Photodegradation of poly(ether sulphone). Part 1. A time-of-flight secondary ion mass spectrometry study

Abstract not available

Investigating the role of anionic surfactant and polymer morphology on the environmental stress cracking (ESC) of high-density polyethylene

The influence of a commercial grade and a pure anionic surfactant (dodecylbenzenesulfonic acid sodium salt, DBS) in aqueous solutions on the environmental stress cracking (ESC) of high-density polyethylene (HDPE) has been investigated. Injection moulded HDPE samples in “dog-bone” shape were exposed to the aqueous solutions of surfactant (0.14 M) at 80 °C under strain (var epsilon = 1.2%) for 5 days. Both the commercial and pure surfactants caused cracks under the experimental conditions. The change in surface chemistry of the HDPE was followed using attenuated total reflectance Fourier transform infrared (ATR-FTIR) and Raman spectroscopy. The thermogravimetric analysis (TGA) did not show any significant differences in thermal stability of the samples studied. Differential scanning calorimetry (DSC) analysis, however, revealed an increase in crystallinity of the exposed samples. Wide Angle X-ray Scattering (WAXS) indicated that the HDPE sample has a boundary of both preferred and random (isotropic) crystallite orientations close and far away from the injection moulding inlet, respectively. The structure of the surfactants in solution was investigated by light scattering (LS). This showed that the commercial grade surfactant forms large aggregates (e.g., 500 nm) both at room temperature and at the exposure temperature of 80 °C, whereas the pure surfactant has a critical micelle temperature (CMT) of around 45 °C. Below the CMT aggregates are formed, and above the CMT the surfactants are unimeric. Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) analysis revealed that the commercial surfactant has a wide distribution of hydrocarbon chains from C-10 to C-13, whereas the pure one contains predominantly hydrocarbon dodecyl (chain of C-12)

Atmospheric pressure plasma treatment of glassy carbon for adhesion improvement

Glassy carbon plates were treated with an atmospheric pressure dielectric barrier discharge (DBD). He gas, gas mixtures of He and reactive gases such as O2, CO2 and NH3, Ar gas and Ar/NH3 gas mixture were used as treatment gases. The oxygen and nitrogen contents on the surface as well as defect density increased with the plasma treatments. Adhesion test of the treated glassy carbon covered with cured epoxy showed cohesive failure, indicating strong bonding after the treatments. This is in contrast to the adhesion tests of untreated samples where the epoxy readily peeled off the glassy carbon