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Journal of Rubber Research
Number of Followers: 1  Hybrid journal (It can contain Open Access articles)ISSN (Print) 1511-1768 - ISSN (Online) 2524-3993 Published by Springer-Verlag  [2468 journals]
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- The main service functions and driving forces of rubber (Hevea
brasiliensis) plantation ecosystem in China-
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Abstract: Rubber (Hevea brasiliensis Müll. Arg.) is a major economic crop grown in tropical areas. However, the various service functions of rubber plantations and their benefit to society, the economy and the environment are still unclear. Data on rubber planting areas, dry rubber and wood yields, carbon sequestration and oxygen release capacities, biodiversity, employment, and market prices for natural rubber and rubber wood were collected. Observations of land use patterns and functions were carried out. The results showed that the capacity of average annual carbon stock capacity of rubber plantations in China was 36.51 million tonnes. The accumulation values of carbon sequestration and oxygen release, 416.89 million tonnes and 304.42 million tonnes, respectively. A total of 849 plant species, 60 bird species, 5 species of ground beetle, 25 species of wild bees, 27 ant species, 10 termite species, 87 spider species and 38 hemipterous species were found in rubber plantations. The average annual dry rubber and rubber wood yields were 676,300 tonnes and 1.29 million m3. From 2000 to 2020, 14.20 million tonnes of dry rubber were produced and 27.02 million m3 of wood were harvested. The average annual output of dry rubber and rubber wood was US$1.86 billion, while total output value summed to US$ 39.08 billion from 2000 to 2020. Rubber cultivation and plantation operation activities employed an average of 1.11 million people annually. Land use management and natural disasters may affect the service functions of rubber plantations, which are carbon sequestration and oxygen release, maintaining biodiversity, providing dry rubber and rubber wood, maintaining water and conserving water sources, absorbing employment, changing unsustainable agricultural practices and habits of smallholders and ethnic minorities, and promoting transfer of technologies. In the future, on the basis of recognising and rationally weighing the various functions of rubber plantations and their main driving factors, smallholders are expected to maximise the social, economic and ecological functions of rubber plantations through effective crop management and utilisation of resources.
PubDate: 2023-05-12
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- Hevea brasiliensis latex dialysed C-serum precipitate subfraction exerts a
negligible level of genotoxicity in the Ames test, mouse lymphoma assay
and micronucleus assay-
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Abstract: Dialysed C-serum precipitate (DCP), a sub-fraction of latex C-serum originating from Hevea brasiliensis, has shown specific in vitro antiproliferative properties towards cancer-origin cell lines. As a potential agent to be used in cancer treatment, preclinical safety assessment tests are crucial. This study focused on investigating the mutagenicity of DCP via bacterial reverse mutation assay (Ames test), Mouse lymphoma assay (MLA), and micronucleus assay according to OECD guidelines. No mutagenicity was exhibited by DCP at concentrations lower than 1 mg/mL for the five different auxotroph strains of Salmonella typhimurium (TA 98, TA 100, TA 1535, and TA 1537) and Escherichia coli WP2uvrA pKM101 in the absence and presence of metabolic activation system (S9-mix). Nonetheless, it has been found that DCP was able to induce negligible mutation in MLA and micronucleus assay. Overall, DCP does express dose-dependant mutagenicity according to the assays conducted and thus, it is crucial to take this into consideration should DCP be used in the development of therapeutic agent.
PubDate: 2023-05-05
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- Nanoscale partitioning of carbon black in styrene butadiene rubber and
butadiene rubber miscible blends and its effect on physico-mechanical
properties-
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Abstract: Determining the partitioning of carbon black [CB] in miscible rubber–rubber blends [RRB’s] is a demanding problem in the rubber industry, testing one’s ability (especially tyre industry); hence, this research work aims to investigate the partitioning of CB in miscible styrene butadiene rubber [SBR]/butadiene rubber [BR] blends. SBR:BR with blend ratios of 70:30/50:50 and 30:70 with 50 phr CB were prepared on two-roll mill. Nanoscale partitioning of CB within the nanoscale phase-separated SBR/BR blends was quantitatively determined using dynamic mechanical analysis [DMA]. DMA confirmed 63%, 93%, and 45% of CB partitioning towards BR phases of 70:30, 50:50, and 30:70 in CB-filled SBR/BR blends. An attempt to determine the partitioning of CB was also made by making use of solid-state nuclear magnetic resonance spectroscopy [SS-NMR spectroscopy] to interrelate the partitioning of CB determined using DMA. TEM images were helpful in observing CB's dispersion and network ability in CB-filled SBR/BR blends. The results of CB partitioning confirm maximum partitioning of CB towards the nano-dispersed phase in CB-filled SBR/BR blends and are in well agreement with the constrained regions of BR and mechanical properties of CB-filled SBR/BR blends. Attenuated total reflectance-Fourier transform infrared spectroscopy’s (ATR-FTIR spectroscopy) spectra were used as a tool to determine the interactions within CB-filled rubbers and RRB’s in comparison to their neat counterparts. To the best of our knowledge, partitioning of CB controlled by nanoscale phase-separated morphology and its effect on mechanical properties has not been studied so far; hence, this study would be significant to academics and industrial researchers working in the area of rubber composites.
PubDate: 2023-05-02
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- Publisher Correction: Soluble protein-free natural rubber latex prepared
using guanidine hydrochloride as a denaturant-
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PubDate: 2023-04-27
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- An experimental study using 3-aminoproplymethyldiethoxysilane (APMDS) to
improve biocompatibility of NR latex film-
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Abstract: To improve the biocompatibility of dipped films from natural rubber latex (NRL) without compromising physical strength, high ammoniated NRL (HA-NRL) compounding formulations were devised by manipulating the amount of compounding ingredients and additive materials. In this study, the compatibility of 3-aminoproplymethyldiethoxysilane (APMDS) with calcium carbonate (CaCO3) filler in zinc diethyldithiocarbamate (ZDEC) accelerated HA-NRL formulas were explored. It was found that ZDEC residue detected using High-Performance Liquid Chromatography (HPLC) was less than 6 μ/g in all NRL-dipped films. Furthermore, the cytotoxicity response of the films showed a lower toxicity effect in the presence of APMDS. The occurrence of chemical interactions between APMDS, CaCO3 and crosslinked NR was confirmed by the Attenuated Total Reflectance-Fourier Transmittance Infra-Red (ATR-FTIR) spectrometer. Interestingly, the physical strength of NRL-dipped film was greatly improved when APMDS was incorporated together with CaCO3 at a low dosage of ZDEC. This may be due to the adequate physical interaction between the APMDS-surface-modified filler particles and APMDS-surface-modified rubber particles. Overall, a biocompatible NRL film with satisfactory physical strength, low ZDEC residue and low cytotoxicity was achieved by employing a low dosage of ZDEC in the presence of APMDS and CaCO3.
PubDate: 2023-04-18
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- Soluble protein-free natural rubber latex prepared using guanidine
hydrochloride as a denaturant-
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Abstract: Purified natural rubber was successfully prepared in the presence of a denaturant named guanidine hydrochloride (GNH). In this work, fresh field natural rubber (FNR) latex was used as a starting material. The conditions of purification such as the effect of GNH concentrations, incubation time and temperature were studied. The results showed that the soluble protein-free natural rubber (SPFNR) contained undetectable extractable (EP) and antigenic (AP) protein, and very low nitrogen content, i.e. 0.013 wt% at GNH concentration of 0.1 phr, after 1-h incubation at 30 °C. These results were supported by the Fourier transform infrared (FTIR) spectroscopy, where the absorption peak of the amine functional group (proteins) disappeared substantially and the fatty acid ester functional group (lipids) decreased swiftly after purification. Transmission electron microscope (TEM) images showed that the non-rubber component matrix disappeared in the SPFNR film. Less water hydration was obtained for the SPFNR film, which was reflected by a lower water uptake percentage than the FNR film. Furthermore, the thermal property determined by a thermogravimetric analyzer (TGA) showed that FNR and SPFNR films were comparable to each other. The stress at break showed that the FNR film was superior to the SPFNR film. Interestingly, the strain at break was about similar for both films, indicating the SPFNR film has softer and more elastic characteristics.
PubDate: 2023-04-09
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- The ambivalent effects of heavy metals present in natural rubber latex
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Abstract: Accumulation of heavy metals in plant parts due to environmental uptake may have repercussions on the plant's health and integrity. In this study, we quantified various heavy metals in natural rubber (NR) latex collected from Mantin, Negeri Sembilan, Malaysia (sub-urban area) and Batu Embun, Pahang, Malaysia (rural area) for 12 consecutive months. Acid digestion as sample pre-treatment was performed prior to detection and quantification of the heavy metals, namely Cr, Cu, Fe, Mn, Pb, and Zn, using inductively coupled plasma–optical emission spectrometer (ICP-OES). Then, plasticity test and preparation of polystyrene/natural rubber (PS/NR) blends were conducted to investigate the effects of heavy metals on the integrity of NR. It was found that the plasticity retention index (PRI) was inversely proportional to the concentration of heavy metals in NR. Conversely, high levels of heavy metals in latex had acted as an excellent compatibilizer in PS/NR blends with improved properties of tensile strength and impact energy. The most deposited heavy metals (4391.2 ppm) compatibilized PS/NR blends with the highest tensile strength of 27.4 MPa and impact energy of 17.55 kJ/m2. In contrast, the least accumulated heavy metals (18.8 ppm) resulted in PS/NR blends with the lowest tensile strength (2.61 MPa) and impact energy (2.70 kJ/m2). The phase distribution of PS/NR was observed to be more uniformed when high levels of heavy metals were available in the blends. Our discovery has indirectly demonstrated the role of NR in eliminating heavy metals from the environment which in turn, acting as a good compatibilizer in the blending of PS/NR.
PubDate: 2023-04-04
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- Optimization of the water–cement ratio of rubberized ceramsite
concrete-
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Abstract: Waste-rubberized ceramsite concrete is an improvised building material that is suitable for lightweight wall panels, which can significantly reduce the bulk density of buildings. In this study, the effects of different water–cement ratios on the mechanical properties, water absorption, ultrasonic velocity, and sulfate corrosion resistance of waste-rubberized ceramsite concrete were investigated, and scanning electron microscopy (SEM) was used to study the microscopic interface. The test results show that the water–cement ratio of 0.45 is optimal. The compressive strength, water absorption rate, and ultrasonic velocity of the specimen first increased and then decreased as the water–cement ratio increased. The sulfate corrosion resistance of specimens with a high water–cement ratio is weaker than that of specimens with a low water–cement ratio. It is of great significance to explore the optimal water–cement ratio of the waste-rubberized ceramsite concrete for further research, and it has important production guidance significance for commercial applications.
PubDate: 2023-03-22
DOI: 10.1007/s42464-023-00195-6
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- Improving the sustainability of ‘green’ tyre tread compound by using
recovered silica filler-
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Abstract: In this study, recovered silica fillers from pyrolysis and geothermal sources, referred to as ‘rSilica’ and ‘geoSilica’, respectively, have been mixed with epoxidised natural rubber (ENR) to determine whether they can be used to improve the sustainability of ‘green’ tyre tread compounds. The effect of using silica recovered by a geothermal and pyrolysis process as filler in an ENR compound with and without X50S silane coupling agent was investigated in this study. Both recovered silicas also have been characterised and the physical and mechanical properties of the filled ENR compounds measured. All the results obtained have been compared with the industrial silica grade of Zeosil 1165. Based on the test results obtained, rSilica did show reasonably good physical properties such as tensile strength, hardness and abrasion resistance as well as good processing characteristics compared to the commercial-grade silica (Zeosil). rSilica-filled ENR compounds with silane also showed better physical properties than the non-silane compound, which indicates that rSilica still can react with the silane, despite the fact that the amount of silanol groups on the rSilica surface were reduced by the pyrolysis process.
PubDate: 2023-03-11
DOI: 10.1007/s42464-023-00196-5
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- Properties of compatibilised kenaf-filled recycled high-density
polyethylene/natural rubber blends under natural weathering condition-
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Abstract: In this study, a novel polymeric blend was developed using recycled high-density polyethylene (rHDPE) and natural rubber (NR), along with kenaf fibre as a natural filler. In addition, the blends were compatibilised by maleic anhydride-grafted polyethylene (MAPE) and maleic anhydride-grafted natural rubber (MANR). In addition, this study focussed on the material’s properties after the natural weathering test. Results indicated that the tensile properties dropped over the period of natural weathering due to the chain scission of polymeric backbones and the degradation of kenaf fibre. It was found that the retention of properties after natural weathering was higher over the addition of kenaf fibre. When considering the tensile strength, adding only 10 phr of kenaf enabled to increase the retention up to 25% higher than the unfilled counterpart. However, the retained properties were limited for the blends with the addition of compatibilisers. Adding compatibilisers might speed up the degradation of the blends due to its tendency to promote degradation. This is very useful for plastic manufacturers to consider this material a choice either to act as a performance booster or a pro-degradant.
PubDate: 2023-02-28
DOI: 10.1007/s42464-023-00194-7
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- Effects of oil palm trunk biochar on the thermal stability and acoustic
properties of specialty natural rubber latex foam-
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Abstract: Specialty natural rubber (SpNR) latex foam is a natural-based acoustic foam material, that can substitute conventional synthetic foams to control noise pollution in buildings and in the transportation industry. However, the thermal stability of SpNR latex foam must be improved to meet the required safety criteria for buildings. The goal of the study is to investigate the feasibility of oil palm trunk biochar (OPTB) as a flame-retardant ingredient in two types of SpNR latex foam: deproteinized natural rubber latex foam and epoxidized natural rubber latex foam. The effects of different levels of OPTB loading (8 phr, 16 phr, and 24 phr) on the thermal stability and acoustic properties of OPTB/SpNR latex foam composites were examined. Thermogravimetric analysis indicates that the OPTB has excellent flame-retardant characteristics. The addition of OPTB to SpNR latex foam decreased the thermal decomposition rate of SpNR latex foam but was still insufficient to meet the building fire rating requirements. This study also found that the addition of OPTB to SpNR latex foam increased sound transmission loss but decreased the sound absorption coefficient values. Owing to the fact that OPTB is cheaper than SpNR latex, the addition of OPTB to SpNR latex foam could lead to cost savings in the production of the acoustic foam material. Additionally, this study contributes to sustainable material development by converting OPTB, a by-product from oil palm plantations into value-added products, which is in line with global environmental aspirations.
PubDate: 2023-02-27
DOI: 10.1007/s42464-023-00193-8
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- Performance evaluation of micro/nano-silica filled silicone rubbers aged
under multiple environmental stresses and bipolar DC voltage-
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Abstract: For the outdoor insulation of high voltage transmission lines, insulating materials made of high-temperature vulcanized silicone rubber (HTV-SiR) are used all over the world. To enhance the performance of these base polymers, fillers of various sizes, concentrations and dimensions are added. In this study, four different types of HTV-SiR materials, one unfilled and three reinforced with silica of micro/nano size were used. Followed by preparation of the samples, aging was performed by placing them in a specially designed weathering chamber with various stresses and bipolar DC voltage for 5000 h. To diagnose integrity of the aged materials, different types of measurements based on hydrophobicity classification, leakage current, mechanical analysis, thermal tests, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were conducted. Results of the hydrophobicity classification revealed S3 to be most hydrophobic having HC2 class under the influence of bipolar DC voltage, whereas, sample S1 was the most hydrophilic resulting in HC4 and HC5 under negative and positive DC voltages, respectively. Similarly, the lowest leakage currents of 5.56 μA and 5.81 μA were recorded for sample S3 after being aged under negative DC and positive DC voltages, respectively. The %age decrease in tensile strength recorded for samples S1, S2, S3 and S4 was 32.3, 25.32, 23.56 and 27.12, respectively, under the positive DC voltage. Thermogravimetric analysis exhibited the least decrease of %yield from 49.3% to 48.9% and 48.4% for sample S3 under negative and positive DC voltages, respectively. Additionally, according to FTIR spectroscopic investigation, hybrid composite S3 kept the highest intactness in siloxane backbone (Si–O–Si) linkages, with a drop in its peak of 37% for positive DC and 11.2% for negative DC. In contrast to the co-filled composites S2 and S3 with improved surface morphology, samples S1 and S4 indicated voids, cracks, increased roughness and structural damages.
PubDate: 2023-02-25
DOI: 10.1007/s42464-023-00192-9
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- The determinants of job satisfaction of rubber latex harvesters: a case
from smallholder rubber lands in Sri Lanka-
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Abstract: To run a smallholder rubber plantation as a productive and profitable venture, the higher motivation of its waged labourers to their operational role in farming is essential. This study adopted Maslow’s hierarchy of needs theory to identify the existing satisfactory level of smallholder rubber plantation labourers in latex harvesting in Sri Lanka. It formulates the relevant probabilities of improving job satisfaction concerning their satisfaction with needs. Using the ordered logistic regression, we examined the socio-demographic and job-specific environmental characteristics of 231 latex harvesters from the smallholder rubber lands in the Kegalle District of Sri Lanka. Our results revealed that the overall satisfaction of a latex harvester lies between dissatisfaction to a neutral level. Moreover, it can be improved by 5%–11% when the satisfaction level goes from dissatisfied to satisfied level in hierarchical needs. Results of the field survey suggest that working environment improvement of latex harvesters, relationships with the owner and incentives to harvesters are the foremost needs to motivate harvesters in the job. Some measures were discussed to uplift the satisfactory level of harvesters while safeguarding the smallholder rubber growers. Further investigation into other regions with diverse socioeconomic characteristics was also discussed to generalise the findings of this study.
PubDate: 2023-02-23
DOI: 10.1007/s42464-023-00191-w
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- Morphology, mechanical and thermal properties of HNBR/AEM blends
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Abstract: Blending is an economical and feasible method to improve the properties of polymers. To improve the mechanical properties of ethylene acrylate rubber (AEM), a series of hydrogenated nitrile butadiene rubber (HNBR)/AEM blends were prepared. The mechanical, thermal properties and compatibility of HNBR/AEM blends were investigated in detail. Carbon black filled HNBR/AEM blends exhibited excellent mechanical properties as well as good resistance to high and low temperature. The reactivity of HNBR was higher than that of AEM at a high temperature (180 °C) in air. The crosslinking reaction was more likely to occur in HNBR rubber, while it is not easy to remove small molecules at high temperature. The degradation temperature (Td5%) of AEM (350 °C) was lower than that of HNBR (390 °C), while the hot-air ageing tests indicate that the retention of tensile strength of AEM (95%) was much higher than that of HNBR (58%). HNBR/AEM blends were compatible within the full range of formulations, and have been mutually validated by SEM, dynamic mechanical analysis and mechanical property models of HNBR/AEM blends.
PubDate: 2023-01-30
DOI: 10.1007/s42464-023-00190-x
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- Properties of concentrated skim rubber latex using membrane separation
process and its comparison with other natural rubber latexes-
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Abstract: Concentrated skim (CSk) latex was prepared from raw skim (RSk) latex of Hevea brasilliensis via membrane separation process. Since the properties of CSk latex have not been reported previously, this work aims to study the properties of CSk latex and juxtapose it with raw skim (RSk), field (FNR) and high ammonia (HANR) latexes. The physicochemical properties of the latexes, such as total solid content (TSC), zeta potential, and pH, were analogous to FNR latex. CSK and RSk latexes were composed of small rubber particles as confirmed by SEM, with low molecular weight polymer as determined by gel permeation chromatography (GPC). The Fourier infra-red transform (FTIR) spectroscopy confirmed that CSk film contained high fatty acid ester, nitrogen and gel contents. After the ultra-filtration (UF) membrane separation, TSC increased from 7.3 wt% to 39.6 wt%. The non-rubber components and metal ion content were markedly decreased by 50%, respectively. About 85% of fatty acid esters were removed by acetone extraction (AE) while nitrogen and gel content remained the same in CSk film. This could be attributed to proteins forming cross-links that lead to high gel content of skim latex. In addition, CSk film showed marked improvement in thermal stability as compared to that of RSk.
PubDate: 2022-12-30
DOI: 10.1007/s42464-022-00189-w
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- A framework for assessing the vulnerability of rubber plantations to the
impacts of climate change with special reference to Kerala, India-
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Abstract: The impacts of climate change are more frequent due to global warming, which will negatively affect the production of natural rubber globally. There is a substantial lack of research on assessing the vulnerability of rubber plantations to extreme weather events in rubber-growing countries around the world. The traditional rubber-growing regions of Kerala state in India have been experiencing impacts of climate change like floods, landslides, droughts, and cyclones due to extreme weather events since 2016, which adversely affected the rubber plantations and latex production. Therefore, appropriate measures must be taken to prevent the frequent impacts of climate change on rubber plantations in the state that produce most of the rubber in the country (67%). It is vital to develop a climate change vulnerability map of rubber-growing regions to ensure the sustainability of rubber plantations. Climate change impacts on rubber plantations lead to permanent damages and substantial economic losses. A detailed review of climate change incidents affecting the state is presented, such as flooding, landslides, droughts, and cyclones, and the need to develop climate change vulnerability maps of rubber plantations. Developing a composite climate change vulnerability model based on multi-criteria decision-making (MCDM) and analytical hierarchy process (AHP) will help characterize rubber-growing regions based on climate change impacts and develop appropriate adaptation strategies to mitigate the impacts on rubber plantations. Thus, the proposed model could be used as a geographic information system (GIS)-based scientific framework to assess the vulnerability of rubber plantations to climate change impacts for rubber-producing countries worldwide.
PubDate: 2022-11-22
DOI: 10.1007/s42464-022-00186-z
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- Structure and properties of blends based on vulcanized rubber waste and
styrene–butadiene–styrene thermoplastic elastomer-
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Abstract: The paper presents the characterization and processing of a post-consumer vulcanized rubber waste for use as a filler to obtain polymer composites with thermoplastic matrix based on styrene–butadiene–styrene block copolymer (SBS). The influence of methods to improve compatibility, such as physical modification of rubber waste or dynamic crosslinking and grafting, on the characteristics of the polymer composites obtained was analyzed. To determine the composition of the rubber waste, the acetonic extract and the amount of ash were determined, and a Burchfield test as well as an FTIR analysis were performed to identify the type of rubber. Based on the analyses performed, it was observed that the base elastomer in the rubber waste is styrene butadiene rubber (SBR). It was filled with silicon dioxide (SiO2) and vulcanized with sulfur (S). The rubber waste was cryogenically milled. Mixtures based on thermoplastic elastomers such as styrene–butadiene–styrene block copolymers and milled vulcanized rubber waste (powder) were obtained using a Plasti-Corder Brabender internal mixer. Crosslinking and grafting were performed by a radical reaction mechanism, in dynamic regime, at temperatures of 135–165 °C and rotational speeds of 80 rpm, using di-2-tert-butylisopropyl benzene as crosslinking agent and trimethylolpropane trimethacrylate as crosslinking coagent. The specimens for characterizing the mixtures were made by compression on a laboratory electrical press. The samples were characterized from a structural point of view and the physical–mechanical properties were determined, in the normal state and after accelerated aging for 168 h at 70 °C. The obtained results indicate that the vulcanized rubber powder acted as an elastic filler, leading to an increase in the hardness and elasticity of the samples. Grafting and crosslinking in a dynamic mode shows a significant improvement in hardness, elasticity and tensile strength. The samples show good stability at accelerated aging.
PubDate: 2022-11-19
DOI: 10.1007/s42464-022-00187-y
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- The effect of solution soaking pretreatments on the surface chemistry of
crumb rubber-
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Abstract: Crumb rubber (CR) is a widely used waste material in asphalt pavement due to its low cost and high elasticity. A broad range of pretreatment methods has been employed to activate CR surface to improve the compatibility between the asphalt materials and CR. However, this was accompanied by increased costs and reduced high-temperature performance of the rubberised asphalt binder. In this study, the outer surface of aggregated CR particles was activated chemically through a series of solution soaking pretreatments. The chemical reactions were detected through the Fourier-Transform Infrared Spectroscopy (FTIR), the surface morphology was verified by a Scanning Electron Microscope (SEM), and the effect of the treatment was investigated by the Dynamic Shear Rheometer (DSR). The results showed that the chemicals used in this study could activate the CR surface. New functional groups such as the carbonyl group bond (C=O) and carbon–nitrogen bond (C-N) were generated, and changes occurred on the C=C stretch peak at 1635 cm−1 and C=C bend peak at 692 cm−1 as the intensity of the peaks increased and decreased, depending on the effect of the solution used. The nitro group intensity was decreased after all pretreatments due to the chemical reactions between the nitro group and the different solutions. The SEM images showed that the mixed solutions (NaOH and KMnO4) had the most significant effect on surface morphology as the CR surface appeared with a large roughness spread over the whole sample. Furthermore, the rutting resistance of the rubberised asphalt binder improved with the decreased index value of the carbonyl and sulfoxide groups of the CR surface. The treatments used in this study improved the surface activation of the CR and enhanced the compatibility of the CR with the asphalt binder.
PubDate: 2022-11-09
DOI: 10.1007/s42464-022-00185-0
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- Anisotropic swelling of rubber: extension of the Flory theory
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Abstract: The anisotropy of the swelling of rubber is examined both theoretically and experimentally. The Flory theory is extended to account for anisotropic swelling, allowing the determination of the average molecular weight between cross-links for rubber with swelling anisotropy for the first time. In addition, specimens from five commercial rubbers manufactured using either compression-moulding or sheet-rolling processes are swollen in appropriate organic solvents. Their linear dimensions and mass are carefully recorded before swelling, in the swollen state, and after drying, to obtain three linear swelling ratios which can differ by up to 10% within each specimen. Compression-moulded rubbers are shown to be transversely isotropic after moulding, whereas rolled rubbers exhibit full anisotropy, with different swelling ratios in all three directions. None of the rubbers examined were found to be truly isotropic. The new anisotropic swelling theory is applied to the experimental data to determine the average molecular weight between cross-links, which is determined as up to 0.5% larger than the value obtained using the Flory isotropic swelling theory.
PubDate: 2022-11-08
DOI: 10.1007/s42464-022-00183-2
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- Carboxylated acrylonitrile butadiene-natural rubber latex blends with
methyl methacrylate grafted natural rubber latex: mechanical properties
and morphology-
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Abstract: Commercially available carboxylated acrylonitrile butadiene latex (XNBR) was physically blended with natural rubber latex (NR) at varying blend ratios to investigate its effect on the mechanical properties and morphology. Methyl methacrylate grafted natural rubber latex (MG) was added to the latex blends as a third polymer to study whether it could enhance the mechanical properties of the latex blend films. It was found that the tensile strength of the blend films irrespective of composition decreased when the two latexes were blended as compared to the virgin latex films. The modulus 300 decreased while the elongation at break and tear strength of the blend films increased gradually as the ratio of NR increased in the blend films. It was found that the MG did not enhance the mechanical properties of the XNBR/NR blend films under the current experimental condition. AFM phase imaging analysis revealed enhanced polymer distribution and evidence of NR-MG-XNBR interactions.
PubDate: 2022-10-26
DOI: 10.1007/s42464-022-00184-1
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