Chemical Modification of Polypropylene with Diisocyanates for Improved Gas Barrier and Mechanical Properties

In this investigation, modification of polypropylene (PP) with an
objective to obtain packaging film with improved gas barrier properties has been
studied. The chemical reaction of PP resin with hexamethylene diisocyanate and
toluene diisocyanate was monitored by Fourier transform infrared spectroscopy,
wherein the appearance of new peaks at 3333 cm−1 for N H stretching,
1620–1641 cm−1 for (C O) NH stretching and 1552–1578 cm−1 corresponding
to N H bending in an amide moiety was observed for both the modified PP
films. Films of excellent clarity and uniform thickness were obtained by the
extrusion of cross-linked polypropylene. The barrier, mechanical, optical, and
thermal properties of the modified PP films were studied. The results clearly
indicated significant changes in gas barrier and mechanical properties. Food compatibility of the films was evaluated by overall migration in to different food
simulants.