Search results for "BIOPOLYMERS"

Polysaccharide-based ionogels as sustainable antioxidant and antimicrobial materials

Effect of the applied organic load rate on biodegradable polymer production by mixed microbial cultures in a Sequencing Batch Reactor

2006

This article studies the operation of a new process for the production of biopolymers (polyhydroxyalkanoates, PHAs) at different applied organic load rates (OLRs). The process is based on the aerobic enrichment of activated sludge to obtain mixed cultures able to store PHAs at high rates and yields. A mixture of acetic, lactic, and propionic acids at different concentrations (in the range 8.5-31.25 gCOD/L) was fed every 2 h in a sequencing batch reactor (SBR). The resulting applied OLR was in the range 8.5-31.25 gCOD/L/day. Even though, as expected, the increase in the OLR caused an increase in biomass concentration (up to about 8.7 g COD/L), it also caused a relevant decrease of maximal po…

Fabrication, characterization, thermal stability and nanoassemblies of novel pullulan-aspirin conjugates

2017

Abstract Present study deals with homogeneous and one-pot synthesis of novel macromolecular prodrugs (MPDs) of aspirin onto naturally occurring hydrophilic biopolymer pullulan. Pullulan-aspirin conjugates were synthesized by using green carboxylic acid activating reagent 1,1′-carbonyldiimidazole (CDI). The aspirin was first reacted with CDI to prepare aspirin-imidazolide at RT for 24 h which in situ reacted with pre-dissolved pullulan and the reaction preceded further for 24 h at 80 °C under nitrogen. Degree of substitution (DS 0.32–0.40) of aspirin onto pullulan was calculated from 1H NMR spectroscopy. Spectroscopic techniques confirmed the high covalent drug loading and purity. Thermal an…

Lifetime predictions of non-ionic and ionic biopolymers: kinetic studies by non-isothermal thermogravimetric analysis

2021

AbstractIn this paper, films based on sustainable polymers with variable charge have been investigated by non-isothermal thermogravimetry in order to predict their lifetime, which is a key parameter for their potential use in numerous technological and biomedical applications. Specifically, chitosan has been selected as positively charged biopolymer, while alginate has been chosen as negatively charged biopolymer. Among non-ionic polymers, methylcellulose has been investigated. Thermogravimetric measurements at variable heating rates (5, 10, 15 and 20 °C min−1) have been performed for all the polymers to study their degradation kinetics by using isoconversional procedures combined with ‘Mas…

Multilayer capsules: a promising microencapsulation system for transplantation of pancreatic islets

2001

In 1980, Lim and Sun introduced a microcapsule coated with an alginate/polylysine complex for encapsulation of pancreatic islets. Characteristic to this type of capsule is, that it consists of a plain membrane which is formed during a single procedural step. With such a simple process it is difficult to obtain instantly a membrane optimized with respect to all the properties requested for islet transplantation. To overcome these difficulties, it is recommended to build up the membrane in several consecutive steps, each optimized for a certain property. In this study, we have analysed such a multilayer microcapsule for the encapsulation of pancreatic islets. Therefore, empty and islet contai…

VALORIZATION OF ANCHOVY FISHBONE WASTES FOR THE PREPARATION OF BIOPOLYMERIC BASED GREEN COMPOSITES FOR FOOD PACKAGING APPLICATIONS

Structure–Property Relationships in Bionanocomposites for Pipe Extrusion Applications

2021

In this work, bionanocomposites based on different biodegradable polymers and two types of nanofillers, namely a nanosized calcium carbonate and an organomodified nanoclay, were produced through melt extrusion, with the aim to evaluate the possible applications of these materials as a potential alternative to traditional fossil fuel-derived polyolefins, for the production of irrigation pipes. The rheological behavior of the formulated systems was thoroughly evaluated by exploiting different flow regimes, and the obtained results indicated a remarkable effect of the introduced nanofillers on the low-frequency rheological response, especially in nanoclay-based bionanocomposites. Conversely, t…

Green Composites Based on Hedysarum coronarium with Outstanding FDM Printability and Mechanical Performance

2022

The addition of natural scraps to biodegradable polymers has gained particular interest in recent years, allowing reducing environmental pollution related to traditional plastic. In this work, new composites were fabricated by adding 10% or 20% of Hedysarum coronarium (HC) flour to Poly (lactic acid) (PLA). The two formulations were first produced by twin screw extrusion and the obtained filaments were then employed for the fabrication of composites, either for compression molding (CM) or by fused deposition modeling (FDM), and characterized from a morphological and mechanical point of view. Through FDM it was possible to achieve dense structures with good wettability of the filler that, on…

Hedysarum coronarium-Based Green Composites Prepared by Compression Molding and Fused Deposition Modeling

2022

In this work, an innovative green composite was produced by adding Hedysarum coronarium (HC) flour to a starch-based biodegradable polymer (Mater-Bi®, MB). The flour was obtained by grinding together stems, leaves and flowers and subsequently sieving it, selecting a fraction from 75 μm to 300 μm. Four formulations have been produced by compression molding (CM) and fused deposition modeling (FDM) by adding 5%, 10%, 15% and 20% of HC to MB. The influence of filler content on the processability was tested, and rheological, morphological and mechanical properties of composites were also assessed. Through CM, it was possible to obtain easily homogeneous samples with all filler amounts.…

Membrane oligo- and polysialic acids

2011

AbstractPolysialic acid (polySia) and oligosialic acid (oligoSia) chains are linear polysaccharides composed of sialic acid monomers. The majority of biological poly/oligoSia chains are bound to membranes. There is a large diversity of membrane poly/oligoSia in terms of chain length, occurrence, biological function, and the mode of membrane attachment. Poly/oligoSia can be anchored to a membrane via a phospholipid (polySia in bacteria), a glycosphingolipid (oligoSia in gangliosides), an integral membrane glycoprotein, or a glycoprotein attached to a membrane via glycosylphosphatidylinositol. In eukaryotic cells, the attachment of a poly/oligoSia chain to the membrane anchor is usually throu…