MISCIBILITY AND THERMAL DEGRADATION KINETICS OF POLY-β-ALANINE/POLY(3-HYDROXYPROPIONATE) BLENDS

Poly-β-alanine (PBA) and poly(3-hidroxypropionate) (PHP) were synthesized via base-catalyzed hydrogen transfer polymerization (HTP) of acrylamide and acrylic acid, respectively. Blends of PBA/PHP with different composition (PHP content, 5% to 75%) were studied using FTIR, DSC, TGA, XRD and polarized optical microscope to reveal both miscibility and thermal degradation kinetics of PBA/PHP blends.  Optical images of blends were transparent and entirely uniform. Characteristic IR bands of both components shifted in higher frequencies with increasing fraction of other component.  Melting temperature (T m ), thermal decomposition temperatures (T d ) and enthalpy of fusion (ΔH f ) of PHP decreased with increasing PBA fraction in blends. Thermal degradation kinetics of both components were studied by Freeman-Carroll method. Activation energies of thermal degradations of blend components were determined with a good regression coefficients (at least 0.994). Activation energies of decomposition decreased from 224.14 to 86.125 kJmol -1 with increasing PHP content. XRD spectra of blends exhibited lower peak intensities than those of neat polymers. The spectroscopic, thermal and optic methods revealed that PBA and PHP were miscible with a good compatibility in amorphous phase.