In Situ Compatibilizer Reinforced Interface between an Amorphous Polymer (Polystyrene) and a Semicrystalline Polymer (Polyamide Nylon 6)

Abstract

We present an investigation of the reinforcement of the interface between a flexible amorphous polymer (polystyrene, PS) and a semicrystalline polymer (a polyamide, Ny6). Poly(styrene-co-maleic anhydride) was used as the compatibilizer. Fracture toughness was measured using the asymmetric double cantilever beam test (ADCB). For bonding temperatures above 190 °C, the adhesion strength was found to increase with bonding time, pass through a peak value, and then reach a plateau. The fracture toughness increased with increasing bonding temperature, passed through a peak near 200 °C, and then decreased with further increase of the bonding temperature. This behavior was more obvious for an amorphous polymer/semicrystalline polymer pair than for a pair of semicrystalline polymers. The variation of the fracture toughness with bonding time and temperature can be plausibly explained in terms of two different failure mechanisms: adhesive failure at the interface for short bonding times and when the bonding temperature is low, and for longer bonding times and at high temperatures, cohesive failure between chains at the interface and the bulk PS due to decreased chain entanglement. As long as the compatibilizer molecular weight is sufficiently large that entanglements form between the matrix polymers, common features of the fracture mechanisms depending on the bonding conditions can be outlined that are independent of the crystallinity of the polymer.

Reactive Compatibilized Polymer-Polymer Interface : Amorphous and Semi-crystalline Polymer Pair

“…1 As long as the copolymers (or the block copolymers added as a compatibilizer) at the interface have sufficiently high molecular weights to become fully entangled with the matrix polymers on both sides of the interface, fracture occurs by chain scission when the areal density of the copolymers at the interface is low. 1,6 If the areal density of a long compatibilizer is above some critical value, the adhesive strength is high enough to withstand the fracture stress. The fracture is then determined by the cohesive strength of the polymers on either side, depending on the states of the individual chains.…”

“…We believe this to be the result of inter-reaction between the surface functional groups (carboxyl groups mostly involved) and the amine end group of Ny6. 1,6 As the interreaction between activated PS molecules and Ny6 molecules proceeded, the fracture toughness increased. After a critical surface coverage of reacted molecules was attained, further reaction at the interface became scarce due to the consumption of functionalized PP molecules at the interface and less diffusion of the other chains from the bulk side due to the crowdedness at the interface.…”

“…The adhesive interface strength at the interface increased with temperature due to more reaction at the interface while the cohesive strength of PS decreases with the temperature due to less entanglement of PS molecules at the interface with other chains in the bulk. 1 For the ion-beam irradiated PS surface bonded at high temperature, the adhesive strength at the interface is strong enough to induce the crack propagate into the PS phase. We emphasize a particularly useful aspect of the ion-beam assisted gas reaction route to polymer surface modification.…”

“…Since most polymer pairs are thermodynamically immiscible, their interfacial adhesion is quite poor due to poor mutual diffusion of molecules at the interface. 1 To fabricate a useful blend, the addition of a compatibilizer at the interface is normally required. 1,2 The addition of a compatibilizer such as a block copolymer is only useful if the compatibilizer is available.…”

“…1 To fabricate a useful blend, the addition of a compatibilizer at the interface is normally required. 1,2 The addition of a compatibilizer such as a block copolymer is only useful if the compatibilizer is available. If no compatibilizer is available, in situ reactive compatibilization is another approach that can be used to improve the interfacial properties.…”