Interfacial micromechanics and effect of moisture on fluorinated epoxy carbon fiber composites

Abstract

Carbon fiber composites have witnessed an increased application in aerospace and other civil structures due to their excellent structural properties such as specific strength and stiffness. However, unlike other structural materials, carbon fiber composites have not been as widely studied. Hence, their increased application is also accompanied with a serious concern about their long‐term durability. Many of these applications are exposed to multiple environments such as moisture, temperature, and UV radiation. Composites based on conventional epoxies readily absorb moisture. However, recently synthesized fluorinated epoxies show reduced moisture absorption and hence potentially better long‐term durability. The aim of this project is to study the effect of moisture absorption on fluorinated‐epoxy‐based carbon fiber composites and their comparison with conventional epoxy carbon fiber‐based composites. Microbond tests are performed on fluorinated and nonfluorinated epoxy‐based single fiber samples before and after boiling water degradation. It is found that fluorinated epoxy‐based single fiber coupons showed relatively reduced degradation of interface when compared with the nonfluorinated epoxy single fiber coupons. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Exploring durability of interfaces in flax fibre/epoxy micro-composites

“…These results differ from those of Pandey et al [12] and Biro et al [30] on carbon/epoxy systems respectively immersed in boiling water and water at 80°C. Biro et al [30] found an increase in friction strength (by more than 200%) and in the friction contribution to τ app after immersion.…”

“…For example, debonding of micro-droplets was used by Zinck et al [11] who showed a decrease in critical strain energy release rate during the first 50 hours of aging (60°C and 98% RH) of glass/epoxy systems . Pandey et al [12] showed a drop in apparent shear strength on carbon/epoxy composites, from 88 to 80 MPa after immersion in boiling water for 48h. They explained this by radial stresses relaxation during immersion.…”

Flammability and thermomechanical properties of dianhydride-modified polybenzoxazine composites reinforced with carbon fiber

“…One important group of polymeric composites is based on carbon fiber reinforcing systems which is often used in weight reduction and high specific strength requirement, i.e., aerospace, automotive, ballistic armor, or extreme sport applications. In addition, an improvement of polymeric material properties particularly by modification of the existing polymers to achieve high thermal properties, i.e., high char yield, and high glass transition temperature ( T g ) becomes increasingly important for an fiber‐reinforced polymer composites . Recently, the developed polybenzoxazine are a novel class of thermosetting polymers that combined the thermal properties and flame retardance of phenolic resin with mechanical performance and molecular design flexibility of epoxy resin.…”

Long-term moisture effects on the interfacial shear strength between surface treated carbon fiber and epoxy matrix

“…In recent years, a few microscopic mechanical testing methods have been developed to investigate the fundamental mechanical properties of interphase between fiber and matrix, including single fiber push-out test [21][22][23], fiber fragmentation test [24,25], and single fiber microbond test [26][27][28], among which it is found that the specimens for the microbond test are more efficient to achieve a good soaking of polymer matrix and fiber/matrix interface due to the small volume of resin droplet size [19,29].…”

“…However, these macro-level characterizations are influenced to a large extent by the moisture resistance of matrix materials and the geometrical feature of composites, which may disturb the study on the properties of fiber/matrix interface [19,20].…”