrile and rubber additives. [ABSTRACT FROM AUTHOR]

Acid coagulation is the most traditional latex coagulation technology, but this coagulation process leads to delayed vulcanization, corrosiveness, and environmental pollution. Different coagulation processes significantly impact the raw rubber network structure, leading to differences in the properties of both raw rubber and rubber vulcanizates. Raw rubber was prepared by three acid‐free coagulation processes: freeze, microwave, and flash drying. The network density, molecular chain flexibility, molecular weight, processing fluidity, and plasticity retention of the raw rubber were characterized, and the vulcanization characteristics, viscoelasticity, mechanical properties, and dynamic mechanical properties of the cured rubber composites were investigated. Raw rubbers prepared by microwave drying and flash drying had higher crosslink density, more flexible molecular chains, larger molecular weight, and wider molecular weight distribution, thereby increasing the crosslink density of rubber vulcanizates. The crosslink density of the raw rubber prepared by microwave drying versus the acid coagulated raw rubber increased by 51% to 105.71 mol/m3, the tensile strength increased by 16% to reach 28.12 MPa, and the elastic modulus and rolling resistance under dynamic stress increased. This paper provides a new idea for analyzing the relationship between the raw rubber network structure and the properties of vulcanized rubber. Highlights: Acid‐free raw rubbers are prepared by freeze, microwave, and flash drying.Coagulation processes significantly impact the raw rubber network structures.Effects of raw rubber network structures on properties are investigated.Crosslink density, plasticity retention, and tensile strength are improved. [ABSTRACT FROM AUTHOR]

A sensitizer or crosslinking promoter must be utilized to improve electron beam irradiation (EBI) vulcanization and achieve optimal results. This work investigated the effect of sensitizers, that is, sulfur and trimethylolpropane trimethacrylate (TMPT), on the properties of EBI‐vulcanized natural rubber (NR). The experiments focused on analyzing the effect of different amounts of sensitizers, that is, 2 and 3 phr, on the swelling, crosslink density, entanglement, and mechanical properties of NR latex. A sample without sensitizers was taken as a reference. Results revealed that the crosslink density of the samples with sensitizers had improved compared with that of the sample without a sensitizer. The sample with sulfur exhibited higher crosslink density than the NR with TMPT. The sulfur‐containing NR exhibited superior mechanical properties, i.e., modulus, tensile strength, and tear strength, as its crosslink density increased. In addition, increasing the sulfur content reduced the crosslink density of the NR latex, resulting in inferior mechanical properties. Furthermore, the different forms, that is, latex and film, of NR were compared. The latex form revealed higher crosslink density than the film form, thus presenting high mechanical properties because it contained water, which could induce the formation of free radical species and enhance crosslinking. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) has gained significant attention as a commercially available biodegradable and biocompatible polymer. However, the brittleness of PLA greatly limits its application. Blending PLA with another rubbery polymer such as thermoplastic polyurethane (TPU) is a simple strategy to toughen PLA. In this study, a largely toughened PLA has been successfully prepared by melt blending with TPU through interfacial compatibilization induced by the simultaneous addition of hydrophobic silica nanoparticles (NPs) and in situ cross‐linking reaction. The torque evolution during melt mixing and rheological analysis confirm a successful dynamic vulcanization process. Scanning electron microscopy images indicate that, dynamic vulcanization and adding NPs synergistically compatibilize the TPU and PLA phases leading to a considerable interfacial adhesion between the phases. Simultaneous addition of NPs at an optimum amount of 5 wt% and in situ cross‐linking reaction significantly improve the elongation at break, and tensile toughness of the PLA/TPU blend as they are achieved 311%, and 91 MJ/m3, respectively. Both dynamic vulcanization and NPs play their role independently in the compatibilization of PLA and TPU phases inducing substantial shear yielding of the matrix phase under stress resulting in a highly toughened blend. The microstructural properties of the blends are studied by rheological analysis. [ABSTRACT FROM AUTHOR]

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Zinc oxide (ZnO) is widely used as an activator in the vulcanization process of natural rubber. However, due to its poor compatibility with natural rubber, a large amount of ZnO needs to use, and the unreacted ZnO can precipitate in various ways, posing significant harm to aquatic organisms and microorganisms. Therefore, it is necessary to reduce the dosage of ZnO in order to minimize its environmental impact. In this study, we applied ZIF‐8, a zinc‐based metal–organic framework, as a vulcanization additive in natural rubber. and it was found that ZIF‐8 could promote the rubber vulcanization reaction by adsorbing sulfur, promoting sulfur ring‐opening, and providing different ligand interactions of Zn2+. Moreover, even at low usage levels of ZIF‐8, it effectively reduces the amount of ZnO while simultaneously improving the mechanical properties of the samples. This work provides an effective method to reduce the amount of ZnO without sacrificing the rubber properties and provides a new idea for the application of ZIF‐8 in rubber materials. Highlights: ZIF‐8 enhances properties of natural rubber composites with low ZnO dosages.Revealing the reason why ZIF‐8 promotes the vulcanization of natural rubber.Investigation of the effect of ZIF‐8 on the vulcanization properties of natural rubber. [ABSTRACT FROM AUTHOR]

This work reported a practical approach to turning conventional natural rubber (NR) into a thermally healable rubber. 4-vinylbenzyl chloride was first polymerized in the NR latex to yield graft copolymers of NR and poly(vinylbenzyl chloride), NR-g-PVBC. The cutting and rejoining process was used to study the healing ability of latex film. The healing behavior was observed after the reassembled film was heated at 100 °C for 1 h and then allowed to heal continuously at room temperature (RT). The healed film displayed a 58.44% regain of the tensile strength (4.57 MPa) after being allowed to recover at RT for 72 h. Additionally, the chloromethyl moieties in the NR-g-PVBC could be converted into quaternary ammonium (QA) groups by reaction with trimethylamine, producing the quaternized NR-g-PVBC (NR-g-QPVBC). Ionic crosslinking of the NR-g-QPVBC film was achieved by incorporating sodium tripolyphosphate (STPP). The latex film had a tensile strength of 15.32 MPa and could withstand a strain of 868% when ionically cured with 2 phr of STPP. After the healing process, the cured film showed a healing efficiency of 49.67% in tensile strength (7.61 MPa). Furthermore, a suturing test was performed to investigate the feasibility of developing a suture training pad from the corresponding cured film. The film’s ability to heal with heat assistance was its significant practical advantage, enhancing its realism and mimicking the healing process in human skin.

Epoxidized natural rubber with 50 mol% epoxide (ENR-50) was compounded with zinc chloride (ZnCl2) and subjected to torque response analysis using a moving die rheometer. It was found that different ZnCl2 concentrations (3, 5, 7, 9, and 12 millimoles (mmol)) mixed in ENR-50 exhibited positive torque responses, prompting further molecular characterization using Fourier transform infrared spectroscopy. The results indicated distinct absorption peaks at wavenumbers of 442 and 809 cm–1, which signify the presence of –O–Zn–O– coordination linkages. The curing characteristics of ENR and ZnCl2 compounds showed that increasing ZnCl2 content resulted in higher minimum and maximum torque values, but also led to a decrease in scorch time and cure rate index (CRI). Moreover, higher ZnCl2 concentrations enhanced the strength properties (tensile strength, moduli, stiffness, toughness, and hardness), crosslink densities, dynamic shear moduli, initial modulus during relaxation experiments, and thermal resistance, as evidenced by temperature scanning stress relaxation (TSSR), thermogravimetric analysis, and dynamic mechanical analysis. However, an increase in ZnCl2 content led to a reduction in elongation at break due to the higher crosslink density within the coordination networks in the ENR matrix, which resulted in the movement constraint of the rubber vulcanizate.

Research into sustainable packaging materials has gained increasing importance due to the pressing environmental concerns related to plastic waste. The present study focused on developing a sustainable paper coating based on modified natural rubber (NR) latex filled with gelatin (GT). The graft copolymer latex of NR and poly(vinylbenzyl chloride) bearing quaternary ammonium groups, abbreviated as NR-g-QPVBC, was first synthesized. GT was then incorporated into the latex, and the combination of these materials resulted in a heat-sealable film with good tensile properties and a water barrier. The ionic crosslinking of the latex film was achieved by the reaction with ethylenediaminetetraacetic acid (EDTA). Heat-sealing studies of the NR-g-QPVBC latex film filled with GT (NR-g-QPVBC/GT) revealed its heat-sealability at 160 °C. Scanning electron microscope (SEM) analysis further confirmed the diffusion of the chains across the interface during heat sealing. Dip coating was a method for depositing latex film on kraft paper. The paper coated with the NR-g-QPVBC/GT latex showed a significant increase in dry and wet-tensile strength compared to the uncoated paper. The sealing process was optimized to achieve a heat-seal strength of 755.31 N/m at a dwell time of 3 s and a temperature of 160 °C. The research's practical application was demonstrated by transforming the coated paper into various heat-sealable bags using a handheld bag sealer.

Natural rubber (NR) composites reinforced with sepiolite and crosslinked with phenolic resin were prepared. Effects of compatibilizer types and contents, namely 3-aminopropyl triethoxysilane (APTES) or epoxidized NR (ENR50), on curing, tensile, strain-induced crystallization, and stress relaxation were investigated. Compared to APTES, ENR50 provided a greater compatibilizing effect in the NR composites. The ENR50 introduced strong physical and chemical interactions between sepiolite and NR, while only physical interaction was present in the APTES compatibilized composites. Stronger interaction between rubber and sepiolite improved filler dispersion, swelling resistance, and tensile strength; and delayed stress relaxation of the composite. Increased addition of ENR50 improved the modulus and tensile strength, and the greatest tensile strength was achieved at 2 phr ENR50 with a 15% improvement over composite without compatibilizer. In the case of APTES, 2 phr level enhanced tensile strength, but a further increase in APTES content degraded tensile, swelling resistance, and stress relaxation responses, due to its plasticizing effect. Moreover, ENR50 enhanced the strain-induced crystallization and delayed stress relaxation of the composites more than APTES. Weaker interaction between rubber and filler in APTES filled composites was due to having only hydrogen bonds formed between rubber and filler, in addition to crosslinks.

Given the increasing need for sustainable solutions and the large amount of improperly discarded end‐of‐life tires, recovered carbon black (rCB) from tire pyrolysis was investigated as a filler for rubber composites. This study considered rCB as an alternative to commercial carbon black due to its sustainability and CO2 emissions reduction. Composites with varying rCB contents (0 to 50 per 100 rubber) were produced and assessed for mechanical properties, such as hardness, abrasion resistance, and rheometric tests. The findings were used to train artificial neural networks (ANNs) with MATLAB software to predict rCB contents. Input parameters included optimal curing time, minimum and maximum torque, and results of mechanical tests like Shore A hardness and abrasion loss. The model was trained on data from 90 samples, with 10 reserved for validation. The predicted outcomes closely matched the experimental data, with a maximum prediction error of less than 3%. This indicates that ANNs are effective tools for intelligently modeling the curing process of natural rubber mixtures, minimizing material waste, optimizing production time, and determining suitable carbon black contents for desired mechanical properties. [ABSTRACT FROM AUTHOR]

This study investigates the impact of aging in methyl diethanolamine (MDEA) solution on cured rubber compounds comprising ethylene‐propylene‐diene monomer rubber (EPDM), butyl rubber (IIR), and blends, utilizing nano (nZnO) and conventional (ZnO) zinc oxides as curing activators. The analysis reveals that MDEA solution induces degradation in the rubber matrix by grafting amine and amide groups onto the rubber backbone, particularly affecting unsaturated units in diene monomers in EPDM and isoprene units in IIR. The Fourier‐transform infrared (FTIR) analysis validated the addition of these functional groups. Aging contributed to the formation of a thin rubber layer covering carbon black particles, likely due to un‐crosslinking and rubber chain scission, resulting in changes in bound rubber as observed in scanning electron microscopy (SEM) images. Tensile strength and elongation at break typically decreased with aging, with EPDM compounds exhibiting the highest initial tensile strength and IIR compounds demonstrating superior initial elongation. Hardness remains largely unaffected by aging. This study showed the detrimental effects of MDEA exposure on rubber compounds, emphasizing the critical importance of material selection and property tailoring for specific applications in MDEA‐rich environments, such as gas refineries. [ABSTRACT FROM AUTHOR]

Dibutyl phosphate-bound natural rubber (DBNR) was prepared by reacting epoxidized natural rubber with 20 mol% (ENR-20) with dibutyl phosphate in a latex medium. Fourier transform infrared spectroscopy (FTIR) was used to confirm the molecular structures of ENR-20 and DBNR and to quantify the epoxide contents. The shear flows and thermal properties of DBNR were then characterized and compared with ENR-20 and natural rubber (NR). The DBNR exhibited the lowest viscosity curves, but it depicted the highest glass transition temperature (Tg) and residue from thermogravimetric evaluation, indicating higher thermal resistance. Subsequently, different NR/DBNR blend ratios were compounded, with and without flame resistance additives, compared with unmodified NR and chloroprene rubber (CR) compounds. We found that all natural rubber compounds exhibited reversion behavior due to the breakage of newly formed sulfidic bonds. However, chloroprene rubber showed marching cured curves, as evidenced by the increasing torque with prolonged testing time. Additionally, antimony trioxide retarded the curing reaction of NR, while tris(2-ethylhexyl) phosphate accelerated it. Therefore, the combination of these additives synergists with the intrinsic flame retardant properties of DBNR. The study revealed that the burning rate of NR/DBNR blends, exhibited very high flame resistance capability compared to gum NR and NR compounded with flame resistance additives.

The structure and property relationships of graft copolymers from natural rubber (NR) and polymethyl methacrylate (PMMA) crosslinked with a phenolic resin were investigated. The NR grafted with PMMA (NR-g-PMMA) having different grafting levels was initially prepared by emulsion polymerization before compounding and vulcanization. Then, proton nuclear magnetic resonance and transmission electron microscopy were used to verify the resultant NR-g-PMMAs. The graft copolymers crosslinked with phenolic resin exhibited improvements in various properties. Tensile modulus and tensile strength increased at least 18 and 95%, respectively, over the un-grafted counterpart and further improved with grafting percentage, while the elongation at break decreased accordingly. Storage modulus in rubbery plateau increased while tanδ peak height decreased with PMMA content. Moreover, the thermal stability of the graft copolymers was also improved over that of the plain NR at least 23 °C, depending on MMA contents. These improvements are tentatively attributed to the strong adhesion between NR and PMMA phases, based on interactions between the functional groups of PMMA and hydrogen bonding between phenolic resin crosslinker and PMMA. The results clearly suggest that the phenolic resin could be an effective crosslinker for NR-g-PMMA.

Thermoplastic vulcanizates (TPVs) were prepared by blending natural rubber (NR) and polypropylene (PP) using dynamic sulfur curing systems with varying accelerator/sulfur ratios: 0.5/2.5, 1.5/1.5, and 2.5/0.5 phr, categorized as conventional (CV), semi-efficient (semi-EV), and efficient (EV). The onset of dynamic vulcanization closely corresponded with scorch time in statically cured NR compounds. Mixing torque decreased over time, reflecting reversion patterns in static curing. The CV system exhibited the highest reversion tendency due to polysulfide linkage breakdown, forming stronger but shorter crosslinks. Dynamic vulcanization induced higher reversion than static curing, influenced by shear and extensional forces. Curing systems caused crosslinking rates, reversion, and crosslink density and distribution variations. Unlike statically cured NR, PP-extracted TPVs exhibited an inverse trend in total crosslink densities and distributions; TPVs primarily comprised shorter crosslinks with opposed total crosslink densities ranked EV > semi-EV > CV. This trend is strongly correlated with superior mechanical strength, toughness, storage modulus, viscosity, and rubber elasticity in the EV-cured TPV. EV system also had the smallest vulcanized NR domains in the PP matrix.

Kauçuk ürünler vulkanizasyonun keşfedilmesiyle beraber günümüzde farklı alanlarda sıkça kullanılmaya başlanmıştır. Bu ürünler beyaz eşya, otomotiv, uçak ve roket sanayi, inşaat ve demir yolu gibi sektörlerde değerli yere sahiptirler. Kauçuk ürünlerin fazla kullanımı kauçuk çeşitliliğinin önemini de arttırmaktadır. Her kauçuk tipinin kendine has özellikleri bulunmaktadır ve kullanım yerlerine göre özel katkı malzemeleri ilaveleriyle bu özellikler daha da geliştirilebilmektedirler. Etilen Propilen Dien Monomer (EPDM) kauçuğu kendine has özelliklerinden dolayı tercih edilen kauçuklar arasındadır ve özel katkı malzemeleri kullanılarak yetersiz yönlerinin geliştirilebilmesi mümkün bir kauçuk türüdür. Bu çalışmanın amacı EPDM kauçuğu kullanılarak oluşturulmuş EPDM karışımına toz grafit katkı malzemesinin ilavesi ile mekanik özelliklerine etkisinin incelenmesidir. Bunun için çalışma kapsamında iki farklı türde kauçuk karışımları oluşturulmuştur. Karışım reçetelerine özel katkı malzemesi olarak toz grafit (EPDM GP) 10 phr oranında eklenmiş, saf karışım reçetesiyle (EPDM 0) reolojik ve mekanik değerleri karşılaştırılmıştır. Kauçuk karışımlarının reolojik değerleri, viskoziteleri, sertlikleri, modül değerleri, kopma mukavemetleri, uzama miktarları, yoğunlukları, külleri, yanma davranışları ve çapraz bağ yoğunlukları analiz edilmiştir. Grafit katkısının kauçuğun mekanik değerlerine olumlu etki ettiği belirlenmiştir. Grafitin karışıma katılmasıyla kauçuk karışımın yanma eğiliminin arttırdığı görülmektedir. Bununla birlikte kauçuk karışıma grafitin eklenmesi çapraz bağ yoğunluklarını (CLD) da arttırmaktadır.

Inverse vulcanization exploits S8 to synthesize polysulfides. However, evolution of products and its mechanism during inverse vulcanization remains elusive. Herein, inverse vulcanization curves are obtained to describe the inverse vulcanization process in terms of three stages: induction, curing and over-cure. The typical curves exhibit a moduli increment before declining or plateauing, reflecting the process of polysulfide network formation and loosing depending on monomers. For aromatic alkenes, in the over-cure, the crosslinked polysulfide evolves significantly into a sparse network with accelerated relaxation, due to the degradation of alkenyl moieties into thiocarbonyls. The inverse vulcanization product of olefins degrades slowly with fluctuated relaxation time and modulus because of the generation of thiophene moieties, while the inverse vulcanization curve of dicyclopentadiene has a plateau following curing stage. Confirmed by calculations, the mechanisms reveal the alkenyl groups react spontaneously into thiocarbonyls or thiophenes via similar sulfur-substituted alkenyl intermediates but with different energy barriers. Inverse vulcanization exploits elemental sulfur to synthesize versatile polysulfides but the mechanism of inverse vulcanization remains elusive. Herein, the authors use inverse vulcanization curves to describe the three-stage structural evolution during the inverse vulcanization process. [ABSTRACT FROM AUTHOR]

Sodium allyl sulfonate (SAS) is a surfactant molecule that has occasional use as a monomer for the formation of functional polymers. A polymerization method is detailed herein, whereby it is demonstrated that the positioning of the individual functional groups can allow for the removal of protons adjacent to a sulfonate position before reaction with an electrophilic center to generate a polymeric material. In this case, sodium polysulfides are applied to promote the formation of a sulfur polymer using a mild synthesis that poses significant safety and energy benefits when compared to other methods of sulfur polymer generation, for example, inverse vulcanization. The polymer product that forms is demonstrated to retain all starting functionalities. Poly‐S‐SAS polymer also demonstrates impressive properties for application as a desiccant with a sorption maximum of 345 w/w % water, or as a flocculant material capable of removing up to 87% of different metals from low ppm solutions rapidly. [ABSTRACT FROM AUTHOR]

The blending of different elastomers can greatly broaden the application range of rubber materials. However, due to the poor compatibility between polar elastomers and non‐polar elastomers, severe phase separation occurs during the blending process, which severely degrades their processing performance and mechanical properties. In this paper, we prepared SBR‐P/XNBR blends by emulsion blending polar modified styrene‐butadiene rubber (SBR‐P) latex with carboxylated nitrile rubber (XNBR) latex. The effects of the blending ratios on the vulcanization behavior, mechanical strength, dynamic mechanical properties, and oil resistance of the rubber compounds were studied. Experimental results showed that the mechanical strength and oil resistance of the modified SBR‐P/XNBR blends are significantly higher than the unmodified SBR and XNBR blends. The dynamic mechanical analysis curve results of the rubber compounds showed that SBR‐P has good compatibility with XNBR. With the increasing addition of XNBR, the oil resistance of the rubber compounds improves, and the solvent adsorption is reduced by over 60%.This study proposes a solution for utilizing non‐polar rubbers, which are typically not oil‐resistant, in oily environments. The proposed solution enables the preparation of composites with excellent mechanical properties in such environments. [ABSTRACT FROM AUTHOR]