Mechanical Properties of Carbon Fiber Reinforced Plastics under Hot-Wet Environment

2011 ◽  
Vol 462-463 ◽  
pp. 207-212 ◽  
Author(s):  
Hideaki Katogi ◽  
Kenichi Takemura ◽  
Yoshinobu Shimamura

Water absorption behavior and flexural strength properties of carbon fiber reinforced plastics (CFRP) under hot-wet environment were examined. Those of epoxy resin were also examined for reference. Weight gains of CFRP and epoxy resin were measured after immersion in distilled water at temperatures under 90°C. Quasi-static flexural tests of CFRP and epoxy resin were conducted after immersion for 180 days. Weight gains of CFRP and epoxy resin increased with increasing water temperature. After immersion for 180 days at 90°C, weight gain of CFRP became 3.3times higher and that of epoxy resin was 2.3 times higher than that at RT, respectively. When CFRP and epoxy resin were immersed in distilled water at 90°C, weight gains of CFRP and epoxy resin increased and then decreased. Flexural strengths of CFRP and epoxy resin decreased in distilled water at temperatures less than 90°C. Flexural strengths of dried CFRP and epoxy resin after immersion recovered but were lower than that of virgin CFRP and epoxy resin. Debonding of fiber/resin interface and crack initiation in epoxy resin in distilled water resulted in the strength reduction.

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1866
Author(s):  
Chun Pei ◽  
Peiheng Guo ◽  
Ji-Hua Zhu

Preserving the integrity of carbon fibers when recycling carbon-fiber-reinforced plastics (CFRPs) has been unfeasible due to the harsh reaction conditions required to remove epoxy resin matrixes, which adversely affect the properties of carbon fibers. We establish a practicable and environmentally friendly reclamation strategy for carbon fibers. Carbon fibers are recycled from waste CFRPs by an electrochemical catalytic reaction with the assistance of phosphotungstic acid (PA), which promotes the depolymerization of diglycidyl ether of bisphenol A/ethylenediamine (DGEBA/EDA) epoxy resin. The removal rate, mechanical strength, and microstructure of the recycled carbon fibers are analyzed to explore the mechanism of the electrochemical treatment. The influence of three factors—current density, PA concentration, and reaction time—are studied via an orthogonal method. Range analysis and variance analysis are conducted to investigate the significance of the factors. The optimal conditions are determined accordingly. The underlying CFRP degradation mechanism is also investigated.


2021 ◽  
pp. 28-37
Author(s):  
P. N. Shkatov ◽  
G. A. Didin ◽  
A. A. Ermolaev

The paper is concerned with increasing sensitivity of eddy current nondestructive testing of most dangerous delamination in carbon-fiber reinforced plastics (CFRP). Increased sensitivity is achieved by separate registration and comparison of eddy current signals obtained from a set of stratifications of carbon fibers with the same orientation. The separation of eddy current signals is possible due to pronounced anisotropy of the electrical conductivity of the layers dominant in the direction of the fibers of the corresponding layer. Eddy-current signals are registered by eddy current probes with maximum sensitivity in a given angular direction. Prior to the scan eddy current signals of the probe are leveled on a defect-free area. The influence of the working gap on the difference between the eddy current signals of the probe is suppressed by normalizing it according to one of the signals. The analysis of the registered signals from delamination has been performed using an approximate calculation model. The reliability of the obtained results has been confirmed by comparison with experimental results and calculations using the finite element method.


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