Synthesis and characterization of thermoreversible K-Ionomers based on butyl rubber: a simple one-step crosslinking method and a novel crosslinking system

摘要

A simple one-step thermoreversible polymer crosslinking method and a novel reversible ionic crosslinking system (maleic anhydride and KOH) have been developed which is performed on high physical mechanical properties and valuable reversibility. The system involves the acid-base reaction of maleic anhydride with potassium hydroxide to form ionic thermoreversible cross-linking network. A series of ionic thermoreversible cross-linking butyl rubber which is called K-ionomers are obtained as a function of the ratio of KOH to maleic anhydride by simple one-step solution method. The ratio is held at 5:1, the degrees of neutralization is up to 70 % that reprocessibility is possible. X-ray diffraction (XRD) shows the presence of microphase-separated aggregates for K-ionomer that act as physical cross-links which are responsible for its outstanding mechanical property and valuable reversiblity. Very high mechanical property in tensile strength up to 5 Mpa was obtained. The reversibility of K-ionomers is investigated in detail by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Hot stage microscopy. ATR-FTIR results show a desired shift back from carboxylate reacted with carboxylic acid to cyclic anhydrides and KOH depending on heating. Hot stage microscopy shows that the reprocessibility of K-ionomer is detected up to 169 degrees C.