Factors Affecting Adhesion of Tie Layers Between Polypropylene and Polyamides

Abstract

Adhesion properties were determined on five-layer coextruded cast films. With a few exceptions, the cap layers consisted of polypropylene, the tie layers consisted of blends of polypropylene and maleic anhydride-grafted polypropylene, and the center layer consisted of various polyamides.The adhesion generally increased as the overall film thickness and the level of maleic anhydride-grafted polypropylene were increased. The molecular weight of the grafted resin had a small effect on adhesion. Homoploymer diluent outperformed random copolymer diluents. Adhesion did not vary much when different types of polyamides were used as the center layer, but each exhibited much greater adhesion than an ethylene-vinyl alcohol center layer.

Influence of Processing Conditions On the Peel Behavior of Polyethylene/ Polybutene-1 Peel Systems

“…polyethylene/polyisobutylene films [12]. Furthermore, various thicknesses, which can be achieved from different size of the die gap or different TUSs, lead to different peel forces [15]. An increased peel force with increased thickness of the film can also be observed for the peel system PE-LD/iPB-1 [17].…”

“…Regarding the fact that the processing conditions influence the material properties, it is expected that they also influence the peel properties. The literature is very rare concerning this content [12,15,16] and, even more, for the peel system PE-LD/iPB-1 [17]. The peel force increases with increasing content of the compatibilizer for the twolayered barrier film polypropylene/polyamide [15].…”

“…The literature is very rare concerning this content [12,15,16] and, even more, for the peel system PE-LD/iPB-1 [17]. The peel force increases with increasing content of the compatibilizer for the twolayered barrier film polypropylene/polyamide [15]. Classical ageing of the used materials is not relevant for the degree of peel force for polyethylene/polyisobutylene films at À408C; however, at ambient temperature a higher migration of polyisobutylene is favored as the major cause for the increase of the cling [16].…”

Quantifying Chemical Reactions and Interfacial Properties at Buried Polymer/Polymer Interfaces

“…A combination of different polymer layers is used to produce films with highly tunable properties to meet specific applications. − For example, polyolefin layers, e.g., polyethylene, provide an excellent moisture barrier and good sealing properties, while internal barrier layers such as nylon or ethyl vinyl alcohol copolymer (EVOH) provide an outstanding oxygen barrier. However, it is challenging to bind dissimilar polymer layers (e.g., polar vs nonpolar layers) as they tend to delaminate. − Maleic anhydride (MAH)-modified polymers such as MAH-modified polyethylene (MAH- g -PE), which is studied in this work, are commonly used as tie layers for binding dissimilar polymers in multilayer film systems. − Typically, the MAH-modified polyolefin tie layer is miscible with the adjacent polyolefin layer and can form covalent bonds via reaction of MAH with a functional group on the barrier layer such as nylon or EVOH, forming a strong linkage between the two polymers. − ,, While MAH-modified polymers have been studied for decades, and many commercial products exist, only recently have we begun to characterize the molecular details of the buried interfacial chemistry responsible for the improved adhesion. ,,− …”