Dynamic two-dimensional FTIR spectroscopy of polymer films

Two-dimensional FTIR spectroscopy has been used to study melt-crystallized nylon 11 and low density polyethylene films. All the sample films are dynamic mechanically oscillated at room temperature at a frequency of 11 Hz while being probed with an infrared light source. The N-H stretching, amide I-amide II, methylene bending and methylene rocking-amide V regions of melt-crystallized nylon 11 films are studied in detail. A two-dimensional correlation analysis of the dynamic spectra indicates that the N-H stretching region splits into two peaks. Analysis of two-dimensional crossplots between the N-H stretching region and amide I-amide II regions shows that the prominent peak in the N-H stretching region (3300 cm{dollar}sp{lcub}-1{rcub}){dollar} is similar in morphological character to the ordered peak (1636 cm{dollar}sp{lcub}-1{rcub}){dollar} of the amide I region. The amide II region resolves into two ordered and one disordered peak. It is observed that a disordered component is associated with the crystalline peaks of methylene rocking-amide V and methylene bending regions.; A two-dimensional correlation analysis on the dynamic spectra of low density polyethylene (LDPE) indicates that neat LDPE is comprised of three regions: an ordered crystalline region; a disordered, liquid like region; and a crystal/amorphous interfacial region. The 1468 cm{dollar}sp{lcub}-1{rcub}{dollar} peak in the methylene bending region is assigned to all-trans structures which primarily reside in the interfacial region. A variety of LDPE samples with different additives are used in order to determine how the additives influence the dynamic mechanical properties of each morphological phase. It is found that a talc additive associates with the crystallites, ethylene vinyl acetate as a copolymer in low concentration is distributed in all three morphological phases of the LDPE, and pyrene associates only with the non-crystalline regions.