Journal of Material Sciences & Engineering
Open Access

Abstract

Aiming at minimizing the environmental impact caused by the use of synthetic, non-renewable polymers, naturally occurring
alternatives have been increasingly studied. Cellulose is a rigid, infusible, water-insoluble and fibrous-like biopolymer. In order
to improve its film-forming properties, its hydroxyl groups are partially etherified into hydroxypropyl and methoxyl groups, resulting
in hydroxypropyl methylcellulose (HPMC). We evaluated the effects of methoxyl content (MC) and average viscosimetric molecular
weight (Mv) on glass transition temperature (Tg), water vapor permeability (WVP), tensile strength (σ), and elastic modulus (E) of
films produced from aqueous film-forming solutions comprising 2% (w/v) of HPMC. We studied METHOCEL™ E15(MC: 28-30%;
Mv: 120,000 g.mol-1; Tg: 174 ˚C; WVP: 0.75 g.mm.kPa-1.h-1.m-2; σ: 31 MPa; E:1.45 GPa), E4M (MC: 28-30%; Mv:530,000 g.mol-1; Tg:
178 ˚C; WVP:0.92 g.mm.kPa-1.h-1.m-2; σ: 67MPa; E: 1.76GPa), and K4M (MC: 19-24%; Mv: 550,000 g.mol-1; Tg: 210 ˚C; WVP: 1.52
g.mm.kPa-1.h-1.m-2; σ: 52 MPa; E: 1.74 GPa). Longer HPMC chains led to stronger (higher σ) and stiffer (higher E) films having higher
Tg due to the increased physical entanglement and lower free volume and mobility. Films with higher MC were stronger due to the
anchoring effect of methoxyl groups. Also, they presented lower Tg and WVP as a result of the lower occurrence of hydroxyl groups,
that provide polarity and hydrophilicity. We demonstrated that both MC and molecular weight influence the physical-mechanical
properties of HPMC films and should be taken into account in the developmentofnovel bio-based materials with suitable properties.

Biography

Caio G Otoni has completed his BSc in Food Engineering from Federal University of Viçosaand is currently a PhD student in Materials Science and
Engineering/Polymers at Federal University of São Carlos. His research project is being developed at the National Nanotechnology Laboratory for Agribusiness,
EmbrapaInstrumentação, a Brazilian federal research organization. He was a research volunteer for one year at the United States Department of Agriculture/ARS/
WRRC. He has published over 14 papers in scientific journals and acts as a reviewer of Journal of Agricultural Science and Technology and Ciência Rural.
Otoni is supported by São Paulo Research Foundation (FAPESP – grant #2014/23098-9).