Global resources have to be used in responsible ways to ensure the world’s future need for advanc... more Global resources have to be used in responsible ways to ensure the world’s future need for advanced materials. Ecologically friendly functional materials based on biopolymers can be successfully obtained from renewable resources, and the most prominent example is cellulose, the well-known most abundant polysaccharide which is usually isolated from highly available biomass (wood and wooden waste, annual plants, cotton, etc.). Many other polysaccharides originating from various natural resources (plants, insects, algae, bacteria) proved to be valuable and versatile starting biopolymers for a wide array of materials with tunable properties, able to respond to different societal demands. Polysaccharides properties vary depending on various factors (origin, harvesting, storage and transportation, strategy of further modification), but they can be processed into materials with high added value, as in the case of gels. Modern approaches have been employed to prepare (e.g., the use of ionic...
Nowadays concerns over global warming favored research to focus on the environmental pollution an... more Nowadays concerns over global warming favored research to focus on the environmental pollution and waste accumulation and on the possibility to recycle and up-cycle the waste. A particular class of such waste consists of natural remains and by-products from agriculture and industries, such as forestry, pulp and paper, furniture, and food industry. There are various methods to upcycle and capitalize the agro-industrial waste: (1) anaerobic digestion for energy production; (2) thermal conversion for the resulting liquids and char that may be further used in obtaining other materials, bioplastics included; (3) industrial processing to obtain natural fibers, long or short, able to be employed as reinforcing materials in biocomposites (multicomponent systems where the matrix consists of polymers or polymer blends, either synthetic or natural; they may also contain emulsifiers, compatibilization agents, antioxidants, as well as inorganic, organic, metal, or metal oxides micro- and/or nanoparticles); and (4) composting. Composites based on agro-industrial waste displayed a level of performance high enough to grant their use in a wide variety of applications: furniture and civil constructions; interior design, fencing, and decking; automotive and aerospace industry; food and general packaging. To obtain such materials, it is necessary to consider specific issues, the most important being the compatibility between matrices and reinforcing material. Characteristics of the final material (mechanical, thermal, water sorption, weather resistance) strongly depend on a good compatibility. A critical assessment of the selected methodology is necessary as it is reflected in the final cost of production, which must be limited in relation to the envisaged application.
Abstract The demand for protective coatings for wood used in outdoor applications, able to preven... more Abstract The demand for protective coatings for wood used in outdoor applications, able to prevent or limit the weathering along with maintaining the wood aesthetical appearance, is increasing and motivated the R&D community to enhance efforts to provide new solutions. Some recent trends focused on the use of natural products, while others aimed at employing nanomaterials. This chapter offers an overview of the most recent data and a critical assessment of some particular issues. Thus the natural products used per se or in various formulations are presented herein divided in major classes. In the case of nanomaterials, due to the wide variety of formulations available, the type of protection provided was used as classification criterion. The behavior and performance of these particular coatings were evaluated in correlation with their complex formulation, the chemistry and compatibility between coatings and wood, processing, impact on the environment and human health, cost efficiency.
Technologies for active carbons obtaining from vegetable by-products such as straw, nut shells, f... more Technologies for active carbons obtaining from vegetable by-products such as straw, nut shells, fruit stones, sawdust, hydrolysis products of corn cobs and sunflower husks have been developed. The physico-chemical characteristics, structural parameters and sorption characteristics of obtained active carbons were determined. The ability of carbonaceous adsorbents for detoxification of soil against pesticides, purification of surface waters and for removal of organic pollutants from wastewaters has been evaluated. The obtained results reveal the effectiveness of their use in a number of environmental technologies.
Cellulose Nanoparticles : Synthesis and Manufacturing, 2021
Polysaccharides represent ubiquitous and complex chemical structures consisting of carbohydrate u... more Polysaccharides represent ubiquitous and complex chemical structures consisting of carbohydrate units linked through glycosidic bonds which are synthesized in nature. Cellulose, as a fascinating hierarchical material, and being the most widespread polysaccharide present in several types of higher plants and trees, can generate a large variety of nano-scale cellulose particles with a versatile chemical structure and different morphologies. Cellulose nanoparticles present an evident propensity for self-assembly processes due to their specific chemical features comprising a large number of interacting surface hydroxyl groups. Different strategies can be applied in order to produce homogeneous mixtures from cellulose nanoparticles and other polysaccharide-type polymer matrices including starch, chitin, chitosan, alginate, and pullulan. In this chapter, some recent investigations related to the obtaining of polysaccharide-based materials comprising cellulose nanoparticles are presented.
Environmental Engineering and Management Journal, 2004
In this study, the obtaining of some composite materials using wood chips as filler and a modifie... more In this study, the obtaining of some composite materials using wood chips as filler and a modified polyamidic polymer as thermoplastic matrix is presented. Characterization was carried out on composite samples by analysis of morphology, mechanical properties and thermal behaviour. It was observed that the tensile strength of composites decreased significantly with the increasing wood chips content. Still, even the bending strength is decreasing; it remains 2-8 times higher than that for the composites based on polyolefinic matrices. The thermal stability of the obtained composite materials is higher to that of the initial wood component.
The production of wood-based polymer composites has gained increasing interest in recent years, e... more The production of wood-based polymer composites has gained increasing interest in recent years, especially regarding sustainability issues, aiming at the recovery, reuse, and up-cycling of by-products from natural resources exploitation, as well as plastics. Due to their reduced cost, low density, and availability, wood components (fibers, flour) are attractive fillers for thermoplastic polymer matrices used in multi-component systems. Performance of wood-based thermoplastic materials mainly depends on the type and strength of interactions at the polymer-wood interface. Different low polarity polymers (high/low density polyethylene, polypropylene, polyvinylchloride) can be successfully used as matrices in such formulations. Various methods may be applied in order to obtain specified performance attributes of wood-based composites. Addition of appropriate compatibilizing agents, chemical and/or physical modification of the filler in order to improve its compatibility towards the matrix, or a judicious combination of these approaches may be employed. This paper briefly reviews some recent literature data, as well as research results by the authors, aiming at a comparative assessment of the materials properties (structure, thermal, mechanical and water sorption behavior) in correlation with the nature and type of components, processing, recycling options, and environmental impact.
New nanocomposites based on high density polyethylene (HDPE) and organically modifi ed nanoclay (... more New nanocomposites based on high density polyethylene (HDPE) and organically modifi ed nanoclay (Cloisite 20A) were obtained by two different methods, namely melt compounding and solution blending, and their properties were comparatively studied by XRD, DSC, POM and SEM in order to establish the dependence of the clay degree of exfoliation/intercalation on the preparation procedure. Nanocomposites prepared in molten state under shear stress were found to posses the most extensive dispersion of nanometric clay particles and high levels of exfoliation.
Understanding the polymer-clay interaction is one of the most important issues in the study of co... more Understanding the polymer-clay interaction is one of the most important issues in the study of composites, since it is giving an insight into the formulation–properties relationship of the analyzed material. By evaluating the composites behaviour under operating conditions in real time, it is possible not only to reach shorter routes from concept to design, but to designate the most appropriate field of applications, as well. It is proven that micro- and nanometer scale fillers (various types and shapes of particles, fibers, tubes, sheets etc.) determine major improvements in the properties of the considered polymers. Factors as the matrix:filler ratio, the nature and compatibility of matrix and filler, the filler aspect ratio, and its wettability by the matrix as an indication on the hydrophil/hydrophob character, may significantly alter the properties improvement. In the case of layered silicates, their corresponding polymeric hybrid materials have shown improved characteristics, mainly in terms of mech...
Some metals and metallic compounds are known to exhibit high toxicity at very low concentrations ... more Some metals and metallic compounds are known to exhibit high toxicity at very low concentrations towards a wide variety of microorganisms. This characteristic – the antimicrobial activity – has been used in medicine and health care for bactericide purposes. This paper summarizes some of the most interesting studies concerning metals and metallic compounds (oxides, salts, complexes etc.) with biocide activity, their formulation and mechanism of action, as well as specific finishing techniques employed in order to obtain metal or metallic compound-functionalized textiles for biomedical applications.
1,2,4-Triazoles are basic aromatic heterocycles that can be prepared using the Einhorn-Brunner re... more 1,2,4-Triazoles are basic aromatic heterocycles that can be prepared using the Einhorn-Brunner reaction (from imides and alkyl hydrazines to form a mixture of isomeric 1,2,4-triazoles) or the Pellizzari reaction (between an amide and a hydrazide). 1,2,4-Triazole derivatives find use in a wide variety of applications, most notably as antifungals (such as fluconazole and itraconazole) or fungicides for plants protection. Many diaryl or triaryl substituted triazoles are known to be potential antibacterial, mostly antituberculotic, as well as antimicrobial agents. There are in the literature a few reactions used in the synthesis of 3,4,5-triaryl-1,2,4-4H-triazoles starting from 2,5-diaryl-1,3,4-oxadiazoles and aromatic amines. These reactions take place at high temperatures or in the presence of polyphosphoric acid. They also can be prepared from diaroylhydrazines and arylphosphazoanilide, or from 5-substituted tetrazoles and carboxylic acid imide chlorides, but these are laborious prot...
Direct polycondensation is a very effective method for polymers synthesis and appeared in order t... more Direct polycondensation is a very effective method for polymers synthesis and appeared in order to offer an alternative to classical ways. This paper offers a view over this method and presents the most known condensing agents used for esters and polyesters synthesis, as well as few brand new condensing agents used for low-molecular weight compounds.
The objective of this study was to obtain and evaluate the thermal, mechanical and morphological ... more The objective of this study was to obtain and evaluate the thermal, mechanical and morphological characteristics, as well as the stability towards moisture, of some new green composites made of wood chips (W), as natural filler, and recycled polyethylene (rPE) or recovered statistic aliphatic copolyamide (coPA) as matrix, as well as rPE matrix with small amounts of coPA as compatibilizer. Experimental data confirmed the better dispersion of particles inside the matrix, as well as the improvement in the interfacial adhesion and tensile properties of rPE-W composites containing 5-20% coPA.
Global resources have to be used in responsible ways to ensure the world’s future need for advanc... more Global resources have to be used in responsible ways to ensure the world’s future need for advanced materials. Ecologically friendly functional materials based on biopolymers can be successfully obtained from renewable resources, and the most prominent example is cellulose, the well-known most abundant polysaccharide which is usually isolated from highly available biomass (wood and wooden waste, annual plants, cotton, etc.). Many other polysaccharides originating from various natural resources (plants, insects, algae, bacteria) proved to be valuable and versatile starting biopolymers for a wide array of materials with tunable properties, able to respond to different societal demands. Polysaccharides properties vary depending on various factors (origin, harvesting, storage and transportation, strategy of further modification), but they can be processed into materials with high added value, as in the case of gels. Modern approaches have been employed to prepare (e.g., the use of ionic...
Nowadays concerns over global warming favored research to focus on the environmental pollution an... more Nowadays concerns over global warming favored research to focus on the environmental pollution and waste accumulation and on the possibility to recycle and up-cycle the waste. A particular class of such waste consists of natural remains and by-products from agriculture and industries, such as forestry, pulp and paper, furniture, and food industry. There are various methods to upcycle and capitalize the agro-industrial waste: (1) anaerobic digestion for energy production; (2) thermal conversion for the resulting liquids and char that may be further used in obtaining other materials, bioplastics included; (3) industrial processing to obtain natural fibers, long or short, able to be employed as reinforcing materials in biocomposites (multicomponent systems where the matrix consists of polymers or polymer blends, either synthetic or natural; they may also contain emulsifiers, compatibilization agents, antioxidants, as well as inorganic, organic, metal, or metal oxides micro- and/or nanoparticles); and (4) composting. Composites based on agro-industrial waste displayed a level of performance high enough to grant their use in a wide variety of applications: furniture and civil constructions; interior design, fencing, and decking; automotive and aerospace industry; food and general packaging. To obtain such materials, it is necessary to consider specific issues, the most important being the compatibility between matrices and reinforcing material. Characteristics of the final material (mechanical, thermal, water sorption, weather resistance) strongly depend on a good compatibility. A critical assessment of the selected methodology is necessary as it is reflected in the final cost of production, which must be limited in relation to the envisaged application.
Abstract The demand for protective coatings for wood used in outdoor applications, able to preven... more Abstract The demand for protective coatings for wood used in outdoor applications, able to prevent or limit the weathering along with maintaining the wood aesthetical appearance, is increasing and motivated the R&D community to enhance efforts to provide new solutions. Some recent trends focused on the use of natural products, while others aimed at employing nanomaterials. This chapter offers an overview of the most recent data and a critical assessment of some particular issues. Thus the natural products used per se or in various formulations are presented herein divided in major classes. In the case of nanomaterials, due to the wide variety of formulations available, the type of protection provided was used as classification criterion. The behavior and performance of these particular coatings were evaluated in correlation with their complex formulation, the chemistry and compatibility between coatings and wood, processing, impact on the environment and human health, cost efficiency.
Technologies for active carbons obtaining from vegetable by-products such as straw, nut shells, f... more Technologies for active carbons obtaining from vegetable by-products such as straw, nut shells, fruit stones, sawdust, hydrolysis products of corn cobs and sunflower husks have been developed. The physico-chemical characteristics, structural parameters and sorption characteristics of obtained active carbons were determined. The ability of carbonaceous adsorbents for detoxification of soil against pesticides, purification of surface waters and for removal of organic pollutants from wastewaters has been evaluated. The obtained results reveal the effectiveness of their use in a number of environmental technologies.
Cellulose Nanoparticles : Synthesis and Manufacturing, 2021
Polysaccharides represent ubiquitous and complex chemical structures consisting of carbohydrate u... more Polysaccharides represent ubiquitous and complex chemical structures consisting of carbohydrate units linked through glycosidic bonds which are synthesized in nature. Cellulose, as a fascinating hierarchical material, and being the most widespread polysaccharide present in several types of higher plants and trees, can generate a large variety of nano-scale cellulose particles with a versatile chemical structure and different morphologies. Cellulose nanoparticles present an evident propensity for self-assembly processes due to their specific chemical features comprising a large number of interacting surface hydroxyl groups. Different strategies can be applied in order to produce homogeneous mixtures from cellulose nanoparticles and other polysaccharide-type polymer matrices including starch, chitin, chitosan, alginate, and pullulan. In this chapter, some recent investigations related to the obtaining of polysaccharide-based materials comprising cellulose nanoparticles are presented.
Environmental Engineering and Management Journal, 2004
In this study, the obtaining of some composite materials using wood chips as filler and a modifie... more In this study, the obtaining of some composite materials using wood chips as filler and a modified polyamidic polymer as thermoplastic matrix is presented. Characterization was carried out on composite samples by analysis of morphology, mechanical properties and thermal behaviour. It was observed that the tensile strength of composites decreased significantly with the increasing wood chips content. Still, even the bending strength is decreasing; it remains 2-8 times higher than that for the composites based on polyolefinic matrices. The thermal stability of the obtained composite materials is higher to that of the initial wood component.
The production of wood-based polymer composites has gained increasing interest in recent years, e... more The production of wood-based polymer composites has gained increasing interest in recent years, especially regarding sustainability issues, aiming at the recovery, reuse, and up-cycling of by-products from natural resources exploitation, as well as plastics. Due to their reduced cost, low density, and availability, wood components (fibers, flour) are attractive fillers for thermoplastic polymer matrices used in multi-component systems. Performance of wood-based thermoplastic materials mainly depends on the type and strength of interactions at the polymer-wood interface. Different low polarity polymers (high/low density polyethylene, polypropylene, polyvinylchloride) can be successfully used as matrices in such formulations. Various methods may be applied in order to obtain specified performance attributes of wood-based composites. Addition of appropriate compatibilizing agents, chemical and/or physical modification of the filler in order to improve its compatibility towards the matrix, or a judicious combination of these approaches may be employed. This paper briefly reviews some recent literature data, as well as research results by the authors, aiming at a comparative assessment of the materials properties (structure, thermal, mechanical and water sorption behavior) in correlation with the nature and type of components, processing, recycling options, and environmental impact.
New nanocomposites based on high density polyethylene (HDPE) and organically modifi ed nanoclay (... more New nanocomposites based on high density polyethylene (HDPE) and organically modifi ed nanoclay (Cloisite 20A) were obtained by two different methods, namely melt compounding and solution blending, and their properties were comparatively studied by XRD, DSC, POM and SEM in order to establish the dependence of the clay degree of exfoliation/intercalation on the preparation procedure. Nanocomposites prepared in molten state under shear stress were found to posses the most extensive dispersion of nanometric clay particles and high levels of exfoliation.
Understanding the polymer-clay interaction is one of the most important issues in the study of co... more Understanding the polymer-clay interaction is one of the most important issues in the study of composites, since it is giving an insight into the formulation–properties relationship of the analyzed material. By evaluating the composites behaviour under operating conditions in real time, it is possible not only to reach shorter routes from concept to design, but to designate the most appropriate field of applications, as well. It is proven that micro- and nanometer scale fillers (various types and shapes of particles, fibers, tubes, sheets etc.) determine major improvements in the properties of the considered polymers. Factors as the matrix:filler ratio, the nature and compatibility of matrix and filler, the filler aspect ratio, and its wettability by the matrix as an indication on the hydrophil/hydrophob character, may significantly alter the properties improvement. In the case of layered silicates, their corresponding polymeric hybrid materials have shown improved characteristics, mainly in terms of mech...
Some metals and metallic compounds are known to exhibit high toxicity at very low concentrations ... more Some metals and metallic compounds are known to exhibit high toxicity at very low concentrations towards a wide variety of microorganisms. This characteristic – the antimicrobial activity – has been used in medicine and health care for bactericide purposes. This paper summarizes some of the most interesting studies concerning metals and metallic compounds (oxides, salts, complexes etc.) with biocide activity, their formulation and mechanism of action, as well as specific finishing techniques employed in order to obtain metal or metallic compound-functionalized textiles for biomedical applications.
1,2,4-Triazoles are basic aromatic heterocycles that can be prepared using the Einhorn-Brunner re... more 1,2,4-Triazoles are basic aromatic heterocycles that can be prepared using the Einhorn-Brunner reaction (from imides and alkyl hydrazines to form a mixture of isomeric 1,2,4-triazoles) or the Pellizzari reaction (between an amide and a hydrazide). 1,2,4-Triazole derivatives find use in a wide variety of applications, most notably as antifungals (such as fluconazole and itraconazole) or fungicides for plants protection. Many diaryl or triaryl substituted triazoles are known to be potential antibacterial, mostly antituberculotic, as well as antimicrobial agents. There are in the literature a few reactions used in the synthesis of 3,4,5-triaryl-1,2,4-4H-triazoles starting from 2,5-diaryl-1,3,4-oxadiazoles and aromatic amines. These reactions take place at high temperatures or in the presence of polyphosphoric acid. They also can be prepared from diaroylhydrazines and arylphosphazoanilide, or from 5-substituted tetrazoles and carboxylic acid imide chlorides, but these are laborious prot...
Direct polycondensation is a very effective method for polymers synthesis and appeared in order t... more Direct polycondensation is a very effective method for polymers synthesis and appeared in order to offer an alternative to classical ways. This paper offers a view over this method and presents the most known condensing agents used for esters and polyesters synthesis, as well as few brand new condensing agents used for low-molecular weight compounds.
The objective of this study was to obtain and evaluate the thermal, mechanical and morphological ... more The objective of this study was to obtain and evaluate the thermal, mechanical and morphological characteristics, as well as the stability towards moisture, of some new green composites made of wood chips (W), as natural filler, and recycled polyethylene (rPE) or recovered statistic aliphatic copolyamide (coPA) as matrix, as well as rPE matrix with small amounts of coPA as compatibilizer. Experimental data confirmed the better dispersion of particles inside the matrix, as well as the improvement in the interfacial adhesion and tensile properties of rPE-W composites containing 5-20% coPA.
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Papers by Fulga Tanasa