Vibration isolators are being used to reduce the orbital micro vibration induced by reaction whee! (RW) operation for spacecraft with sensitive optical payload like CARTOSAT, MICROSAT and GISAT. Vibration isolators are also required to isolate high frequency vibration generated by bearing and unbalance mass during RW operation. The room temperature vulcanizable (RTV) vibration isolators completely isolate the vibration transmission from the RW to the moulding platform. Electronic components and sensors are highly sensitive to pyroshock environments (near and mid-field) and may lead to damage or failure while resistant to low frequency environments (far-field), sine vibrations and random vibrations. Pyroshock is defined as the transient response of the structure (which includes structural elements, components, assemblies, subsystems and/or systems) to loading induced by the activation of pyrotechnic devices attached to the structure. Generally pyrotechnic devices are explosive or propellant activated. Hence it is necessary to isolate these electronic components and sensors positioned in near or mid-field pyro shock environments. To achieve shock isolation in near or mid-field without altering thermal environment, an isolation system was designed and tested. Characterization such as mechanical and thermal properties was carried out. Tensile strength of 221 kPa and thermal stability above 500°C was achieved. Beside these, silicone rubber had low outgassing property. Acousto ultrasonic (AUS) detection test confirmed that the newly developed system was devoid of defects such as bubbles, air entrapment, holes etc.

In the present study, PA80 was blended with different grades of EPDM terpolymer with variable raw rubber viscosity; among them, two were oil-extended grades. The processability and mechanical properties of the PA80/EPDM blends were studied in detail to identify the EPDM grade suitable with PA80 for extrusion application. The unsaturation content among the EPDM grades was comparable and was relatively compatible with PA80. Accordingly, the technical properties of the blend depend particularly on the ethylene-propylene ratio as well as on the degree of oil extension (lubrication effect). The filler dispersion was also found satisfactory for all the samples studied. The fine extrudates produced from oil-extended EPDM grade made smoother surfaces, but their dimensional tolerance (die swell) was poor. Moreover, the oil-extended matrix undergoes faster degradation under thermal ageing conditions and failed to retain its properties. Therefore, blending EPDM with PA80 can be considered as a technical strategy to compensate for these losses along with the processability advantages. The prime concern in achieving the complete benefits was to select materials with comparable raw rubber viscosities.

Natural rubber (NR) tends to harden during processing and storage, increasing its viscosity and necessitating extended mastication or the use of costly peptisers. To address this, constant viscosity natural rubber (CV-NR) NR treated to maintain consistent viscosity has gained popularity among manufacturers. Currently, CV rubber is marketed only in bale form as ISNR 3CV. This study explores the preparation of constant viscosity natural rubber sheets (CV-NRS) using hydroxylamine sulphate (HS) as a viscosity stabilizer at varying concentrations. The influence of HS on Mooney viscosity, plasticity retention index (PRI), vulcanization behavior and mechanical properties were evaluated both initially and after six months of storage. Fourier Transform Infrared Spectroscopy (FTIR) analysis was conducted to examine the chemical modifications induced by HS. Results showed that CV-NRS maintained stable viscosity, exhibited improved PRI and yielded vulcanizates with enhanced mechanical properties. FTIR spectra confirmed the formation of stabilizing chemical structures, indicating of HS effectiveness in inhibiting oxidative degradation and preventing premature crosslinking. These findings underscore the potential of HS as a cost-effective stabilizer for NR, enhancing both its processing characteristics and long-term performance.

Plants are traditional sources of several bioactive compounds like alkaloids, flavonoids, tannins, saponins, terpenes and phenolic compounds. In this study, three different clones of Hevea brasiliensis, namely RRII 105, RRII 414 and RRII 430, were selected and subjected to successive solvent extraction using methanol, isopropanol, acetone and cyclohexane, followed by GC-MS/MS analysis for the identification of various bioactive compounds. The chromatogram was recorded and matched with the NIST library for identification of compounds. Qualitative assays confirmed the presence of alkaloids, flavonoids, phenolics, tannins, saponins and terpenoids across all clones. Extraction efficiency differed among solvents, with methanol consistently yielding the highest recovery of compounds. Notable compounds identified included friedelinol, ẞ-D- glucosyloxyazoxymethane, loliolide, para-vinylguaiacol and 2,3-dihydrobenzofuran, which are associated with antioxidant, anti-inflammatory, antimicrobial, anticancer and biopolymer precursor activities. These findings establish Hevea leaves as a promising source of bioactive secondary metabolites and the use of these compounds in various fields needs to be explored, especially in drug development and to gain an understanding of the metabolic pathways in plants.

Natural Rubber (NR), Chloroprene Rubber (CR) and NR/CR latex blend-based nanocomposites were prepared using layered clays. Fluorohectorite (synthetic) and Bentonite (natural) in 10 parts for 100 parts of rubber were incorporated during the prevulcanization stage for the production of nanocomposites. An amorphous grade of clay (English Indian clay) was also mixed with the same combination of latices for the relative comparison. The mechanical properties and X-ray diffractometric analysis of the rubber nanocomposites showed that fluorohectorite and bentonite clays improved the compatibility of NR-CR blends, resulting in enhanced mechanical properties of the nanocomposite. The presence of layered silicates led to distinct nano-level reinforcement in the latex blend composites.