Search results for "dab"
showing 10 items of 1280 documents
Biodegradable Polymers for the Production of Nets for Agricultural Product Packaging
2021
It is well known that the need for more environmentally friendly materials concerns, among other fields, the food packaging industry. This regards also, for instance, nets used for agricultural product (e.g., citrus fruits, potatoes) packaging. These nets are typically manufactured by film blowing technique, with subsequent slicing of the films and cold drawing of the obtained strips, made from traditional, non-biodegradable polymer systems. In this work, two biodegradable polymer systems were characterized from rheological, processability, and mechanical points of view, in order to evaluate their suitability to replace polyethylene-based polymer systems typically used for agricultural prod…
Effect of cold drawing on mechanical properties of biodegradable fibers.
2016
Purpose Biodegradable polymers are currently gaining importance in several fields, because they allow mitigation of the impact on the environment related to disposal of traditional, nonbiodegradable polymers, as well as reducing the utilization of oil-based sources (when they also come from renewable resources). Fibers made of biodegradable polymers are of particular interest, though, it is not easy to obtain polymer fibers with suitable mechanical properties and to tailor these to the specific application. The main ways to tailor the mechanical properties of a given biodegradable polymer fiber are based on crystallinity and orientation control. However, crystallinity can only marginally be…
The Effect of Calcium Carbonate on the Photo-Oxidative Behavior of Poly(butylene adipate-co-terephthalate)
2020
The aim of this work is to evaluate the influence of nanosized CaCO3 on the photo-oxidation of poly(butylene adipate-co-terephthalate) (PBAT)-based nanocomposites. The PBAT/CaCO3 nanocomposites are prepared by using a corotating twin-screw extruder with 0, 2, and 5 wt% of CaCO3. The films are obtained by film blowing process. Specimens of the nanocomposites and that of the pure polymer are subjected to accelerated aging with a cycle of 8 h of light at a temperature of 55 °C followed by 4 h condensation at 45 °C to evaluate the effects of the CaCO3 addition on the photo-oxidation of PBAT. The results indicate that the modulus and tensile strength of the nanocomposites are increased significa…
Film Blowing of Biodegradable Polymer Nanocomposites for Agricultural Applications
2021
Films for agricultural applications, such as greenhouses films or mulching films are generally made of polyolefins such as linear low-density polyethylene (LLDPE) or low-density polyethylene. However, the use of biodegradable and/or compostable polymers is increasing, which enjoy the additional advantage that they can be left on the site since a fine life would be gradually assimilated to the underlying soil. Nevertheless, biodegradable polymeric films often do not have suitable mechanical performances. In this work, biodegradable polymer-based nanocomposite films are prepared by film blowing and compared with traditional LLDPE based nanocomposites. In particular, a biodegradable polymer bl…
Injection Molding and Mechanical Properties of Bio-Based Polymer Nanocomposites
2018
The use of biodegradable/bio-based polymers is of great importance in addressing several issues related to environmental protection, public health, and new, stricter legislation. Yet some applications require improved properties (such as barrier or mechanical properties), suggesting the use of nanosized fillers in order to obtain bio-based polymer nanocomposites. In this work, bionanocomposites based on two different biodegradable polymers (coming from the Bioflex and MaterBi families) and two different nanosized fillers (organo-modified clay and hydrophobic-coated precipitated calcium carbonate) were prepared and compared with traditional nanocomposites with high-density polyethylene (HDPE…
Poly(N-isopropylacrylamide) and Copolymers: A Review on Recent Progresses in Biomedical Applications.
2017
The innate ability of poly(N-isopropylacrylamide) (PNIPAAm) thermo-responsive hydrogel to copolymerize and to graft synthetic polymers and biomolecules, in conjunction with the highly controlled methods of radical polymerization which are now available, have expedited the widespread number of papers published in the last decade—especially in the biomedical field. Therefore, PNIPAAm-based hydrogels are extensively investigated for applications on the controlled delivery of active molecules, in self-healing materials, tissue engineering, regenerative medicine, or in the smart encapsulation of cells. The most promising polymers for biodegradability enhancement of PNIPAAm hydrogels are probably…
Hyperbranched poly(glycolide) copolymers with glycerol branching points via ring-opening copolymerization
2015
Abstract Sn(Oct) 2 -catalyzed synthesis of hyperbranched poly(glycolide) copolymers with glycerol branching points in the backbone is possible via ring-opening multi-branching copolymerization (ROMBP) of glycolide and 5HDON (5-hydroxymethyl-1,4-dioxan-2-one). Using this strategy, well-defined and soluble branched polyesters with apparent molecular weights (M n ) in the range of 1300–2000 g mol −1 and varying comonomer content (5HDON/glycolide = 30:70–70:30) were obtained. 2D NMR spectroscopy, thermal analysis and MALDI-TOF mass spectrometry confirmed the successful incorporation of both monomers and the resulting branched structure. Multiple end group functionality offers the possibility fo…
Degradation and Recycling of Films Based on Biodegradable Polymers: A Short Review
2019
The environmental performance of biodegradable materials has attracted attention from the academic and the industrial research over the recent years. Currently, degradation behavior and possible recyclability features, as well as actual recycling paths of such systems, are crucial to give them both durability and eco-sustainability. This paper presents a review of the degradation behaviour of biodegradable polymers and related composites, with particular concern for multi-layer films. The processing of biodegradable polymeric films and the manufacturing and properties of multilayer films based on biodegradable polymers will be discussed. The results and data collected show that: poly-lactic…
Evaluation of biodegradability on polyaspartamide-polylactic acid based nanoparticles by chemical hydrolysis studies
2015
Here, the synthesis of two graft copolymers based on ?,?-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA) and poly(lactic acid) (PLA), the O-(2-aminoethyl)-O'-galactosyl polyethylene glycol (GAL-PEG-NH2) or the methoxypolyethylene glycol amine (H2N-PEG-OCH3) is described. Starting from the obtained PHEA-PLA-PEG-GAL and PHEA-PLA-PEG copolymers, polymeric nanoparticles were prepared by high pressure homogenization-solvent evaporation method. To demonstrate their biodegradability as a function of the matrix composition, a chemical stability study was carried out until 21 days by incubating systems in two media mimicking physiological compartments (pH 7.4 and pH 5.5). The degradability of both nan…
Effect of Moisture Content on the Processing and Mechanical Properties of a Biodegradable Polyester
2021
This work is focused on the influence of moisture content on the processing and mechanical properties of a biodegradable polyester used for applications in injection molding. The pellets of the biodegradable polyester were exposed under different relative humidity conditions at a constant temperature before being compression molded. The compression-molded specimens were again placed under the above conditions before the mechanical testing. With all these samples, it is possible to determine the effect of moisture content on the processing and mechanical properties separately, as well as the combined effect of moisture content on the mechanical properties. The results obtained showed that th…