ABSTRACT
The present study dealt with the fabrication of zinc sulfide (ZnS) nanoparticles (NPs), prepared using the chemical precipitation method, mediated poly(hydroxybutyrate) (PHB)/poly(lactic acid) (PLA) composite films employing the solution casting approach. The films were characterized based on structural, surface, chemo-physical, thermal, electrical, antibacterial, UV protection and degradation profiles. The results demonstrated the successful formation of nanobiocomposite films with good intercalation of the constituents. The surface morphology results expressed the placement of ZnS NPs in the polymeric blend as supported by elemental analysis. The XRD analysis exhibited the crystalline behavior of the nanobiocomposite films. The surface wettability analysis indicated that with the inclusion of ZnS NPs, the water contact angle of the resultant film was observed to be 119.57°. The prepared nanobiocomposite film exhibited thermal stability up to 214 °C and tensile strength of 25.0 ± 2.4 MPa as compared to that of native PHB (as 15.0 ± 1.5 MPa) and PLA (as 20.0 ± 2 MPa) films. The nanobiocomposite films expressed good antibacterial properties as compared to the control. The prepared films expressed the degradability trends in the natural environment. The ZnS NPs inclusion in the PLA/PHB blend could enhance the AC conductivity of the resultant nanobiocomposite film with acceptable UV protection properties applicable for UV protective packings.
Subject(s)
Nanocomposites , Polyesters , Polyesters/chemistry , Nanocomposites/chemistry , Hydroxybutyrates , Anti-Bacterial Agents/chemistryABSTRACT
Fossil fuels are energy recourses that fulfill most of the world's energy requirements. However, their production and use cause severe health and environmental problems including global warming and pollution. Consequently, plant and animal-based fuels (also termed as biofuels), such as biogas, biodiesel, and many others, have been introduced as alternatives to fossil fuels. Despite the advantages of biofuels, such as being renewable, environmentally friendly, easy to source, and reducing the dependency on foreign oil, there are several drawbacks of using biofuels including high cost, and other factors discussed in the fuel vs. food debate. Therefore, it is imperative to produce novel biofuels while also developing suitable manufacturing processes that ease the aforementioned problems. Polyhydroxyalkanoates (PHAs) are structurally diverse microbial polyesters synthesized by numerous bacteria. Moreover, this structural diversity allows PHAs to readily undergo methyl esterification and to be used as biofuels, which further extends the application value of PHAs. PHA-based biofuels are similar to biodiesel except for having a high oxygen content and no nitrogen or sulfur. In this article, we review the microbial production of PHAs, biofuel production from PHAs, parameters affecting the production of fuel from PHAs, and PHAs biorefineries. In addition, future work on the production of biofuels from PHAs is also discussed.
ABSTRACT
A series of composites was prepared from a diglycidyl ether of bisphenol A (DGEBA) with different graphene filler contents to improve their mechanical performance and thermal stability. Graphene oxide (GO) and GO modified with hexamethylene tetraamine (HMTA) were selected as reinforcing agents. As a latent cationic initiator and curing agent, N-benzylepyrizinium hexafluoroantimonate (N-BPH) was used. The effect of fillers and their contents on the mechanical properties and thermal stability of the composites were studied. Fracture toughness improved by 23% and 40%, and fracture energy was enhanced by 1.94- and 2.27-fold, for the composites containing 0.04 wt.% GO and HMTA-GO, respectively. The gradual increase in fracture toughness at higher filler contents was attributed to both crack deflection and pinning mechanisms. Maximum thermal stability in the composites was achieved by using up to 0.1 wt.% graphene fillers.
ABSTRACT
Polyhydroxyalkanoates (PHAs) have become an attractive biomaterial in research in the past few years due to their extensive potential industrial applications. Being long chain hydroxyl fatty acid molecules, the PHAs are hydrophobic in nature, and have less functional groups. These features limit their applications in various areas. To enhance their usage, these polymers may need to be modified including surface and chemical modifications. Such modifications may alter their mechanical properties, surface structure, amphiphilic character and rate of degradation to fulfil the requirements for their future applications. Chemical modifications allow incorporation of functional groups to PHAs that could not be introduced through biotechnological methods. These chemically reformed PHAs, with enhanced properties, could be used for broad range of applications. This review aims to introduce different chemical modification approaches including some recent methods that had not been explored or discussed so far for PHAs as possible technologies for widening the range of product and application potentials. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:29-41, 2018.