Background: Poly-3-hydroxybutyrate (PHB) has attracted much consideration as
biodegradable biocompatible polymer. This thermoplastic polymer has comparable material
properties to polypropylene. Materials with more valuable properties may result from blending, a
common practice in polymer science.
Objective: In this paper, blends of PHB (extracted from cyanobacterium Nostoc muscorum NCCU-
442 with polyethylene glycol (PEG) were investigated for their thermal, tensile, hydrophilic and
Methods: Blends were prepared in different proportions of PHB/PEG viz. 100/0, 98/2, 95/5, 90/10,
80/20, and 70/30 (wt %) using solvent casting technique. Morphological properties were
investigated by using Scanning Electron Microscopy (SEM). Differential scanning calorimetry and
thermogravimetric analysis were done for thermal properties determination whereas the mechanical
and hydrophilic properties of the blends were studied by means of an automated material testing
system and contact angle analyser respectively. Biodegradability potential of the blended films was
tested as percent weight loss by mixed microbial culture within 60 days.
Results: The blends showed good misciblity between PEG and PHB, however increasing
concentrations of plasticizer caused morphological alteration as evidenced by SEM micrographs.
PEG addition (10 % and above) showed significant alternations in the thermal properties of the
blends. Increase in the PEG content increased the elongation at break ratio i.e enhanced the required
plasticity of PHB. Rate of microbial facilitated degradation of the blends was greater with increasing
Conclusions: Blending with PEG increased the crucial polymeric properties of cyanobacterial PHB.