Investigation into the morphology of aliphatic segmented block copolymers with controlled thickness of crystalsстатья
Информация о цитировании статьи получена из
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 28 мая 2015 г.
Аннотация:In the present paper, aliphatic thermoelastoplastics, consisting of alternating segments of polytet
rahydrofuran and monodisperse segments of glycine and βalanine bisoxalamides, are studied. Phase transi
tions and the orientation of crystals are determined by experiments using Xray structural analysis during the
drawing process in situ. Two types of morphology have been revealed. Fibrillar crystals with chains oriented
perpendicularly to the drawing direction are formed at low draw ratio values. At high deformation degrees, a
fracture of large crystals and a reorientation of polymer chains along the drawing direction are observed. It is
shown that the thickness of the hard block crystals is constant and independent of the sample thermal prehis
tory. The tilting angle of bisoxalamide chains is determined using fourspot smallangle patterns. It turns out
that in the case of glycine the tilting angle is rather small (~5–15°), while for alanine it reaches 24°. The flex
ible block crystallization during the drawing process at room temperature was found regardless of the block
length. The surface free energy of hard block crystals proved to be rather low (~18 erg/cm2), which is probably
due to the entropic contribution from flexible blocks.