Study on the mechanism and law of temperature, humidity and moisture content on the mechanical properties of molded fiber products

The change of temperature, humidity and moisture content (MC) will lead to the change of mechanical properties of molded fiber products (MFP). However, it is difficult to decouple the effects of temperature, humidity and MC on the mechanical properties of MFP, and predict the mechanical properties of MFP during the use. In this study, the laws and mechanism of mechanical properties of MFP with ambient temperature, humidity and MC were studied. The results showed that the direct effect of temperature (20−70 °C) on mechanical properties of MFP was insignificant, and the mechanical properties of MFP were mainly changed by MC. The MC was related to ambient temperature and humidity, and the relationship between the three could be described by the modified Guggenheim-Anderson-de Boer (GAB) model (20−70 °C and 30%−90% relative humidity). With the increase of MC, the elastic modulus and fracture strain was increased and decreased linearly, the yield strength and failure strength were presented GaussAmp laws, and the failure strain was presented asymptotic regressed distribution law. Two fracture modes of MFP, brittle fracture and ductile fracture, were revealed by the scanning electron microscopy of the mesoscopic fiber structure of sugarcane bagasse molded fiber products. The mathematical models and the changes of fiber structure were verified by wheat straw molded fiber products and waste paper molded fiber products. This study was contributed to understand the effects and mechanism of the change of temperature, humidity and MC on the mechanical properties of MFP.