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Thermal transitions of ethylene‐vinyl chloride copolymers and their blends
Author(s) -
Bowmer Trevor N.,
Tonelli A. E.
Publication year - 1986
Publication title -
journal of vinyl technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.295
H-Index - 35
eISSN - 1548-0585
pISSN - 0193-7197
DOI - 10.1002/vnl.730080303
Subject(s) - copolymer , comonomer , polymer chemistry , vinyl chloride , materials science , glass transition , crystallinity , differential scanning calorimetry , melting point , amorphous solid , polyethylene , ethylene , polymer , crystallography , chemistry , organic chemistry , composite material , thermodynamics , physics , catalysis
Differential Scanning Calorimetry (DSC) measurements were performed on a series of ethylene‐vinyl chloride copolymers (E‐V) prepared via reductive dechlorination of poly(vinyl chloride) with tributyltin hydride. The copolymers were identical in chain length and branching distribution; differing only in comonomer content, sequence distribution, and stereoregularity of adjacent —V— units. Extrapolation of glass transition temperatures, T g , measured for our E‐V copolymers to pure polyethylene (PE) predicted a T g = −85 ± 10°C for amorphous PE. E‐V copolymers with greater than 60 mol percent —E— units exhibited melting endotherms from 20 to 128°C and degrees of crystallinity from 12 to 63 percent. The melting point depressions observed for our E‐V copolymers were in agreement with Flory's theory, if the CH 2 CH 2 moiety is considered to be the crystallizable unit and the moiety is assumed to prevent the CH 2 CH 2 units attached on either side from being incorporated into the crystal. In general, the E‐V copolymer blends with PE were incompatible, while those with PVC were compatible only for E‐V copolymers with high V contents (>80 mol percent). Blends of the amorphous E‐V copolymers were found compatible if their V contents differed by less than 15 mol percent, while blends where one or both E‐V copolymers are crystalline were found to be incompatible. The properties of these copolymers will be discussed in terms of their microstructure.