Single-step adhesives are permeable membranes.

The sensitivity of several conductive polymer composites (CPC) to solvent vapours has been studied. Electrical properties of three CPC poly(amide12-b-tetramethylene oxide)-carbon black (PEBAX-CB), poly(propylene)-carbon black (PP-CB) and poly(ethylene-co-ethyl acrylate)-carbon black (EEA-CB) were investigated in the presence of four organic solvent vapours, chloroform, toluene, methanol and ethanol. The experiments show that it is possible to use extruded CPC textiles to combine acceptable conductivity for heating and satisfying response for vapour detection. Moreover, the investigation of the mechanisms involved during the solvent vapours diffusion into the CPC, shows that not only the response of the systems Δ R / R 0 can be used for vapour detection but also the shape of the curves, i.e., the diffusion mode characterised by Δ R / R max versus t curves slope and onset. The diffusion curve shape analysis together with the use of CPC of different chemical nature and structure (comonomer content and crystallinity) is expected to decrease the number of CPC necessary for vapour detection.

Evolution of electrical properties of some conductive polymer composite textiles with organic solvent vapours diffusion

This review represents a comprehensive study of nanocomposites for power cables insulations based on thermoplastic polymers such as polyethylene congeners like LDPE, HDPE and XLPE, which is complemented by original results. Particular focus lies on the structure-property relationships of nanocomposites and the materials’ design with the corresponding electrical properties. The critical factors, which contribute to the degradation or improvement of the electrical performance of such cable insulations, are discussed in detail; in particular, properties such as electrical conductivity, relative permittivity, dielectric losses, partial discharges, space charge, electrical and water tree resistance behavior and electric breakdown of such nanocomposites based on thermoplastic polymers are described and referred to the composites’ structures. This review is motivated by the fact that the development of polymer nanocomposites for power cables insulation is based on understanding more closely the aging mechanisms and the behavior of nanocomposites under operating stresses.

Polyethylene Nanocomposites for Power Cable Insulations

Epoxy coating destruction as a result of sulphuric acid aqueous solution action

The mechanisms governing coating/metal oxide delamination are not fully understood, although adhesive interactions at the interface are considered to be an important prerequisite for excellent durability. This review aims to better understand the formation and degradation of these interactions. Developments in adhesion science made it clear that physical and chemical interfacial interactions are key factors in hybrid structure durability. However, it is very challenging to get information directly from the hidden solid/solid interface. This review highlights approaches that allow the (in situ) investigation of the formation and degradation of molecular interactions at the interface under (near-)realistic conditions. Over time, hybrid interfaces tend to degrade when exposed to environmental conditions. The culprits are predominantly water, oxygen, and ion diffusion resulting in bond breakage due to changing acid–base properties or leading to the onset of corrosive de-adhesion processes. Therefore, a thorough understanding on local bond interactions is required, which will lead to a prolonged durability of hybrid systems under realistic environments.

/pdf/probing-the-formation-and-degradation-of-chemical-20ohg51v8n.pdf

Probing the formation and degradation of chemical interactions from model molecule/metal oxide to buried polymer/metal oxide interfaces

A method based on Fourier transform infrared-multiple internal reflection (FTIR-MIR) spectroscopy was developed for measuring the apparent diffusion coefficient of water in a coating applied to a substrate. The method requires an appliction of a coating of any thickness on an internal reflection element, which serves as the substrate, with the attachment of a water chamber to the coated specimen. Water is introduced to the chamber and FTIR-MIR spectra are collected automatically without disturbing the specimen or the instrument. The amount of water at the coating/substrate interface was determined using a model based on the theory of internal reflection spectroscopy. A mass-time curve for water at the interface is established, which provides the time-lag value, the time required for water to diffuse through the coating film and reach the interface. The diffusion coefficient (D) is then determined by the time-lag equation. For thick coating films (>25 μm), D may be estimated from the FTIR-MIR in situ intensity data only. The sensitivity of FTIR-MIR spectroscopy and the strong FTIR absorption of water molecules make this an ideal method for measuring the diffusivity of liquid water through a coating applied to a substrate

D. Bentz

Papers

Method for measuring water diffusion in a coating applied to a substrate