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84 results on '"Alexandrescu, Laurentia"'

13. Mechanical Properties and Equilibrium Swelling Characteristics of Some Polymer Composites Based on Ethylene Propylene Diene Terpolymer (EPDM) Reinforced with Hemp Fibers

Author

Stelescu, Maria Daniela, primary, Airinei, Anton, additional, Bargan, Alexandra, additional, Fifere, Nicusor, additional, Georgescu, Mihai, additional, Sonmez, Maria, additional, Nituica, Mihaela, additional, Alexandrescu, Laurentia, additional, and Stefan, Adriana, additional

Published
2022
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15. BIODEGRADABLE POLYMER COMPOSITE BASED ON POLYVINYL CHLORIDE AND WOOD WASTE. DEVELOPMENT AND CHARACTERIZATION.

Author

BARBULESCU, VLAD, ALEXANDRESCU, LAURENTIA, NITUICA, MIHAELA, GEORGESCU, MIHAI, SONMEZ, MARIA, STELESCU, DANIELA-MARIA, and GURAU, DANA

Subjects
WOOD waste, POLYVINYL chloride, WOOD, SHOE soles, POLYMERS, BIODEGRADABLE plastics
Abstract

This work deals with the development and characterization of biodegradable polymer composites based on of polyvinyl chloride (PVC) and wood waste (WW) postconsumer waste. Wood waste resulting from wood processing into finished products is cryogenically ground to min. 500 nm, mechanically functionalized at temperature with polydimethylsiloxane (PDMS) (7%) and compounded in varying proportions (10%, 20%, 50%). The new composite is biodegradable due to the compounding with wood fibers, have low density and implicitly the products made from, a lower weight, reduced costs and recover waste. Soles for shoes will be processed by injection using these materials. [ABSTRACT FROM AUTHOR]

Published
2023
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16. "GREEN" DYNAMICALLY VULCANIZED THERMOPLASTIC POLYMER COMPOSITES BASED ON PE/PE-G-MA/EPDM REINFORCED WITH FUNCTIONALIZED SEASHELL WASTE.

Author

Alexandrescu, Laurentia, Georgescu, Mihai, Sonmez, Maria, Nituica, Mihaela, and Gurau, Dana

Subjects
*THERMOPLASTIC composites, *SEASHELLS, *RECYCLABLE material, *FIBROUS composites, *CIRCULAR economy
Abstract

Environmental concerns related to the implementation of circular economy has led to the development of new generations of materials. Interest in polymer composites reinforced with natural-organic/inorganic fillers is growing. Producers of polymer composites convert their production to optimize and replace traditional products with new ones with a high content of bio, recyclable materials, for sustainability and responsible actions. Research and industrial awareness are focused on ecological composites based on natural fillers from food production and aquaculture waste due to their low cost and high availability. This work aims to test "green" dynamically vulcanized thermoplastic polymer composites based on PE/PE-g-MA/EPDM reinforced with functionalized seashell waste, resistant to high temperatures for specific products used in the food, pharmaceutical and electronics industries. Seashell waste contains a high percentage (95-97%) of CaCO3 and will be ground to sizes of 100-500nm and functionalized in controlled conditions by silanization for compatibility with the polymer matrix. These composites will have characteristics such as resistance to microorganisms, at high temperatures for long working time and eco-friendliness derived from the use of seashell waste and the recycling of products injected from these materials. There will be a major impact on society due to the solutions that will be offered for reintegration into the natural circuit by increasing the degree of biodegradability after the end of the products' life cycle. [ABSTRACT FROM AUTHOR]

Published
2023
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17. POLYAMIDE WASTE/POLYSTYRENE/CARBON FIBRES NANOCOMPOSITES: OBTAINING AND CHARACTERIZATION.

Author

Alexandrescu, Laurentia, Georgescu, Mihai, Sonmez, Maria, and Ficai, Anton

Subjects
*MALEIC anhydride, *FIBERS, *POLYSTYRENE, *POLYAMIDES, *CARBON nanofibers, *CARBON fibers, *POLYMERIC nanocomposites
Abstract

In this paper were obtained waste/polymeric nanocomposites - polyamide waste (PAW) and polystyrene (PS), compatibilized with maleic anhydride grafted polystyrene, and reinforced with carbon nanofibers (CF). PolyamideWaste / polystyrene (PAW / PS) composites are studied because both components are relatively cheap, with beneficial properties, and can be processed by injection. Compatibility of polymer and waste compounds can be achieved by adding a grafted copolymer, the segments of which have physical or chemical affinity with the two immiscible homopolymers. In this case, maleic anhydride grafted polystyrene (PS-g-MA) was used. Carbon fiber composites are considered to be a new generation of materials with predetermined properties, in this case impact resistance. The combined effects of carbon fiber and compatibilizing polymer (PS-g-MA) have been studied on the structure, and rheological and physicomechanical properties of PAW / PS-g-MA / PS / CF composites. The studied nanocomposites have higher values compared to the control sample -PA, and the Romanian Railway Authority requirements of impact resistance of 5 KJ/m2. Carbon fiber concentrations above 1.5% cause slight drops in impact resistance values, similar to tensile strength, but not lower than control sample values. This conclude that the percentages of carbon fibers in the range of 0.1-1.5% reach the maximum values of physico-mechanical parameters. [ABSTRACT FROM AUTHOR]

Published
2022
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19. Dolomite surface modification with titanium and silicon precursors and its morphostructural and thermal characterisation

Author

Sonmez, Maria, primary, Juganaru, Mircea, additional, Ficai, Anton, additional, Ficai, Denisa, additional, Oprea, Ovidiu, additional, Gurau, Dana, additional, Alexandrescu, Laurentia, additional, Stelescu, Maria Daniela, additional, Georgescu, Mihai, additional, Nituica, Mihaela, additional, Melinescu, Alina, additional, and Marin, Minodora, additional

Published
2020
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21. Improvement of mechanical, thermal and morphostructural properties of SBS thermoplastic elastomer using kaolin and dolomite microparticles with modified surface

Author

Sonmez, Maria, primary, Juganaru, Mircea, additional, Ficai, Anton, additional, Oprea, Ovidiu, additional, Trusca, Roxana, additional, Georgescu, Mihai, additional, Gurau, Dana, additional, Ficai, Denisa, additional, Alexandrescu, Laurentia, additional, Constantinescu, Doina, additional, Stelescu, Maria Daniela, additional, Nituica, Mihaela, additional, and Marin, Minodora, additional

Published
2020
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26. Radiation Processing and Characterization of Some Ethylene-propylene-diene Terpolymer/Butyl (Halobutyl) Rubber/Nanosilica Composites

Author

Manaila, Elena, primary, Airinei, Anton, additional, Stelescu, Maria Daniela, additional, Sonmez, Maria, additional, Alexandrescu, Laurentia, additional, Craciun, Gabriela, additional, Pamfil, Daniela, additional, Fifere, Nicusor, additional, Varganici, Cristian-Dragos, additional, Doroftei, Florica, additional, and Bele, Adrian, additional

Published
2020
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31. Biodegradable Polymer Composite based on Recycled Polyurethane and Finished Leather Waste

Author

Alexandrescu Laurentia, Sonmez Maria, Deselnicu Viorica, Deselnicu Dana Corina, Nituica Mihaela, Pang Xioyan, and Georgescu Mihai

Subjects
chemistry.chemical_compound, Materials science, Polymer science, chemistry, Composite number, Biodegradable polymer, Polyurethane
Abstract

The issue of polluting waste has been addressed over the years by means of several methods: depollution, recovery by reuse and/or energy recycling and/or mechanical and/or chemical recycling. In the integrated plastic waste management concept, along with these methods are included the possibilities of reducing the quantities by using biodegradable polymeric materials. The goal paper is to recover footwear waste after use: polymer and finished leather by making new biodegradable polymeric composites. The waste is ground to 1-5 mm and compounded by melt extrusion-granulation, processable by injection into new products (footwear soles) with pre-established advanced features. Biodegradable polymer composite based on post-consumption thermoplastic polyurethane (WTPU) waste compounded with post-consumption finished leather waste, ground and functionalized. This composite will be made into a low-density product, with low cost, recovery and reuse of waste, containing both polymer and protein, and last but not least, biodegradable. The methodology for making the new materials involves the following steps: sorting waste, grinding, functionalization and compounding. These operations are easy to manage and do not involve new equipment. Compounding, the most important operation, will be carried out on a corotating twin-screw extruder-granulator with the possibility of adapting the length of the screw depending on the material (L/D-35). Waste transformation (ground and functionalized) in new value-added products will lead to remarkable improvements in the life cycle of raw materials and the sustainable use of this waste, contributing to sustainability, improving eco-efficiency and economic efficiency and reducing the “pressure” of waste on the environment.

Published
2019
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39. The Effect of the Functionalizing Agent Type on Processability, Mechanical and Thermal Properties of Polypropylene-Based Composites

Author

Sonmez, Maria, primary, Alexandrescu, Laurentia, additional, Georgescu, Mihai, additional, Stelescu, Maria Daniela, additional, Nituica, Mihaela, additional, Gurau, Dana, additional, Ficai, Anton, additional, Ficai, Denisa, additional, Ardelean, Ioana Lavinia, additional, Oprea, Ovidiu, additional, and Trusca, Roxana, additional

Published
2016
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44. ECOCOMPOSITES BASED ON NATURAL RUBBER AND PLASTICIZED STARCH.

Author

Stelescu, Maria Daniela, Georgescu, Mihai, Alexandrescu, Laurentia, Sönmez, Maria, and Niţuică, Mihaela

Subjects
COMPOSITE materials, RUBBER, STARCH, ELASTOMERS, FILLER materials
Abstract

This paper presents studies on the development of ecocomposites based on natural rubber and plasticized starch. Natural rubber is the most commonly used elastomer worldwide due to its low cost; it is renewable, non-toxic and shows excellent physical properties. Natural rubber is not used as such but in the form of mixtures which generally contain: fillers, plasticizers, crosslinking agents and other ingredients that provide various features to the final product. Replacement of active fillers in rubber mixtures such as carbon black or silica (which have adverse effects on health) with a biodegradable filler, such as starch provides many advantages, namely: environmental protection, non-toxicity, low density and cost, etc. Ecocomposites were made containing 10 phr, 20 phr, and 30 phr starch, respectively. Starch was plasticized and then incorporated in natural rubber in the roll mill, and then other ingredients were added (compatibilizer, curing agents, antioxidant); the resulting mixtures were cured in an electrical press. The physico-mechanical and chemical characteristics of resulting composites depends on the amount of plasticized starch added to the rubber mixture, as follows: (a) hardness increases while elasticity decreases due to the increased amount of plasticized starch in the mixture, indicating that a reinforced rubber mixture may be obtained by replacing the inorganic filler; (b) tensile strength increases, elongation at break decreases and tear strength has a non-uniform variation; (c) the optimal curing time decreases; (d) mass variation in: water, ethyl alcohol, sunflower oil, 10% glucose solution, 0.9% sodium chloride solution for 22 h has values below 15%. Ecocomposites can be used to obtain products with applications in the food industry, pharmaceutical industry, agriculture, etc. [ABSTRACT FROM AUTHOR]

Published
2017
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49. Innovative Materials and Technologies for Sustainable Production in Leather and Footwear Sector

Author

Deselnicu, Viorica, primary, Crudu, Marian, additional, Zainescu, Gabriel, additional, Albu, Madalina Georgiana, additional, Deselnicu, Dana Corina, additional, Guta, Sergiu Adrian, additional, Ioannidis, Ioannis, additional, Gurau, Dana, additional, Alexandrescu, Laurentia, additional, Constantinescu, Rodica Roxana, additional, Chirila, Corina, additional, Macovescu, Gabriela, additional, and Bostaca, Gheorghe, additional

Published
2014
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