scholarly journals Synthesis and Physicochemical Characteristics of Chitosan-Based Polyurethane Flexible Foams

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1394
Author(s):  
Agnieszka Piotrowska-Kirschling ◽  
Adam Olszewski ◽  
Jakub Karczewski ◽  
Łukasz Piszczyk ◽  
Joanna Brzeska
Keyword(s):  
Thermal Properties ◽  
Circular Economy ◽  
Water Sorption ◽  
Chemical Structure ◽  
Oil Spills ◽  
Water Environment ◽  
Physicochemical Characteristics ◽  
Shrimp Waste ◽  
Structure Morphology ◽  
Promising Solution

The use of shrimp waste to obtain chitosan (Ch) is an essential issue, considering a circular economy, waste management, and its application to environmentally friendly materials. In this study, northern prawn shells were utilized to obtain Ch, which could then be used for synthesizing chitosan-based polyurethane (PUR+Ch) foams with different Ch concentration. The chemical structure, morphology, hardness, thermal properties, viscoelastic properties, and sorption properties in relation to oil and water of these materials were determined. The results present that the addition of Ch into PUR influences the physicochemical characteristics and properties of the tested materials. PUR+Ch foams with 1–3 wt% Ch had more open cells and were softer than neat PUR. PUR+Ch1 had the best thermal properties. PUR+Ch2 foam with 2 wt% Ch as a whole was characterized as having the highest water sorption. The PUR+Ch1 foam with 1 wt% Ch had the best oil sorption. This paper shows that the modification of PUR by Ch is a very promising solution, and PUR+Ch foams can be applied in the water treatment of oil spills, which can be dangerous to the water environment.

scholarly journals Energy-Water-Environment Nexus and the Transition Towards a Circular Economy: The Case of Qatar

2021 ◽  
Author(s):  
Abdul-Jalil Ibrahim ◽  
Nasim Shah Shirazi
Keyword(s):  
Water Supply ◽  
Development Strategy ◽  
Water Use ◽  
Circular Economy ◽  
Public Awareness ◽  
Water Environment ◽  
National Development ◽  
Supply System ◽  
Water Supply System ◽  
Vision 2030

Abstract Background Qatar’s per capita consumption of both energy and water is among the highest in the world. Documentation of methods to reduce energy and water use and its impact on the environment is crucial. A circular economy (CE) ensures that economic growth must not necessarily lead to more resource consumption. Materials and methods This study aims to discuss the CE approach with a focus on understanding the interdependencies between energy and water and their impact on the environment. The study explores the energy-water-environment nexus and how Qatar can leverage this to transition to a CE. The policy landscape and strategies related to energy and water use sectors are presented, addressing efficiencies and substitutes from a circular economic viewpoint. Results The findings show that electricity and mobility sectors(energy perspective of the CE) and agriculture and water supply system (water perspective of the CE) of the Qatari economy provide an opportunity for regeneration, virtualising, exchanging, optimising, sharing and closing loops to achieve CE growth. Conclusions The nexus between the mobility, electricity, agriculture and water supply system needs consideration for optimal policy outcome for the CE in Qatar. The study recommends a need to embark on public awareness on moving away from linear economic to the circular economic paradigm and developing a comprehensive policy on Qatar’s circular economic approach that consolidates the Qatar National Vision 2030 and the National Development Strategy 2018–2022 to provide policy clarity and communication towards CE.

Liposomal Polyamine−Dialkyl Phosphate Conjugates as Effective Gene Carriers: Chemical Structure, Morphology, and Gene Transfer Activity

2010 ◽  
Vol 21 (5) ◽  
pp. 844-852 ◽  
Author(s):  
Takehisa Dewa ◽  
Tomohiro Asai ◽  
Yuka Tsunoda ◽  
Kiyoshi Kato ◽  
Daisuke Baba ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Chemical Structure ◽  
Transfer Activity ◽  
Gene Carriers ◽  
Structure Morphology ◽  
Dialkyl Phosphate

Oxidative Polymerization of 3-Amino,2'-,(3')–Nitrodiphenylazomethin

2018 ◽  
Vol 935 ◽  
pp. 134-139 ◽  
Author(s):  
Timur A. Borukaev ◽  
A.Kh. Malamatov ◽  
M.K. Vindizheva ◽  
A.V. Orlov ◽  
S.G. Kiseleva
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
Chemical Structure ◽  
Oxidative Polymerization ◽  
Polymerization Process ◽  
Chain Growth ◽  
Polymer Product ◽  
Two Stages

Oxidative polymerization of 3-amino,2'-,(3')-nitrodiphenylazomethine was carried out in various ways. A possible mechanism for the polymerization of 3-amino,2'-,(3')- nitrodiphenylazomethine, where chain growth occurs as type N-C, is shown. It has been found that the yield of the polymer product is affected by the polymerization process and time. The chemical structure of the polymers obtained is established. The study of the thermal properties of polymers showed a low thermal stability and the process of destruction proceeds in two stages.

scholarly journals Brazilian gutta-percha points. Part II: thermal properties

2007 ◽  
Vol 21 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Cláudio Maniglia-Ferreira ◽  
Eduardo Diogo Gurgel-Filho ◽  
João Batista Araújo Silva Jr ◽  
Regina Célia Monteiro de Paula ◽  
Judith Pessoa Andrade Feitosa ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Physical Properties ◽  
Ambient Temperature ◽  
Amorphous Phase ◽  
Thermal Behaviour ◽  
Chemical Structure ◽  
Scanning Calorimetry ◽  
Gutta Percha ◽  
Thermal Manipulation

This study was undertaken to explore the effect of heating on gutta-percha, analyzing the occurrence of endothermic peaks corresponding to the transformation that occurs in the crystalline structure of the polymer during thermal manipulation. This study also seeked to determine the temperature at which these peaks occur, causing a transformation from the beta- to the alpha-form, and from the alpha- to the amorphous phase. Eight nonstandardized gutta-percha points commercially available in Brazil (Konne, Tanari, Endopoint, Odous, Dentsply 0.04, Dentsply 0.06, Dentsply TP, Dentsply FM) and pure gutta-percha (control) were analysed using differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The transition temperatures were determined and analysed. With the exception of Dentsply 0.04 and Dentsply 0.06, the majority of the products showed thermal behaviour typical of beta-gutta-percha, with two endothermic peaks, exhibiting two crystalline transformations upon heating from ambient temperature to 130°. Upon cooling and reheating, few samples presented two endothermic peaks. It was concluded that heating dental gutta-percha to 130°C causes changes to its chemical structure which permanently alter its physical properties.

Degradation of Gel-Coat Layer in Glass/Polyester Laminate in Seawater Environment

2011 ◽  
Vol 183 ◽  
pp. 107-110
Author(s):  
M. Landowski ◽  
M. Budzik ◽  
K. Imielińska
Keyword(s):  
Water Sorption ◽  
Water Environment ◽  
Hot Water ◽  
Subsurface Cracks ◽  
Significant Difference ◽  
Microscopic Studies ◽  
Seawater Environment ◽  
Small Cracks ◽  
Coat Layer ◽  
Different Thickness

Glass/polyester laminate coated with gelcoat layer of different thickness 0,5; 1,5; 3 mm was studied in terms of blistering behaviour and water sorption in hot water environment. Blistering was found to be accelerated for thin (0,5 mm) gel-coat layer compared to the thick (1,5; 3 mm), however no significant difference in blistering behaviour was observed between the laminates with gel-coat thickness 1,5 and 3 mm which may suggest that increasing the gel-coat thickness is effective only to a certain thickness limit. Microscopic studies demonstrated that blistering behaviour was related to the formation of subsurface cracks – longer and less densely distributed in thin gel-coat layers in contrast to numerous small cracks formed in the thick gel-coats.

Crystallization behavior, structure, morphology, and thermal properties of crystalline and amorphous stereo diblock copolymers, poly(l-lactide)-b-poly(dl-lactide)

2020 ◽  
Vol 11 (36) ◽  
pp. 5711-5724 ◽  
Author(s):  
Hideto Tsuji ◽  
Kazumasa Iguchi ◽  
Kohji Tashiro ◽  
Yuki Arakawa
Keyword(s):  
Thermal Properties ◽  
Crystallization Behavior ◽  
Diblock Copolymers ◽  
Structure Morphology

Some fractions of poly(dl-lactide) chains were confined in the amorphous regions between the crystalline regions, but the remaining parts of the poly(dl-lactide) chains should have been located outside of the alternately layered crystalline and amorphous regions.

Performance of polylactide against UV irradiation: Synergism of an organic UV absorber with micron and nano-sized TiO2

2020 ◽  
Vol 54 (18) ◽  
pp. 2489-2504 ◽  
Author(s):  
Ulas Can ◽  
Cevdet Kaynak
Keyword(s):  
Weight Loss ◽  
Thermal Properties ◽  
Uv Irradiation ◽  
Chemical Structure ◽  
Mechanical And Thermal Properties ◽  
Screw Extruder ◽  
Melt Mixing ◽  
Uv Absorber ◽  
Fluorescent Lamps ◽  
Twin Screw

The main purpose of this study was to investigate mechanical and thermal performance of polylactide specimens against UV irradiation; first when only adding benzotriazole benzotriazole-based organic UV absorber (UVA), micro (200 nm) and nano (50 nm) sized titania (TiO2) particles alone, and then to reveal possible synergism when they are added together. Compounds were prepared by twin-screw extruder melt mixing, while the 2 mm thick specimens were shaped by compression molding. Specimens were exposed to UV irradiation under fluorescent lamps (UVB-313) with 0.50 W/m2 for the periods of 12 and 24 days. Changes in the performance of UV irradiated specimens were evaluated in terms of % weight loss, changes in color and chemical structure, including the decreases in the mechanical and thermal properties. Various tests and analysis revealed that synergistic benefits of using micro and nano TiO2 particles together with benzotriazole-type UVA were not only due to the effective stiffening, strengthening and toughening actions of titania particles, but also due to their very significant “UV screening” actions absorbing the photons of the UV irradiation, thus decreasing the degree of the detrimental photodegradation reactions leading to chain scissions in their PLA matrix.

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