Temperature scanning stress relaxation measurements: A unique perspective for evaluation of the thermomechanical behavior of shape memory polymer blends

Abstract

Shape memory polymer has the inherent capability of fixing its shape to a deformed or unconstrained shape that gives the material shape fixity and to revert back to its permanent shape that results shape recovery of the material. Temperature scanning stress relaxation (TSSR) studies of uncrosslinked and radiation crosslinked polymer blends of ethylene octene copolymer and ethylene propylene diene rubber has been carried out over a certain temperature range that gives the idea about the thermomechanical behavior of the material. With increasing radiation dose, TSSR index value of the radiation crosslinked blends increases, which is an indication of the improvement of the elasticity of the crosslinked network and thus results better shape recovery of the crosslinked blends when compared to the uncrosslinked one. Higher elasticity of the crosslinked network is also well supported by higher crosslink density and lower tension set value of the radiation crosslinked blends.

A relative study of the effect of static and dynamic vulcanization upon shape memory nature of thermally actuated peroxide crosslinked polyolefinic blends

“…The yellow and brown regions illustrate the existence of hard phase (EOC phase) and soft phase (EPDM phase), respectively. [ 43,44 ] The phase images of the EO 50 EP 50 blend shows that both the hard and soft phases are continuous and there is a uniform distribution of the hard and soft phases.…”

An alternative antioxidant for sulfur-vulcanized natural rubber: Henna

“…Cross-link density is one of the most dominant factors on stress relaxation of elastomers. From this point of view, cross-link densities of the original vulcanizates (before aging) have been calculated using initial slope values of their non-isothermal relaxation curves according to rubber elasticity theory, 22,[26][27][28][29][30] and the results are given in Table 5. Equivalent calculations were performed for aged vulcanizates, and the results are given in Table 6.…”

Assessing thermomechanical properties of a reactive maleic anhydride grafted styrene‐ethylene‐butylene‐styrene/thermoplastic polyurethane blend with temperature scanning stress relaxation method

“…To the date, only a limited number of studies have been reported employing TSSR to investigate TPEs. Chatterjee et al [15] used TSSR as a unique method to examine the thermomechanical behavior of shape memory polymer blends based on radiation crosslinked ethylene octene copolymer and ethylene propylene diene rubber blends. Increase in TSSR index and crosslink density (CLD) gave a direct idea of the improved elasticity in the system with radiation curing.…”

“…The test was carried out in a TSSR instrument (Brabender GmbH, Duisberg, Germany, which is commercially available). [9,11,12,15] The TSSR instrument is equipped with an electrical heating chamber in which the sample to be tested is positioned between two clamps. A definite uniaxial extension was applied to the sample through a linear drive unit connected to the clamps.…”

“…The renowned theory of rubber elasticity states that in the case of an ideal rubber network, the mechanical stress σ is proportional to the absolute temperature T. [9,15,27] It is expressed as;…”