scholarly journals INFLUENCE OF THE POLYETHYLENE GLYCOL MOLECULAR MASS ON THERMAL TRANSITIONS OF NANOSIZED COPPER OXIDE

2021 ◽  
pp. 937-946
Author(s):  
Мария Анатольевна Ясная ◽  
Андрей Владимирович Блинов ◽  
Алексей Борисович Голик ◽  
Давид Гурамиевич Маглакелидзе ◽  
Алексей Алексеевич Гвозденко ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Copper Oxide ◽  
Hydrodynamic Radius ◽  
Correlation Spectroscopy ◽  
Colloidal Solutions ◽  
Thermal Transitions ◽  
Monoclinic Crystal ◽  
Molecular Weights

В данной работе получены образцы наноразмерного оксида меди, стабилизированного полиэтиленгликолем различных марок с молекулярными массами от 200 до 6000 Да. Методом рентгеновской дифрактометрии исследована кристаллическая структура полученных образцов наноразмерного оксида меди. В результате рентгенофазового анализа установлено, что структура образцов представляет собой моноклинную кристаллическую решетку, с пространственной группой C2/ c. Методом фотонно-корреляционной спектроскопии изучено влияние молекулярной массы полимера на размер наночастиц. Анализ результатов исследования показал наличие во всех образцах наноразмерного оксида меди (II), стабилизированного полиэтиленгликолем с различной молекулярной массой, одной фракции частиц, распределение которых по размеру носит мономодальный характер. Установлено, что молекулярная масса полиэтиленгликоля оказывает, влияние на размер частиц CuO в коллоидных растворах, при этом фазовый состав и размеры кристаллитов остаются неизменными. Средний гидродинамический радиус частиц CuO в полученных образцах составляет порядка 140 ± 40 нм. Наименьшие значения гидродинамического радиуса 70 ± 15 нм наблюдаются в образце наноразмерного оксида меди, стабилизированного полиэтиленгликолем с молярной массой 6000 Дa. Методом синхронного термического анализа исследовано влияние стабилизатора с различными молекулярными массами на фазовые переходы образцов при термической обработке. В результате термического анализа установлено, что оптимальной температурой прокаливания порошков наноразмерного CuO является 500°C. In this work, samples of nanosized copper oxide stabilized with polyethylene glycol of various grades with molecular weights from 200 to 6000 Da were obtained. The crystal structure of the samples was investigated by X-ray diffractometry. As a result of the XRD analysis, it was found that the samples have a monoclinic crystal lattice with space group C2 / c . The effect of the molecular weight of the polymer on the size of nanoparticles was studied by the photon correlation spectroscopy method. Analysis of the results showed the presence of one fraction of particles in all samples, the size distribution was monomodal. It was found that the molecular weight of polyethylene glycol has an effect on the CuO particle size in colloidal solutions, while the phase composition and crystallite size remain unchanged. The average hydrodynamic radius of CuO particles in the obtained samples was about 140 ± 40 nm. The smallest hydrodynamic radius of 70 ± 15 nm was observed in a sample of nanosized copper oxide stabilized with polyethylene glycol with a molecular weight of 6000 Da. The effect of stabilizers with different molecular weights on the phase transitions of samples during heat treatment was investigated by the synchronous thermal analysis. As a result of thermal analysis, it was found that the optimum temperature for calcining nanosized CuO powders was 500 °C.

Comparison of Electron and Infrared Spectroscopy with Thermal Analysis to Study Molecular Weight Effects in PVC-PMMA Blends

1993 ◽  
Vol 47 (10) ◽  
pp. 1636-1642 ◽  
Author(s):  
Cindy A. Burkhardt ◽  
Joseph A. Gardella
Keyword(s):  
Thermal Analysis ◽  
Molecular Weight ◽  
Differential Scanning Calorimetry ◽  
Infrared Spectroscopy ◽  
Lower Molecular Weight ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Solvent Cast ◽  
Pmma Blends

The effects of homopolymer molecular weight on the miscibility of PVC/PMMA solvent cast blends were studied. Two significantly different molecular weights were chosen for each of the homopolymers, and a series of blends was prepared from the four possible homopolymer-homopolymer combinations. Angle-dependent ESCA results suggest that the surfaces of the blends are enriched with PMMA. The extent of this enrichment is dependent on molecular weight, with the most enrichment seen in blends containing the lower-molecular-weight PMMA homopolymer. Differential scanning calorimetry (DSC) results are also presented.

Isoprene and Rubber. Part 41. The Hydrogenation of Rubber and Balata

1934 ◽  
Vol 7 (3) ◽  
pp. 496-502
Author(s):  
H. Staudinger ◽  
E. O. Leupold
Keyword(s):  
Molecular Weight ◽  
Particle Sizes ◽  
Colloidal Solutions ◽  
Uniform Size ◽  
Micellar Structure ◽  
Molecular Weights ◽  
Rubber Particles ◽  
Rubber Part ◽  
Points Of View ◽  
Molecular Substances

Abstract Viscosity measurements of dilute solutions of rubber and of balata led to the following values for the size and form of the molecules of these hydrocarbons. It is therefore not a question of definition whether the particle sizes shown above are to be regarded as the molecular or the micellar weights of these substances, for here the concept of molecular weight has the same significance as in the case of lower molecular substances, i. e., the molecule comprises the sum of all atoms combined by normal, i. e., homopolar atoms. The only difference between low and high molecular substances is that low molecular substances are composed of molecules of uniform size, whereas high molecular substances are a mixture of homologous polymers, so that the values above refer to average molecular weights. These results, which explain the nature of colloidal solutions of rubber, are at variance with the views of most investigators of colloids, who ascribe a micellar structure to the rubber particles, and in this way explain the property which rubber has of forming colloidal solutions. This makes clear why until very recently explanations of the constitution of rubber have been open to question among these particular investigators themselves. In order to lend further support to our opinion, the reduction of rubber and balata and low molecular homologous polymeric hydrocarbons was undertaken from certain points of view, as shown in the work which follows.

PEG Molecular Weight Effects on Physical and Mechanical Properties of ETICS Plaster, Hardening at Lowered Positive and Small Negative Temperatures

2014 ◽  
Vol 1004-1005 ◽  
pp. 1482-1485 ◽  
Author(s):  
Stanislav Pashkevich ◽  
Andrey Pustovgar ◽  
Aleksey Eremin ◽  
Aleksey Adamtsevich ◽  
Sergey Nefedov
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Compressive Strength ◽  
Polyethylene Glycol ◽  
Physical And Mechanical Properties ◽  
Negative Temperature ◽  
Polystyrene Foam ◽  
Molecular Weights ◽  
Negative Temperatures

The paper presents the influence of polyethylene glycol additives wit h molecular weights of 2000... 6000 on basic physical and mechanical properties of plaster hardening at low positive and negative temperature s . The dependence of adhesion s trength to the polystyrene foam as well as compressive strength of plaster hardening at tempe rature s (+5... -10) oC on PEG molecular weight was established.

scholarly journals Effect of Different Molecular Weight and Concentration of Polyethylene Glycol (PEG) on Tensile and Morphology of Sago Starch Film

2021 ◽  
Vol 16 ◽  
pp. 1-10
Author(s):  
Norzita Yacob
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Polyethylene Glycol ◽  
Tensile Stress ◽  
Sago Starch ◽  
Elongation At Break ◽  
Molecular Weights ◽  
Peg 4000 ◽  
Starch Films ◽  
Ftir Technique

Sago starch is a seasonal based plantation and widely found in Asia country. Its application mainly in cooking such as biscuits and as a thickener in jellies. To further utilize its application, bioplastic from sago starch was developed. In this study, sago starch films were prepared through a blending and casting method using polyethylene glycol (PEG) as a plasticizer by varying its molecular weights and concentrations. The interaction between starch and PEG in the blend was studied using FTIR technique. The effect on transparency, tensile stress, Young’s modulus as well as elongation percentages of the films was also examined. The results suggested that the addition of low molecular weight PEG (400 g.mol-1) increased the tensile stress of sago films from 33.51 MPa up to 39.11 MPa. Nevertheless, incorporation of high molecular weight of PEG (4000 g.mol-1) decreased the tensile strength of the film. Tensile strength and elongation at break of sago films increased with increasing of PEG concentration up to 2% and decreased with further increased of PEG content. Results indicated that there was a miscibility between these two components.

scholarly journals Fire Resistance, Thermal and Anti-Ageing Properties of Transparent Fire-Retardant Coatings Modified with Different Molecular Weights of Polyethylene Glycol Borate

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4206
Author(s):  
Long Yan ◽  
Xinyu Tang ◽  
Xiaojiang Xie ◽  
Zhisheng Xu
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
High Molecular Weight ◽  
Fire Resistance ◽  
Fire Retardant ◽  
Phosphate Ester ◽  
Low Molecular Weight ◽  
Molecular Weights ◽  
Flame Retarded ◽  
Residual Weight

Four kinds of polyethylene glycol borate (PEG-BA) with different molecular weights were grafted into cyclic phosphate ester (PEA) to obtain flexible phosphate esters (PPBs), and then applied in amino resin to obtain a series of transparent intumescent fire-retardant coatings. The comprehensive properties of the transparent coatings containing different molecular weights of PEG-BA were investigated by various analytical instruments. The transparency and mechanical analyses indicate that the presence of PEG-BA slightly decreases the optical transparency of the coatings but improves the flexibility and adhesion classification of the coatings. The results from fire protection and cone calorimeter tests show that low molecular weight of PEG-BA exerts a positive flame-retarded effect in the coatings, while high molecular weight of PEG800-BA behaves against flame-retarded effect. Thermogravimetric and char residue analyses show that the incorporation of low molecular weight of PEG-BA clearly increases the thermal stability and residual weight of the coatings and generates a more compact and stable intumescent char on the surface of the coatings, thus resulting in superior synergistic flame-retarded effect. In particular, MPPB1 coating containing PEG200-BA exerts the best flame-retarded effect and highest residual weight of 36.3% at 700 °C, which has 57.6% reduction in flame spread rate and 23.9% reduction in total heat release compared to those of MPPB0 without PEG-BA. Accelerated ageing test shows that low molecular weight of PEG-BA promotes to enhance the durability of structural stability and fire resistance of the coatings, while PEG800-BA with high molecular weight weakens the ageing resistance. In summary, the fire-resistant and anti-ageing efficiencies of PEG-BA in the coatings depend on its molecular weight, which present the order of PEG200-BA > PEG400-BA > PEG600-BA > PEG800-BA.

Permeabilization of Piceaglauca protoplasts to macromolecules

1989 ◽  
Vol 19 (10) ◽  
pp. 1316-1321 ◽  
Author(s):  
Faouzi Bekkaoui ◽  
David I. Dunstan
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Fluorescein Isothiocyanate ◽  
White Spruce ◽  
Fluorescent Dye ◽  
Molecular Weights ◽  
Chemical Permeabilization ◽  
Protoplast Viability

Chemical permeabilization (polyethylene glycol, molecular weight 3350) and electropermeabilization (electroporation) treatments were applied to white spruce protoplasts to determine their effectiveness for uptake of membrane impermeable macromolecules. The two techniques have been compared using the membrane impermeable fluorescent dye calcein (molecular weight 622). The effects of varying the polyethylene glycol concentration, or the capacitance and voltage, were tested. In both techniques, the viability of protoplasts decreased after treatment compared with the controls. However, electroporation (capacitance 25 μF; voltage 300 V, 750 V•cm−1) gave better-permeabilization results (55% protoplast viability with 96% of these being fluorescent protoplasts) than the best treatment with polyethylene glycol (20%) (30% protoplast viability with 15% being fluorescent protoplasts). An investigation was made with the dye fluorescein isothiocyanate dextrans at different average molecular weights: 4000, 70 000, and 150 000. The degree of internalization by electroporation of each of these molecules did not substantially differ, though they were all low compared with calcein, which is suggestive of a limitation in permeability. The protoplasts subjected to either polyethylene glycol or electroporation treatments gave rise to callus and proembryos.

Polyethylene glycol oligomers as siloxane modificators in consolidation of carbonate stones

2016 ◽  
Vol 88 (12) ◽  
pp. 1117-1128 ◽  
Author(s):  
Bruno Sena da Fonseca ◽  
Susana Piçarra ◽  
Ana Paula Ferreira Pinto ◽  
Maria de Fátima Montemor
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Carboxylic Acid ◽  
Sol Gel ◽  
Silica Matrix ◽  
Strength Increase ◽  
Molecular Weights ◽  
Uniform Strength ◽  
End Groups ◽  
Stone Consolidants

AbstractThe overall performance of alkoxysilanes as stone consolidants is constrained by stone mineralogy (particularly in the carbonate varieties) and by their tendency to crack during drying. In an attempt to overcome these problems, polyethylene glycol “chains” with two carboxylic acid end-groups (PEG-CA) were introduced in siloxane sols obtained by sol-gel chemistry using tetraethoxysilane (TEOS) as precursor. Different pre-condensation degrees (by varying the stirring times of sol-gel reaction: 10 min, 2, and 24 h) and PEG-CA chains with different molecular weights were studied as variables affecting the initial efficacy of the consolidants when applied into a limestone. The sol containing siloxanes with the lowest pre-condensation degree (10 min stirring) was quite susceptible to the carbonate media and thus a poor consolidation was achieved. The sol with the highest pre-condensation degree (24 h stirring) together with the PEG-CA chains with intermediate molecular weight produced significant and uniform strength gains along the stone depth. The consolidation also showed to be highly dependent on the molecular weight of the PEG-CA chains, the PEG-CA with highest molecular weight produced a non-uniform strength increase with potential harmful side effects. The results confirmed the role of carboxylic acid end-groups as efficient sol-gel catalysts and their ability to be incorporated into the silica matrix in the presence of carbonate stone.

scholarly journals Application of 1H DOSY NMR in Measurement of Polystyrene Molecular Weights

2020 ◽  
Vol 36 (2) ◽  
Author(s):  
Nguyen Hoai Nam ◽  
Nguyen Huu Tho ◽  
Nguyen Minh Ngoc ◽  
Pham Quang Trung
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficient ◽  
Hydrodynamic Radius ◽  
Gel Permeation Chromatography ◽  
Resonance Spectroscopy ◽  
Solvent Interaction ◽  
Molecular Weights ◽  
External Calibration Curve ◽  
Dosy Nmr

In this work, we studied the applicability of diffusion ordered nuclear magnetic resonance spectroscopy (DOSY NMR) as an alternative method in determination of polystyrene molecular weight. DOSY NMR spectroscopy allows measuring the diffusion coefficient of molecule which directly depend on hydrodynamic radius and so on, average molar mass in weight (Mw). By using commercial polystyrene (PS) standards, an external calibration curve was established. Based on the excellent linear correlation between diffusion coefficient (logD) and molecular weight (logM), the molecular weight of polystyrene can be predicted using the following equation . The validation was done by comparing with the Mw value obtained by gel permeation chromatography within less than 5% deviation. From the diffusion coefficient, some property of polystyrene in solution, such as Flory coefficient and polymer-solvent interaction, were also studied. The Flory coefficient confirmed that chloroform is a good solvent for PS.

Study on Chain Extension and Modification of Poly(Lactic Acid) by Isophorone Diisocyanate /Polyethylene Glycol

2012 ◽  
Vol 476-478 ◽  
pp. 2067-2070 ◽  
Author(s):  
Zhao Zhang ◽  
Guo Dong Fan ◽  
Hai Yan Yang
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Polyethylene Glycol ◽  
Chain Extension ◽  
Poly Lactic Acid ◽  
Isophorone Diisocyanate ◽  
Molecular Weights ◽  
Peg 400 ◽  
Peg 4000 ◽  
Better Than

Poly(lactic acid)(PLA)was end-capped by isophorone diisocyanate(IPDI) to get PLA-IPDI under the condition of temperature of 176°C and pressure of 0.090 MPa for 13 mins, and then the PLA-IPDI was chain-extended with different molecular weights polyethylene glycol (PEG)-400, PEG-600, PEG-800, PEG-4000 and PEG-6000 to produce a series of block copolymer PLA-IPDI-PEGs. when n(–OH)/n(–NCO)=1.5:1, the molecular weight of PLA-IPDI is maximum. All the copolymer PLA-IPDI-PEGs were characterized by GPC, FTIR, DSC and contact angle testing. The results show that the polymeric degree of PLA-IPDI-PEG-800 is the best and its molecular weight is the biggest. Tg of PLA-IPDI-PEG-800 is the lowest and its hydrophilicity is better than the others modification PLA-IPD-PEGs and pure PLA.

Synthesing and Studying the Structure of Nanoscale Copper (II) Oxide Stabilized by Polyethylene Glycol

2020 ◽  
pp. 56-70
Author(s):  
A.V. Blinov ◽  
А.А. Gvozdenko ◽  
М.А. Yasnaya ◽  
А.А. Blinova ◽  
A.A. Kravtsov ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Copper Oxide ◽  
Sol Gel ◽  
Interaction Model ◽  
Copper Oxide Nanoparticles ◽  
Correlation Spectroscopy ◽  
Composition Analysis ◽  
Oxide Nanoparticles ◽  
Optical Absorption Band ◽  
Sol Gel Process

We developed a method for synthesising polyethylene glycol-stabilized copper oxide nanoparticles via a sol-gel process, obtained samples and investigated their structure, morphology and properties. We used photon correlation spectroscopy to establish that the copper oxide nanoparticles feature a monomodal size distribution with the average hydrodynamic radius of a particle being approximately 50 nm irrespective of the stabiliser molar mass. We detected an optical absorption band at 290 nm in all samples. We established that copper oxide samples consist of aggregates formed out of spherical nanoparticles whose diameters lie in the range of 10 to 30 nm. Phase composition analysis of the copper oxide samples revealed that the samples consist of particles featuring a monoclinic structure. We simulated the process of polyethylene glycol interacting with the copper oxide. We show that the most energetically favourable interaction model includes bond formation between the neighbouring intramolecular etheric oxygen atoms and the copper atom

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