Aggregation structure and molecular motion of (glass-fiber/matrix nylon 66) interface in short glass-fiber reinforced nylon 66 composites

Aggregation structure and thermal molecular motion of an adhered polymer layer on a glass-fiber (GF) surface after a removal of nylon 66 from a short glass-fiber reinforced nylon 66 were studied on the basis of photoacoustic spectroscopy–infrared spectroscopy (PAS–IR), pyrolysis–gas chromatography (Py–GC), X-ray photoelectron spectroscopy (XPS) and scanning viscoelasticity microscopy (SVM). PAS–IR, Py–GC and XPS measurements of the GF surface showed the presence of strongly adhered nylon 66 layer on the surface of aminosilane-treated GF. The glass transition temperature, Tg, of the adhered nylon 66 layer on the glass-fiber surface was directly evaluated on the basis of SVM measurement. In the case of the GF treated with an aminosilane coupling agent and a sizing agent, the magnitude of Tg at the (GF/nylon 66) interfacial layer was higher than that of the matrix nylon 66 due to the effective restriction of thermal molecular motion of nylon 66 at the (GF/nylon 66) interfacial layer. It is reasonable to consider that the sizing agent affects the strong interfacial interaction between a glass-fiber surface and matrix nylon 66 with covalent bond formation accompanying the network structure formation.