Search results for "Materiali"
showing 10 items of 876 documents
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…
Collapsibility of metastable sand by non-conventional oedometer tests
2018
The stability of foundations soils could represent a clear and present threat for the conservation of even well preserved buildings, particularly for Architectural heritage conservation and land art heritage. A dramatic case is the presence of collapsible metastable sands as foundation soils, as it occurs in the sacral complex Valle dei Templi in Agrigento. This site listed by UNESCO, stands on a crest of a calcarenite cuesta, overlaying a layer of these sands. When the collapsible sand is dry, the structure is strong enough to bond the sand particles together. When the sand becomes wet, a de-structuration mechanism occurs and the soil’s strength is compromised. This paper has a twofold aim…
3D cultures of rat astrocytes and brain capillary endothelial cells on Poly-L-lactic acid scaffolds
2016
Tissue engineering is an emerging multidisciplinary field that aims at reproducing in vitro and/or in vivo tissues with morphological and functional features similar to the biological tissue of the human body. In this communication we report setting of three-dimensional structures able to mimic the extracellular matrix of the nervous system: we prepared Poly-L-Lactic Acid (PLLA) porous scaffolds via thermally induced phase separation (TIPS), and investigated the parameters that influence porosity, average pore size and degree of interconnection, i.e. polymer concentration, temperature and time of process. Astrocytes and brain capillary endothelial cells (BCECs) were cultured on these three-…
Effect of adding new phosphazene compounds to poly(butylene terephthalate)/polyamide blends. I: Preliminary study in a batch mixer
2005
Abstract Poly(butylene terephthalate) (PBT) and a sample of polyamide have been melt processed in the presence of two new phosphazene compounds, namely 2,2-dichloro-4,4,6,6-bis[spiro(2′,2″dioxy-1′,1″biphenyl)]cyclotriphosphazene (2Cl-CP) and 2,2-bis-(2-methoxy-4-methyleneoxy-phenoxy)-4,4,6,6,-bis[spiro(2′,2″dioxy-1′,1″biphenyl)]cyclophosphazene (CP-2EPOX). The blends were prepared by using polyamide 6 (PA6) at 25/75 w/w and 75/25 w/w composition. In order to perform a preliminary analysis on the behaviour of the blends, the materials were prepared in a batch mixer. The materials have been completely characterized from a rheological, morphological, mechanical point of view. The results indic…
Antimicrobial additives for poly(lactic acid) materials and their applications: current state and perspectives
2018
Poly(lactic acid)-based antimicrobial materials received considerable attention as promising systems to control microbial growth. The remarkable physicochemical properties of PLA such as renewability, biodegradability, and US Food and Drug Administration (FDA) approval for clinical use open up interesting perspectives for application in food packaging and biomedical materials. Nowadays, there is an increasing consumer demands for fresh, high-quality, and natural foods packaged with environmentally friendly materials that prolong the shelf life. The incorporation of antimicrobial agents into PLA-based polymers is likely to lead to the next generation of packaging materials. The development o…
Durability of basalt/hemp hybrid composites
2017
This study focused on the performance of injection-molded short hemp fibre and hemp/basalt fibre hybrid high density polyethylene composites. Results showed that hybridization with basalt fibre enhanced the performance properties. Analysis of fiber length distribution in the composite and fracture surface was performed to study the fiber breakage and fracture mechanism. Prolonged moisture absorption and accelerated ageing of short hemp fibre and hemp-basalt hybrid reinforced thermoplastic composites was addressed. Ageing in water did not result in a reduction of the strength of the composite samples, while it was found to decrease stiffness of hemp fibre reinforced composites. Mechanical pr…
Structure and Morphology Control in Polymer Forming Through the Thermal History
2011
Two examples of the application of the Continuous Cooling Transformation (CCT) method for investigating polymer solidification under processing conditions are illustrated. One example concerns the solidification behaviour of syndiotactic polystyrene (sPS) from the melt, showing an anomalous trend of density versus cooling rate, exhibiting a minimum around 1 °C/s. Once phase composition is obtained from WAXD deconvolution, density can be closely predicted, its minimum depending on the competition among crystalline phases upon increasing cooling rate. Another example regards the formation of Poly-Left Lactic Acid (PLLA) foams via Thermally Induced Phase Separation (TIPS) by starting from ther…