Attenuated Total Reflectance/Fourier Transform Infrared (ATR/FTIR) Mapping Coupled With Chemometrics For Studying The Miscibility And Persibility Of Polymer Composites

The miscibility and the dispersibility of the polymer composites have a great influence on their performance and the compatibilizer was often used to improve the miscibility of the system. A number of methods are often used to investigate the miscibility and dispersibility of polymers. By combining FTIR spectroscopy with bright field microscopy, FTIR mapping provide a powerful technique for simultaneously collecting the spatial and spectral information of a sample in a micro-region. Nevertheless, the conventional univariate imaging method cannot track the minor changes of the spectra and some low-content species may also be ignored because of the weak characteristic bands. The chemometrics method can be used to obtain the quantitative or qualitative information of the chemical compositions, structure and the concentration at the most extent, thus reveal the hidden relevant changes in the image dataset. This dissertation employing the FTIR mapping coupled with chemometrics method to systematically study the miscibility and dispersibility of the polymer composites.ATR/FTIR mapping was adopted to study the influence of the compatibilizer, maleic anhydride grafted polypropylene (PP-g-MAH), on the miscibility behavior of CIIR/PA-12 blends. The image area was 200×200 μm2. The univariate method is used to generate the images based on the bands at 1640 cm-1 (PA-12) and 1365 cm-1 (CIIR). It showed that the miscibility was improved with the increase of PP-g-MAH and the best, miscibility was acquired by introducing 15 phr PP-g-MAH into the blend. The principal component analysis (PCA) results showed that the first three principal components (PCs) were meaningful in the system, MCR-ALS results indicated that an amide copolymer comprised of CIIR and PA-12 (CIIR-g-PA-12) was formed in the interphase of the blend system when the compatibilizer was not introduced; while an imide copolymer comprised of PP-g-MAH and PA-12 (PP-g-PA-12) was formed in the interphase when larger than 10 phr PP-g-MAH was introduced. The the pure spectra of these two interface compounds were aslo obtained by such MCR method. MCR results also proved that the best miscibility was acquired by introducing 15 phr PP-g-MAH into the blend.The dispersibility of MMT in the MMT/PDII nanocomposites was also studied using ATR/FTIR spectroscopic mapping, the image area was 150×150 μm2. The univariate methods based on A1724 and A1040/A1724 were used to generate the images. The fitting results of the median value of the absorbance ratio (A1040/A1724) versus the CMMT(1-CMMT) value showed that good dispersion of MMT in PDII matrix were acquired when more than 30 phr MMT were added into 100 phr PDⅡ; while the serious aggregation occurred when more than 40 phr MMT was introduced into the polymer matrix, it was serious reunion in the PDⅡ matrix. When performing PCA on the images the intensity ratios of the band at 1040 cm-1 to the one at 1724 cm-1 (I1040/I1724) of PC1 versus the content of MMT were in accordance with the univariate method. It is worth to emphasize that some minor or trace fillings in the MMT/PDII nanocomposites can be easily to track when MCR was used to the images. Besides, the concentration distribution maps of such fillings can also be simultaneously acquired.