Structural Investigation of Polyamide-6 and Polyamide-6 Composites Using exp 13 C Cross Polarization/Magic Angle Spinning NMR

Natural-abundance exp 13 C NMR spectra of pure polyamide-6 (PA6) and polyamide-6 composites were measured with CP and MAS techniques. The microcomposites were made by adding glass microspheres, a silane coupling agent, or prefunctionalized glass spheres to PA6. exp 13 C NMR spectra of these samples show the presence of three components: two crystalline phases and an amorphous component. The chemical shifts of both carbons adjacent to the amide group are sensitive to the PA6 crystal structure; in the dominant alpha polymorph, C1 and C5 are 3 ppm downfield from their chemical shift values in the gamma polymorph. Both the X-ray diffraction powder patterns and the exp 13 C NMR spectra show a change in the relative amounts of the two crystalline components when the composites are made. 20 ref.--AA