Vassilka Ivanova Ilieva

Biodegradable Thermoplastic Composites Based on Polyvinyl Alcohol and Algae

Algae constitute a largely available, low value material from renewable resources of marine origin to be used for the production of eco-compatible composites. Fibers of the green alga Ulva armoricana from the French coast were positively evaluated for the production of composites with a hydrophilic, eco-compatible polymer, such as poly(vinyl alcohol) (PVA) as continuous matrix by casting of aqueous suspensions and compression molding. PVA, Ulva, and starch were also successfully processed by the melt in the presence of glycerol. Positive results were obtained for film-forming properties and mechanical characteristics also with limited amounts of PVA (40%) attesting for Ulva suitability to be introduced in composites (up to 30%). Degradation in soil of Ulva and an Ulva-based composites outlined a rapid mineralization of Ulva in the selected medium (over 80% in 100 days) while the composite samples underwent a mineralization rate affected by the different component propensity to degradation.

Environmentally Compatible Foamed Articles Based on Potato Starch, Corn Fiber, and Poly(Vinyl Alcohol)

Potato starch foam trays based on blends of poly(vinyl alcohol) and corn fibers (CFs), co-product of the corn-wheat wet-milling process, are prepared by baking the blended mixtures in a preheated mold. Materials are evaluated for processing parameters, foam strength, flexibility, and water resistance as a function of fibers content. Addition of CF in formulations improved not only moisture resistance of foam, but has a potential to lower the overall cost of the foamed materials substantially. Interestingly, addition of up to 45% fiber in formulations was possible without compromising the foaming process. Degradability is evaluated both in compost than simulating a disposal in the environment (soil burying and soil surface). Trays are biodegraded within 30—60 days in compost and soil. Particularly, trays containing starch and fiber degraded at much faster rates than trays prepared using starch without natural fillers.

Polyhydroxyalkanoate biosynthesis by Hydrogenophaga pseudoflava DSM1034 from structurally unrelated carbon sources.

In the present paper we report the exclusive microbial preparation of polyhydroxyalkanoates (PHA) containing 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV) and 4-hydroxybutyrate (4HB) as comonomers through the use of unexpensive carbon sources such as whey from dairy industry. Polymers were produced by growing H. pseudoflava DSM 1034 in minimal medium supplemented with sucrose, lactose or whey without any co-substrate added. The chemical and physical properties of the polymers were fully characterized by GPC, DSC, TGA analyses and the composition by GC and (1)H NMR examinations to especially confirm the content of different monomeric units. The presence of 4HB units into PHA samples is particularly aimed in thermoplastic applications where greater flexibility is required and conventional rigid PHAs tend to fail. Usually the insertion of 4HB into chain backbone consisting of 3-hydroxyalkanoates requires expensive carbon sources mostly of petrochemical origin. According to our study the production of P(3HB-co-3HV-co-4HB) terpolymer can be obtained directly by the use of lactose or waste raw materials such as cheese whey as carbon sources. Although the amount of 4HB in the produced terpolymers was usually low and not exceeding 10% of the total molar composition, a PHA containing 18.4% of 4HB units was produced in 1 step fermentation process from this structurally unrelated carbon sources. The crystallinity of the terpolymer is basically to be markedly affected with respect to that of conventional PHAs, thus obtaining a comparatively less rigid material and easier to be processed.

Hybrid composites based on fibres of marine origin

A series of polymeric formulations has been prepared based on oxobiodegradable (PVA) and hydrobiodegradable (starch, PLA, Bionolle) macromolecular materials used as continuous matrices and fillers derived from a marine sea-weed (Zostera). The formulations have been submitted to processing trials under different experimental conditions selected in order to prevent the thermal decomposition of the fillers utilised in the form of powder. Composite specimen produced by either casting from water suspension and compression moulding, were submitted to mechanical characterisation with the aim of selecting formulations enabling promising practical exploitation. Composites based on blends of PLA and Bionolle, used as plasticiser turned out to be processable in tomato clip, as a typical example of agriculture environmentally compatible items, susceptible to be disposed their service life to controlled composting infrastructures together with the agricultural waste.

Biobased Polymeric Materials for Agriculture Applications

Owing to their low production cost, good physical properties and lightweight, plastic objects have slowly substituted glass, paper and metals in several fields of application including agriculture. Polymeric materials started to be applied in agricultural practices from the sixty’s, mostly in replacing glass as greenhouses and tunnels covering. Thus plastics made possible the introduction of mulching films, a novel agriculture technology not applied before the production of plastic films. The used polymeric materials consisted mainly of polyethylene and poly(vinyl chloride)1.

Overview of environmentally compatible polymeric materials for food packaging.

Publisher Summary Petrochemical-based plastics such as polyolefins, polyesters, and polyamides have been increasingly used as food packaging materials because of their availability in large quantities at low cost and favorable functionality characteristics such as good tensile and tear strength, good barrier properties to O2 and aroma compounds, and heat sealing. In contrast, they have a very low water vapor transmission rate and most importantly, they are totally non-biodegradable and therefore might potentially lead to environmental pollution, thus posing serious ecological problems. The combination of environmentally degradable plastic and composting is one of the best ways to control plastic wastes and hence environmental pollution. New biodegradable plastics should be a more appropriate option where the degradation constitutes a benefit in specific applications by defraying the cost inherent in the management of the disposal of post-consumer items. The improvement in polymer technologies and the use of smart additives is going to confer on bio-based packaging the same performance as conventional packaging, with the added value of compostability.

The Microbial Production of Polyhydroxyalkanoates from Waste Polystyrene Fragments Attained Using Oxidative Degradation

Excessive levels of plastic waste in our oceans and landfills indicate that there is an abundance of potential carbon sources with huge economic value being neglected. These waste plastics, through biological fermentation, could offer alternatives to traditional petrol-based plastics. Polyhydroxyalkanoates (PHAs) are a group of plastics produced by some strains of bacteria that could be part of a new generation of polyester materials that are biodegradable, biocompatible, and, most importantly, non-toxic if discarded. This study introduces the use of prodegraded high impact and general polystyrene (PS0). Polystyrene is commonly used in disposable cutlery, CD cases, trays, and packaging. Despite these applications, some forms of polystyrene PS remain financially and environmentally expensive to send to landfills. The prodegraded PS0 waste plastics used were broken down at varied high temperatures while exposed to ozone. These variables produced PS flakes (PS1–3) and a powder (PS4) with individual acid numbers. Consequently, after fermentation, different PHAs and amounts of biomass were produced. The bacterial strain, Cupriavidus necator H16, was selected for this study due to its well-documented genetic profile, stability, robustness, and ability to produce PHAs at relatively low temperatures. The accumulation of PHAs varied from 39% for prodegraded PS0 in nitrogen rich media to 48% (w/w) of dry biomass with the treated PS. The polymers extracted from biomass were analyzed using nuclear magnetic resonance (NMR) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) to assess their molecular structure and properties. In conclusion, the PS0–3 specimens were shown to be the most promising carbon sources for PHA biosynthesis; with 3-hydroxybutyrate and up to 12 mol % of 3-hydroxyvalerate and 3-hydroxyhexanoate co-monomeric units generated.