Effect of the wine lees wastes as cost‐advantage and natural fillers on the thermal and mechanical properties of poly(3‐hydroxybutyrate‐co‐hydroxyhexanoate) (PHBH) and poly(3‐hydroxybutyrate‐co‐hydroxyvalerate) (PHBV)

Abstract

Solid wine wastes named wine lees (WL) have been tested as cost-advantage filler within biopolymers such as poly(3-hydroxybutyrate-co-hydroxyhexanoate) and poly(3-hydroxybutyrate-co-hydroxyvalerate). WL have been first characterized and subsequently mixed within the polymers through a twin-screw extruder in different concentrations (10, 20, and 40 phr). Moreover, the role of 3-methacryloxypropyltrimethoxysilane tested as coupling agent has been investigated within the 20 phr formulation. The obtained materials have been characterized from a thermal, mechanical, rheological, and morphological point of view through: differential scanning calorimetry, melt flow rate, tensile and creep tests, dynamic mechanical analysis, and scanning electron microscopy. Results have shown how WL can improve the biopolymers overall properties without compromising their bio-based origin. Several micromechanical models have been exploited to extend the mechanical behavior and correlations between biocomposites properties and WL contents have been carried out. Finally, the economic analysis has shown how these biocomposites could be suitable also for large-scale applications.

Effect of the wine wastes on the thermal stability, mechanical properties, and biodegradation's rate of poly(3‐hydroxybutyrate)

“…Comparing TGA and OIT results is possible to note that PHB 0.6 Sext has exhibited the best TGA response meanwhile PHB 0.6Irg has guaranteed the higher OIT times. This discrepancy could be explained by the different conditions involved in the two tests (isothermal for OIT and dynamic for the TGA) that may affect differently the stabilizer efficiency, as also reported in a previous work 8 …”

“…(Lugo [RA], Italy) during the winemaking 2018 season; Irganox 1010 (Irg1010) has been purchased by Sigma Aldrich. Preparation methods of WL fillers as well as extraction conditions of Sext are already reported in References [8] and [7], respectively.…”

“…Sext has been selected because in a previous work, 7 it showed excellent stabilization's responses within polypropylene and thus we have been intrigued by the possibility to test this extract also within PHB. On the other hand, WL have been selected because of their encouraging results shown within other biopolymers, 8,9 their cheapness (0.05–0.10€/kg) 10 and their huge availability (4 × 10 5 ton for year only in Italy 11 ). Briefly, WL are spherical‐flakes particles of nearly 25 μm, characterized by high inorganic fractions (40%) and by a significant intrinsic thermal stability ( T deg of 270°C).…”

“…This has been done in order to collect experimental evidences concerning the relation between mechanical properties, thermal stability, and biodegradation. In fact, despite different agroindustrial wastes have been tested as PHB fillers 8,12–15 and stabilizers, 16–21 evidences and explanation regarding how reinforcing fillers and, especially, natural stabilizers could affect the other PHB key‐properties, such as the biodegradation behavior, are scarcely present in the literature.…”

Cascade strategies for the full valorisation of Garganega white grape pomace towards bioactive extracts and bio-based materials

“…Literature reports some attempts to enhance its physical and mechanical properties by blending or filling techniques, using different types of natural fibres [26][27][28]. Recently, the use of wine lees as filler for PHBV was described [29] demonstrating the economic feasibility of PHBV-wine lees biocomposites and reporting an economic profit ranging between 0.05 and 1.02 €/kg of composite, as a function of the filler amount.…”