Abstract
This work represents an innovative study that, for the first time, explores the possibility to use waste flours to produce thermoplastic polymeric bio-films. To the best of our knowledge, this is the first time that waste flours, derived from bakeries, pizzerias or pasta factories, have been proposed for the production of bio-polymers, as a replacement of neat starch. To this aim, durum waste flour derived from a pasta factory, soft waste flour derived from pizzerias and neat maize starch used as control material were firstly analyzed from dimensional, morphological and chemical points of view. Afterwards, waste flour films were produced by the addition of a nature-based plasticizer, glycerol. Mechanical characterization of the plasticized thermoplastic films, produced by compression molding, evidenced low performances, even in the case of the neat maize starch. In order to improve the mechanical properties, the possibility to include polylactic acid and cardanol-based plasticizer was also investigated. Mass transport properties of all the produced bio-films were investigated by measuring their water vapor permeability and hygroscopic absorption. The durability properties of the bio-films were assessed by accelerated ageing tests, while the bio-degradability of the waste-based films was evaluated by measuring the solubility and the degradation in water. The physicochemical analyses of the novel bio-films evidenced good mechanical properties; specifically, the waste-based films showed a lower hygroscopic absorption and water solubility than those of the blends containing neat starch.
Highlights
For more than a century, starch has been the most widely used natural polysaccharide for the production of polymeric bio-films because of its wide availability in agriculture, biodegradability and cheapness
Neat maizestarch starch (MS) was used as a control material due to its widespread employment for the production of thermoplastic films; both waste flours, namely durum waste flour (DWF) and soft waste flour (SWF), were compared to the corresponding produced flours, namely DF
This work proposed an innovative method for producing biodegradable thermoplastic polymeric films by employing waste flours derived from pasta factory (DWF) and pizzeria (SWF) waste
Summary
For more than a century, starch has been the most widely used natural polysaccharide for the production of polymeric bio-films because of its wide availability in agriculture, biodegradability and cheapness. It is considered one of the most abundant renewable materials, but, if compared to the synthetic polymers, it presents two great disadvantages: a high hygroscopicity, due to the presence of hydroxyl groups [1], and a narrow processing window, due to fast degradation. The processability of the starch, is feasible only by destroying the crystalline structure This phenomenon occurs by heating starch in conditions of high pressure and shear, with a proper amount of plasticizer (such as water or polyols) [4,5] that decreases the melting temperature. A reversible process of rearrangement of the amylose and amylopectin chains of the gelatinized starch takes place, and the Polymers 2020, 12, 1414; doi:10.3390/polym12061414 www.mdpi.com/journal/polymers
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
