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, T_g, 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 T_g 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.