Thermodynamic probe of intermolecular coupling in the interphase region of glass fiber reinforced polymer composites

Mechanical properties of polymer composites are enhanced by an interphase having a brush‐like structure, due to the entanglement of stretched compatibilizer chains and neighboring polymer molecules. Lipatov's model provides a calorimetric method for characterizing the fiber‐matrix interactions and determining the interfacial thickness, i.e., the heat capacity jump at T g is sensitive to the combined effects of fiber glass content and intermolecular coupling in the interphase region. By a correlation between computed interfacial thickness from DSC methodology and measured tensile strength, we have a quantitative means to develop polypropylene composites having “mega coupled” tensile behavior.