Hybrid matrices (epoxidized of ethylene–propylene–diene monomer (eEPDM) -g-aminopropyltriethoxysilane (APTES)/hydroxyl terminated polydimethylsiloxane (HTPDMS)/polyurethane (PU)) were developed based on eEPDM with 3-APTES coupling agent and varying weight percentages (0.75, 1.50, 2.25, and 3.00 wt%) of PU prepolymer as coreactant using 7.5 wt% of HTPDMS as chain extender using suitable experimental conditions. The formation of hybrid matrices and their structure were characterized by Fourier transform infrared (FTIR). The thermal and morphological properties of the hybrid matrices were analyzed using differential scanning calorimetry and scanning electron microscope, respectively. Mechanical properties (tensile strength, elongation at break (%), Young’s modulus, and hardness) were characterized as per ASTM standards. Data resulted from mechanical studies, it was noticed that the incorporation of 3-APTES, HTPDMS, and PU into eEPDM has improved the elongation at break (%) and lowered the values of tensile strength, Young’s modulus, and hardness according to the percentage concentration. Morphological studies indicate the presence of heterogeneous morphology. Data obtained from different studies, it suggested that the hybrid matrices developed in the present work can be used as cable insulates for high-performance industrial and engineering applications.
The chitosan functionalized multiwalled carbon nanotubes reinforced epoxy bionanocomposite (CS-g-MWCNTs/EP) was developed. Chitosan (CS) was grafted to multiwalled carbon nanotubes (MWCNTs), first by reacting the oxidized carbon nanotubes (MWCNT-COOH) with thionyl chloride to form acyl-chlorinated multiwalled carbon nanotubes (MWCNT-COCl) followed by subsequent dispersion in chitosan. The chitosan grafted multiwalled carbon nanotubes (CS-g-MWCNTs) were reinforced in the epoxy matrix using high speed stirrer and then cured. The TEM of CS-g-MWCNTs shows a visible coating of chitosan on the surface of MWCNTs. FT-IR spectra of CS-g-MWCNTs indicate an overlap of the amide band and the free amino groups of the chitosan. The mechanical properties such as tensile and impact strength of epoxy matrix increases to 16 and 52 %, respectively by the reinforcement of 1.5 wt. % CS-g-MWCNTs, which clearly reveals that the free amino groups of CS-g-MWCNTs acted as a curing agent and was covalently attached into epoxy matrix. Morphologies of pure chitosan, MWCNT, MWCNT-COOH and CS-g-MWCNTs/EP bionanocomposites were studied by scanning electron microscope.
ABSTRACT:A new terpolymer of vinyloxyaminosilane (VOS) grafted onto ethylene-propylene-diene terpolymer (EPDM) has been synthesised in a Haake Rheocord-90, torque rheometer. Vinyloxyaminosilane grafted ethylenepropylene-diene terpolymer/linear low density polyethylene (EPDM-g-VOS/LLDPE) blends with different compositions were prepared using a two roll mixing mill. The electrical properties such as surface and volume resistivities, dielectric strength and arc resistance are decreased and dielectric constant and dielectric loss are increased with increasing percentage composition of LLDPE in EPDM-g-VOS/LLDPE blends due to enhanced crosslink density. The incorporation of VOS moiety onto EPDM improves the inception decomposition and final decomposition temperatures due to stable three dimensional network and high bond energy of -Si-O-Si-linkage. The values of T g are increased with increasing concentration of LLDPE in the EPDM-g-VOS/LLDPE blends due to enhanced crystallinity and crosslink density. Thermal aging studies on mechanical properties show that the tensile strength, elongation at break and Young modulus are decreased due to disruption of crosslinking at LLDPE sites.KEY WORDS Vinyloxyaminosilane grafted Ethylene-Propylene-Diene Terpolymer/Linear Low Density Polyethylene (EPDM-g-VOS/LLDPE) Blends / Dielectric Strength / Arc Resistance / Dielectric Constant / Inception Decomposition / Thermal Ageing / Synthetic polymers find number of applications in the field of electrical insulation, as molded components and as extruded cables. Crosslinking of thermoplastic polymers with organic and/or other curing agents leads to a three dimensional network structure having adequate thermal endurance properties coupled with good dielectric and mechanical properties. A good combination of flexibility and strength is an essential requirement of cable insulant. A continuous effort is being made to improve mechanical and thermal endurance properties of cable insulant without significant loss of dielectric characteristics. The advent of a newer technique, involving the grafting of silanes onto the polymer chain followed by its subsequent condensation reaction in the presence of moisture and catalyst is more attractive due to various advantages. The service life of cable insulant materials suffers from thermooxidative aging and degradation. Thermal stability of these polymers depends upon the type and nature of cross-link system.The selection of polymeric insulating material for cable application depends upon various factors. 1-3 Different thermal and electrical testing techniques are applied for quality checkup for cable materials. [4][5][6] Cables for special applications areas such as resistance to oil, resistance to flame and fire requires specific characteristics. 7,8 Gartasegna 9 developed low-voltage and mediumvoltage cable insulant products using vinyltrimethoxysilane (VTMO) grafted and moisture crosslinked ethylene-propylene copolymer (EPR) and ethylenepropylene-diene terpolymer (EPDM) and charecterised. Tanida et al. 10...
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