scholarly journals Alleviating Molecular-Scale Damages in Silica-Reinforced Natural Rubber Compounds by a Self-Healing Modifier

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 39
Author(s):  
Bashir Algaily ◽  
Wisut Kaewsakul ◽  
Siti Salina Sarkawi ◽  
Ekwipoo Kalkornsurapranee
Keyword(s):  
Natural Rubber ◽  
Zinc Acetate Dihydrate ◽  
Crosslinking Agent ◽  
Annealing Treatment ◽  
Self Healing ◽  
Rubber Compounds ◽  
Healing Efficiency ◽  
Molecular Scale ◽  
Transesterification Catalyst ◽  
Natural Rubber Vulcanizates

The property retentions of silica-reinforced natural rubber vulcanizates with various contents of a self-healing modifier called EMZ, which is based on epoxidized natural rubber (ENR) modified with hydrolyzed maleic anhydride (HMA) as an ester crosslinking agent plus zinc acetate dihydrate (ZAD) as a transesterification catalyst, were investigated. To validate its self-healing efficiency, the molecular-scale damages were introduced to vulcanizates using a tensile stress–strain cyclic test following the Mullins effect concept. The processing characteristics, reinforcing indicators, and physicomechanical and viscoelastic properties of the compounds were evaluated to identify the influences of plausible interactions in the system. Overall results demonstrate that the property retentions are significantly enhanced with increasing EMZ content at elevated treatment temperatures, because the EMZ modifier potentially contributes to reversible linkages leading to the intermolecular reparation of rubber network. Furthermore, a thermally annealing treatment of the damaged vulcanizates at a high temperature, e.g., 120 °C, substantially enhances the property recovery degree, most likely due to an impact of the transesterification reaction of the ester crosslinks adjacent to the molecular damages. This reaction can enable bond interchanges of the ester crosslinks, resulting in the feasibly exchanged positions of the ester crosslinks between the broken rubber molecules and, thus, achievable self-reparation of the damages.

scholarly journals A Self-Healing System Based on Ester Crosslinks for Carbon Black-Filled Rubber Compounds

2021 ◽  
Vol 5 (3) ◽  
pp. 70
Author(s):  
Bashir Algaily ◽  
Wisut Kaewsakul ◽  
Siti Salina Sarkawi ◽  
Ekwipoo Kalkornsurapranee
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Zinc Acetate Dihydrate ◽  
Polymer Networks ◽  
Crosslinking Agent ◽  
Fatigue Properties ◽  
Butadiene Rubber ◽  
Self Healing ◽  
Rubber Compounds ◽  
High Fatigue

Carbon black-reinforced rubber compounds based on the blends of natural rubber (NR) and butadiene rubber (BR) for tire sidewall applications were formulated to investigate the self-healing efficacy of a modifier called EMZ. This modifier is based on epoxidized natural rubber (ENR) modified with hydrolyzed maleic anhydride (HMA) as the ester crosslinking agent plus zinc acetate dihydrate (ZAD) as the transesterification catalyst. The influence of EMZ modifier content in sidewall compounds on processing characteristics, reinforcement, mechanical and fatigue properties, as well as property retentions, was investigated. Increasing the content of EMZ, the dump temperatures and Mooney viscosities of the compounds slightly increase, attributed to the presence of extra polymer networks and filler–rubber interactions. The bound rubber content and Payne effect show a good correction that essentially supports that the EMZ modifier gives enhanced filler–rubber interaction and reduced filler–filler interaction, reflecting the improved homogeneity of the composites. This is the key contribution to a better flex cracking resistance and a high fatigue-to-failure resistance when utilizing the EMZ modifier. To validate the property retentions, molecular damages were introduced to vulcanizates using a tensile stress–strain cyclic test following the Mullins effect concept. The property retentions are significantly enhanced with increasing EMZ content because the EMZ self-healing modifier provides reversible or dynamic ester linkages that potentially enable a bond-interchange mechanism of the crosslinks, leading to the intermolecular reparation of the rubber network.

Influence of Crosslink Characteristics Induced by Aromatic-Based Antioxidants on the Swelling and Stress-Strain Behavior of Natural Rubber Vulcanizates

2003 ◽  
Vol 76 (2) ◽  
pp. 334-347 ◽  
Author(s):  
Tarek M. Madkour ◽  
Rasha A. Azzam
Keyword(s):  
Natural Rubber ◽  
Crosslinking Agent ◽  
Oxidative Degradation ◽  
Thermal Oxidative Degradation ◽  
Stress Strain ◽  
Strain Behavior ◽  
Strain Induced Crystallization ◽  
Elastomeric Chains ◽  
Natural Rubber Vulcanizates ◽  
Induced Crystallization

Abstract Stress-strain measurements were performed on dry and swollen natural rubber vulcanizates prepared using both sulfur as the crosslinking agent and aromatic-based bound antioxidants acting as a second crosslinking agent. The aromatic-based antioxidants were synthesized and analyzed spectroscopically in order to relate the final behavior of the vulcanizates to the nature of the crosslink characteristics. The anomalous upturn in the modulus values of these networks in response to the imposed stress was shown to persist in the dry as well as the swollen state. Since the swollen elastomeric chains cannot undergo a strain-induced crystallization, the abnormal upturns in the modulus values in an absence of a filler were explained on the basis of the limited extensibility of the short chains of networks prepared using two different crosslinking agents in line with earlier modeling predictions. Remarkably, the swelling experiments revealed the increase in the crosslink density of the networks in the early stages of the thermal oxidative degradation procedure indicating a post-cure of the chemically bound antioxidants to the elastomeric chains, which incidentally corresponds to a maximum in the modulus values of the networks. The rheological and other mechanical properties such as the hardness were shown not to have been affected as a result of the incorporation of the chemically bound antioxidants.

Thermal Expansion Phenomena in Filled and Unfilled Natural Rubber Vulcanizates

1980 ◽  
Vol 53 (2) ◽  
pp. 313-320 ◽  
Author(s):  
J. L. Thiele ◽  
R. E. Cohen
Keyword(s):  
Thermal Expansion ◽  
Carbon Black ◽  
Natural Rubber ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Linear Thermal Expansion Coefficient ◽  
Linear Thermal Expansion ◽  
Rubber Compounds ◽  
Expansion Behavior ◽  
Natural Rubber Vulcanizates

Abstract As with polybutadiene and SBR compounds, filled and unfilled vulcanizates of natural rubber exhibit long transients in their linear thermal expansion response following sudden changes in temperature. This is particularly noticeable when the materials are prestretched well beyond the point of thermoelastic inversion. Incorporation of 50 phr of carbon black significantly reduces the magnitude of the linear thermal expansion coefficient for natural rubber compounds; this reduction is greater than expected on the basis of comparisons with previous data on filled SBR vulcanizates. Changes in the surface chemistry of the filler have little effect on the thermal expansion behavior. For the unfilled vulcanizate, an equation based on rubber elasticity theory was successful in predicting the strain dependence of the linear thermal expansion coefficient up to moderate levels of strain. At higher strains the large deviations from theory were observed.

scholarly journals Aging Resistance of Biocomposites Crosslinked with Silica and Quercetin

2021 ◽  
Vol 22 (19) ◽  
pp. 10894
Author(s):  
Anna Masek ◽  
Olga Olejnik
Keyword(s):  
Natural Rubber ◽  
Crosslinking Agent ◽  
Mechanical Tests ◽  
Epoxidized Natural Rubber ◽  
Hydroxyl Groups ◽  
Self Healing ◽  
Aging Resistance ◽  
Before And After ◽  
Free Hydroxyl ◽  
The Impact

This research focuses on revealing the double role of quercetin accompanied by silica in epoxidized natural rubber. A crosslinking ability with antioxidative properties exists and reveals the dependence of these functions on quercetin content. Here, the aging resistance of self-healable biocomposites was analyzed. The self-healing properties were presented in our previous work. The stabilizing effect of quercetin applied as a crosslinking agent has been studied in epoxidized natural rubber with a 50 mol% of epoxidation (ENR-50). Some of five -OH moiety groups existing in the quercetin structure are able to react with epoxy rings of ENR-50 and cure this elastomer, whereas other free hydroxyl groups can donate the hydrogen molecule to a radical molecule, stabilizing it. The aging resistance of prepared composites was estimated by mechanical tests conducted before and after different types of aging, as well as by differences in color and surface energy between aged and un-aged samples. Changes within the oxygen function, which occurred as a result of the aging process, were observed using FT-IR absorbance spectroscopy. Furthermore, the impact of quercetin content on composites’ thermal stability was investigated by thermogravimetry (TGA). According to the results, a proper dose of quercetin can act as a crosslinker and antioxidant in ENR-50 at the same time.

PREPARATION AND CHARACTERIZATION OF BROMINATED NATURAL RUBBER APPLIED IN SILICA-FILLED NATURAL RUBBER VULCANIZATES

2016 ◽  
Vol 89 (3) ◽  
pp. 406-418 ◽  
Author(s):  
Nuchanart Onchoy ◽  
Pranee Phinyocheep
Keyword(s):  
Natural Rubber ◽  
Bromine Atom ◽  
Proton Nuclear Magnetic Resonance ◽  
Strong Emission ◽  
X Ray ◽  
Rubber Compounds ◽  
Silica Filler ◽  
Natural Rubber Vulcanizates

ABSTRACT Functionalization of NR with a bromine atom was developed and explored for its application in a silica-reinforced NR system. Two possible pathways were investigated: the direct addition of a bromine atom using N-bromosuccinimide (NBS) with FeCl2 as a catalyst in the latex phase (NR–Br); and an indirect method using a ring opening of epoxidized natural rubber (ENR) with 2-bromopropionic acid (ENR–Br). The chemical structure, including determination of the bromine contents, was analyzed with proton nuclear magnetic resonance and Fourier transform infrared spectroscopy. The occurrence of bromine in NR–Br was confirmed using scanning electron microscopy with energy dispersive x-ray spectroscopy. Strong emission peaks for Br Kα at 1.5 eV was evidenced. Moreover, glass transition temperature of modified NRs increased after bromination. Two types of brominated NR, that is, NR–Br and ENR–Br containing 2 and 4 mol% of bromine function, respectively, were used in a range of 1–5 phr in the silica-reinforced NR system with silica loading of 10 and 30 phr. Both cure and mechanical properties of the rubber compounds were investigated. The incorporation of the bromine function in NR of both ENR–Br and NR–Br enhanced the cure reactivity of the NR–silica vulcanization system. The modified NRs may have a role as a coupling agent between the NR and the silica filler.

Construction of a Dual Ionic Network in Natural Rubber with High Self-Healing Efficiency through Anionic Mechanism

2020 ◽  
Vol 59 (28) ◽  
pp. 12755-12765 ◽  
Author(s):  
Jinhui Liu ◽  
Chunlin Xiao ◽  
Jian Tang ◽  
Yudong Liu ◽  
Jing Hua
Keyword(s):  
Natural Rubber ◽  
Self Healing ◽  
Healing Efficiency

Effect of Carbon Black on Self-healing Efficiency of Natural Rubber

2019 ◽  
Vol 17 ◽  
pp. 1064-1071 ◽  
Author(s):  
S.R Khimi ◽  
S.N. Syamsinar ◽  
T.N.L. Najwa
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Self Healing ◽  
Healing Efficiency

scholarly journals Self-Healable Biocomposites Crosslinked with a Combination of Silica and Quercetin

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4028
Author(s):  
Olga Olejnik ◽  
Anna Masek ◽  
Małgorzata Iwona Szynkowska-Jóźwik
Keyword(s):  
Natural Rubber ◽  
Healing Process ◽  
Crosslinking Density ◽  
Mechanical Tests ◽  
Epoxidized Natural Rubber ◽  
Self Healing ◽  
Human Beings ◽  
Healing Efficiency ◽  
Before And After ◽  
The Impact

In this publication, novel bio-based composites made of epoxidized natural rubber with 50 mol% of epoxidation (ENR-50) are presented. The obtained materials, partially cured with a totally environmentally friendly crosslinking system consisting of natural ingredients, including quercetin and silica, exhibit a self-healing ability resulting from the self-adhesion of ENR-50 and reversible physical forces between the curing agent and the matrix. The impact of natural components on the crosslinking effect in uncured ENR-50 matrix was analyzed based on rheometric measurements, mechanical tests and crosslinking density. The partially crosslinked samples were next cut into two separate pieces, which were instantly contacted together under a small manual press, left at room temperature for a few days for the healing process to occur and finally retested. The healing efficiency was estimated by measuring mechanical properties before and after the healing process and was also confirmed by photos taken using optical and scanning electron microscope (SEM). According to the results, a combination of silica and quercetin is a totally safe, natural and effective crosslinking system dedicated to epoxidized natural rubber. The novel composites containing ingredients safe for human beings exhibit promising self-healing properties with a healing efficiency of up to 45% without any external stimuli and stand a chance of becoming innovative biomedical materials.

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