Premium
Peroxide induced cross‐linking by reactive melt processing of two biopolyesters: Poly(3‐hydroxybutyrate) and poly( l ‐lactic acid) to improve their melting processability
Author(s) -
Wei Liqing,
McDonald Armando G.
Publication year - 2015
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.41724
Subject(s) - materials science , fourier transform infrared spectroscopy , crystallinity , glass transition , molar mass , rheology , polymer , branching (polymer chemistry) , cross link , dynamic mechanical analysis , shear rate , polymer chemistry , rheometry , chemical engineering , lactic acid , melt flow index , composite material , copolymer , engineering , biology , bacteria , genetics
Poly(3‐hydroxybutyrate) (PHB) and poly( l ‐lactic acid) (PLLA) were individually cross‐linked with dicumyl peroxide (DCP) (0.25–1 wt %) by reactive melt processing. The cross‐linked structures of the polymer gel were investigated by nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopies. The size of the polymer crystal spherulites, glass transition temperature ( T g ), melting transition temperature ( T m ), and crystallinity were all decreased as a result of cross‐linking. Cross‐linking density (ν e ) was shown to increase with DCP concentration. Based on parallel plate rheological study (dynamic and steady shear), elastic and viscous modulus ( G ″ and G ′), complex viscosity (η * ) and steady shear viscosity (η) were all shown to increase with cross‐linking. Cross‐linked PHB and PLLA showed broader molar mass distribution and formation of long chain branching (LCB) as estimated by RheoMWD. Improvements in melt strength offer bioplastic processors improved material properties and processing options, such as foaming and thermoforming, for new applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 41724.