Physical aspects of polymer structure: A dictionary of terms

1986 ◽  
Vol 63 (5) ◽  
pp. 418 ◽  
Author(s):  
Charles E. Carraher ◽  
Raymond B. Seymour
Keyword(s):  
Polymer Structure

ULTRASONIC STUDIES OF THE POLYMER STRUCTURE OF THE CHALCOGENIDE GLASSES

1981 ◽  
Vol 42 (C4) ◽  
pp. C4-955-C4-958
Author(s):  
V. A. Ratobylskaja ◽  
L. A. Simonova
Keyword(s):  
Chalcogenide Glasses ◽  
Polymer Structure

Biodegradable Polyurethanes Cross-Linked by Multifunctional Compounds

2017 ◽  
Vol 14 (6) ◽  
pp. 778-784 ◽  
Author(s):  
Joanna Brzeska
Keyword(s):  
Polymer Structure ◽  
Cross Linking ◽  
Plant Oils ◽  
Lignocellulosic Materials ◽  
Soft Or ◽  
Native State ◽  
Synthetic Compounds ◽  
Multifunctional Compounds ◽  
Hard Segments ◽  
Synthetic Origin

Background: Cross-linking structure of polyurethanes determines no degradability of these materials. However, introducing the hydrolysable substrates (of natural or synthetic origin) into the cross-linked polyurethanes structure makes them biodegradable. Moreover compounds (such as polycaprolactone triol, glycerin, lysine triisocyanate, etc.) that are used for polyurethane cross-linking are degraded in non-toxic products. All these kinds of compounds can be introduced into soft or hard segments via urethane bonds. Objective: The review focuses on kind of multifunctional polyols and isocyanates, and low molecular crosslinkers used for cross-linked polyurethanes obtaining. These compounds are natural substrates (in the native state or after modification) or are synthetic compounds with degradable linkages. They belong to polyesters, plant oils, proteins, saccharides, and others (e.g. lignocellulosic materials), and they are synthesized chemically or via biosynthesis by algae, plants, microorganisms, and by animals. Conclusion: Incorporation of degradable groups (such as ester moieties) into the polymer structure, and using of substrates with the structure known and metabolized by microorganisms for soft or hard segments building, facilitate degradation of cross-linked polyurethanes.

Polymer structure and catalytic activity of ion exchangers

1981 ◽  
Vol 46 (7) ◽  
pp. 1577-1587 ◽  
Author(s):  
Karel Jeřábek
Keyword(s):  
Catalytic Activity ◽  
Ethyl Acetate ◽  
Active Sites ◽  
Crosslinking Agent ◽  
Reaction Medium ◽  
Polymer Structure ◽  
Local Concentration ◽  
Ion Exchangers ◽  
Styrene Divinylbenzene ◽  
Kinetics Of

Catalytic activity of ion exchangers prepared by partial sulphonation of styrene-divinylbenzene copolymers in reesterifications of ethyl acetate by methanol and propanol, hydrolysis of ethyl acetate and in synthesis of bisphenol A has been compared with data on polymer structure of these catalysts and with distribution of the crosslinking agent, divinylbenzene, calculated from literature data on kinetics of copolymerisation of styrene with divinylbenzene. It was found that the polymer structure of ion exchangers influences catalytic activity predominantly by changing the local concentration of acid active sites. The results obtained indicated that the effect of transport phenomena on the rate of catalytic reactions does not depend on the degree of swelling of the ion exchangers in reaction medium but it is mainly dependent on the relative affinity of reaction components to the acid groups or to the polymer skeleton.

Multi-cycle reversible control of gas permeability in thin film composite membranes via efficient UV-induced reactions

2021 ◽  
Vol 57 (27) ◽  
pp. 3391-3394
Author(s):  
Abdalrahman U. Alrayyes ◽  
Ze-Xian Low ◽  
Huanting Wang ◽  
Kei Saito
Keyword(s):  
Thin Film ◽  
Polymer Coating ◽  
Gas Permeability ◽  
Composite Membranes ◽  
Polymer Structure ◽  
Film Composite ◽  
Thin Film Composite ◽  
Thin Polymer

This communication reports the use of light to reversibly constrict or ease the flow of oxygen through a very thin polymer coating. This is achievable by reversibly changing the polymer structure from a dense and rigid film to a loose and soft film.

scholarly journals Density Functional Theory of Polymer Structure and Conformations

Polymers ◽  
2016 ◽  
Vol 8 (4) ◽  
pp. 121 ◽  
Author(s):  
Zhaoyang Wei ◽  
Nanying Ning ◽  
Liqun Zhang ◽  
Ming Tian ◽  
Jianguo Mi
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Polymer Structure ◽  
Functional Theory
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