Study On The Hygrothermal Aging Properties Of Carbon/Ramie Fiber Reinforced PETG Composites

Fiber reinforced polymer composites(FRPC)have been widely used in ships,automobiles,outdoor and underwater structures due to its excellent mechanical properties and chemical resistance.However,due to the inevitable impact of water,heat,and other environmental factors on the actual use of FRPC,it will have a negative impact on the structural morphology and mechanical properties of FRPC.Therefore,studying the damp heat aging behavior and performance degradation mechanism of FRPC is of great significance for practical engineering applications.In this paper,the thermoplastic resin PETG(polyethylene terephthalateco-1,4-cylclohexylenedimethylene terephthalate)with low hygroscopicity was selected as the matrix,and three types of FRPC materials were prepared using carbon fiber,ramie fiber,and ramie/carbon fiber hybrid reinforcement.The moisture absorption behavior,water diffusion finite element analysis,and mechanical property degradation mechanism were investigated to explore its characteristics and application prospects.1、Carbon fiber reinforced PETG composites(CF/PETG)were prepared by hot pressing process.Moisture absorption aging tests were conducted on CF/PETG laminates to investigate the effects of different temperatures on their moisture absorption behavior and mechanical properties.The effects of moisture heat aging on the morphology and structure of CF/PETG were observed using a microscope system.Based on the experimental results,a moisture absorption aging mathematical model was established to further analyze the moisture absorption behavior of CF/PETG in a humid and hot environment.The results show that CF/PETG has lower moisture absorption and higher bending strength.The minimum moisture absorption rate can reach 0.44%,and the maximum bending strength can reach 407 MPa.2、Ramie fiber reinforced PETG composites(RF/PETG)were prepared by hot pressing process.In order to reduce the moisture absorption of natural fibers,three surface modification techniques have been used to improve their performance.The effects of different surface modification methods on the damp heat aging properties of RF/PETG were analyzed,and the aging behavior of natural fiber reinforced thermoplastic composites,represented by ramie fiber,was studied in the damp heat environment.The results showed that the surface modification of ramie fiber can increase the bending strength and modulus of RF/PETG by up to 20.5%and 24.5%respectively.But the moisture absorption rate of RF/PETG before and after modification is significantly higher than that of CF/PETG,and the bending property is also lower than that of CF/PETG.3、Considering the properties and costs of the composites,ramie/carbon hybrid fiber reinforced PETG composites(R/CFRP)were prepared with four different stacking sequences.The effects of different stacking sequences on the hygrothermal aging behavior and mechanical properties of R/CFRP were analyzed.The results show that[C/C/R/R]_s has the lowest moisture absorption rate of 2.36%,but[C/R/C/R]_s shows the most excellent bending strength of 190.22 MPa.R/CFRP has lower moisture absorption and better bending performance than RF/PETG,and has lower cost compared to CF/PETG.In this paper,the hygrothermal aging behavior and mechanical property degradation mechanism of PETG based carbon/ramie fiber reinforced composites were systematically studied,providing a theoretical basis for the engineering application of such thermoplastic composites...