Search results for " MATERIALI"
showing 10 items of 710 documents
Modification of EVOH copolymers with e-caprolactone: synthesis and compatibilization effects in PE/PVC blends
2001
Polyethylene-polycaprolactone graft copolymers with different chemical structures (i.e. different number and length of PCL grafts and molecular weight of PE backbone) were synthesized from various EVOH copolymers and e-caprolactone, using Aluminum isopropoxide as catalyst, and were tested for their compatibilizing capability in PE/PVC blends. PE and PCL segments in the graft copolymers were found completely immiscible, while PCL segments of the graft copolymers were found completely miscible with PVC. When graft copolymers were added to PE/PVC blends they proved to be good agents for the dispersion of PVC phase in the PE matrix. SEM showed also improved adhesion between the dispersed PVC ph…
Oxazoline functionalization of polyethylenes and their blends with polyamides and polyesters
2001
The compatibilization of blends of polyamide-6 (PA6) with linear low density polyethylene (LLDPE) and of poly(ethylene terephthalate) (PET) with high density polyethylene (HDPE), by functionalization of the polyethylenes with oxazoline groups was investigated. Chemical modification of LLDPE and HDPE was carried out by melt free radical grafting with ricinoloxazoline maleinate. Blends preparation was made either with a two-steps procedure comprising functionalization and blending, and in a single step in which the chemical modification of polyethylene with the oxazoline monomer was realized in situ, during blending. The characterization of the products was carried out by FTIR spectroscopy an…
Oxazoline-containing compatibilizers for polyamide/SAN and polyamide/ABS blends
2002
Polyamide (PA) and acrylonitrile/butadiene/styrene copolymer (ABS) may appear as a mixture in the recycled plastic stream. The incompatibility of these blends results in a blend with poor mechanical properties. The aim of this work is to partially convert the nitrile groups of the acrylonitrile/styrene copolymer (SAN) into oxazoline groups by reaction with aminoethanol (AE). Such modified SAN (SAN-m) can react with the amine or carboxylic acid end groups of PA, and therefore used as compatibilizers for blends of PA with ABS. SAN-m was found to reduce the SAN-domain size in the PA/SAN-blends. The initial acrylonitrile content of SAN-m had a strong influence on the degree of conversion into o…
Electrical transport in carbon black-epoxy resin composites at different temperatures
2013
Citation: J. Appl. Phys. 114, 033707 (2013); doi: 10.1063/1.4815870 (Received 3 May 2013; accepted 27 June 2013; published online 17 July 2013) Results of broadband electric/dielectric properties of different surface area—carbon black/epoxy resin composites above the percolation threshold are reported in a wide temperature range (25–500 K). At higher temperatures (above 400 K), the electrical conductivity of composites is governed by electrical transport in polymer matrix and current carriers tunneling from carbon black clusters to polymer matrix. The activation energy of such processes decreases when the carrier concentration increases, i.e., with the increase of carbon black concentration…
Development and characterization of xyloglucan-poly(vinyl alcohol) hydrogel membrane for Wireless Smart wound dressings
2018
Abstract Hydrogel-based smart wound dressings that combine the traditional favourable properties of hydrogels as skin care materials with sensing functions of relevant biological parameters for the remote monitoring of wound healing are under development. In particular, lightweight, ultra-high frequency radiofrequency identification (UHF RFID) sensor are adjoined to xyloglucan-poly(vinyl alcohol) hydrogel films to battery-less monitor moisture level of the bandage in contact with the skin, as well as wireless transmit the measured data to an off-body reader. This study investigates the swelling behavior of the hydrogels in contact with simulated biological fluids, and the modification of th…
Assessment of pro-oxidant activity of natural phenolic compounds in bio-polyesters
2018
Abstract In this work, natural phenolic compounds, such as Vanillic Acid (VA), Ferulic Acid (FA) and Thymol (Th), at very high concentrations, have been considered as pro-oxidant agents for Polylactic acid (PLA). Specifically, thin films of neat PLA and PLA-based systems containing 2 and 3 wt% of VA, FA and Th have been produced and subjected to accelerated degradation in different environmental conditions. Preliminary characterizations, through rheological, mechanical, optical and morphological analysis, of the formulated PLA-based systems show that the VA and FA, even less the Th, are able to exert a plasticizing action during the processing and subsequently, the PLA crystallinity and rig…
Biocomposite PBAT/lignin blown films with enhanced photo-stability.
2022
Lignin can be obtained as a byproduct during cellulose-rich pulp fibers production and it is habitually treated as waste or intended for low-value destinations. However, due to UV absorption and mechanical properties, lignin can contribute to the fabrication of biodegradable blown films with superior performances. In this study, it was established the suitability of lignin for manufacturing biocomposite PBAT blown films with higher stiffness and photo-oxidation resistance. The effect of the filler concentration on the melt rheological behavior in non-isothermal elongational flow was investigated. The results allowed us to choose the correct filler concentration for producing films through a…
Evaluation of the temperature effect on the fractional linear viscoelastic model for an epoxy resin
2016
The paper deals with the evolution of the parameters of a fractional model for different values of temperature. An experimental campaign has been performed on epoxy resin at different levels of temperature. It is shown that epoxy resin is very sensitive to the temperature.
2-3 gadīgu bērnu adaptācijas sekmēšana, izmantojot dabas vidi
2018
Darba nosaukums. 2-3 gadīgu bērnu adaptācijas sekmēšana, izmantojot dabas vidi Darba autore. Marina Ļebediņeca Darba vadītāja. Aņita Ieriķe Darba mērķis. Analizēt kā izmantotajama dabas vide pirmsskolā 2 – 3 gadīgu bērnu adaptācijas sekmēšanai. Darba autore apkopoja, raksturoja un izanalizēja dažādu autoru atziņas par adaptācijas procesu 2-3 gadus bērniem pirmsskolas izglītības iestādē. Darba autore apkopoja, raksturoja un izanalizēja dažādu autoru atziņas par 2-3 gadīgu bērnu adaptācijas procesu pirmsskolas izglītības iestādē. Tika pieņemts, kā bērnu adaptācijas process notiek labvēlīgāk un mierīgāk, ja: •pedagogs ievēro bērnu attīstības līmeni pa nedēļām; •vecāki pakāpeniski sagatavos bēr…
Arundo Donax Fibers as Green Materials for Oil Spill Recovery
2020
Oil spillage is considered one of the most devastating forms of pollution, for its effect on the environment, particularly on aquatic life. This kind of disaster can impact in two ways, directly caused by the polluting spilled oil or due to the cleanup process. In fact, oil floating on water does not allow sunlight to pass through and its toxicity puts the life of aquatic animals at risk. Furthermore, other factors can also contribute to this damage. In fact, a wrong oil recovery system can add a further pollution level. Polymer sorbents used for the oil spill recovery, if not properly treated, increase the level of marine and ground pollution. For this reason, in the last years, green mate…