FTIR-microscopy as a tool for the measurement of the morphology of industrial, polymeric products

Abstract

Many polymeric products are manufactured or fabricated into forms in which the polymer chains are oriented (aligned) to some extent. For example, fibres tend to have directional (longitudinal) stiffness imparted by polymer chains that have a preferred orientation towards or along the fibre long axis. By contrast, in many film and bottle products the macromlecular chains are typically organised to impart a balanced or nearbalanced system, that is they are biaxially oriented with respect to the product surface plane. Polarised infrared spectroscopy is a particulary useful, well established and readily practible tool for investigating polymer anlsortropy. Associated with or independent of molecular orientation may be material density varlations throughout a product. FTIR-microscopy is especially suited to determining and profilling localised extents of both molecular orientation and conflguration. Depending on the study purpose, sample geomerty, sample dimensions and sample absorption characteristics, then either a transmission or reflection, technique may be employed. This article will outline briefly the principles of determining crystallinity and molecular orientaion by mid-infrared techniques. It will, through case studies, Illustrate applications of different. FTIR-microscopy or micro-sampling technique approaches to characterising either crystallinity or molecular orientation over a range or plastic products.