Fiber volume control of composite materials by loss angle

Fiber volume plays a critical role in achieving stable mechanical and physical properties in composite structures. This study develops a method to control this parameter in carbon fiber reinforced plastics (CFRPs) on the basis of the viscoelastic character of the thermosetting matrix resin. This method relies on the loss angle δ to quantitatively control fiber volume. CFRP flat panels are manufactured at varying initiating times of pressure application depending on the δ value of the CFRP matrix resin. An analysis of the manufactured panels clearly shows that the target fiber volumes can be obtained at an appropriate δ range. Specifically, CFRP fiber volumes can be controlled through the loss angle of the matrix resin. Defining this δ range is very important for establishing mechanically and physically stable CFRP structures. POLYM. COMPOS., 37:1307–1311, 2016. © 2014 Society of Plastics Engineers