Original article Poly(lactic acid) foams reinforced with cellulose micro and nanofibers and foamed by chemical blowing agents Matheus VG Zimmermann 1 , Michelle Paola da Silva 2 , Ademir J Zattera 2 and Ruth MC Santana 1 Abstract Biodegradable polymeric foams have gained increasing attention as an alternative to conventional polymeric foams, whose recycling is economically unviable due to its low density. Based on this, this article discusses the development of poly(lactic acid) foams produced with the insertion of four and eight parts hundred resin (phr) of long and short cellulose fibers and nanofibers. Short fibers of nanocellulose were obtained by mechanical defibrillation and dried by lyophilization, and long fibers by CO 2 supercritical fluid extraction. The poly(lactic acid) foams were produced by adding a chemical blow- ing agent with a pressure-free expansion method. In general, short fibers of cellulose act as nucleating agents during the expansion of the foam, which is observed by its greater number of smaller-size cells than the non-reinforced poly(lactic acid) foams. The inser- tion of long fibers of cellulose restricts the mobility of the polymer matrix during the expansion, thus hindering the foam its growth and formation of bubbles. Keywords Poly(lactic acid), foam, nanocellulose, chemical blowing agent 1 Graduate Program in Mining, Metals and Materials Engineering (PPGE3M), Federal University of Rio Grande do Sul (UFRGS), Brazil 2 Graduate Program in Process and Technology Engineering (PGEPROTEC), University of Caxias do Sul (UCS), Brazil Corresponding author: Matheus VG Zimmermann, Graduate Program in Mining, Metals and Materials Engineering (PPGE3M), Federal University of Rio Grande do Sul Bento Gonc ¸alves Avenue, 9500 Porto Alegre, 91501-970, Brazil. Email: matheus.vgz@gmail.com Journal of Cellular Plastics 0(0) 1–20 ß The Author(s) 2017 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0021955X17720155 journals.sagepub.com/home/cel