Structure-property relationship of electron-beam-modified EPDM rubber

Abstract

Electron-beam-initiated grafting of trimethylolpropane triacrylate (TMPTA) onto the bulk ethylene propylene diene monomer (EPDM) was carried out with varying concentrations of TMPTA at a constant irradiation dose of 100 kGy and over a wide range of irradiation doses (0 -500 kGy) at a fixed concentration (10%) of TMPTA. The rubber was also modified in the bulk by tripropylene glycol diacrylate (TPGDA, 10%) and tetramethylol methane tetraacrylate (TMMT, 10%) at an irradiation dose of 100 kGy. The modified rubbers were characterized by IR spectroscopy, crosslinking density measurements, and mechanical, dynamic mechanical, and electrical properties. The IR studies indicated increased peak absorbances at 1730, 1260, and 1019 cm Ϫ1 due to increased ͘CAO and COOOC concentrations up to certain levels of TMPTA and irradiation dose. These are accompanied by an increase in the crosslinking density. The tensile strength of the samples increases gradually with increasing both the concentration of the monomer and radiation dose up to a certain level. The values of the modulus also increase at the expense of the elongation at break. An increase in the number of double bonds from two in the case of the diacrylate to four in the case of the tetraacrylate also brings about an increase in the tensile strength and moduli values. The elongation at break, however, decreases. The DMTA measurements indicate changes in the glass transition temperature, T g , and tan ␦ max on modification. The T g shifts to a higher temperature with a simultaneous lowering of the tan ␦ max values as the TMPTA level is increased. A similar trend is observed when the irradiation dose is increased and the nature of the monomer changes from di-to tetraacrylate. The dielectric loss tangent registers an increase on modification by irradiation of TMPTA while the permittivity is decreased. All the results could be explained on the basis of the structural modification and crosslinking density.

Structure-Property Relationship in Terms of Dynamic Mechanical Properties of High Energy Radiation Treated Industrially Important Thermoplastic Elastomer Blend

“…There are various thermoplastics, which are unique for easy processing, availability, and low cost. Among the polyolefins, low density polyethylene (LDPE) and linear low density poly ethylene (LLDPE) are widely used plastics in the packaging and consumer industries because of their advantages like higher tensile strength, stress crack resistance, flexibility, thermal, chemical and excellent dielectric properties [1] [2] whereas EPDM elastomer exhibits high crosslinking ability, radiation resistance, thermal resistance, impact strength, flexibility and dynamic damping properties [3]. Thus, by judicial selection of properties of LDPE and EPDM scientists have made blends of above two, to get selected combination of properties [4] [5].…”

Dynamically vulcanized blends of polypropylene and ethylene octene copolymer: Influence of various coagents on mechanical and morphological characteristics

“…Subsequently, chain transfer reaction takes place, which leads to the formation of new polymeric radical. The same sequence takes place on the other coagent molecules and results in the formation of a crosslinked structure 20–22. Unlike the coagents of first type (Type I), most of the coagents of the second type (Type II) contain both readily accessible vinyl unsaturation (sites for radical addition) and an ample amount of easily abstractable allylic hydrogen atoms.…”

Grafting of butyl acrylate and methyl methacrylate on butyl rubber using electron beam radiation

“…In recent time, radiation treatment of polymers is an important process for the production of new and improved polymers with desirable properties 8–10. The radiation‐induced grafting of vinyl monomers has been found to be an efficient method and many reports have been published 8, 11–15. Electron beam (EB) radiation is a new technique, which is increasingly being used in polymer processing and polymer modification 8, 9.…”