PLA/PBSA biopoliester nahasteetan oinarritutako filmeak: konposizioaren eragina morfologia, hesi-propietate eta propietate termiko eta mekanikoetan

Abstract

[EU] Gradu amaierako lan honetan, poli(azido laktiko) (PLA)/poli(butilen sukzinato-ko-adipato) (PBSA) nahaste bitarraren filmeak prestatu dira konposizio desberdinetan, urrats bakarreko nahaste-prozesu bat eta, ondoren, puzte bidezko estrusioa erabiliz. Era berean, propietate mekanikoak, termikoak, morfologikoak eta hesi-propietateak aztertu dira konposizioaren eragina behatzeko. Izan ere, plastikoak ingurumenean degradatzeko duten arazoari aurre egiteko PLAren propietateen hobekuntza ikertu nahi izan da PBSAren gehikuntzarekin; horrela, jatorri berriztagarrietatik eratorritakoa eta biodegradagarria den biopolimeroa lortzeko, gehienbat paketatze aplikazioetarako erabiliko dena. TEM bitartez egindako azterketa morfologikoek biopoliesterren arteko elkarrekintza egokia agerian utzi dute fase aldaketa nabarmen batekin batera. PBSA partikulak PLA matrizean sakabanatuta daude PLA/PBSA 40/60 konposiziora arte; PBSA eduki handiagoekin, PBSA matrizea izatera pasatzen da. Hau argi eta garbi islatzen da propietate mekaniko zein hesi-propietateetan. PBSAren edukia handitu ahala, elastikotasun modulua zein isurpenarekiko erresistentzia jaitsi egiten dira. Baina, haustura deformazioan eta urradurarekiko erresistentzian aldeko igoera bat ematen da ur-lurrunarekiko, oxigenoarekiko eta karbono dioxidoarekiko iragazkortasunarekin batera. Analisi termikoak bi biopoliesterren nahasezintasuna baieztatu du, baita PBSAren presentziagatik emandako PLA matrizean nukleazio heterogeneo efektua ere. Horrez gain, filmeek makina-norabidean (machine direction, MD) propietate hobeak aurkezten dituzte zeharkako-norabidean (transversal direction, TD) baino, kate molekularrek jasandako orientazioa eta, beraz, kristaltze-maila dela eta. Euskera

[EN] In this end-of-grade work, poly(lactic acid) (PLA)/poly(butylene succinate-co-adipate) (PBSA) biobased binary blends have been prepared using a single step blending process, followed by blown film extrusion process. Likewise, mechanical, thermal, morphological and barrier properties have been analyzed to observe the effect of the composition. In fact, to face the problem of the environmental degradation of plastics, the improvement of the properties of PLA has been pursued with the addition of PBSA in order to obtain a biodegradable and renewable resourced biopolymer to be used mainly in packaging applications. Morphological studies performed using TEM have revealed the proper interaction between the biopolyesters together with a significant phase change. The PBSA particles are dispersed in the PLA matrix up to a 40/60 PLA/PBSA composition . From that point on, when more PBSA is added, the PBSA becomes the matrix. This is clearly reflected in both the mechanical and barrier properties. As the PBSA content increases, both the modulus of elasticity and the yield strength decrease. However, in elongation at break and tear resistance there is a favorable increase along with permeability to water vapor, oxygen and carbon dioxide. The thermal analysis has confirmed the immiscibility of both biopolyesters with a heterogeneous nucleation effect in the PLA matrix due to the presence of PBSA. Furthermore, the films present better properties in the machine direction (MD) than in the transversal direction (TD) due to the orientation undergone by the molecular chains and, therefore, to the degree of crystallization. Ingelesa