Supramolecular polymer for enhancement of adhesion and processability of hot melt polyamides

Blends of a semi-crystalline supramolecular polymer and a commercial polyamide resin are investigated in view of high-performance hot melt adhesive formulations. Both components are derived from vegetable oil fatty acids. Morphology and macroscopic properties of the blends are analyzed by cloud point, differential scanning calorimetry (DSC), polarizing optical microscopy (POM), dynamic mechanical analysis (DMA), rheometry and time-resolved X-ray diffraction (XRD) experiments. The adhesion is assessed by T-peel tests of polypropylene web/adhesive/polyethylene film stacks.In the polyamide matrix, the supramolecular polymer plays the dual role of (1) reinforcing filler at room temperature and (2) plasticizer for temperatures above the melting point. Furthermore, the hot-melts blends show a more abrupt softening behaviour on heating and accelerated hardening on cooling. The significant improvement in adhesion properties (up to a 6-fold increase in the peeling force) can be explained by the crystallisation of the supramolecular polymer in the blends.As a consequence, the amount of adhesive for a given application as well as the temperature, energy and time needed to process it can be decreased significantly.