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

Abstract

In this work, two different wine derived additives, seeds extracts (Sext) and wine lees (WL), have been tested within poly(3-hydroxybutyrate) (PHB) for different purposes. First, the effect of wine seed polyphenolic extracts (Sext) on the PHB thermal stability has been investigated considering the molecular weight decrease (gel permeation chromatography), the impact on the viscosity (mass flow rate), the thermogravimetric analysis (TGA) curves, and the oxidation induction times. Different stabilizers formulations have been tested and the results have been compared with unstabilized PHB. Subsequently, WL have been mixed in different concentration (10, 20, and 40 phr) within PHB by twin-screw extrusion and the obtained biocomposites have been characterized from a thermal (differential scanning calorimetry and TGA) and mechanical (dynamic mechanical analysis and tensile test) points of view exploiting also the micromechanics models of Voigt, Halpin-Tsai and Pukanszky. Finally, biodegradation tests in soil and in marine water have been carried out for each investigated PHB formulation in order to evaluate the effect of Sext and WL on the microbial degradation.

Recycling of Chrome-Tanned Leather and Its Utilization as Polymeric Materials and in Polymer-Based Composites: A Review

“…Moreover, this route of valorization would offer new possibilities to the agro-industrial companies, which are often in trouble with the disposal and management of their wastes [ 106 ]. Examples may regard the use of coffee wastes, wine wastes [ 107 , 108 ], and rice wastes [ 109 ]. Similarly, in the last years, leather wastes have started to be tested as reinforcing fillers within different biopolymers.…”

“…The addition of additives, such as inorganic fillers or more flexible polymers (natural rubber and ethylene-vinyl acetate), led to an improvement in the mechanical properties of the composite, such as yield stress, tensile, and impact strength, especially for a fiber content of 10% [ 114 ]. In composite films with PVC as polymer matrix, it has been noticed that the size of the fibers plays a fundamental role on the properties of the composite [ 108 ]. By decreasing the size of leather particles, the weak points of the stress concentration in tested specimens were reduced.…”

Biodegradability and improved mechanical performance of polyhydroxyalkanoates/agave fiber biocomposites compatibilized by different strategies

“…They also have good moisture resistance and good barrier properties to gases 3 . Nevertheless, these PHA have some important drawbacks like brittleness, low thermal stability, and high production costs 5–7 …”

Wine By-Products as Raw Materials for the Production of Biopolymers and of Natural Reinforcing Fillers: A Critical Review

“…Finally, wine derived fillers have not significantly affected the glass transition temperature (T g ) of biopolymers. The addition of grape pomace to PBS [ 153 ] or of wine lees to PHBV [ 147 ] has increased T g values of neat biopolymers of only a few degrees (1–4 °C), testifying that these fillers do not immobilize polymer chains along the particle-matrix interface.…”

“…In fact, wine by-products are rich in polyphenols, a class of natural antioxidants, which, thanks to their structure (one or more aromatic rings with one or more hydroxyl group attached), can interrupt the polymer degradation. The possibility of using wine antioxidants (extracts) has been deeply investigated; wine by-product extracts have been tested as stabilizers within polyolefin [ 156 , 175 , 176 ], Mater-Bi [ 177 ], poly(3-hydroxybutyrate) (PHB) [ 147 , 178 ], and poly(butylene succinate) (PBS) [ 179 ]. Since antioxidant efficiency depends also on the polymer degradative mechanism, it can be summarized that simple polyphenol molecules (such as Gallic acid and simple Catechins) are the best stabilizing system for polyolefin, which are characterized by a radical degradative pathway, meanwhile long chain polyphenols (such as proanthocyanidins) are preferable within polyester, which exhibit a not radical chain-scission degradation.…”