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Structure and properties of high‐speed melt‐spun filaments of poly(butylene terephthalate)
Author(s) -
Chen Shida,
Spruiell Joseph E.
Publication year - 1987
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1987.070330429
Subject(s) - materials science , differential scanning calorimetry , amorphous solid , melt spinning , birefringence , polymer , spinning , composite material , crystal (programming language) , ultimate tensile strength , shrinkage , phase (matter) , crystallography , thermodynamics , optics , chemistry , programming language , physics , organic chemistry , computer science
Filaments of poly(butylene terephthalate) were prepared by melt spinning with take‐up velocities in the range 1000–5600 m/min. Two polymers with different molecular weights were used (intrinsic viscosities of 0.75 and 1.0 dL/g). The filaments were characterized using measurements of density, birefringence, shrinkage, thermal properties (differential scanning calorimetry), crystal size, crystalline orientation and phases present (wide angle X‐ray diffraction), and tensile mechanical properties. Filaments spun from the 0.75 IV polymer with a mass throughput of 6 g/min at 1000 m/min have essentially amorphous structures, while higher take‐up velocities result in α‐form crystals or, at the highest take‐up velocity, a mixture of α‐form and β‐form crystals. Only α‐form crystals were detected in the higher IV polymer. Crystal size varied with crystallographic direction but generally increased as take‐up velocity increased. At the lowest take‐up velocities the filaments increased in length during thermal shrinkage measurements. With increasing take‐up velocity the shrinkage became positive and continued to increase until reaching a maximum in the range of the highest sprinning speeds. This behavior correlates with the variation of the orientation factors of the amorphous phase. A plateau was observed in stress versus strain curves corresponding to strain‐induced transformation from α‐form to β‐form crystals. The length of this plateau increased with increase of take‐up velocity and the α‐form crystal content in the sample. Both morphology and physical properties varied with polymer molecular weight and melt spinning conditions.