In this study, in order to overcome the fragility and cost disadvantages of PHB-based
films, PHB was blended with PCL. Additionally, allyl isothiocyanate (AITC) was incorporated
as an active component. The resulting PHB, PCL, and PHB/PCL composite films with/without
allyl isothiocyanate (AITC) prepared via the casting method were analyzed for their
physicochemical, thermal, mechanical, barrier, morphological properties and antimicrobial
and antioxidant activities. While neat PHB films showed the highest tensile strength
(TS) of 19.82 MPa and the lowest elongation at break (EB) of 1.13%, PHB/PCL blend
films exhibited lower TS (15.34 MPa) and higher EB values (21.33%). AITC addition
decreased TS significantly while showing no significant impact on EB. PHB/PCL blend
films had the highest water vapor permeability (WVP) values, possibly due to their
increased porosity, while neat PCL- and PHB-based films showed better oxygen and water
vapor barrier properties, respectively. DSC analysis showed that PHB and PCL films
had a crystalline phase, while in the case of PHB/PCL blend films, both polymers maintained
their characteristic melting behaviors. The addition of AITC affected the thermal
stability by increasing the melting temperature of the PHB films and decreasing the
melting temperature of the PCL films. SEM analyses revealed that PHB and PHB-A films
had a homogeneous structure, while irregular spherical structures and cracks were
also observed in PCL and PCL-A films. The incorporation of AITC into the film samples
(PHB-A, PCL-A, and PHB/PCL-A) brought remarkable antimicrobial (from 16.25 mm to 37.25
mm of inhibition zones) and antioxidant activity (from 281.85 to 286.41 mg trolox
equivalent/1 g film sample, as measured by CUPRAC), while no activity was observed
in the control films without AITC (PHB, PCL, and PHB/PCL). In conclusion, new AITC-activated
PHB-, PCL-, and PHB/PCL-based films were successfully designated with additional functionalities
and showed valuable potential to be used in active biodegradable food packaging applications.
