The effect of copolymer composition on the dynamics of random copolymers in a homopolymer matrix

2006 ◽  
Vol 125 (9) ◽  
pp. 094902 ◽  
Author(s):  
Sudesh Y. Kamath ◽  
Mark D. Dadmun
Keyword(s):  
Random Copolymers ◽  
Copolymer Composition

Poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) random copolymers: effect of copolymer composition and microstructure on the thermal properties and crystallization behavior

RSC Advances ◽  
2015 ◽  
Vol 5 (74) ◽  
pp. 60570-60580 ◽  
Author(s):  
Tingting Chen ◽  
Guodong Jiang ◽  
Guoyu Li ◽  
Zhipeng Wu ◽  
Jun Zhang
Keyword(s):  
Glass Transition ◽  
Thermal Properties ◽  
Crystallization Behavior ◽  
Random Copolymers ◽  
Sequence Length ◽  
Copolymer Composition ◽  
Poly Ethylene Glycol ◽  
Average Sequence Length ◽  
Average Sequence ◽  
Poly Ethylene

The glass transition temperature of the statistically random PETG copolymers increased linearly with the increasing CT content. An increase in the average sequence length resulted in a higher melting temperature.

Preparation and Properties of Condensation Block Copolymers

1957 ◽  
Vol 30 (1) ◽  
pp. 283-295 ◽  
Author(s):  
D. H. Coffey ◽  
T. J. Meyrick
Keyword(s):  
Melting Point ◽  
Block Copolymers ◽  
Impact Strength ◽  
Hexamethylene Diisocyanate ◽  
Random Copolymers ◽  
Copolymer Composition ◽  
Block Copolymerization ◽  
Random Arrangement ◽  
Composition Curve ◽  
Point Composition

Abstract By using diisocyanates to link together two different polyesters having terminal hydroxyl or carboxyl groups, copolymers have been obtained in which the two repeating units occur in blocks and not in the random arrangement obtained by normal methods of preparing copolymers. Melting points have been measured by a penetrometer method and the effects of copolymer composition on melting point determined. In a series of crystalline copolymers made by linking various amounts of polyethylene sebacate and polyethylene adipate with hexamethylene diisocyanate, a step-shaped melting point-composition curve is obtained. Copolymers containing up to about 40 per cent of polyethylene adipate have the same melting point as that of polyethylene sebacate. Further increase in the polyethylene adipate content results in a rapid drop in melting point until the melting point of polyethylene adipate is reached. Thereafter increasing amounts of polyethylene adipate do not alter the melting point. Random copolymers of ethylene adipate and ethylene sebacate give a V-shaped melting point-composition curve. The step-shaped curve of block copolymers is almost identical with the melting point-composition curve of melt blends of the two polymers. Stress-strain characteristics and impact strengths of the block copolymers have been measured. In the polyethylene adipate/polyethylene sebacate/ hexamethylene diisocyanate series no great differences are found between random and block copolymers. If, however, the crystalline polyethylene adipate is replaced by the noncrystalline polypropylene adipate, then block copolymers containing 15–30 per cent of polypropylene adipate have outstanding impact strength. Similar high impact strength is obtained by using a compatible rubbery polymer as an external plasticizer with hexamethylene diisocyanate modified polyethylene sebacate. This method of block copolymerization has an advantage over random copolymerization in that a crystalline copolymer can be modified without reduction of its melting point, and by suitable selection of a second component it affords a means of “building in” a plasticizer.

Photodegradation behavior and mechanism of poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) (PETG) random copolymers: correlation with copolymer composition

RSC Advances ◽  
2016 ◽  
Vol 6 (104) ◽  
pp. 102778-102790 ◽  
Author(s):  
Tingting Chen ◽  
Jun Zhang ◽  
Hongjun You
Keyword(s):  
Ethylene Glycol ◽  
Random Copolymers ◽  
Copolymer Composition ◽  
Type I ◽  
Poly Ethylene Glycol ◽  
Crosslinking Degree ◽  
Norrish Type ◽  
Poly Ethylene

Norrish type I and II mechanisms occurred in PETG copolymers. The inherent photostability of PETG decreased with increasing CHDM content. The higher CHDM content resulted in the higher crosslinking degree.

Electron microscopy of crystalline structure in thermotropic random copolymers

1991 ◽  
Vol 49 ◽  
pp. 1054-1055
Author(s):  
Afzana Anwer ◽  
S. Eilidh Bedford ◽  
Richard J. Spontak ◽  
Alan H. Windle
Keyword(s):  
Electron Microscopy ◽  
Crystalline Structure ◽  
Liquid Crystalline ◽  
Elevated Temperatures ◽  
Random Copolymers ◽  
Molecular Characteristics ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Identical Monomer ◽  
Periodic Layer

Random copolyesters composed of wholly aromatic monomers such as p-oxybenzoate (B) and 2,6-oxynaphthoate (N) are known to exhibit liquid crystalline characteristics at elevated temperatures and over a broad composition range. Previous studies employing techniques such as X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) have conclusively proven that these thermotropic copolymers can possess a significant crystalline fraction, depending on molecular characteristics and processing history, despite the fact that the copolymer chains possess random intramolecular sequencing. Consequently, the nature of the crystalline structure that develops when these materials are processed in their mesophases and subsequently annealed has recently received considerable attention. A model that has been consistent with all experimental observations involves the Non-Periodic Layer (NPL) crystallite, which occurs when identical monomer sequences enter into register between adjacent chains. The objective of this work is to employ electron microscopy to identify and characterize these crystallites.

Fluctuation Theory of Random Copolymers

1995 ◽  
Vol 5 (3) ◽  
pp. 365-377 ◽  
Author(s):  
Andrey V. Dobrynin ◽  
Igor Ya. Erukhimovich
Keyword(s):  
Fluctuation Theory ◽  
Random Copolymers
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