Effect of biopolymer blends on physical and Acoustical properties of biocomposite foams

Effects of different pre-treatments on the properties of polyhydroxyalkanoates extracted from sidestreams of a municipal wastewater treatment plant

The paper deals with effects of two different widespread extraction methods (conventional extraction and Soxhlet extraction) and four different pre-treatments (homogenization with pressure and with blades, sonication, and impact with glass spheres) on the extraction yields and properties of polyhydroxyalkanoate (PHA) extracted from biomass coming from an innovative process (short-cut enhanced phosphorus and PHA recovery) applied in a real wastewater treatment plant. The results show that the two different extraction processes affected the crystallization degree and the chemical composition of the polymer. On the other hand, the extractive yield was highly influenced by pre-treatments: homogenization provided a 15% more extractive yield than the others. Homogenization, especially at high pressure, proved to be the best pre-treatment also in terms of the purity, visual appearance (transparency and clearness), thermal stability, and mechanical performances of the obtained PHA films. All the PHA films begin to melt long before their degradation temperature (Td > 200 °C): this allows their use in the fields of extrusion or compression moulding. SYNOPSIS: Optimizing the extraction of PHAs from municipal wastewater gives a double beneficial environmental impact: wastewater treatment and circular bio-based carbon upgrade to biopolymers for the production of bioplastics and other intersectoral applications.

Fabrication and characterization of polymeric cellular foams for low-density computed tomography phantom applications

Computed tomography imaging phantom devices have proven to be beneficial in improving computed tomography diagnostic techniques. Though commercial phantoms are available with tissue mimicking properties, there is a lack of low-density tissue specificity and variety. This study proposes a method for the fabrication of various low-density tissue mimicking computed tomography imaging phantoms. By illustrating the fabrication technique, material properties can be shown to be controlled and assessed against characteristic computed tomography imaging properties, most particularly, the computed tomography number in Hounsfield Units. A batch cellular foaming technique was utilized on thermoplastic polyurethane with ranging heated water bath foaming times from 0.5 to 10 min to fabricate polymeric computed tomography phantoms of controlled foam material properties. Computed tomography number values were experimentally measured. Additionally, separate experimental measurements were made on the foam characteristic properties of fabricated thermoplastic polyurethane foams. A relative decreasing trend was exhibited between the foam characteristic properties of cell density, average cell size, and material density to computed tomography number.

Acid-Base Polymeric Foams for the Adsorption of Micro-oil Droplets from Industrial Effluents

Separation of toxic organic pollutants from industrial effluents is a great environmental challenge. Herein, an acid-base engineered foam is employed for separation of micro-oil droplets from an aqueous solution. In acidic or basic environments, acid-base polymers acquire surface charge due to protonation or dissociation of surface active functional groups. This property is invoked to adsorb crude oil microdroplets from water using polyester polyurethane (PESPU) foam. The physicochemical surface properties of the foam were characterized using X-ray photoelectron spectroscopy, inverse gas chromatography, electrokinetic analysis, and micro-computed tomography. Using the surface charge of the foam and oil droplets, the solution pH (5.6) for maximum separation efficacy was predicted. This optimal pH was verified through underwater wetting behavior and adsorption experiments. The droplet adsorption onto the foam was governed by physisorption, and the driving forces were attributed to electrostatic attraction and Lifshitz-van der Waals forces. The foam was regenerated and reused multiple times by simple compression. The lowest trace oil content in the retentate was 3.6 mg L^-1, and all oil droplets larger than 140 nm were removed. This work lays the foundation for the development of a new class of engineered foam adsorbents with the potential to revolutionize water treatment technologies.

Towards the development of uniform closed cell nanocomposite foams using natural rubber containing pristine and organo-modified nanoclays

A closed cell rubber foam, based on a natural rubber (NR)/nanoclay nanocomposite, was produced using a one-step foaming process with compression molding.