Dynamic mechanical relaxation and X-ray scattering study of poly(butylene terephthalate)/polyarylate blends

Journal Article · Mon Aug 02 04:00:00 EDT 1993 · Macromolecules; (United States)

DOI:https://doi.org/10.1021/ma00068a031· OSTI ID:5992477

Huo, P P; Cebe, P ^[1]; Capel, M ^[2]

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1. Massachusetts Inst. of Technology, Cambridge, MA (United States). Dept. of Materials Science and Engineering
2. Brookhaven National Lab., Upton, NY (United States). Dept. of Biology

Blends of poly(butylene terephthalate) and polyarylate have previously been shown to be miscible for all blend compositions in the melt state or in the quenched amorphous state. Recently, the authors showed that all compositions of these blends exhibit depression of the thermodynamic melting point and a negative Flory interaction parameter. Once PBT crystallizes, it will form crystal lamellae consisting of pure PBT and an amorphous phase of noncrystalline PBT and PAr. The composition of the amorphous phase is the subject of the present study. Dynamic mechanical analysis shows that there exist two tan [delta] maxima, indicating two amorphous regions, which are assigned to a mixed amorphous phase and a region primarily consisting of amorphous PAr. The location of the PAr depends on the blend composition and was studied by small-angle X-ray scattering (SAXS). For PAr composition <0.50, the long period of lamellar stacks, obtained from SAXS, increases as PAr composition increases, while for PAr > 0.50, it decreases. Lamellar thickness can be estimated from the breadth of (001) using wide-angle X-ray scattering. By combining the long period, lamellar thickness, and crystallinity, the authors derive a general methodology to describe the morphology of the blends. One main conclusion of this work is that the long period is strongly affected by the degree of undercooling. When blends of different composition are prepared with the same thermal history (i.e., the same [Tc]), their long periods will vary due to the different degrees of undercooling and competition between crystallization and phase separation. The results show that, for PBT/PAr blends, interlamellar PAr structure holds for blends with PAr < 0.40, while either interfibrillar or interspherulitic structure exists for blends with PAr > 0.40.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5992477
• Journal Information: Macromolecules; (United States), Journal Name: Macromolecules; (United States) Vol. 26:16; ISSN MAMOBX; ISSN 0024-9297
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure &amp; Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400101 -- Activation
Nuclear Reaction
Radiometric &amp; Radiochemical Procedures
AMORPHOUS STATE
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
MORPHOLOGY
PHASE STUDIES
POLYMERS
RELAXATION
SCATTERING
X-RAY DIFFRACTION