New Multifunctional Poly(lactide acid) Composites: Mechanical, Antibacterial, and Degradation Properties E. Fortunati, 1 I. Armentano, 1 A. Iannoni, 1 M. Barbale, 2 S. Zaccheo, 2 M. Scavone, 3 L. Visai, 3,4,5 J. M. Kenny 1,6 1 Materials Engineering Centre, UdR INSTM, NIPLAB, University of Perugia, Terni, Italy 2 Novamont S.p.A., Novara, Terni, Italy 3 Molecular Medicine Department University of Pavia, Viale Taramelli 3/b and Center for Tissue Engineering (CIT), University of Pavia, Via Ferrata 1, Pavia 27100, Italy 4 Fondazione S. Maugeri, IRCCS, Istituto Scientifico di Pavia, Via S. Maugeri, 4, Pavia 27100, Italy 5 International Centre for Studies and Research in Biomedicine (I.C.B.), 16 a, Bd. de la Foire, L-2015 Luxembourg 6 Institute of Polymer Science and Technology, CSIC, Juan de la Cierva 3, Madrid 28006, Spain Received 4 March 2011; accepted 1 June 2011 DOI 10.1002/app.35039 Published online 3 October 2011 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: The aim of this work was to study the effect of the innovative combination of microcrystalline cellulose (MCC) and silver nanoparticles (Ag) on the poly (lactide acid) (PLA) composite properties, to modulate the PLA mechanical response and induce an antibacterial effect. The preparation and characterization of PLA-based composites with MCC and Ag nanoparticles by twin-screw extrusion followed by injection molding is reported. A film procedure was also performed to obtain PLA and PLA composite films with a thickness ranged between 20 and 60 lm. The analysis of disintegrability in composting conditions by means of visual, morphological, thermal, and chemical investigations was done to gain insights into the post-use degradation processes. Tensile test demon- strated the MCC reinforcing effect, while a bactericidal ac- tivity of silver-based composites against a Gram-negative bacteria (Escherichia coli) and a Gram-positive bacteria (Staphylococcus aureus) was detected at any time points and temperatures analyzed. Moreover, the disintegrability in composting showed that MCC is able to promote the degradation process. The combination of MCC and Ag nanoparticles in PLA polymer matrix offers promising per- spectives to realize multifunctional ternary composites with good mechanical response and antibacterial effect, maintaining the optical transparency and the disintegrabil- ity, hence suitable for packaging applications. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: 87–98, 2012 Key words: biodegradable; composites; compounding; degradation; nanoparticle INTRODUCTION Biodegradable polymers have attracted great scien- tific and technological interest world wide because they have a well-grounded role in reducing the polymer waste problem. 1 In the family of biodegrad- able synthetic polymers, poly(lactide acid) (PLA) appears one of the most attractive for applications in agriculture and as packaging material 2 for its bio/ hydro-degradability and the biorenewable profile. 3,4 PLA is a thermoplastic polyester, derived from the fermentation of starch and other polysaccharide sources 5 and it is becoming increasingly popular due to its high mechanical strength and easy processability compared with other biopolymers. Moreover, PLA is naturally degraded in soil or com- post 6–8 and the resulting degradation products are totally assimilated by microorganisms such as fungi or bacteria. 2 However, PLA has lower water vapour permeability, poor mechanical and thermal proper- ties, and limited barrier properties compared with equivalent petroleum based polymers. 9 The prepara- tion of micro- and nano-composites represents a promising method to improve the physical proper- ties of biopolymers, without affecting the transpar- ency. 10–12 Microcrystalline cellulose (MCC) is used as a highly effective additive to improve the proper- ties of polymer in several application fields. 13 Demand for safe, minimally processed, food prod- ucts presents major challenges to the food-packaging industry to develop packaging concepts for main- taining the safety and quality of products. In this contest, the active food-packaging concepts provide some additional functions in comparison with tradi- tional passive materials that are limited to protection of the food product against external influences. Correspondence to: I. Armentano (ilaria.armentano@unipg. it). Contract grant sponsor: INSTM. Contract grant sponsor: Regione Umbria and Italian Ministry of Education, University, and Research coordinated by Novamont; contract grant number: DM43839 (to S. Z.). Journal of Applied Polymer Science, Vol. 124, 87–98 (2012) V C 2011 Wiley Periodicals, Inc.