Effect of a natural polyphenolic extract on the properties of a biodegradable starch-based polymer P. Cerruti a,1 , G. Santagata a,1 , G. Gomez d’Ayala a , V. Ambrogi b, * , C. Carfagna a , M. Malinconico a , P. Persico a a Institute of Polymer Chemistry and Technology (ICTP-CNR), via Campi Flegrei 34, 80078 Pozzuoli (Na), Italy b Department of Materials and Production Engineering, University of Napoli “Federico II”, p.le Tecchio 80, 80125 Napoli, Italy article info Article history: Received 26 November 2010 Received in revised form 31 January 2011 Accepted 4 February 2011 Available online 13 February 2011 Keywords: Starch Thermal oxidation Natural antioxidants Bio-disintegration Polyphenols Processing aid abstract A polyphenol-containing extract from winery bio-waste (EP) has been used as an additive for a starch- based polymer (Mater-Bi). EP was used to tailor Mater-Bi properties, thus avoiding the use of synthetic polymer additives. It was found that EP was able to efficiently modulate the processing, mechanical, thermal and biodegradation properties. The observed decrease in melt viscosity showed that EP could improve productivity in polymer processing. Owing to the plasticizing activity of the additive, larger values of elongation at break were found. Moreover, the Mater-Bi crosslinking, which occurs upon thermal aging, was delayed in the presence of EP. Finally, the bio-disintegration rate of doped Mater-Bi decreased, thus suggesting that EP acted as an antimicrobial agent by interfering with the bio-digestion of the polymer films. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Renewable biodegradable polymers represent a valid alternative to traditional oil-derived polymers in packaging and agricultural applications, to reduce environmental impact and to develop eco-sustainable cost-competitive products [1]. When disposed in bioactive environments, biopolymers are degraded by the enzy- matic action of microorganisms, such as bacteria, fungi and algae, and converted into biomass, CO 2 , CH 4 , water and other natural substances [2]. Depending on their origin, biodegradable polymers can be synthetic or natural. The latter, which are referred to as biopolymers, include polysaccharides, proteins and polyesters produced by microorganisms [3,4], whereas poly(vinyl alcohol) and polyesters are the most representative among the synthetic biodegradable polymers [5]. The use and industrial development of biodegradable polymers is limited because of their poor chemicalephysical properties, unsuitable mechanical performances and difficult processability [6]. Therefore, research has focused growing attention on biode- gradable polymer systems, such as composites and blends, in which the biodegradable polymeric matrix is associated with reinforcing fibers [7], organic and inorganic additives [8] and degradable or non-degradable polymers [9]. Among biopolymers, starch is one of the most widely investi- gated, as it is widely available and easily modified to get a ther- moplastic polymer [10]; nevertheless, due to the hydrophilic nature responsible for fast degradation via hydrolysis, thermoplastic starch applications are limited [6]. To overcome this experimental drawback, starch is generally modified by blending with synthetic polymers, such as polyesters or vinyl alcohol copolymers [10]. This approach has been adopted by Novamont under the MatereBi trademark [11]. Target markets of Mater-Bi include packaging materials, disposable cutlery, consumer goods and agricultural tools [12]. The increasing demand to improve Mater-Bi properties, often unsuit- able for specific commercial goals, has led to different strategies of investigation. To get inherent improvements in processability and chemicalephysical performance, Mater-Bi-based composites have been prepared by using different cellulose fibers [13,14]. Enhance- ment of mechanical properties, decrease in water sorption, and modulation of biodegradation kinetics have been observed due to the fiber presence [14,15]. Furthermore, the use of suitable additives could provide upgrading of processing and manufacturing performance, and enhancement of physico-chemical properties. As a matter of fact, * Corresponding author. Tel.: þ39 0817682511; fax: þ39 0817682404. E-mail address: ambrogi@unina.it (V. Ambrogi). 1 These authors equally contributed to this work. Contents lists available at ScienceDirect Polymer Degradation and Stability journal homepage: www.elsevier.com/locate/polydegstab 0141-3910/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymdegradstab.2011.02.003 Polymer Degradation and Stability 96 (2011) 839e846