The Influence of Environmental Stress Cracking (ESC) and Gamma Irradiation on the Mechanical Properties of Polycarbonate: Study of Synergistic Effects

Abstract

Polycarbonate is an engineering polymer due its outstanding properties and is widely used in several different applications. In some of these applications it can be exposed to certain liquids/solvents. In many cases, this liquid exposure may cause an effect known as Environmental Stress Cracking (ESC), which may lead to crack formation on the polymer surface and consequent reduction of its mechanical resistance, with loss of lifetime. On the other hand, polycarbonate medical supplies are often exposed to gamma rays in the radio-sterilization process, at doses up to 25 kGy. This exposure causes main chain scissions. In this present work, the viscosity average molecular weight decreased about 10% at 25 kGy. Elongation at break was drastically affected by ESC phenomenon. When simultaneously exposed to the ESC agents (methanol or isopropanol) and gamma radiation, combined effects of both takes place. Moreover, the stress relaxation rate of ~1000 Pa/s (air or methanol) and ~2200 Pa/s (isopropanol) at the dose of 100 kGy, suggests strong influence of isopropanol as surfactant on PC. Results of elongation at break and stress relaxation rate were reliable data to evaluate ESC and radiolytic effects on PC.

Chemical and mechanical resistance of waterborne polyurethane/graphene (WPU/GO) nanocomposite coatings

“…This likely occurred because the polar part of PU chain, as C=O, was attacked by the high polarity part of alcohol chain. This phenomenon was attributed to a match between dispersion and polar cohesion energy of Hansen's solubility parameters of ethyl alcohol and polyurethane [28,38] . For PU, the energy from polar intermolecular forces δ P is 9,3 and for ethyl alcohol is 8.8 MPa 0.5 and from dispersive δ D is 18.1 and 15.8 MPa 0.5 [39] .…”

Environmental Stress-Induced Fracture Behavior of Polypropylene Battery Separators: Insights into Creep Behavior and Mechanical Stability

“…Environmental stress-induced failure in polymers typically results in brittle fractures at low-stress levels and ductile fractures under higher stresses, with fibrillation and cracks appearing on fractured surfaces. , The rate of crack growth in polymers exhibits slow and fast phases . The slow phase is influenced by both stress intensity and environmental factors, while the fast phase is primarily governed by environmental viscosity, not stress intensity.…”

Polycarbonate/Titania Composites Incorporating TiO2 with Different Nanoscale Morphologies for Enhanced Environmental Stress Cracking Resistance in Dioctyl Phthalate

“…ESC involves crack generation and propagation on the surface and is also enhanced by the presence of residual stresses in the polymeric surface, presumably introduced during manufacturing and not eliminated during polymer annealing. In other words, the synergistic effects of chemical agents and the mechanical stresses cause polymer chain scission due to polymer degradation, thus, creating microscopic defects giving rise to surface initiation and rapid propagation [2][3][4][5]. The numerous environments encountered in application end-use include organic liquids (solvents), synthetic oils, naturally occurring oils, detergents/surfactants, mold release agents, plasticizers, sealants/caulking agents, adhesive formulations, inks, anti-corrosion additives, lubricants, and metal cutting fluids.…”