Thin wall injection‐overmoulding of polyamide 6/polypropylene multilayer parts: PA6/PP‐g‐ma interfacial adhesion investigations

Abstract

This work investigates the interfacial adhesion of PA6/PP‐g‐MA in a thin‐walled multilayer part obtained by injection overmoulding. This process is a good solution to the need of weight reduction for the sustainable and economic growth of food packaging. A rigid plastic food package is a complex multilayer structure obtained from the association of polymers with different properties to achieve good barrier, environment, or thermo‐mechanical performance. The present study aims to obtain a complete understanding of the interfacial adhesion of PA6/PP‐g‐MA interface in a three‐layer PA6/sealant/PP assembly through microscopy analysis, mechanical characterization, and inter‐diffusion models. Optical microscopy, XPS, and AFM analyses showed the presence of a copolymer interphase. This layer is greatly dependent on the holding pressure applied, which revealed to be the key parameter to obtain the best results in terms of failure strength. A better interface wettability improves the inter‐diffusion distance and thus chemical grafting efficiency. Other interface improvements were achieved by the addition of EVA in the PP‐g‐MA layer. The lowest viscosity of the EVA dispersed phase has led to a fully cohesive failure due to an interface diffusion efficiency. The presence of EVA increased more than 80% of the peeling performance of the assemblies.

Investigating the Effect of Interface Temperature on Molecular Interdiffusion during Laser Transmission Welding of 3D-Printed Composite Parts

“…As suggested in [ 8 , 38 , 39 ], complete interdiffusion can only be achieved when the quadratic distance of diffusion is greater than the mean square end-to-end distance ( m 2 ). Therefore, the degree of healing ( ) can be calculated by the following equation (hereafter “Model 2”): …”

Effect of Injection Overmolding Parameters on the Interface Bonding Strength of Hybrid Thermoset–Thermoplastic Composites

“…Therefore, one of the aims of this research is to study the influence of injection overmolding parameters on the interfacial bonding strength of overmolded hybrid TSC-PA6 structures. For overmolded thermoplastic-thermoplastic interfaces, many researches have investigated the bonding mechanism through reptation theory [19][20][21][22]. However, for thermoset-thermoplastic interfaces, the bonding mechanism changes due to the inability of thermoset materials to remelt at high temperature.…”

Analyses of the Adhesion Interphase of Isotactic Polypropylene Using Hot-Melt Polyolefin Adhesives

“…Recent drastic developments of the instruments for interfacial analyses and inspection have revealed not only the structure and properties of the interphase but also molecular behaviors of the polymer chains at the interphase. There are various candidates of instruments for the precise analyses of the interphase, for example, transmission electron microscope (TEM), ,− atomic force microscope (AFM), − confocal Raman scattering microspectroscope, ,,− AFM-infrared spectroscope (AFM-IR), − sum frequency generation (SFG) vibrational spectroscope, − X-ray photoelectron spectroscope (XPS), − neutron reflectometer (NR), − X-ray absorption fine structure (XAFS) measurement, , Rutherford scattering measurements, − and so on. These advanced analysis technologies provide the information at the interphase including nanostructure, molecular orientation, distribution, and chemical bond states.…”