Study Of Polymer Composites By Attenuated Total Reflection Fourier Transforminfrared Mapping Coupled With Multivariate Curve Resolution

Polymer composites are widely used in various fields of life and industry due to the excellent performance of heterogeneous components.The properties of composite materials depend on their compositions and structures that have been investigated by a number of approaches.Unfortunately,they are destructive to the samples more or less,and there are still many difficulties in the study of blind samples,especially when analyzing the trace components of blind sample or the minor changes of structure of polymer composite.Infrared imaging is a nearly non-destructive technique as a powerful tool for microanalysis.It can obtain spectral and spatial information of sample in micro-area with little to no sample preparation and without staining or dyeing.Multivariate curve resolution(MCR)is a chemometric method,which can extract useful information of pure components spectra and concentration profiles without any prior knowledge from images that containing massive amounts of data.In this dissertation,a new MCR method was developed and we used it combined with ATR/FTIR mapping to study the polymer composites.Different from the existing methods that the number of components have to be determined in advance,the new MCR method was implemented by directly repeating MCR algorithm at increasing number of components.After that,each retrieved pure spectrum of as-resulted MCR component was compared with a real-world pixel spectrum of the local high concentration in the corresponding MCR map.One component was affirmed only if the characteristic bands of the MCR component had been included in its pixel spectrum.Trace additives in two blind polymer samples A and B were identified by ATR-FTIR mapping in conjunction with the new developed MCR method.First,the major components of two polymer blind samples were identified by infrared spectroscopy.Then,we implemented the repeating MCR calculation to FTIR images by simply increasing the number of components one by one from 3 to 10.Furthermore,the retrieved MCR spectra were compared with the real-world pixel spectra of the corresponding local high concentration in MCR map.It demonstrates that the characteristics of each MCR component were included in corresponding pixel spectrum,suggesting the real existence of the resolved MCR components.Finally,the chemical structures of these pure components were confirmed by comparing with the standard spectra library.The trace additives identified for blind sample of A are talc,calcium carbonate,carboxylate,zinc and amide of 2-mercaptobenzothiazole while for B are zinc stearate,amide,carboxylate and trans-polyisoprene.A series of poly(L-lactic acid)/montmorillonite(PLLA/MMT)composites with different MMT amounts were studied by ATR-FTIR mapping combined with the established MCR method.Two different crystal forms,a and a',of PLLA were identified,which was supported by the results of both X-ray diffraction analysis and DSC analysis.The spectra of the two crystal forms and their distributions were obtained by MCR analysis.In addition,the robustness of our newly established MCR method was verified by using PLLA/MMT binary hybrid system with known composition.