1 research outputs found
Balancing Melt Solubility and Morphology in Epitaxial Nucleation: The Case of Nicotinic Acid and Poly(hydroxybutyrate-<i>co</i>-hydroxyhexanoate)
Nicotinic acid was evaluated as a melt-soluble nucleator
for a
poly(hydroxybutyrate-co-hydroxyhexanoate)
(PHBHHx) copolymer for melt-processing applications. A series of nicotinic
acid concentrations (1–5 wt %) were analyzed to determine the
best concentration for overall nucleation performance. 2 w/w% nicotinic
acid was found to be the optimal concentration, successfully crystallizing
PHBHHx at a peak temperature of 73 °C under nonisothermal conditions.
When
extrusion is performed at 150 °C, 2 w/w% of nicotinic acid occupies
an optimal concentration within the polymer where all the nicotinic
acid is dissolved in the PHBHHx matrix, which is not the case at higher
concentrations. 2 w/w% also recrystallizes rapidly to produce many
fine, needle-like crystals that are highly active toward PHBHHx nucleation,
which is not observed with other concentrations. Powder X-ray diffraction
(PXRD) analysis of the differing nicotinic acid crystals determined
that the (110) and (120) faces are likely responsible for nucleation.
Gel permeation chromatography (GPC) analysis revealed a modest degradation
of molecular weight, likely due to the E1cb degradation mechanism
common in PHAs