The influence of different fillers on mechanical and physical properties of high-molecular-weight biodegradable aliphatic polyesters

2016 ◽  
Vol 58 (4) ◽  
pp. 585-592 ◽  
Author(s):  
A. G. Potapov ◽  
I. K. Shundrina
Keyword(s):  
Molecular Weight ◽  
Physical Properties ◽  
High Molecular Weight ◽  
Aliphatic Polyesters ◽  
Mechanical And Physical Properties

Relation between Molecular Weights and Physical Properties of Rubber Fractions

1941 ◽  
Vol 14 (3) ◽  
pp. 580-589 ◽  
Author(s):  
G. Gee ◽  
L. R. G. Treloar
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Physical Properties ◽  
High Molecular Weight ◽  
Elastic Properties ◽  
Elastic Material ◽  
Experimental Results ◽  
Molecular Weights ◽  
High Elasticity ◽  
Latex Rubber

Abstract As high elasticity is a property possessed only by substances of high molecular weight, it is of interest to enquire into the relation between the elastic properties of a highly elastic material such as rubber and its molecular weight. An investigation on these lines has been made possible through the work of Bloomfield and Farmer, who have succeeded in separating natural rubber into fractions having different average molecular weights. The more important physical properties of these fractions have been examined with the object of determining which of the properties are dependent on molecular weight and which are not. Fairly extensive observations were made on the fractions from latex rubber referred to as Nos. 2, 3 and 4 by Bloomfield and Farmer, and some less extensive observations were carried out on the less oxygenated portion of fraction No. 1 obtained from crepe rubber (called hereafter 1b) . Before considering these experimental results, and their relation to the molecular weights of the fractions, it will be necessary to refer briefly to the methods used for the molecular-weight determinations, and to discuss the significance of the figures obtained.

Chemical synthesis of poly(β-hydroxybutyrate) by the polymerization of (R,S)-β-butyrolactone with aluminoxane catalysts

1995 ◽  
Vol 41 (13) ◽  
pp. 274-281 ◽  
Author(s):  
Robert W. Lenz ◽  
John Yang ◽  
Bin Wu ◽  
C. Jeff Harlan ◽  
Andrew R. Barron
Keyword(s):  
Molecular Weight ◽  
Chemical Synthesis ◽  
Physical Properties ◽  
High Molecular Weight ◽  
Crystalline Polymers ◽  
Group 4 ◽  
Catalyst Systems

Racemic β-butyrolactone can be polymerized to crystalline polymers of reasonably high molecular weight by the use of aluminoxane catalysts. Investigations in this and other laboratories have shown that these polymers can be fairly highly isotactic, and in that form they are closely related in structure and physical properties to a reserve polyester produced by many bacteria: poly(β-hydroxybutyrate). In the present investigation, Ziegler–Natta type aluminoxane catalyst systems and a new aluminoxane derivative, tert-butylaluminoxane, were evaluated in attempts to polymerize racemic β-butyrolactone in higher yields to polymers of higher molecular weight and higher stereoregularity. The addition of group 4 metallocenes as cocatalysts for both methylaluminoxane and iso-butylaluminoxane catalysts gave higher yields of the isotactic polymer than those obtained with these catalysts alone, but surprisingly, the tert-butylaluminoxane catalysts produced predominantly syndiotactic rather than isotactic polymers.Key words: poly(β-hydroxybutyrate), β-butyrolactone, aluminoxane catalysts, isotactic poly(β-hydroxybutyrate), syndiotactic poly(β-hydroxybutyrate).

scholarly journals New 1,2,3-Triazole Containing PolyestersviaClick Step-Growth Polymerization and Nanoparticles Made of Them

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Tengiz Kantaria ◽  
Temur Kantaria ◽  
Giorgi Titvinidze ◽  
Giuli Otinashvili ◽  
Nino Kupatadze ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Sodium Azide ◽  
Dicarboxylic Acids ◽  
Solution Concentration ◽  
One Pot ◽  
Bromoacetic Acid ◽  
Aliphatic Polyesters ◽  
Step Growth ◽  
Step Growth Polymerization

High-molecular-weight AA-BB-type aliphatic polyesters were synthesizedviaCu(I)-catalyzed click step-growth polymerization (SGP) following a new synthetic strategy. The synthesis was performed between diyne and diazide monomers in an organic solvent as one pot process using three components and two stages. The dipropargyl esters of dicarboxylic acids (component 1) were used as diyne monomers, di-(bromoacetic acid)-alkylene diesters (component 2) were used as precursors of diazide monomers, and sodium azide (component 3) was used for generating diazide monomers. The SGP was carried out in two steps: at Step  1 dibromoacetates interacted with two moles of sodium azide resulting in diazide monomers which interacted in situ with diyne monomers at Step  2 in the presence of Cu(I) catalyst. A systematic study was done for optimizing the multiparameter click SGP in terms of the solvent, duration of both Step  1 and Step  2, solution concentration, catalyst concentration, catalyst and catalyst activator (ligand) nature, catalyst/ligand mole ratio, and temperature of both steps of the click SGP. As a result, high-molecular-weight (MWup to 74 kDa) elastic film-forming click polyesters were obtained. The new polymers were found suitable for fabricating biodegradable nanoparticles, which are promising as drug delivery containers in nanotherapy.

THEORETICAL MODEL OF INCREASED RESOURCE UPGRADED DOUBLE DISC COULTERS GRAIN DRILL

2020 ◽  
Author(s):  
A.T. Lebedev ◽  
◽  
R.A. Notov ◽  
R.R. Iskenderov ◽  
◽  
...  
Keyword(s):  
Molecular Weight ◽  
Theoretical Model ◽  
Physical Properties ◽  
High Molecular Weight ◽  
Time Interval ◽  
Agricultural Enterprises ◽  
Ultra High Molecular Weight ◽  
Technical Terms

Existing agro-technical terms put agricultural enterprises in a situation where they are forced to wait for the necessary physical properties of soils before starting sowing work. The use of ultra-high molecular weight UHMWPE polyethylene for the modernization of the design of disc coulters can extend the time interval in which the sowing process will take place without disrupting its performance.

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