Model of Nylon 6 Fibers Microstructure Microfibrillar Model or “Swiss-Cheese” Model?

Abstract

The microfibrillar morphological structure of aliphatic polyamide fibers has been consistently presented by the three phase microfibrillar model proposed by Prevoršek and not by the two phase microfibrillar model proposed by Peterlin. A widely spread opinion is that the 3-phase or “Swiss-cheese” model is applicable in all cases, either in case of high-tenacity fibres or in case of standard Nylon 6 textile fibers. Although the 3-pbase X-ray analysis is now routinely performed, the basic issue of 2-phase vs. 3-phase model has not yet been resolved. We have investigated the suitability of both models and found out that the 3-phase model which is suitable for high-tenacity Nylon 6 fibres cannot be applied in case of aliphatic Nylon 6 fibres manufactured by standard melt spun process. The microfibrillar structure of these fibers resembles to the microfibrillar model of PE more than to the morphology of high-tenacity Nylon 6 fibres. The generally established opinion about applicability of the 3-phase model for all aliphatic Nylon 6 fibres, regardless of the fiber forming process, is not acceptable. The key finding is. however, that Nylon 6 fibers can exist, depending on the forming process, in two morphologically different modifications corresponding to the above-mentioned models. By altering the fiber forming process it is possible to alter the morphology and to control the distribution of amorphous extended interfibrillar and intrafibrillar molecules, and to widen the range of mechanical and thermal properties.