Hygrothermal effects on dynamic mechanical snalysis and fracture behavior of polymeric composites

Abstract

Polymer composites used above their glass transition temperatures Tg present a substantial degradation of physical properties; therefore a material's glass transition temperature and its change with moisture absorption are of practical importance. Little attention has been paid to the role of the adhesive bonding between the reinforcing fiber and matrix, particularly for BMI matrix. In this work the effect of moisture on the dynamic mechanical behavior and the fiber/matrix interface was investigated. Two systems were evaluated: carbon fabric/epoxy and carbon fabric/bismaleimide laminates. The results demonstrated that the moisture absorbed by the laminates causes either reversible or irreversible plasticization of the matrix. The humidity combined with the temperature effects may cause significant changes in the Tg matrix and toughness affecting the laminate strength. Moisture absorption was correlated to the fracture mode of the laminate demonstrating the deleterious effect of moisture on the interface. This leads to debonding between fiber and matrix. This behavior was investigated by scanning electron microscopy and dynamic mechanical analysis

Comparative Study of the Durability Behaviors of Epoxy- and Polyurethane-Based CFRP Plates Subjected to the Combined Effects of Sustained Bending and Water/Seawater Immersion

“…The values of τ and the correlation coefficient (R 2 ) of both CFRPs are listed in Table 3 by fitting Figures 9 and 10 using Equation (21). It is noteworthy that the fitting parameters of the free/moderately strained PU-based CFRP samples cannot be obtained since the strong postcuring effect results in higher tensile strength at 60 than at 20 • C. Moreover, the small values of R 2 in a few cases are also caused by postcuring.…”

“…In Shanghai in China, for example, the tensile strength retention data of epoxy-based CFRPs in Figure 11 are transformed into those of Figure 20 by multiplying the immersion time at 20 • C and 60 • C with the corresponding TSF values. The predicted curve as a function of the immersion time (years) at Shanghai can be obtained by fitting Equation (21) to the data in Figure 20. Following these steps, the predicted curves of both epoxy-and PU-based CFRPs for the four cities were obtained as in Figures 20-23, respectively.…”

Review on hygroscopic aging of cellulose fibres and their biocomposites

“…The absorbed water begins to form intermolecular hydrogen bonding with the fibres and in so doing reduces the interfacial adhesion between the fibres and the polymer, and soluble constituents will start leaking from the fibres. These ultimately lead to the debonding between the fibre and the polymer (Alomayri, Assaedi, Shaikh, & Low, 2014;Costa, Almeida, & Rezende, 2005;Zhang, Milanovic, Zhang, Su, & Miao, 2014).…”

Low‐velocity impact behavior of a carbon/bismaleimide composite proposed for supersonic flight simulation after hygrothermal cycling

“…The T g of BMI and C/BMI both show a similar increase after 300 cycles. According to Costa et al , the hygrothermal aged BMI experiences a significant drop in T g owing to the moisture absorption associated with the inter‐chain bond breakage. One possible explanation to the increase in T g of BMI and C/BMI composite of this study after 300 cycles is that the absorbed moisture, which has a plasticization effect in BMI, was removed during exposure to high temperature environment, meanwhile the postcuring and oxidation effect also induced by high temperature decreased the flexibility of the segments and prevented the macromolecular motion leading to an increase in T g .…”