Effect of co-monomer on the adhesive performance of PP-g-MAH between cast polypropylene film and aluminum foil

Three functionalized polypropylenes (PPs) were successfully prepared for use as the inner adhesive layer of aluminum/polymer laminated film by melt grafting of maleic anhydride (MAH) on PP with styrene (St), diallyl phthalate (DAP) and triallyl isocyanurate (TAIC) as co-monomers, respectively. The effects of these co-monomers (St, DAP and TAIC) on the grafting degree of MAH, gel content, thermal property and adhesive performance of MAH grafted PP (PP-g-MAH) were investigated. The results show that the T-peeling and heat-sealing strengths of TAIC-assisted PP-g-MAH (PP-g-MAH/TAIC) are 28.6 and 70.4 N /15 mm, which are increased by 33.6% and 20.8% compared to DAP-assisted PP-g-MAH (PP-g-MAH/DAP), and by 142.4% and 81.0% compared to St-assisted PP-g-MAH (PP-g-MAH/St), respectively. The grafting degree of MAH reaches a maximum of 2.3 wt% in PP-g-MAH/TAIC, which leads to a higher crystallization temperature than PP-g-MAH/DAP and PP-g-MAH/St. PP-g-MAH/TAIC also has better thermal stability than the other two functionalized PPs, as TAIC can effectively reduce PP chain scission and promote the formation of a cross-linked structure during the melt grafting.