Hari Shankar Singhania Elastomer And Tyre Research Institute

ABSTRACT The segregation of carbon black within a blend of NR/EPDM rubber at different mixing proportions (especially 70/30 and 30/70) was investigated via various microscopic techniques—transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM)-mapping, field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM)—to analyze the characteristics of the rubber matrix in pristine rubber to final filled rubber blends. The investigation spans from the unfilled rubber to ultimate filled blends with low (25 phr) and high (50 phr) carbon black content. The use of OsO4 for selective chemical staining, in conjunction with microscopy, made it possible to distinctly understand each rubber phase within the blend, greatly aiding in the identification of filler migration to the preferred rubber phase. In addition, STEM-mapping confirmed the phase distribution by identifying the continuous and dispersed phases through precise detection and validation of the stained areas. The combined outcome of the microscopic studies (TEM, FESEM, and AFM) revealed that the carbon black filler is more inclined to move toward the unsaturated NR phase due to its active graphitic edges, making it more compatible with the NR phase, which has a higher degree of unsaturation than EPDM.

Hyperbranched poly(ethylene glycol)–trimesic acid polyesters serve as adaptable scaffolds capable of regulating oxidative stress, maintaining calcium balance, and facilitating neuro–keratinocyte interactions for tissue engineering applications.

Good dispersion of compounding ingredients in a rubber formulation is crucial for mechanical performance. After mixing, certain materials like sulfur, recycled materials, and zinc oxide can remain undispersed within the rubber matrix, which can lead to critical flaws and influence performance. Improper dispersion is one of the reasons for poor physico mechanical properties. The influence of temperature, mixing time and storage time of different grades of insoluble sulfur collected from one source are studied along with the standard sample of different sources. To better understand the reason for poor sulfur dispersion and high blooming, all the chemical and physical properties are analysed. The topological structures are evaluated using the thermomechanical techniques. The reason for poor dispersion and premature failure of the rubber specimen has been studied by SEM-EDS. The degradation of insoluble sulfur to soluble sulfur can be negligible during the melt mixing if the mixing is done in a controlled way. The final mixing temperature shall be maintained at 90 °C to 95 °C to restrict the insoluble to soluble sulfur conversion. This paper highlights the methodology of the development of oil-coated sulfur in rubber composites and provides insight into the dispersion of polymeric sulfur in natural rubber-based tyre carcass compounds.

<div class="section abstract"><div class="htmlview paragraph">There are two key factors driving the tyre manufacturers to increase their focus on improving the noise characteristics of the tyre: Strict homologation requirements for tyre and vehicle noise and the increasing prevalence of Electric vehicles. With developing infrastructure and vehicle technology, the tyre noise impact on overall vehicle noise is becoming more and more important. The principal focus of the study is to perform experimental analysis for understanding the effect of various operational parameters such as load, inflation pressure (IP) and speed on overall tyre noise in a semi-anechoic chamber under controlled conditions. To understand the impact of the operational parameters, five C1 class radial tyres with different rim sizes (14”-18”) and same tread patterns were used. The study includes measuring the overall tyre noise expressed as Sound pressure level (SPL) in dB(A) using microphones at three different locations inside the semi-anechoic chamber on a 2m steel drum i.e., Leading edge Mic (LM), Trailing edge Mic (TM), and Center Mic (CM). These three microphone locations will help us to recognize the impact of the operational parameters on aerodynamic, vibrational and amplification or reduction noise generating mechanisms. A test matrix with varying load (50%-125%), speed (40km/h-100km/h) and inflation pressure (200-260kPa) were used to capture the overall noise characteristics.</div></div>

Electron beam radiation (EBR) technology is one of the most promising technologies among other radiation-driven technologies and has been used in the rubber and tyre industry due to its ability to cross-link certain rubbers depending on their chemical structures. EBR can provide good green strength to rubber and rubber products by partial cross-linking which has practical importance in the radial tyre building process. The tyre components where EBR has practical application include tyre treads, inner liners, belt, and body ply skim compounds. This book chapter discusses the effect of EBR on the structure and properties of tyre rubbers, such as natural rubber (NR), styrene-butadiene rubber (SBR), polybutadiene rubber (BR), synthetic polyisoprene (IR), and isobutylene-isoprene rubber or butyl rubber (IIR). The impact of EBR on the performance triangle properties of the tyre such as rolling resistance, wet grip, and abrasion resistance are discussed in detail. The viability of the application of this process in the modern-day tyre industry is also highlighted.

Abstract The specific geometry and distinct properties of one‐dimensional nanostructures make them the most ideal candidates as reinforcing elements in composites and the dependence of physical, mechanical, thermal, and wear properties of polymer composites on their dimensionality, nature, and dispersion is interesting. The upsurging demands for high‐performance elastomer composites require the application of such nanomaterials as reinforcing agents. Here, we offer a detailed characterization of some of the novel fibrous nanofillers such as silicon carbide nanofibers, aramid nanofibers, carbon nanotubes, and graphite nanofibers. Morphology, crystallinity, surface chemistry, polarity, and thermal stability of these nanofibers were analyzed using techniques such as electron microscopy, X‐ray diffraction, infrared and Raman spectroscopy, and thermogravimetric analysis. Natural Rubber nanocomposites were developed using these fibrous nanofillers, and their rheometric, mechanical, dynamic mechanical, and thermal properties were studied. ANF‐reinforced compounds gave the highest increment in 300% modulus while the highest tensile strength was obtained by CNT reinforced compounds at 4 phr filler loading. CNT and GNF‐reinforced compounds improved the wear resistance simultaneously by 43% and 33% respectively, while SiC and ANF improved it by 10% and 8% respectively. Lower tan delta and better thermal stability were also recorded. Future exploration may involve the use of these nanofibers in conjunction with carbon black or silica to achieve high‐performance elastomer compounds for real‐life applications.

Abstract Based on the viscous energy dissipation parameter around the crack tip, several intrinsic factors tend to govern the dissipation factor which in turn leads to the characteristic crack growth mechanism of the rubber vulcanizate. Herein, the crack growth behavior of different filled natural rubber (NR), styrene butadiene rubber (SBR), and NR/SBR blends was studied. It was deciphered that the 80/20 NR‐SBR (NSS) compound exhibited the lowest crack growth (dc/dn) value at all strain percentages which was in good accordance with its highest viscous energy dissipation as observed from the DMA (strain sweep) results. Also, from the theoretical calculations, dissipated energy per unit volume for NSS was 4.73 MPa, which was the highest out of all the compounds. This led to a decrement in crack growth. The lowest intensity peak in tan δ versus temperature curve, 6.5% decrement in ΔE'(storage modulus), and almost 44% decrement in ΔG’ (Payne Effect) indicates higher polymer‐filler interaction and lower filler‐filler disintegration respectively, as compared to 100 NR (NRS). The results from optical microscopy and scanning electron microscope suggested that NSS exudes the smallest crack deviation and extent of crack growth with lesser filler agglomerates making NSS the best fatigue‐resistant compound.

Abstract Rubber products, especially tire, experiences millions of fatigue cycles during their service life. In this period, penetration or cuts owing to any sharp objects brings calamitous failure. Thus, the fatigue crack growth (FCG) characteristic of tire components has become an important parameter to inspect. In the present study, the FCG behavior of sustainable filler, lignin‐filled composite is investigated. The impact of rubber matrix (epoxidation of natural rubber) on crack growth behavior is scrutinized in this article. Epoxy group introduction in natural rubber leads to a significant change in tearing energy throughout the strain range (10%–25%). Higher mol% of the epoxy group brings in a lower crack growth rate. An increase in polar interaction amongst the matrix through epoxide—hydroxyl functionality contributes significantly to the FCG rate. Inter‐molecular interaction promotes higher cross‐link density in epoxidized natural rubber containing composites which are reflected in static as well as dynamic‐mechanical properties. Morphological evidence (Field‐emission scanning electron microscope [FE‐SEM] and microscopic images) establishes the fact that stiffening at the crack tip, arising from intrinsic strain‐induced crystallization and high‐density network formation in the concerned matrix are the major contributors to the reduction in fatigue crack growth rate of a composite.

Tirthankar Bhandary, Abhijit Pal*, Saurabh Mathur, Maitreya Dutta, Saikat Dasgupta and Rabindra Mukhopadhyay Author Affiliations Hari Shankar Singhania Elastomer and Tyre Research Institute (HASETRI), Raghupati Singhania Centre of Excellence, 437, Hebbal Industrial Area, Mysore-570016, Karnataka, India Received: April 28, 2021 | Published: May 05, 2021 Corresponding author: Abhijit Pal, Hari Shankar Singhania Elastomer and Tyre Research Institute (HASETRI), Raghupati Singhania Centre of Excellence, 437, Hebbal Industrial Area, Mysore-570016, Karnataka, India DOI: 10.26717/BJSTR.2021.35.005721