Effect of Na-ionomer on dynamic rheological, dynamic mechanical and creep properties of acrylonitrile styrene acrylate (ASA)/Na⁺¹poly (ethylene-co-methacrylic acid) ionomer blend

Abstract

A special class of engineered copolymers, called ionomers, comprising both electrically neutral repeating units and a fraction of ionized units was melt blended to weather resistant acrylonitrile/styrene/acrylate (ASA) terpolymer for improved electrical conductivity, heat sealing ability, direct adhesion to several polymers, glass and metals without affecting the aesthetics and colorability of ASA. The similar chemical nature of one of the components of each blended materials viz. acrylate rubber in ASA and acrylic acid of Na-ionomer in addition to the presence of ionic crosslinking within Na-ionomer, polar acrylonitrile group in ASA affects chain dynamics as compared to neat polymers. In this context, dynamic rheological properties, DMA properties, creep behavior and DSC of the newly developed ASA/Na-ionomer blends were analyzed. Based on Na-ionomer content, the blend system either forms "mushroom" or "brush" type conformation and formation of ionic crosslinking in "brush regime" leads to three tiers Caylay tree conformation. The different chain topology resulted into characteristic loss modulous (G″) curve during stress relaxation process. The chain conformation as well as ionic crosslinking and ion-dipole interaction between the blend components also affected DSC endotherm peak and glass transition temperature. The tan δ peak temperature from DMA also revealed the similar observation. The creep compliance of the blends was dependent on Na-ionomer content and with temperature. The Findley model analysis of creep compliance suggested that the creep compliance was depended on Na-ionomer content and ionic crosslinking controlled the creep. The findings can be utilized to design weather resistant smart polymer using suitable filler system.

Thermal, dynamic mechanical, and creep behavior of carbon nanotube reinforced ASA/Na‐ionomer blend

“…The matrix blend components are ASA Luran S 777 (density 1.07 g/cm 3 , melt flow rate at 220°C/10 kg load 13 g/10 min) from BASF and Surlyn™ 1601‐2 (density 0.94 g/cm 3 , melt flow rate of 1.3 g/10 min at 190°C/2.16 kg load, differential scanning calorimetry (DSC) melting point of 96.1°C) from DuPont India. Surlyn™ 1601‐2 copolymer comprises ethylene and 10 mol% of methacrylic acid, which is 53% neutralized by suitable Na‐salt .…”

“…When the ionomer content was less than 30%, the ionomer chains were present in “lying” condition on ASA matrix phase, and above 30% ionomer content (the “brush” regime), the ionomer chains were present in “standing” condition; both were verified by the scanning electron microscopy (SEM) images . Both the “mushroom” and “brush” conformations were presented pictographically in literature . The ionomer chains are grafted on the polymer backbone comprising PSAN of ASA and were designated as “Arm.” The ionic aggregates of ionomer formed ionic crosslinks in “standing” position due to the close proximity of the ionomer chains, and these ionic crosslinks divided the “Arm” into two parts—“Arm I” and “Arm II.” The “Arm I” originated from the ionic crosslink and formed free dangling arm, and the “Arm” portion between the backbone and the ionic crosslink was designated as “Arm II.”…”

“…The ASA and ionomer blend systems have been recently studied by Datta et al They investigated the mechanical and thermal behaviors, morphology, linear and non‐linear rheology, and dynamic mechanical and creep behaviors of the ASA/Na‐ionomer blend system and ASA/Zn‐ionomer blend system . Conformational transition from the “mushroom” structure to “brush” structure was observed when the ionomer content was more than 30% in the ASA/ionomer blend system.…”

“…Both the “mushroom” and “brush” conformations were presented pictographically in literature . The ionomer chains are grafted on the polymer backbone comprising PSAN of ASA and were designated as “Arm.” The ionic aggregates of ionomer formed ionic crosslinks in “standing” position due to the close proximity of the ionomer chains, and these ionic crosslinks divided the “Arm” into two parts—“Arm I” and “Arm II.” The “Arm I” originated from the ionic crosslink and formed free dangling arm, and the “Arm” portion between the backbone and the ionic crosslink was designated as “Arm II.”…”

“…The 50/50 blend was selected because of its “brush” conformation. The improved thermal stability and heat‐sealing affinity to metal were the added advantages . The prepared nanocomposite system can find the outdoor applications, such as a coating for telecommunication components.…”