In-situ formation of ZnO anchored silica: Sustainable replacement of conventional ZnO in SBR/NR blends
Sreethu Thiyyanthiruthy Kumbalaparambil
, Ajay Haridas Chandaparambil, Kinsuk Naskar
, Ajay Haridas Chandaparambil, Kinsuk NaskarVol. 17., No.12., Pages 1268-1285, 2023
DOI: 10.3144/expresspolymlett.2023.96
DOI: 10.3144/expresspolymlett.2023.96
Corresponding author: Kinsuk Naskar 
GRAPHICAL ABSTRACT
ABSTRACT
The global concern over zinc leaching into aquatic ecosystems has led researchers to seek ways to reduce zinc oxide (ZnO) content in rubber products. Conventional microsized ZnO, commonly used in the rubber industry, poses dispersion challenges due to its hydrophilic nature and micron size within the hydrophobic rubber matrix. Therefore, higher amounts of ZnO are added, elevating the risk to aquatic life. A promising alternative involves using highly dispersible ZnO with active zinc (Zn) centers instead of conventional ZnO. Another approach includes incorporating ZnO-anchored silica particles into the rubber matrix, which requires additional ex-situ fabrication. This study presents an innovative method where ZnO-anchored silica is generated in situ during the blending of styrene-butadiene rubber/natural rubber (SBR/NR). The study also evaluates the effectiveness of active, nano-sized, and octylamine-modified ZnO as activators compared to conventional ZnO, by introducing silica filler, octylamine-modified and high surface area ZnO anchor onto the silica surface, forming Si–O–Zn covalent bonds. This protective layer reduces filler aggregation and the Payne effect. Even with 60% less usage, these activators in the SBR/NR blend significantly enhance tensile strength (31.27%) and elongation at break (49.13%) compared to conventional ZnO. These results point towards the possibility of a cost-effective and sustainable replacement for conventional ZnO.
RELATED ARTICLES
Nabil Hayeemasae, Sitisaiyidah Saiwari, Siriwat Soontaranon, Mohamad Irfan Fathurrohman, Abdulhakim Masa
Vol. 19., No.3., Pages 339-349, 2025
DOI: 10.3144/expresspolymlett.2025.24
Vol. 19., No.3., Pages 339-349, 2025
DOI: 10.3144/expresspolymlett.2025.24
Natural rubber (NR) composites filled with silica and crosslinked with phenolic resin were prepared in this study. The influence of a small sepiolite addition (1–5 part(s) per hundred parts of rubber, phr) on the properties of NR composites was studied. It was found that sepiolite reduced silica aggregate size, allowing improved dispersion in the NR matrix. Sepiolite facilitates silica dispersion by locating at the silica surfaces and acting as a barrier that prevents agglomeration of silica filler. The swelling resistance, crosslink density, tensile strength, and strain-induced crystallization were all strengthened by incorporating sepiolite because of the improved silica dispersion. The greatest tensile strength was achieved at a 2 phr sepiolite addition level. The improvement was about 18% over the reference composite due to the greatest filler-rubber interactions and the finest filler dispersion. The results clearly indicate that sepiolite clay can be applied as a dispersing agent in silica-containing rubber composites.
Marek Pöschl, Radek Stoček, Petr Zádrapa, Martin Stěnička, Gert Heinrich
Vol. 18., No.12., Pages 1178-1190, 2024
DOI: 10.3144/expresspolymlett.2024.90
Vol. 18., No.12., Pages 1178-1190, 2024
DOI: 10.3144/expresspolymlett.2024.90
This paper extends previous studies by the authors that aimed to describe the effect of apparent cross-link density (CLD) of the rubber polymer networks on the fracture mechanism caused by cut and chip (CC) wear of natural rubber (NR), demonstrating the positive effect of conventional vulcanization (CV). This work is focused on the determination of the effect of CLD while keeping constant the accelerator-to-sulfur ratio A/S = 0.2, typical for CV systems. For this ratio, different sulfur quantities were chosen, and the concentration of the accelerator N-tert-butyl-benzothiazole sulphonamide (TBBS) was calculated to achieve CLDs in a range from 35 to 524 μmol・cm–3. Standard analyses such as tensile tests, hardness, rebound resilience and DIN abrasion were performed. From these analyses, the optimum physical properties of the NR-based rubber were estimated to be in the CLD range of approximately 60 to 160 μmol・cm–3. A CC wear analysis was performed with an Instrumented cut and chip analyzer (ICCA) and it was found that the highest CC wear resistance of the NR is in the CLD range of 35 to 100 μmol・cm–3. Furthermore, the effect of straininduced crystallization (SIC) of NR on CC wear and its dependence on the CLD region was discussed. For the first time, we determine a CLD range for a CV system in which the material achieves both optimal mechanical properties and CC wear resistance.
Agata Rodak, Józef Haponiuk, Shifeng Wang, Krzysztof Formela
Vol. 18., No.12., Pages 1191-1208, 2024
DOI: 10.3144/expresspolymlett.2024.91
Vol. 18., No.12., Pages 1191-1208, 2024
DOI: 10.3144/expresspolymlett.2024.91
Carbon black migration between ground tire rubber (GTR) and rubber matrix is essential in developing high-performance rubber/GTR composites. In this work, carbon black N220 (surface area: 107.1 m2/g, particle size: 20–25 nm) and N660 (surface area: 33.1 m2/g, particle size: 49–60 nm) were used as the reinforcement fillers for styrene-butadiene rubber (SBR) blended with reclaimed GTR. The combined effects of GTR devulcanization level and carbon black grade on the properties of SBR/GTR composites were investigated considering curing characteristics, thermal stability, physico-mechanical properties, dynamic mechanical properties, swelling behavior, and morphology. The results showed that, regardless of GTR devulcanization level and carbon black grade, application of GTR resulted in deterioration of mechanical properties compared to a reference sample without GTR. It was observed the reinforcement effect of carbon black in SBR/GTR composites was more visible with higher devulcanization level of GTR and lower particle sizes of carbon black fillers. SBR/GTR composites reinforced with carbon black N220 were characterized by tensile strength in the range of 15.3–16.3 MPa and abrasion resistance in the range of 120–123 mm3, which justify their potential application in the manufacturing of technical rubber goods or footwear.
Kamonthip Rittimas, Skulrat Pichaiyut, Charoen Nakason
Vol. 18., No.11., Pages 1149-1163, 2024
DOI: 10.3144/expresspolymlett.2024.87
Vol. 18., No.11., Pages 1149-1163, 2024
DOI: 10.3144/expresspolymlett.2024.87
Epoxidized natural rubber with 50 mol% epoxide (ENR-50) was compounded with zinc chloride (ZnCl2) and subjected to torque response analysis using a moving die rheometer. It was found that different ZnCl2 concentrations (3, 5, 7, 9, and 12 millimoles (mmol)) mixed in ENR-50 exhibited positive torque responses, prompting further molecular characterization using Fourier transform infrared spectroscopy. The results indicated distinct absorption peaks at wavenumbers of 442 and 809 cm–1, which signify the presence of –O–Zn–O– coordination linkages. The curing characteristics of ENR and ZnCl2 compounds showed that increasing ZnCl2 content resulted in higher minimum and maximum torque values, but also led to a decrease in scorch time and cure rate index (CRI). Moreover, higher ZnCl2 concentrations enhanced the strength properties (tensile strength, moduli, stiffness, toughness, and hardness), crosslink densities, dynamic shear moduli, initial modulus during relaxation experiments, and thermal resistance, as evidenced by temperature scanning stress relaxation (TSSR), thermogravimetric analysis, and dynamic mechanical analysis. However, an increase in ZnCl2 content led to a reduction in elongation at break due to the higher crosslink density within the coordination networks in the ENR matrix, which resulted in the movement constraint of the rubber vulcanizate.
Rattanawadee Ninjan, Bencha Thongnuanchan, Natinee Lopattananon, Subhan Salaeh, Phakawat Thongnuanchan, Pornsuwan Buangam
Vol. 18., No.11., Pages 1077-1093, 2024
DOI: 10.3144/expresspolymlett.2024.83
Vol. 18., No.11., Pages 1077-1093, 2024
DOI: 10.3144/expresspolymlett.2024.83
Research into sustainable packaging materials has gained increasing importance due to the pressing environmental concerns related to plastic waste. The present study focused on developing a sustainable paper coating based on modified natural rubber (NR) latex filled with gelatin (GT). The graft copolymer latex of NR and poly(vinylbenzyl chloride) bearing quaternary ammonium groups, abbreviated as NR-g-QPVBC, was first synthesized. GT was then incorporated into the latex, and the combination of these materials resulted in a heat-sealable film with good tensile properties and a water barrier. The ionic crosslinking of the latex film was achieved by the reaction with ethylenediaminetetraacetic acid (EDTA). Heat-sealing studies of the NR-g-QPVBC latex film filled with GT (NR-g-QPVBC/GT) revealed its heat-sealability at 160 °C. Scanning electron microscope (SEM) analysis further confirmed the diffusion of the chains across the interface during heat sealing. Dip coating was a method for depositing latex film on kraft paper. The paper coated with the NR-g-QPVBC/GT latex showed a significant increase in dry and wet-tensile strength compared to the uncoated paper. The sealing process was optimized to achieve a heat-seal strength of 755.31 N/m at a dwell time of 3 s and a temperature of 160 °C. The research's practical application was demonstrated by transforming the coated paper into various heat-sealable bags using a handheld bag sealer.
