Temperature-Induced Shape Memory Characteristics of Epoxy Resin-Based Fabric-Reinforced Composites

Shape memory characteristics of woven glass and carbon fiber fabric reinforced epoxy resin-based composites were assessed in bending mode using a dynamic mechanical analyzer. The reinforcement strongly improved the recovery stress but impaired the bending deformability. Composites with asymmetric fabric lay-up showed better performance when the reinforced section experienced local tension than compression during flexural loading

Shape memory performance of asymmetrically reinforced epoxy/carbon fibre fabric composites in flexure

In this study asymmetrically reinforced epoxy (EP)/carbon fibre (CF) fabric composites were prepared and their shape memory properties were quantified in both unconstrained and fully constrained flexural tests performed in a dynamic mechanical analyser (DMA). Asymmetric layering was achieved by incorporating two and four CF fabric layers whereby setting a resin- and reinforcement-rich layer ratio of 1/4 and 1/2, respectively. The recovery stress was markedly increased with increasing CF content. The related stress was always higher when the CF-rich layer experienced tension load locally. Specimens with CF-rich layers on the tension side yielded better shape fixity ratio, than those with reinforcement layering on the compression side. Cyclic unconstrained shape memory tests were also run up to five cycles on specimens having the CF-rich layer under local tension. This resulted in marginal changes in the shape fixity and recovery ratios

Toward reliable morphology assessment of thermosets via physical etching: Vinyl ester resin as an example

The morphology of peroxide-cured, styrene crosslinked, bisphenol A-based vinyl ester (VE) resin was investigated by atomic force microscopy (AFM) after ‘physical’ etching with different methods. Etching was achieved by laser ablation, atmospheric plasma treatment and argon ion bombardment. Parameters of the etching were varied to get AFM scans of high topography resolution. VE exhibited a nanoscaled nodular structure the formation of which was ascribed to complex intra- and intermolecular reactions during crosslinking. The microstructure resolved after all the above physical etching techniques was similar provided that optimized etching and suitable AFM scanning conditions were selected. Nevertheless, with respect to the ‘morphology visualization’ these methods follow the power ranking: argon bombardment > plasma treatment > laser ablation

Populations of grape phylloxera gallicoles on rootstock foliage in Hungary

Populations of gallicole grape phylloxera (Daktulosphaira vitifoliae FITCH) were monitored in Keszthely, Hungary from June through October 1998 on foliage of the Vitis berlandieri PLANCH. x V. riparia MICHX. rootstock cultivar Teleki 5 C. Though population size peaked in August, leaves from June through September were equally supportive of gallicole development and egg production. Demography varied with leaf position on shoots with the leaf in the terminal position having the most immature populations. Leaves 5 through 7 from the shoot terminal had highest population densities and the highest egg production. Population densities correlated with gall densities. Populations on the rootstock cultivar Rupestris du Lot and Vitis amurensis RUPR. were low but populations were high on the rootstock cultivars 101-14 MGT, T. K. 5 BB and Fercal. However, magnitude of phylloxera eggs/ adult on cultivars tested was not numerically distinguishable. High phylloxera population numbers were correlated with decreased vine productivity as measured by shoot growth

Shape memory performance of epoxy resin-based composites

One - way shape memory (SM) epoxy resin (SMEP) based systems and composites ha ve been produced and characterized. Incorporation of different reinforcements along with their positioning were used to improve the recovery stress of the corresponding systems. Attempt was made to provide SMEPs with additional functionalities, such as sel fhealing