Trans-2-Butene-1,4-Diol as an Olefinic Building Block to Prepare Biobased Unsaturated Copolyesters with High Molecular Weight: Synthesis, Characterization, and Physical Properties

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.

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

Canadian Journal of Microbiology ◽

10.1139/m95-197 ◽

1995 ◽

Vol 41 (13) ◽

pp. 274-281 ◽

Cited By ~ 4

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).

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THEORETICAL MODEL OF INCREASED RESOURCE UPGRADED DOUBLE DISC COULTERS GRAIN DRILL

STATE AND DEVELOPMENT PROSPECTS OF AGRIBUSINESS. In the frame of the XXIII Agribusiness Forum of the South of Russia and the Exhibition «Interagromash» Volume 1 ◽

10.23947/interagro.2020.1.666-669 ◽

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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