Rubber Content Research Articles

CORRELATION BETWEEN COMPOSITION OF MASONRY BLOCKS USING RECYCLED RUBBER AGGREGATES AND PROFITABILITY OF PRODUCTION LINE

A correlational study between the composition of masonry blocks with recycled rubber aggregates and the profitability of their production line was carried out. Masonry blocks were designed and manufactured with different contents of rubber aggregates from end-of-life tires. We started from a factorial design of experiments with response surface L4 (22). The factors considered were aggregate granulometry, water/cement ratio and rubber content. The outputs of the experiment were the ultimate compressive strength and the profitability of the production line (IRR/NPV). A model was defined that correlates the input factors with the defined responses. Through an ANOVA, the significant factors on the profitability of the production line in different production scenarios were determined. It was found that there is an inversely proportional relationship between the amount of rubber aggregate and the compressive strength. The maximum aggregate content that allows meeting the resistance requirements of the NTE INEN 3066 standard was 10% (p/p). On the other hand, from the economic-financial analysis it is concluded that the maximum economically profitable rubber content is 5% (p/p). These results make it possible to define the limits of profitability of a production line of masonry blocks that comply with current regulations.

Morphology evaluation and mechanical properties of oil-resistant thermoplastic vulcanizates comprising carboxylated nitrile butadiene rubber and thermoplastic polyurethane and their comparison with commercial grades

The morphology, the mechanical properties, and the oil-resistance of thermoplastic vulcanizates (TPVs) of carboxylated nitrile butadiene rubber (XNBR) and thermoplastic polyurethane (TPU) were studied & compared with the commercial ethylene-propylene-diene monomer (EPDM)/polypropylene (PP) TPVs from two suppliers. The rubber phase in these new generations of TPVs was cured with an addition-type curative, and no oil & compatibilizer were required to make these TPVs processable. Three XNBR/TPU TPVs were made with different rubber/plastic ratios (15/85, 30/70, and 45/55). The AFM analysis showed that the morphology shifted from a continuous plastic phase to a co-continuous phase with increased rubber content. The rubber domains in these TPVs were not as discrete as reported in the literature for the EPDM/PP TPVs. Still, because of using an addition-type curative, unlike peroxide and resole phenolic resin curatives for the latter, the former TPVs had a significantly better balance of rubber and plastic properties. The oil resistance of these TPVs was 3.5–5 times better than the commercial EPDM/PP TPVs. These promising results show advancement in the TPV world and make these TPVs appealing for hydraulic oil applications.

Dynamic uniaxial compression mechanical properties of self-compacting rubber concrete subjected to different strain rates

Rubber concrete is a kind of light green building material, which is prepared by mixing rubber powder or rubber crumb into ordinary concrete in a certain proportion and then introducing rubber concrete through vibration-free technology to prepare self-compacting rubber concrete. Uniaxial compression tests were carried out on self-compacting rubber concrete with two particle sizes at different strain rates, and the effects of strain rate and rubber content on the dynamic mechanical properties of self-compacting rubber concrete were studied. The microstructure of self-compacting rubber concrete before and after damage was analyzed. Compared with ordinary concrete, the self-compacting rubber concrete is capable of maintaining good integrity during damage, when the rubber powder content exceeds 10% and the rubber crumb content exceeds 15%. The results indicate that as the strain rate increases, both the peak stress and the elastic modulus increase, indicating the strain rate enhancement effect, while the strain rate effect of the peak strain is not evident. Moreover, the model equations of peak stress and elastic modulus strain rate effect were established, the dynamic damage constitutive model was proposed, the damage evolution was analyzed, and the stress intervals were assigned to the various stages of damage evolution.

Effect of Latex Rubber as Asphalt Additive to the Characteristics of AC-WC Mixture

Quality improvement can be achieved by making innovations in the development of rubber asphalt material. This research was conducted to determine the effect of adding natural rubber as an additive to the wear-resistant Laston mixture (AC-WC). This study made 33 total samples, which were divided into 18 conventional asphalt mixtures and 15 rubber asphalt mixtures, with normal asphalt variations ranging from 5.5% - 8% and for rubber with variations of 5% - 7% of optimum asphalt weight, respectively each with an interval (0.5 %). It was mixed using a wet process. Based on the 2018 General Highways Specifications, Optimum Asphalt Content (OAC) was obtained at 7.5% and Optimum Rubber Content (ORC) at 6%. The test results for the stability and melting values of normal asphalt were 1786.22 kg and 3.56 mm, while the tests for the stability and melting values for rubber asphalt were 1181.22 kg and 3.6 mm. It can be interpreted that adding this rubber content increases the stability of the value 2x greater than the point where the stability value falls on the normal asphalt content variation of 8%.

Mechanical Properties of Rubberised Geopolymer Concrete.

The environmental impact of non-biodegradable rubber waste can be severe if they are buried in moist landfill soils or remain unused forever. This study deals with a sustainable approach for reusing discarded tires in construction materials. Replacing ordinary Portland cement (OPC) with an environmentally friendly geopolymer binder and integrating crumb rubber into pre-treated or non-treated geopolymer concrete as a partial replacement of natural aggregate is a great alternative to utilise tire waste and reduce CO2 emissions. Considering this, two sets of geopolymer concrete (GPC) mixes were manufactured, referred to as core mixes. Fine aggregates of the core geopolymer mixes were partially replaced with pre-treated and non-treated rubber crumbs to produce crumb rubber geopolymer concrete (CRGPC). The mechanical properties, such as compressive strength, stress-strain relationship, and elastic modulus of a rubberised geopolymer concrete of the reference GPC mix and the CRGPC were examined thoroughly to determine the performance of the products. Also, the mechanical properties of the CRGPC were compared with the existing material models. The result shows that the compressive strength and modulus of elasticity of CRGPC decrease with the increase of rubber content; for instance, a 33% reduction of the compressive strength is observed when 25% natural fine aggregate is replaced with crumb rubber. However, the strength and elasticity reduction can be minimised using pre-treated rubber particles. Based on the experimental results, stress-strain models for GPC and CRGPC are developed and proposed. The proposed models can accurately predict the properties of GPC and CRGPC.

Studying the effects of the butadiene rubber and nitrile butadiene rubber ratio on the elastomers properties

In this study the influence of the content of SKD-B butadiene rubber and BNKS-18 AMN nitrile rubber in the blend on the properties of the resulting elastomers is investigated. The combination of frost-resistant and aggressive media resistant rubbers in the blend allows to adapt the properties of vulcanizates to the required operating conditions. The research revealed that the level of physical and mechanical properties, aggressive media resistance and frost resistance depend on the ratio of rubbers. The study of properties of elastomers revealed two glass transition temperatures and two thermal transitions at negative temperatures corresponding to nitrilebutadiene and butadiene rubbers. The phase morphology of elastomers, characteristic for butadiene nitrile or butadiene rubbers in dependence on their ratio in the blend, was investigated by electron microscopy. Based on the developed elastomer, dust covers for CV-joints were produced. They were tested in real operating conditions in the temperature range from –52 to 33°C.

Effect of Glass Fiber and Rubber on the Properties of Expansive Soil and Its Utilization as Subgrade Reinforcement in Road Application

Expansive soil is a problematic material for construction due to its high potential for volume change, which can cause damage to road infrastructure. This study aims to investigate the effect of glass fiber and rubber on the properties of expansive soil and its suitability as subgrade reinforcement in road applications. The maximum dry density (MDD), optimum moisture content (OMC), and California Bearing Ratio (CBR) were evaluated for varying percentages of glass fiber and rubber in the soil. The results showed that the addition of glass fiber and rubber had a positive effect on the soil properties. The MDD and CBR increased with increasing fiber and rubber content, while the OMC decreased. Additionally, the reinforced soil exhibited a significant improvement in strength compared to the unreinforced soil. The study suggests that the incorporation of glass fiber and rubber can enhance the performance of expansive soil as subgrade reinforcement in road applications.

Investigation of constitutive properties of high plasticity clay soils mixed with crushed rubber tire waste

Addressing the enormous waste resulting from discarded worn rubber tires is an environmental challenge. Recycling and using crushed rubber tire waste (CRTW) in construction materials can help in addressing this challenge. This study investigates the effect of addition of CRTW on the engineering properties of high plasticity clay soils (HPCS). There is a paucity of research in the application of CRTW in HPCS. This research tries to fill this research gap. Specifically, this study seeks to investigate the effect of mixing CRTW on the constitutive properties of HPCS. After identifying a locally available HPCS, mixtures of the clay and several percentages (0%, 6%, 12%, 18%, and 24%) by weight of CRTW were prepared. A range of CRTW shapes and sizes were investigated. Three different particle shapes of CRTW (granular rubber, rubber chips, and rubber fiber), and two particle sizes (fine and coarse) were studied. The parameters studied included unconfined compressive strength (UCS), strain at failure, post-peak strength loss (PPSL), modulus of elasticity, failure modes/mechanisms, repeatability of tests results, and examination of CRTW particles and mixtures via binocular and SEM microscope. Our findings unveiled that the highest level of repeatability was observed in granular CRTW, with a maximum variability of only 5%. Moreover, the mixtures containing granular CRTW exhibited, on average, 10% and 15% higher strength and modulus of elasticity, respectively, in comparison to mixtures incorporating other shapes of CRTW. In general, the HPCS-CRTW mixtures displayed higher shear strains, averaging 25% greater than pure HPCS. Furthermore, the addition of CRTW to HPCS resulted in a reduction of its PPSL and a transition in behavior from brittle to slightly ductile. Examination of failed specimens revealed the existence of two primary failure modes: shear plane failure and shear plane failure accompanied by multiple vertical cracks within the mixtures. These results suggest that the utilization of granular CRTW in HPCS can improve certain properties of HPCS. However, it is advisable to limit the rubber content in this mixture to 6% to mitigate significant adverse effects on its strength.

High temperature and fire properties of sustainable syntactic foam reinforced by end‐of‐life tyre‐derived rubber particles

AbstractThe management of end‐of‐life tyres faces challenges due to insufficient recycling infrastructure and technologies, as well as limited markets for the materials recovered from them. To mitigate this, waste rubber can be upcycled and used as filler material for polymer matrix composites. Before rubber‐reinforced composites can be certified for fire‐prone applications, their thermal and flammability properties must be understood. This research investigates the effect of rubber fillers on the thermal stability, flammability and flame spread characteristics of epoxy matrix syntactic foam. Thermogravimetric analysis, Fourier Transform Infrared spectrometry (FTIR), scanning electron microscopy and attenuated total reflection FTIR spectrometry were employed to elucidate changes in thermal degradation behaviours. The influence of rubber fillers on the flammability of syntactic foam was assessed using the cone calorimeter. The fire reaction properties of rubber‐reinforced foam were affected by the intensity of the incident heat flux. Regardless of the incident heat flux, an increase in rubber content led to higher total heat release. At the lower heat flux of 35 kW/m2, the fire growth rate increased with rubber content, but at the higher heat flux of 50 kW/m2, the fire growth rate decreased as the rubber content increased. Importantly, all rubber‐reinforced syntactic foams achieved a UL94 HB ranking and exhibited reduced flame spread rates compared to the unmodified foam. This study demonstrated the potential for upcycling waste rubber into sustainable engineering products and expanded the knowledge base on fire reaction properties and flame spread characteristics of such hybrid composite materials.

Effect of internal and external damping in the reduction of non-exhaust particulate matter emissions in a low metallic friction material formulation

Friction-induced vibrations in an automotive braking system are of serious concern, leading to different repercussions. Numerous conventional and unconventional methods have been proposed to curb these vibrations, which are also observed to be directly related to generating non-exhaust particulate matter emissions. In this study, an in-house formulated friction material, tested in the form of pins, was subjected to internal damping by adding rubber content from 0 to 3 wt% and external damping by wrapping the different pins in rubber tape. The DMTA showed a decrease in storage modulus and an increase in loss factor with the increase in rubber content. The pin density decreased with the increase in the rubber content. Dry sliding friction, wear, emissions, and vibrations tests were conducted on a pin on disc tribometer with relevant attachments to measure emissions and vibrations. A large drop in vibrations was observed with the rubber content, irrespective of external damping. On the other hand, a significant reduction in wear, emissions, and vibrations was observed with the sample containing the highest rubber addition and with the damping tape. This study showed the feasibility of employing the combination of internal and external damping, emphasizing the optimum rubber content in friction material formulations.

Energy Dissipation Efficiency of Geotechnical Seismic Isolation with Gravel-Rubber Mixtures: Insights from FE Non-Linear Numerical Analysis

ABSTRACT This paper provides new and useful insights into the performance and efficiency of geotechnical seismic isolation (GSI) systems with gravel-rubber mixtures containing 10%, 25% and 40% volumetric rubber content (VRC). Finite element numerical models were developed in OpenSees and subjected to sinusoidal ground motions with varying input base acceleration and frequency. The best seismic performance was attained for VRC = 40% at a frequency of 8 Hz. Using a newly developed GSI efficiency index, the energy dissipation efficiency of VRC = 40% was found to vary between good to excellent, while that of VRC = 10% and 25% is poor.

Study on the Dynamic Performance and Damage Evaluation of Rubber-Modified Non-Autoclaved Concrete Pipe Piles under Axial Drop Hammer Impact

In order to improve the weak impact resistance of non-autoclaved concrete pipe piles, this study replaced sand in the concrete with rubber particles of different volume contents to obtain rubber-modified non-autoclaved concrete pipe piles (with volume contents of 0%, 5%, 10%, and 15%). The dynamic impact response characteristics of rubber-modified non-autoclaved concrete pipe piles were obtained through large-scale axial hammer impact experiments. The results indicate the following. (1) Non-autoclaved concrete pipe piles without rubber additives were prone to expansion deformation instability under impact. When the rubber content was 10%, the expansion deformation of the piles was the weakest, and the state was the most stable. (2) When the impact energy exceeded 48 kJ, the deformation energies of piles with 5% and 10% rubber contents significantly increased. (3) The damage levels of the piles after hammer impact were classified into four grades: no damage, mild damage, moderate damage, and severe damage. When the impact energy was greater than or equal to 48 kJ, rubber-modified non-autoclaved concrete pipe piles exhibited damage. The zone with no damage for piles with 10% rubber content was the smallest, making it less prone to damage under impact loads. The rubber-modified non-autoclaved concrete pipe piles with 10% rubber content not only had excellent impact resistance but also utilized the advantages of being environmentally friendly and energy-saving. They filled a certain knowledge gap in green building materials.

Experimental Study on Dynamic Modulus of High Content Rubber Asphalt Mixture

Currently, the research on the mechanical properties of rubber-modified asphalt mixtures primarily focuses on small-scale investigations, with insufficient exploration into the performance of rubber particles and their relationship with the mechanism and properties of modified asphalt mixtures. Limited studies have been conducted on large-scale rubber modification in asphalt mixtures. Due to frequent use and subsequent high damage to existing asphalt pavements, incorporating rubber-modified asphalt mixtures can partially alleviate premature deterioration. Dynamic modulus tests were conducted using MTS equipment under unconfined conditions to investigate the viscoelastic behavior of rubber-modified asphalt mixtures with high rubber content and elucidate the influence of rubber particle content on the elastic deformation and recovery capability. The dynamic mechanical properties of the mixtures were determined at different loading rates, temperatures, and types of rubber-modified asphalt mixtures. Based on the test data, variations in the dynamic modulus, phase angle, storage modulus, loss modulus, loss factor, and rut factor of the rubber-modified asphalt mixtures under different loading frequencies, temperatures, and types were analyzed. The results demonstrate the pronounced viscoelastic behavior of rubber-modified asphalt mixtures. The mixtures exhibit enhanced elasticity at low temperatures and high frequencies, while their viscosity becomes more prominent at high temperatures and low frequencies. Under constant test temperatures, an increase in load loading frequency leads to a higher dynamic modulus; conversely, a decrease in dynamic modulus is observed with increasing test temperatures. The dynamic modulus of ARHM-25 at a frequency of 10 Hz is found to be 12.99 times higher at 15 °C compared to that at 60 °C, while at 30 °C, the dynamic modulus at 25 Hz is observed to be 2.72 times greater than that at 0.1 Hz. Furthermore, the rutting resistance factors of the asphalt mixtures increase with loading frequency but decrease with temperature. The rutting factor for ARHM-13 at a frequency of 10 Hz is found to be 22.98 times higher at 15 °C compared to that at 60 °C, while at a temperature of 30 °C, the rutting factor for this material is observed to be 3.09 times greater at a frequency of 25 Hz than at 0.1 Hz. These findings suggest that rutting is most likely when vehicles drive at low speeds in hot weather conditions.

Assessment of sulphur content in nitrile rubber through ultrasonic measurement

ABSTRACT Ultrasonic testing is a popular non-destructive method for characterising engineering materials and detecting their properties. Diverse quantities of sulphur are incorporated into an uncured rubber compound, which is subsequently cured under specific pressure and heat conditions to attain the desired properties in the final product. The present work represents a quantitative estimation of sulphur content for cured NBR (Nitrile Butadiene Rubber) samples by an ultrasonic approach. The experiments have been conducted using cured NBR samples with varying sulphur content, ranging from 0% to 1.34%. Ultrasonic pulse behaviour at different temperatures (30°C to 160°C) has been observed using an ultrasonic setup which has been developed in-house. A-scan data is obtained at a sampling rate of 80 MHz using an 18 mm diameter broadband transducer with a 1 MHz central frequency. The ultrasonic longitudinal velocity (ULV) of rubber is determined from A-scan data using time-of-flight, and sulphur content has a significant impact on the ULV. At a temperature of 160°C, the ultrasonic longitudinal velocity (ULV) is measured at 1262 m/s for a sample with 0.62% sulphur content, and at 1321 m/s for a sample with 1.34% sulphur content.

Hybrid nonlinear regression model versus MARS, MEP, and ANN to evaluate the effect of the size and content of waste tire rubber on the compressive strength of concrete

Tire rubber waste is globally accumulated every year. Therefore, a solution to this problem should be found since, if landfilled, it is not biodegradable and causes environmental issues. One of the most effective ways is recycling those wastes or using them as a replacement for normal aggregate in the concrete mixture, which has high impact resistance and toughness; thus, it will be a good choice. In this study, 135 data were collected from previous literature to develop a model for the prediction of rubberized concrete compressive strength; the database comprised different mixture proportions, the maximum size of the rubber (1–40 mm), and the rubber percentage (0–100%) replacing natural fine and coarse aggregates were among the input parameters in addition to cement content (380–500 kg/m3) water content (129–228 kg/m3), fine aggregate content (0–925 kg/m3), coarse aggregate content (0–1303 kg/m3), and curing time of the samples (1–96 Days); then the collected data were used in developing Multi Expression Programming (MEP), Artificial Neural Network (ANN), Multi Adaptive Regression Spline (MARS), and Nonlinear Regression (NLR) Models for predicting compressive strength (CS) of rubberized concrete. The parametric analysis reveals that as the maximum rubber size increases, the reduction in compressive strength becomes more pronounced. Notably, this strength decline is more significant when rubber replaces coarse aggregate than its replacement of fine aggregate. Among the input parameters considered, it is evident that the fine aggregate content exerts the most substantial influence on the compressive strength of rubberized concrete. Its impact on predicting compressive strength surpasses other factors, with the concrete samples' curing time ranking second in importance. According to the assessment tools, the ANN model performed better than other developed models, with high R2 and lower RMSE, MAE, SI, and MAPE. Additionally, ANN and MARS models predicted the CS of different sizes better than MEP and NLR models. Subsequently, we employed the collected data to develop predictive models using Multi Expression Programming (MEP), Artificial Neural Network (ANN), Multi Adaptive Regression Spline (MARS), and Nonlinear Regression (NLR) techniques to forecast the compressive strength (CS) of rubberized concrete. The statistical analysis tools assessed the performance of these developed models through various evaluation criteria, including the Coefficient of Determination (R2), Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Scatter Index (SI), and Mean Absolute Percentage Error (MAPE). In summary, our study underscores the efficacy of recycling rubber materials in concrete production. It presents a powerful predictive model for assessing the compressive strength of rubberized concrete, with the ANN model standing out as the most accurate and reliable choice for this purpose.

Assessment of sulfur content in nitrile rubber through ultrasonic measurement

ABSTRACT Ultrasonic testing is a popular non-destructive method for characterising engineering materials and detecting their properties. Diverse quantities of sulphur are incorporated into an uncured rubber compound, which is subsequently cured under specific pressure and heat conditions to attain the desired properties in the final product. The present work represents a quantitative estimation of sulphur content for cured NBR (Nitrile Butadiene Rubber) samples by an ultrasonic approach. The experiments have been conducted using cured NBR samples with varying sulphur content, ranging from 0% to 1.34%. Ultrasonic pulse behaviour at different temperatures (30°C to 160°C) has been observed using an ultrasonic setup which has been developed in-house. A-scan data is obtained at a sampling rate of 80 MHz using an 18 mm diameter broadband transducer with a 1 MHz central frequency. The ultrasonic longitudinal velocity (ULV) of rubber is determined from A-scan data using time-of-flight, and sulphur content has a significant impact on the ULV. At a temperature of 160°C, the ultrasonic longitudinal velocity (ULV) is measured at 1262 m/s for a sample with 0.62% sulphur content, and at 1321 m/s for a sample with 1.34% sulphur content.

Impact Resistance of Rubberized Alkali-Activated Concrete Incorporating Recycled Aggregate and Recycled Steel Fiber

Alkali-activated concrete (AAC) features excellent mechanical properties and sustainability. The incorporation of crumb rubber (CR), recycled concrete aggregates (RCAs), and recycled steel fibers (RSFs) can further enhance environmental sustainability. This paper mainly investigated the dynamic behaviors of a novel rubberized AAC incorporating RCAs and RSFs (RuAAC) through Split-Hopkinson Pressure Bar (SHPB) tests. The variables included three types of RSF content (1%, 2% and 3%), five types of rubber content (0%, 5%, 20%, 35% and 50%) and five impact pressures (0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa and 0.9 MPa). Dynamic stress–strain curves, dynamic strength, the dynamic increase factor (DIF), impact toughness and the synergistic effects of RSF and CR were discussed. The results show that increasing RSF and CR contents could improve the impact resistance of RuAAC under impact loading. The RuAAC exhibited significant strain rate sensitivity, and the sensitivity increased with larger contents of RSF and CR. The increase in strain rate sensitivity was more pronounced with higher CR contents, which was reflected in larger dynamic increase factor (DIF) values. Under high impact pressure, the impact toughness was obviously enhanced with higher RSF contents, while the contribution of increased CR content to impact toughness was not apparent, which may be attributed to the fact that this study only calculated the integral under the dynamic stress–strain curve before the peak stress to determine impact toughness, neglecting the potential contribution of CR particles after the peak point. The obvious strain sensitivity exhibited by the RuAAC in the SHPB tests indicated superior impact performance, making it particularly suitable for architectural structures prone to seismic or explosive impacts.

Preparation and Characterization of Activated Palm Kernel Shell/Carboxylated Nitrile Butadiene Rubber (APKS/XNBR) Vulcanizate

Malaysia is one of the most important palm oil producers and exporters in the whole wide world. There has been a rapid development of new palm oil plantations and palm oil mills in this country. The palm oil industry plays a vital role in the economic growth of Malaysia. However, as the palm oil industry grows bigger and wider, a huge amount of palm oil waste is produced which is an alarming issue considering it can cause pollution and have a negative effect on the environment. Raw Palm Kernel Shell (PKS) derived from palm oil waste can be converted into Activated Palm Kernel Shell (APKS) which has the potential to be a value-added biofiller in rubber vulcanizates. Thus, in this study, APKS is prepared through a carbonization process at a temperature of 900 °C and an activation process via steam treatment and used as filler in Carboxylated Nitrile Butadiene Rubber (XNBR). The aim of this study is to evaluate the influence of different loading ratios of APKS on theswelling index measurement, bound rubber content (BRC), abrasion resistance, compression set, and hardness of XNBR vulcanizates. APKS is incorporated in XNBR at different loading ratios, ranging from 0 to 50 phr and these APKS-filled XNBR vulcanizates are prepared with a two-roll mill. The overall physico-mechanical properties of APKS-filled XNBR vulcanizates showed increment in terms of BRC, compression set, and hardness as the loading ratio of APKS increased. XNBR vulcanizates with a higher loading ratio of APKS also showed a decrease in swelling index measurement and volume loss which would indicate high abrasion resistance. These results could be attributed to the porosity of APKS as shown in the morphological analysis which provided a high surface area of contact for crosslinking and mechanical interlocking. This proves APKS could potentially be a semi-reinforcing filler for rubber vulcanizates, especially for XNBR vulcanizates as XNBR vulcanizates were able to achieve high abrasion resistance and high hardness with the incorporation of APKS. With this, the conversion of PKS into APKS could help to reduce palm oil waste and provide an environmentally friendly, sustainable biofiller option to rubber researchers and manufacturers who are looking for an alternative to petroleum-based fillers. This would be very beneficial for both the palm oil industry and the rubber industry.

Configuration of a gravel-rubber geotechnical seismic isolation system from laboratory and field tests

We present the outcomes derived from controlled laboratory experiments on utilizing gravel rubber mixtures (GRM) as a geotechnical seismic isolation (GSI) stratum beneath the foundational structure of the EuroProteas prototype. The study encompassed three distinct GRM compositions characterized by varying rubber proportions relative to the total mixture weight (0%, 10%, and 30%) employed as the foundation soil. These GSI-structure systems were subjected to external harmonic forces applied atop the structure of EuroProteas across a broad spectrum of frequencies and force magnitudes. Preceding the commencement of field experiments, resonant column and cyclic triaxial compression assessments were conducted on specimens featuring identical rubber fractions and mean grain size ratios. Our laboratory tests revealed that an increase in rubber content resulted in a reduction of the shear modulus (Go) and an augmentation of the damping ratio (Do) while concurrently inducing a more linear character in the G/Go-logγ-D profiles. The findings derived from the laboratory examinations align closely with those ascertained from field investigations. Expressly, it was confirmed that a GSI layer with a thickness of 0.50 meters, composed of a GRM incorporating 30% rubber content, exhibited a discernible reduction in the overall stiffness of the GSI-structure system, accompanied by a corresponding alteration in its fundamental vibrational frequency. The enhanced damping within the system manifested through observable reductions in acceleration recordings and diminished strain development at the base of the GRM layer with 30% rubber content, encompassing a wide range of frequencies.

Improving the tracking and erosion resistance of silicone rubber using Fe2O3 and platinum catalyst

AbstractIn typical HTV silicone rubber for composite insulators subjected to a 4.5 kV inclined plane (IP) test, alumina trihydrate loading exceeds 40 wt%, which limits the rubber content and weakens the antiaging properties. This study compares two methods for enhancing tracking and erosion resistance while reducing ATH content to meet IP test requirements. Increasing Fe2O3 content from 1.5 wt% to 3 wt% promotes the formation of mullite. The formed ceramic layer isolates heat and oxygen and hence facilitates the specimen to pass the IP tests with less content of ATH. By contrast, Pt/NS system cannot suppress the tracking efficiently by forming the SiOC ceramics at high ATH loading. The decomposition of ATH will generate water vapor and lead to holes in the surface. Both moisture and oxygen absorbed have a detrimental effect on the suppression mechanism of the Pt/NS system. Consequently, it is recommended that the content of Fe2O3 can be increased slightly to lower the ATH content in the traditional HTV SiR formula used for the composite insulator. Besides, when the content of ATH is relatively high, the use of the Pt/NS system is not recommended.