We investigated the novel pressure sensitive adhesives (PSAs) composed of polylactic acid (PLA) and polycaprolactone (PCL) with sugar alcohol as the core material. These PSAs have the multibranched structure and are also a kind of star-shaped polymer. As is well known, PLA and PCL is a famous biodegradable polymer, and furthermore, PLA is a plant-based polymer that is made of renewable biomass. The application to PSA has been found to be useful as the usage of PLA. These PSAs were synthesized by bulk ring-opening polymerization of L-lactide (LLA) and -caprolactone (CL) initiated from poly-OH (hydroxyl group) in D-sorbitol or xylitol with stannous octoate as a catalyst. Summarizing our findings, it was found that the applicable products as PSA had around the compositions of CL/LLA = 60/40 for molar percentage, by the evaluations in terms of both mechanical and thermal properties. In addition, it was revealed that the balance of three PSA properties was further improved by the cross-linking treatment with hexamethylene diisocyanate (HMDI).
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