Sustainable pressure sensitive adhesives based on epoxidized soybean oil, sebacic acid and a cardanol-based bifunctional epoxy resin

TEPER MARINELLI, LAUTARO G.; RUSECKAITE, ROXANA A.; CIANNAMEA, EMILIANO M.

Virtual

Congreso; III Congresso Brasileiro Interdisciplinar em Ciência e Tecnologia; 2022

Universidade Federal dos Vales do Jequitinhonha e Mucuri

Abstract. Pressure-sensitive adhesives (PSAs) are a special category ofpolymeric materials that are permanently tacky at the operating temperature andcan adhere any given substrate under a slight pressure in a short time, withoutany chemical reaction, phase change or solvent evaporation. Driven by needs forregulatory compliance and environmental issues, biobased PSAs have emerged asgreen alternatives that can compete with synthetic ones, with the additionalbenefits of being sustainable. The motivation of this study was the design ofcompletely renewable PSAs with tuneable properties based on epoxidized soybeanoil (ESO, EEW=233,47), sebacic acid (SA) and a commercial flexible bifunctionalepoxy resin based on cardanol (Cardolite NC-514, EEW=456). PSAs were obtainedfrom a solvent-free one-step reaction in absence of catalysts between ESO and adi-acid with stoichiometric acid/epoxi ratio. Two types of bifunctional acidswere used to produce PSAs, SA and a linear polymeric acid synthesized fromdifferent acid/epoxi equivalent ratio (1.23,1.5,1.76) of NC-514 and SA. Oscillatoryisothermic tests were performed in a rheometer to determine the gel time andstablish the curing parameters of the different PSAs. Thermal analysis (TGA,DSC) were used to determinethe thermal stability (TGA) and glass transition temperature (DSC, 2 scans) of rawmaterials, polymeric diacids and PSAs. Fourier-transforminfrared spectroscopy (FTIR) spectrums were obtained to identify functional groups and get abetter understanding of the reaction between ESO and diacids. Finally,frequency sweep measurements were performed in a rheometer to verificate theapplicability of these polymers as PSAs. The synthetized materials showed adequaterheological performance, thermal stability and glass transition temperature to beused as PSAs, with the benefit of being fully biobased and sustainable.