Rebound Resilience Research Articles

Effect of Tackifier Addition on Cushion Compound Formulation for Tire Retreading Application

Tire retreading is a prospective industry. Old tires are repaired and retreaded with suitable tread compounds to fulfill the requirement as the new ones. One of the important components in tire retreading process is cushion compound. Cushion compound consists of unsaturated rubber, in this case natural rubber Hevea brasiliensis was used, less phr of filler compared to the retread compound, and additives such as peptizer, tackifier, processing oil, antioxidant, activator, accelerator and curatives. Tackifier is an important component in cushion compound since its role to make a bonding between different layer, the initial tire after buffing and new retread layer. Tackifier should has good resistance, good compatibility and does not affect the rheological and dynamical properties of bonded rubber. The general tackifier that used in industries are hexamethyl tetramine as methylene donor and resorcinol as methylene acceptor. There is certain reaction between those two additives that determine how good the performance of cushion compound and its effect to retreading process. To obtain optimum reaction, comparison between resorcinol and hexamethyl tetramine were varied as 1:1 (FRR1), 1:2 (FRR2) and 1:3 (FRR3). Hardness test, compression test, rebound resilience, tensile and tear strength, and FTIR were done to observe the optimum variation for retread application. Compared to the control with no tackifier at all, FRR2 showed the optimum result with 21.75 MPa (min. 19 Mpa) and 454,54% elongation at break (min. 450%). The most interesting result was observation by using FTIR, it was detected that the crosslink density was significantly higher than other formulation. It is a new breakthrough which is minimum tackifier with certain treatment could give better performance.

Rotational Molding of Linear Low-Density Polyethylene Composites Filled with Wheat Bran.

Application of lignocellulosic fillers in the manufacturing of wood polymer composites (WPCs) is a very popular trend of research, however it is still rarely observed in the case of rotational molding. The present study aimed to analyze the impact of wheat bran content (from 2.5 wt.% to 20 wt.%) on the performance of rotationally-molded composites based on a linear low-density polyethylene (LLDPE) matrix. Microscopic structure (scanning electron microscopy), as well as physico-mechanical (density, porosity, tensile performance, hardness, rebound resilience, dynamic mechanical analysis), rheological (oscillatory rheometry) and thermo-mechanical (Vicat softening temperature) properties of composites were investigated. Incorporation of 2.5 wt.% and 5 wt.% of wheat bran did not cause significant deterioration of the mechanical performance of the material, despite the presence of ‘pin-holes’ at the surface. Values of tensile strength and rebound resilience were maintained at a very similar level, while hardness was slightly decreased, which was associated with the porosity of the structure. Higher loadings resulted in the deterioration of mechanical performance, which was also expressed by the noticeable rise of the adhesion factor. For lower loadings of filler did not affect the rheological properties. However, composites with 10wt.% and 20 wt.% also showed behavior suitable for rotational molding. The presented results indicate that the manufacturing of thin-walled products based on wood polymer composites via rotational molding should be considered a very interesting direction of research.

Characterization of eco-friendly processing aids for styrene butadiene rubber composites with silica

With the development of environmentally friendly “green tires” in the tire industry, silica has been used as a reinforcing filler material in tread compounds. With regard to this rubber compounding process, non-toxic, and renewable processing aids are required. We fabricated such processing aids with multi-alcohol components of hydrophobic and hydrophilic groups (M-A-S) to make the hydrophilic silica compatible with the hydrophobic rubber matrix. The rubber composites with M-A-S showed remarkable enhancements in the mechanical properties, specifically the tensile strength, elongation and fatigue properties due to the improved dispersion of silica in the rubber matrix. They also exhibited outstanding heat build-up, good rebound resilience, and abrasion levels at low loadings. Furthermore, M-A-S were added directly to tread compounds to make a pneumatic tire with enhanced high-speed durability and enhanced dry and wet braking due to the strong interfacial interaction between the silica and the rubber matrix. These results demonstrate the advantages of the proposed potential replacement for metal-ion processing aids for tire engineering.

Mechanical, Thermal and Rheological Properties of Polyethylene-Based Composites Filled with Micrometric Aluminum Powder.

Investigations related to polymer/metal composites are often limited to the analysis of the electrical and thermal conductivity of the materials. The presented study aims to analyze the impact of aluminum (Al) filler content (from 1 to 20 wt%) on the rarely investigated properties of composites based on the high-density polyethylene (HDPE) matrix. The crystalline structure, rheological (melt flow index and oscillatory rheometry), thermal (differential scanning calorimetry), as well as static (tensile tests, hardness, rebound resilience) and dynamic (dynamical mechanical analysis) mechanical properties of composites were investigated. The incorporation of 1 and 2 wt% of aluminum filler resulted in small enhancements of mechanical properties, while loadings of 5 and 10 wt% provided materials with a similar performance to neat HDPE. Such results were supported by the lack of disturbances in the rheological behavior of composites. The presented results indicate that a significant content of aluminum filler may be introduced into the HDPE matrix without additional pre-treatment and does not cause the deterioration of composites’ performance, which should be considered beneficial when engineering PE/metal composites.

The effect of various alternative filler granularity on the properties of elastomeric vulcanizate

This work deals with the influence of different alternative filler granularities or fractions (size) on properties of real elastomeric blend. Alternatively, the filler was subjected to a sieve analysis to obtain individual fractions of filler as well as to determine the ratio of individual fractions in a determined amount of alternative filler. The main objective was to evaluate the effect of the granularities on the basic properties of the elastomeric blend. Prepared elastomeric blends were studied in terms of their properties and vulcanization characteristics. The resulting vulcanizates were tested from the aspect of hardness and rebound resilience. In the case of commercially available fillers (e.g. carbon black), the granularity is a significant parameter affecting the properties of the elastomeric blends. From the results of tests for the prepared materials, it is possible to determine the most suitable granularity of the alternative filler for the preparation of elastomeric materials. In relation to given suitable granularity, the application of the basic alternative filler is not suitable to achieve better quality parameters. The results show a significant granularity effect of the alternative filler on the properties (hardness, rebound resilience, rheological, vulcanization characteristics) of the elastomeric vulcanizate.

Exploration of mechanical properties of polyurea coated mild steel plate and aluminium plate sandwich composites

Abstract Polyurea (PU) is a copolymer formed by the rapid reaction of an isocyanate and an amine component which is used in membranes, linings and caulk. PU specimens are prepared with different thickness from 1.8 mm to 2.6 mm. PU coated Aluminium and Mild Steel composites were fabricated by the spray-up technique process. The mechanical properties of these specimens were investigated by conducting the various mechanical tests like hardness, rebound resilience, tensile and low velocity impact tests. When PU thickness increased, the mechanical properties also gradually increased. The PU coated Mild Steel exhibits better mechanical properties than PU coated Aluminium sandwich composites.

Effect of single-walled carbon nanotubes on the cure and mechanical properties of reclaimed rubber/natural rubber blends

Reclaimed rubber (RR) is a recovered rubber material and has lower quality and properties compared to virgin rubber. To enhance its properties and subsequently widen the scope of applications, it is often blended with virgin natural rubber (NR). However, properties of the resultant RR/NR blends are negatively affected as the proportion of RR in the RR/NR blends is increased. This study seeks to explore the use of single-walled carbon nanotubes (SWCNTs) in RR/NR blends, where the dominant component is RR. Based on the tensile properties of specific formulations, the amounts of SWCNTs were first optimised by mixing varying amounts of SWCNTs and NR using conventional laboratory equipment. The effect of optimised SWCNTs on the cure and mechanical properties of RR/NR blends was thereafter investigated. The obtained results showed that upon the incorporation of SWCNTs, the minimum torque of RR/NR blends decreased while the scorch time and cure rate increased. Both the ultimate tensile strength and modulus at 100 %, 300 % and 500 % elongation increased, while the elongation at break slightly decreased. Furthermore, it was found that SWCNTs considerably increased hardness of RR/NR blends but insignificantly decreased the rebound resilience.

Effect of Nanoclay/Nanosilica on the Mechanical Properties, Abrasion and Swelling Resistance of EPDM/SBR Composites

In this research work, ethylene-propylene-diene monomer (EPDM)/styrene butadiene rubber (SBR) hybrid composites reinforced with nanoclay (NC) and nanosilica (NS) were prepared and investigated. The synergistic effect of NC and NS on the mechanical properties of the EPDM/SBR hybrid composites was examined. Three different crosslinking systems were used, namely: sulphur, dicumyl peroxide and the mixed system consisting of sulphur and peroxide in this research work. The tensile strength, elongation at break, 100% modulus, tear strength, hardness, rebound resilience, abrasion resistance, compression set, swelling resistance and microstructure of the EPDM/SBR hybrid composites were evaluated. The concentration nanosilica along with nanoclay plays a most vital role in the micro-structural, mechanical and other properties of the nanocomposites. From the study, it was clear that the nanocomposites containing 7.5 parts per hundred rubber (phr) of nanoclay and 4 phr of nanosilica shows a maximum mechanical properties along with its abrasion and swelling resistance characteristics. In particular, the sulphur cured EPDM/SBR hybrid composites containing nanoclay and nanosilica results in best mechanical properties and abrasion resistance.

Effect of NR-g-cellulose coupling agent into NR-cellulose composite dispersibility and its physical properties

Natural rubber and cellulose are two materials with very different compatibility, so it is difficult to produce homogenous composite without using coupling agent. Natural rubber is nonpolar while cellulose is polar. The combination of natural rubber with cellulose is expected to produce composite with higher strength. The reinforcement concept of polymeric materials, such as natural rubber with cellulose as filler, results from increased rubber-filler interactions. This study aims to determine the effect of NR-g-Cellulose as coupling agent on the dispersibility of the composite and its physical properties. Hexamine/resorcinol and silane were used as a reference for a commercial coupling agent. Cellulose material was mixed in two-roll open mill together with natural rubber and other chemicals using three types of coupling agents, hexamine/resorcinol, silane, and NR-g-Cellulose. The FESEM result of the surface of composite indicated that composite with NR-g-Cellulose as coupling agent showed homogenously dispersed compared to two other types of coupling agent but it is lower in physical properties, especially in tensile strength, tear strength, compression set, and rebound resilience of the composite. It may be caused by the NR-g-Cellulose coupling agent not working optimally and therefore it needs a high temperature to optimize the coupling agent to react with natural rubber and cellulose.

Green in Situ Growth Solid Electrolyte Interphase Layer with High Rebound Resilience for Long-Life Lithium Metal Anodes.

Lithium (Li) metal is one of the most promising anodes for the high-energy density lithium batteries. Nevertheless, it is still a great challenge to construct a dendrite-free Li anode with stable solid electrolyte interphase (SEI) by adopting environmentally friendly approaches. Herein, a green artificial Li polylactic acid (LiPLA) SEI layer with biodegradability and highly rebound resilience is fabricated via an in situ reaction to regulate Li metal plating/stripping behavior. Guided by this stable environmentally friendly LiPLA SEI, the Li anode shows excellent stability with suppressive dendrites as demonstrated by a stable cycling of 850 h in LiPLA-Li/LiPLA-Li symmetric batteries and a significant capacity retention rate enhancement of 18% in LiPLA-Li/LiFePO4 full batteries and 25% in LiPLA-Li/LiNi3/5Co1/5-Mn1/5O2 full batteries. This proposed strategy provides a green and facile way to ameliorate the stability of the Li anode for safe and long-life lithium metal batteries.

Influence of Thermal Aging in Oil on the Friction and Wear Properties of Nitrile Butadiene Rubber

An experimental study on the influence of thermal aging on the friction and wear properties of a nitrile butadiene rubber (NBR)–steel pair was carried out. Rubber specimens were aged in hydraulic oil at 60 °C and 90 °C for 0–70 days. The Shore hardness, Young’s modulus, rebound resilience, and other mechanical properties were measured. The friction coefficient and wear volume were tested to evaluate the tribology performance. To investigate the mechanism of NBR thermal aging, the molecular structure and crosslinking degree were analyzed. Crosslinking with rubber aging in oil led to differences in the physical and mechanical properties. The Shore A hardness decreased initially and then increased. The Young’s modulus increased and the rebound resilience decreased. The friction coefficient increased but the wear volume decreased with aging time. These differences affected the friction and wear behavior of the NBR against the steel shafts and resulted in sealing-ring degradation and failure.

Optimization of physical and mechanical properties of glycerol - modified natural rubber/starch - filled carbon black composites using two level factorial design

A statistical model was developed in this study to describe cure characteristic, rebound resilience and tensile strength of natural rubber/starch composites which was prepared by using a Haake internal mixer. Response surface methodology (RSM) based on central composite centered design (CCD) was employed to statistically evaluate and optimize the conditions for maximum cure characteristic, rebound resilience and tensile strength and study the significance and interaction of carbon black and glycerol on rebound resilience and tensile strength yield. The experimental runs were carried out according to a 22 full factorial design for the two identified design independent variables, namely, carbon black (X1) and glycerol (X2). With the use of the developed quadratic model equation, a maximum rebound resilience 71% was obtained to be a carbon black loading of 50 phr and glycerol loading of 7 %.

Fabrication and Properties of a Novel Porous Material from Biopolymer and Natural Rubber for Organic Compound Absorption

Maleate poly (vinyl alcohol) (PVAM)-graft water soluble polymer with deproteinized natural rubber (DPNR) porous materials were prepared using the freeze drying technique. The effect of the water soluble polymer type (chitosan (CS) and gelatin (GT)) and the DPNR content was studied. The mechanical properties of the porous materials were improved by the addition of the DPNR. The results showed that the addition of the DPNR improved the water resistance of the porous material. Many micro-voids were formed after the PVAM was grafted with the water soluble polymers as observed under SEM, leading to changes in porosity and density. The highest number of micro-voids was found in the PVAM-graft-chitosan (sPVAM-g-CS) sample while the minimum number of microvoids was found in the maleate poly (vinyl alcohol) (sPVAM). The swelling ratio of the nPVAM significantly improved after the freeze drying process. The PVAM-graft-gelatin (sPVAM-g-GT) gave the maximum swelling ratio in water. After the DPNR was added to the sPVAM-g-GT, the pore size of the porous material significantly decreased and the size distribution became narrower. The moisture absorption, moisture content and swelling ratio of the porous material decreased after blending with the DPNR but the tear strength and rebound resilience of the porous material was enhanced. The macroporous material was able to be reused the maximum number of over 30 times as organic compound-absorbent material and it easily decomposed in nature.

Investigation of Epoxidized Palm Oils as Green Processing Aids and Activators in Rubber Composites

Epoxidized palm oil (EPO) is environmentally friendly, biodegradable, and a relatively less costly processing aid. In this study, we investigated the suitability of EPO in place of aromatic processing oils in styrene butadiene rubber. The curing properties, mechanical properties, abrasion resistance, and heat buildup properties of rubber composites with EPO were compared with those of the standard with aromatic oils. The rubber composites with EPO showed enhanced mechanical properties including modulus, tensile strength, and elongation at break. This is ascribed to the improved dispersion of fillers in the rubber matrix and interaction between the filler and the polymer. Furthermore, EPO in the rubber matrix showed remarkable abrasion resistance, rebound resilience, and heat buildup at low loadings. EPO in a rubber composite presents feasibility as a renewable raw material that can serve as an alternative to petrochemical oils in various applications.

Novel green composites from styrene butadiene rubber and palm oil derivatives for high performance tires

ABSTRACTIn rubber compounding, renewable, nontoxic, and degradable palm oil is used as a safe alternative softener or stabilizer process oil. In the tire industry, with the development of environment‐friendly “green tires,” silica has been used as a reinforcing filler for tread compounds. To make the hydrophilic silica compatible with the hydrophobic rubber matrix, the addition of amphiphilic oil is required. We, for the first time, prepared an amphiphilic palm oil derivative (PO) with hydrophobic and hydrophilic functional groups in bulk. Rubber composites prepared with the PO exhibited remarkable improvements in mechanical properties, including tensile strength, elongation, and fatigue. These improvements are attributed to the enhanced dispersion of the fillers in the rubber matrix due to the PO. Also, the mixing of PO in the rubber matrix resulted in outstanding abrasion, rebound resilience, and heat buildup properties at low loadings. We then prepared pneumatic tires with a tread composite using PO, and conducted virtual tests using a vehicle‐mounted pneumatic tire. The pneumatic tire exhibited enhanced high speed durability, dry and wet braking. The strong interfacial interactions between the silica and the rubber matrix due to the PO resulted in improved viscoelastic properties. These results show that PO is a renewable potential replacement for conventional aromatic oils in tire engineering applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47672.

Influence of highly dispersible silica filler on the physical properties, tearing energy, and abrasion resistance of tire tread compound

ABSTRACTRubber industry is facing a stiff challenge in the years to come. There are rising price for fossil fuel and shortage of resources. There is more stringent legislation to protect the environment and reduce the emission. Filler plays an important role in imparting useful properties to rubber products. In this article, the effects of new generation filler, on the physical properties, tearing energy, and abrasion resistance were investigated. The new generation filler, highly dispersible silica, has a dibutyl phthalate (DBP) absorption value of more than 180cc 100 g−1, more branched structure and relatively higher amount of small aggregates. Four different loadings of silica (up to 45 phr) were investigated. With increasing filler loading, the tensile strength and modulus at 300% elongation increased and the elongation‐at‐break decreased. The rebound resilience decreased and tan delta value improved with increasing silica content. The abradability continuously decreased with concomitant increase in the side coefficient force. The fatigue resistance was found to be better at higher silica loading. The silica particles due to its surface structure helps in crack arresting. The abradibility was related to tearing energy, loss modulus, and breaking energy. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47560.

Preparation and properties of new elastomeric systems containing alternative fillers

The present paper deals with a preparation of new elastomeric compounds containing two kinds of alternative additives based on wastes from glass production and energetics. Named alternative fillers were mixed into rubber compounds asa replacement of commonly used fillers – carbon black and silica. Rheological properties, vulcanization characteristics as well as hardness and rebound resilience of vulcanizates, which are important parameters for their industrial application, have been studied in the new prepared elastomeric systems. The resulting vulcanizates containing alternative fillers exhibit improved properties, in particular low rolling resistance and high rebound resilience, while maintaining optimal hardness values. Used raw material substitution can also bring significant environmental and economic effects.

The Effect of Palm Oil-Based Hybrid Oils as Green Multifunctional Oils on the Properties of Elastomer Composites.

Hybrid oils in an elastomer matrix provide superior physical and chemical properties over conventional elastomer composites. In this study, we investigated the possibility of utilizing palm-based hybrid oil as a processing oil, with various other added oils such as methylester, palm monoglyceride and dammar, and their effects on the curing characteristics, mechanical, abrasion resistance and heat build-up properties of elastomer composites. The elastomer composites with the hybrid oils exhibit remarkable improvements in mechanical properties such as modulus, tensile strength, elongation and toughness, which were ascribed to the enhanced dispersion of the fillers in the elastomer matrix. Also, the hybrid oils in the elastomer matrix showed outstanding heat build-up, abrasion and rebound resilience properties at low loadings. The synergistic effects in the elastomer matrix achieved by the hybridization of palm oil and other oils represent a significant contribution to advanced, stronger elastomer composites in various applications.

Optimisation of Formulation for Starch Modified Natural Rubber Composites by Using Response Surface Methodology

Starch modified natural rubber vulcanisates were prepared by the melt compounding method using a two-roll mill at a constant starch loading of 20 phr. Four formulation parameters consisted of black filler, white filler, silane coupling agent (SCA) and glycerol content in the composites which were optimised using two-level factorial design via response surface methodology (RSM). The cure characteristics and rebound resilience were selected as the responses. The significance of the factors and interaction were analysed using ANOVA and the model’s ability to represent the system was confirmed using the constant of determination, R2 for a value above 0.90. The R2 values for all responses were obtained in the range between 0.96 and 0.99 which are close to the union (R2 = 1). The final combination of factors used to achieve the highest rebound resilience and cure characteristics were with a high black filler loading of 60 phr and high glycerol of 5 % loading. These findings were further supported by morphological the characteristics observed under scanning electron microscopy (SEM). Therefore, the chemical modification using both glycerol and SCA was proven to improve the cure characteristics and rebound resilience value through the enhancement of the interfacial interaction between the starch and natural rubber (NR) particles. It is expected that the findings in this study will be useful for rubber product manufacturers to explore the possibility of producing biodegradable products in the future.

Fabrication of Wood Fiber-rubber Composites with Reclaimed Rubber

This research investigated the use of reclaimed rubber (RR) from waste tires to partially replace the rubber compound (RC) when making wood fiber-rubber composites (WRCs). Ninety panels of WRC containing RR were manufactured with RR contents of 0% to 40%, mixing times of 6 min to 14 min, and vulcanizing temperatures of 150 °C to 170 °C. There were three steps, which were the fiber-rubber mixing, tabletting, and vulcanization molding processes. Four regression equations for the tensile strength, elongation at break, hardness, and rebound resilience as functions of the RR content, mixing time, and vulcanizing temperature were derived, and a nonlinear programming model was developed to obtain the optimum panel properties. It was found that when the RR content was within 20%, the wood fibers were well encapsulated and embedded in the RC/RR blends, and the processability of the WRCs were improved by adding RR. The incorporation of RR into the WRCs increased the average tensile strength and hardness by 33.9% and 2.3%, respectively, while the swelling ratio in toluene and 24-h water absorption were reduced by 13% and 42%, respectively.