the relationship between the basic structure parameters of a polycaproamide (pca) substrate and the structure of grafted polyacrylonitrile (pan) was studied. the influence of the total degree of crystallinity of the pca fiber, its crystal modification, and the orientation of crystallites on the pan structure in the copolymer were analyzed. the structure of pca-pan graft copolymers was studied by infrared spectroscopy (dichroism and atr), x-ray structure analysis, nuclear magnetic resonance, and scanning electron microscopy. the development of an oriented isotactic structure was found in pan grafted to a pca substrate having a high degree of orientation. the type of crystal modification of pca does not affect the structure formation process in pan. the oriented structures in pan arise directly in the course of synthesis rather than on the subsequent rearrangement of the molecular chains under the action of orientation drawing. in contrast to earlier findings, our studies indicate that synthesis under the conditions specified increases the degree of crystallinity of pca and crystallite size. the grafted pan chains are presumed to grow epitaxially under the influence of pca crystallites. (author abstract) 30 refs