scholarly journals Preparation of High Molecular Weight Poly(urethane-urea)s Bearing Deactivated Diamines

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1914
Author(s):  
Alejandra Rubio Hernández-Sampelayo ◽  
Rodrigo Navarro ◽  
Ángel Marcos-Fernández
Keyword(s):  
Molecular Weight ◽  
Experimental Work ◽  
High Performance ◽  
Polymerization Reaction ◽  
Quantum Mechanical ◽  
Synthetic Approach ◽  
Molecular Weights ◽  
Mechanical Methods ◽  
Electronic Parameters ◽  
High Molecular Weight Poly

The synthesis of poly(urethane-urea) (PUUs) bearing deactivated diamines within the backbone polymer chain is presented. Several deactivated diamines present interesting properties for several applications in the biomaterial field due to their attractive biocompatibility. Through an activation with Chloro-(trimethyl)silane (Cl-TMS) during the polymerization reaction, the reactivity of these diamines against diisocyanates was triggered, leading to PUUs with high performance. Indeed, through this activation protocol, the obtained molecular weights and mechanical features increased considerably respect to PUUs prepared following the standard conditions. In addition, to demonstrate the feasibility and versatility of this synthetic approach, diisocyanate with different reactivity were also addressed. The experimental work is supported by calculations of the electronic parameters of diisocyanate and diamines, using quantum mechanical methods.

scholarly journals Effects of Molecular Weight of Functionalized Liquid Butadiene Rubber as a Processing Aid on the Properties of SSBR/Silica Compounds

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 850
Author(s):  
Donghyuk Kim ◽  
Byungkyu Ahn ◽  
Kihyun Kim ◽  
JongYeop Lee ◽  
Il Jin Kim ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Anionic Polymerization ◽  
High Performance ◽  
Crosslink Density ◽  
Functional Group ◽  
Vital Role ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Mooney Viscosity ◽  
Silica Dispersion

Liquid butadiene rubber (LqBR) which used as a processing aid play a vital role in the manufacturing of high-performance tire tread compounds. However, the studies on the effect of molecular weight, microstructure, and functionalization of LqBR on the properties of compounds are still insufficient. In this study, non-functionalized and center-functionalized liquid butadiene rubbers (N-LqBR and C-LqBR modified with ethoxysilyl group, respectively) were synthesized with low vinyl content and different molecular weights using anionic polymerization. In addition, LqBR was added to the silica-filled SSBR compounds as an alternative to treated distillate aromatic extract (TDAE) oil, and the effect of molecular weight and functionalization on the properties of the silica-filled SSBR compound was examined. C-LqBR showed a low Payne effect and Mooney viscosity because of improved silica dispersion due to the ethoxysilyl functional group. Furthermore, C-LqBR showed an increased crosslink density, improved mechanical properties, and reduced organic matter extraction compared to the N-LqBR compound. LqBR reduced the glass transition temperature (Tg) of the compound significantly, thereby improving snow traction and abrasion resistance compared to TDAE oil. Furthermore, the energy loss characteristics revealed that the hysteresis loss attributable to the free chain ends of LqBR was dominant.

Comparison of exopolysaccharides from mucoid and nonmucoid strains of Clavibacter michiganensis subspecies sepedonicus

1993 ◽  
Vol 39 (3) ◽  
pp. 291-296 ◽  
Author(s):  
Paul J. Henningson ◽  
Neil C. Gudmestad
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Size Exclusion ◽  
Enzyme Linked Immunosorbent Assay ◽  
Low Molecular Weight ◽  
Neutral Sugar ◽  
Clavibacter Michiganensis ◽  
Serological Reaction ◽  
Molecular Weights ◽  
Exclusion Chromatography

The exopolysaccharides produced by six strains of Clavibacter michiganensis ssp. sepedonicus were isolated and purified by liquid chromatography. Neutral sugar composition and molecular weights were determined for each polysaccharide fraction, using gas chromatography and high-performance size-exclusion chromatography. The serological reaction of each fraction was tested using enzyme-linked immunosorbent assay. Exopolysaccharide from nonmucoid strains contained only low molecular weight polysaccharides (1.5 × 103 to 1.1 × 104). Exopolysaccharide from mucoid and intermediate strains could be separated into low (4.0 × 103 to 1.1 × 104) molecular weight and high (5.0 × 105 to 1.6 × 106) molecular weight fractions. High molecular weight polysaccharides were composed almost exclusively of galactose, glucose, and fucose. The ratios of these sugars were highly variable among strains. Low molecular weight polysaccharides were primarily composed of galactose with significant and varying amounts of glucose, rhamnose, mannose, and ribose. All polysaccharide fractions except one, produced by a nonmucoid strain, reacted in the immunoassay test.Key words: exopolysaccharide, polysaccharide, Clavibacter, michiganensis, sepedonicus.

Hardware and quantum mechanical calculations

1992 ◽  
Vol 341 (1661) ◽  
pp. 361-371
Keyword(s):  
High Performance ◽  
System Size ◽  
Computational Effort ◽  
Computer Hardware ◽  
Software Systems ◽  
Quantum Mechanical ◽  
Metal Compounds ◽  
Mechanical Methods ◽  
Tightly Coupled ◽  
Wave Methods

The remarkable progress in the architecture, speed and capacity of computer hardware continues to drive the development of quantum mechanical methods, thus allowing calculations on increasingly complex systems. Using high-end computers, accurate quantum mechanical all-electron studies are now possible for solids such as transition metal compounds containing about fifty atoms per unit cell. Pseudo-potential plane-wave methods are being applied to unit cells with 400 silicon atoms, and organic molecules consisting of over 100 atoms have become tractable using ab initio methods. Smaller, yet still useful calculations can be carried out on workstations. The combination of graphics workstations and high-performance supercomputers, integrated in tightly coupled heterogeneous networks, has allowed the design of software systems with unprecedented convenience and visualization capabilities. Despite this progress, however, there is still an urgent need for new quantum mechanical methods which converge systematically to the exact solution of Schrodinger’s equation while maintaining a reasonable scaling of the computational effort with the system size.

Particulate glycogen of mammalian liver: specificity in binding phosphorylase and glycogen synthase

1992 ◽  
Vol 70 (7) ◽  
pp. 523-527 ◽  
Author(s):  
Alexander Vardanis
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Glycogen Phosphorylase ◽  
Hydrophobic Interactions ◽  
Glycogen Synthase ◽  
Early Period ◽  
Glycogen Particle ◽  
Molecular Weights ◽  
Glycogen Deposition ◽  
A Minor

The glycogen particle – glycogen metabolizing enzyme complex was investigated to gain some understanding of its physiological significance. Fractionations of populations of particles from mouse liver were carried out utilising open column and high performance liquid chromatography, and based either on the molecular weight of the particles or the hydrophobic interactions of the glycogen-associated proteins. The activities of glycogen phosphorylase and glycogen synthase were measured in these fractions. Fractionations were of tissue in different stages of glycogen deposition or mobilization. In animals fed ad libitum, glycogen synthase was associated with the whole spectrum of molecular weights, while the glycogen phosphorylase distribution was skewed in favour of the lower molecular weight species. Under conditions of glycogen mobilization, the phosphorylase distribution changed to include all molecular weights. The hydrophobic interaction separations demonstrated that glycogen synthase binds to a specific subpopulation of particles that is a minor proportion of the total. In general, there was a direct relationship of the total amount of phosphorylase and synthase bound during periods of mobilization and deposition, respectively. Two notable exceptions were the large amounts of glucose-6-P dependent synthase present during the early period of glycogen mobilization and the high amounts of active phosphorylase appearing shortly after food withdrawal, in spite of interim glycogen deposition from presumably already ingested food.Key words: glycogen particle, glycogenolysis, glycogenesis, glycogen phosphorylase, glycogen synthase.

Chemical synthesis of novel biodegradable polyesters

1995 ◽  
Vol 41 (13) ◽  
pp. 282-288 ◽  
Author(s):  
Y. Hori ◽  
Y. Takahashi ◽  
A. Yamaguchi ◽  
T. Hagiwara
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Lactone Ring ◽  
Ring Opening Polymerization ◽  
Optically Active ◽  
Bond Breaking ◽  
Carbonyl Carbon ◽  
Biodegradable Polyesters ◽  
Molecular Weights ◽  
High Molecular Weight Poly

Distannoxane complexes catalyze the ring-opening polymerization of optically active β-butyrolactone (β-BL) to afford a high molecular weight poly(3-hydroxybutyrate). When 1-ethoxy-3-chlorotetrabutyldistannoxane was used as a catalyst (catalyst/(R)-β-BL = 1/8000 at 100 °C for 4 h), poly((R)-3-hydroxybutyrate) was obtained from (R)-β-BL in a yield of 99%. The copolymerizations of (R)-β-BL with racemic β-BL in several ratios gave corresponding stereocopolymers. The copolymerizations of (R)-β-BL with ε-caprolactone, δ-valerolactone, β-methyl-δ-valerolactone, and L-lactide afforded novel optically active and biodegradable polyesters of high molecular weights, comprising (R)-3-hydroxybutyrate (3HB). The polymerization of (R)-β-BL catalyzed by the distannoxane complexes proceeded by bond breaking between the carbonyl carbon and oxygen atom of the lactone ring (acyl cleavage) with retention of the configuration and little or no racemization. Polymers that have over 80 mol% of the (R)-3HB unit were found to have almost the same degree of biodegradability as the copolyester of 3-hydroxybutyrate and 11% 3-hydroxyvalerate produced by the microbial method.Key words: distannoxane, ring-opening polymerization, poly(3-hydroxybutyrate), poly(3-hydroxyalkanoates), biodegradable polymer.

scholarly journals High Performance Conditioning Shampoo with Hyaluronic Acid and Sustainable Surfactants

Cosmetics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 71
Author(s):  
Kelly Yorke ◽  
Samiul Amin
Keyword(s):  
Molecular Weight ◽  
Surface Tension ◽  
Hyaluronic Acid ◽  
High Performance ◽  
Low Cost ◽  
Hair Follicles ◽  
Shear Rates ◽  
Molecular Weights ◽  
Surface Activity Properties ◽  
Alkyl Polyglucoside

Recently, consumers have become invested in more natural and sustainable ingredients contained in personal care products. Unfortunately, cationic surfactants are still heavily relied on as primary conditioning agents in products such as conditioning shampoos because of their ability to cling well to the negatively charged surface of hair follicles. Additionally, sulfates are utilized as cleansing agents because they are highly effective and low cost. The objective of this study is to find a more sustainable formulation for a conditioning shampoo without compromising the desired wet combing, rheological, and surface activity properties. The systems which were investigated contained hyaluronic acid (HA) at a variety of molecular weights and concentrations, in combination with a surfactant, either acidic sophorolipid (ASL) or alkyl polyglucoside (APG), and varying the presence of sodium chloride. A Dia-stron was utilized to test the wet combing force, a rheometer recorded the viscosity at various shear rates, and a tensiometer measured the surface tension of the samples before a visual foaming study was conducted. Molecular weight and concentration seemed to have a large impact on wet combing force, as well as rheology, with the largest molecular weight and concentration producing the lowest friction coefficient and desired rheological profile. The addition of a surfactant significantly aids in the reduction in surface tension and increased foamability. Therefore, the optimal system to achieve the largest reduction in wet combing force, large viscosity with shear-thinning behavior, and relatively low surface tension with decent foaming is composed of 1% HA at 800 kDa, 10% ASL and 1% NaCl. This system shows a viable sulfate-free and silicone-free option that can achieve both conditioning and cleansing.

scholarly journals Synthesis, spinning, and properties of very high molecular weight poly(acrylonitrile-co-methyl acrylate) for high performance precursors for carbon fiber

Polymer ◽  
2014 ◽  
Vol 55 (25) ◽  
pp. 6471-6482 ◽  
Author(s):  
E. Ashley Morris ◽  
Matthew C. Weisenberger ◽  
Stephanie B. Bradley ◽  
Mohamed G. Abdallah ◽  
Sue J. Mecham ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Carbon Fiber ◽  
High Molecular Weight ◽  
Methyl Acrylate ◽  
High Performance ◽  
Poly Acrylonitrile ◽  
Very High ◽  
High Molecular Weight Poly
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