New insights into pressure-sensitive and hot-melt adhesives from renewable resources

TOUS L.; RUSECKAITE, R.A.; CIANNAMEA, E. M.

Dublín

Conferencia; ECO-BIO Challenges in Building a Sustainable Biobased Economy; 2018

Elsevier, Be-basic

Vegetaloils and proteins are very attractive renewable raw materials for themanufacture of diverse adhesives than can compete with those derived frompetrochemical sources, but with the benefit of being sustainable. In this worktwo different biobased adhesives were developed: Pressure Sensitive Adhesives(PSAs) based on epoxidized soybean oil (ESO) and sebacic acid (SA) and Hot-MeltAdhesives (HMAs) from soybean protein isolate (SPI), polycaprolactone (PLA) andcastor oil (CA). Completelybiobased PSA with tunable viscoelastic properties were obtained by mixing ESOand SA through a solvent-free one-step reaction without catalyst. Curingconditions and pot-life were determined for different acid/epoxy ratio. Curingtime was ranged from the gel point (tgel) to tgel+30 min at 170°C, to study thecorrelation between the reaction, rheological behavior and potential adhesiveperformance. Produced PSAs can be tailored by controlling the curing parametersaccording to the desire application (i.e. permanent or removable). Inparticular, the PSAs cured at 170°C at 65-75 min showed the best balancebetween tack and cohesion. Potentiallybiodegradable HMAs with high content of biogenic raw materials were developedby mixing   PCL with SPI (0-50% w/w PCL)at 140°C for 30 min, using CA (0-50% w/w mixture) compatibilizer/plasticizeragent. Adhesives were characterized by infrared spectroscopy, calorimetry,thermogravimetric analysis and X-ray diffraction. Adhesion and rheologicalstudies were performed to elucidate the adhesive and viscoelastic properties ofthe materials as a function of their composition. Adhesion strength wasevaluated on fiberboard following the procedure described in ASTM 1002. Theadhesion strength of the HMAs was not affected by the replacement of PCL by SPIup to 50% w/w, implying a reduction on the product cost and an increase in thebiobased content. Resultsreveal the great potential for these biogenic materials in the design of a newgeneration of environmentally responsible PSAs and HMAs.