Desarrollo, optimización y modelización de compuestos de alto rendimiento medioambiental derivados de poli (butilén succinato) - pbs y residuos de cáscara de almendra

Resumen

In the last decade, a remarkable change in our society, focused on increased environmental sensitiveness, has been detected. Topics such as recycling, upgrading, biodegradation, and so on are acquiring great relevance. This situation is much more pronounced in the field of polymers and composite materials since most of them are petroleum-derived materials and do not provide, in general, biodegradation, thus leading to waste accumulation with the subsequent environmental problems. For these reasons, research is being developed to overcome or minimize the environmental impact of conventional polymers and composite materials. This research is being conducted from several points of view. Ono of these points of views is the origein; thus, today it is possible to find a wide variety of polymers and composites from renewable resources which positively contribute to reduce to carbon footprint as well to delay the petroleum depletion process. Among these materials, it is worthy to note the increasing use of poly(lactic acid) - PLA, bacterial polymers such as poly(hydroxyalkanoates) - PHAs, polymers from polysaccharides (starch, cellulose, quitin, and so on), and protein-derived polymers (gluten, soy protein, casein, collagen, and so on). Another standpoint is that which considers the environmental efficiency at the end-of-life by developing biodegradable polymers and composite materials (disintegrable in controlled compost). Among others, it is important to highlight the increasing use of some poly(esters) that, although they are petroleum-derived polymers, they offer fully biodegradation, thus contributing to avoid waste accumulation. These poly(esters) include poly(¿-caprolactone) - PCL, poly(butylene succinate) - PBS, poly(butylene adipate-co-terephthalate) - PBAT, among others. Within this context, this doctoral thesis intends to develop new composite materials derived from an aliphatic poly(ester), namely poly(butylene succinate) - PBS that currently is being obtained from petroleum resources but it is possible to synthesize it following a renewable resource by using bio-derived acid succinic. PBS is an expensive and flexible polymer. For these reasons, the aim of this research work is to reinforce PBS by using a worldwide available waste, namely almond shell which can contribute to reduce the oveall cost and, in addition, to improve some mechanical properties. Given the highly hydrophilic nature of the almond shell flour and the extremely high hydrophobic nature of PBS, the first approach considers to potential effectiveness of several compatibilizers families which include acylic monomers, maleinized derivatives (alkenyl succinic anhydrides and modified vegetable oils) and epoxidized derivatives, mainly obtained from vegetable oils. In this section, the amount of almond shell flour (ASF) remains constant and the effectiveness of each family, in general, and each compatibilizers, in particular, is studied. Once the optimum compatibilizers/s to improve interactions among polymer-lignocellulose filler interface are selected, an in depth study of the optimum loading of compatibilizer agent is carried out to obtaine good-balanced properties on PBS-ASF composites by following the evolution of mechanical, thermal, morphological, thermomechanical properties, among others. This way, it is possible to define the optimum cellulosic filler to compatibilizer ratio that could givethe best balanced properties on PBS-ASF composites. Finally, with the aim of obtaining a wide range of materials with tailored properties that could fit in several engineering applications, the effect of the lignocellulosic filler content is studied on PBS-ASF composites.