Role of the Macromolecular Architecture of Copolymers at Layer–Layer Interfaces of Multilayered Polymer Films: A Combined Morphological and Rheological Investigation

Abstract

It is known that copolymers are critical in modifying interfaces of multilayered polymeric products. However, not much is known about the influence of the macromolecular architecture of copolymers on the interfacial morphology evolution, viscoelasticity, and processability of layered systems. Therefore, we demonstrate the role of macromolecular architecture of copolymers at layer−layer interfaces of multilayered polymers from the equilibrium to flow conditions, based on a combined morphological and rheological investigation. Intriguingly, in comparison to a pure grafting case, the formation of interfacial copolymers of a complex grafting architecture of a branching and cross-linking mixture substantially increases the overall viscosity. With a higher grafting density of copolymers of such an architecture, layer−layer interfaces become more corrugated upon reaction. Particularly, under real coextrusion processing flows, with these copolymers, interfacial roughness and irregularities are further amplified in the die exit as compared to that in the feedblock because of the accelerated reaction kinetics by the compressive flow field. Besides, the configuration of copolymers containing a mixture of branched and cross-linked chains at the interface significantly hinders the structural stress relaxation process and resists the interfacial slip. Under fast extensional flows, multilayered films display an unexpected strain-hardening behavior with a strong dependence on the number of layers, arising from the interfacial stitching and elastic network formed with copolymers of the complex architecture. These findings will enable the better understanding of copolymer architectures in the control of interfaces of multilayered films with improved flow stability and macroscopic properties.

Structure Regulation of Polypropylene/Poly(ethylene-co-vinyl alcohol) Hollow Fiber Membranes with a Bimodal Microporous Structure Prepared by Melt-Spinning and Stretching: The Role of Melt-Draw Ratio

“…The island structure is formed by EVOH, which is tightly wrapped and uniformly distributed in the sea structure formed by the PP phase. A compatible interface will be created between the PP and EVOH phase after adding PP- g -MAH . EVOH islands in the center can maintain a nearly spherical structure during spinning because the compatible interface is more susceptible to deformation.…”

“…Although the oriented PP lamellae are formed under stress, the EVOH phase still exists as an island structure. The formation of the two-phase interface region is based on the reaction between the acid anhydride groups in PP- g -MAH and the hydroxyl groups in EVOH . Since the compatibility interface is amorphous, it is easier to deform than EVOH islands under stress perpendicular to the draw direction during the spinning process.…”

“…A compatible interface will be created between the PP and EVOH phase after adding PP-g-MAH. 38 EVOH islands in the center can maintain a nearly spherical structure during spinning because the compatible interface is more susceptible to deformation. However, the stress perpendicular to the melt-draw direction increases as the melt-draw ratios increase.…”

A Journey from Processing to Recycling of Multilayer Waste Films: A Review of Main Challenges and Prospects

“…Over the last five decades, continued research and development in the academic and industry domains allowed a continual growth and expansion of the micro and nanolayered film coextrusion technology [79] to commercial relevancy. Meanwhile, many interfacial and rheological phenomenon during the co-extrusion and forced assembly are also deeply studied [80][81][82][83]. Nearly 500 issued patents for composition of micro or nanolayered materials applications have been published between 2000 and 2010 [84].…”

Interfacial Phenomena in Multi-Micro-/Nanolayered Polymer Coextrusion: A Review of Fundamental and Engineering Aspects

“…Lamnawar and coworkers [81][82][83] prepared multilayer films of PA6/PP and EVOH/PP systems with maleic anhydride-grafted polypropylene (PP-g-AM) as a tie layer using reactive coextrusion. The macromolecular architecture of the copolymers formed at the interfaces critically influences the interfacial morphology evolution, viscoelasticity and processability of layered systems.…”