Temperature-dependent relaxation of crystal/amorphous interphase in semicrystalline polymers and blends

Miscellaneous · Fri Jan 01 00:00:00 EST 1993

OSTI ID:7017501

Huo, P

The behavior of crystal/amorphous interphase has been investigated for semicrystalline polymers, poly(phenylene sulfide) (PPS), poly(ether ether ketone) (PEEK), NEW-TPI polyimide, and polymer blends with one crystallizable component, poly(butylene terephthalate)/polyarylate (PBT/PAr). The mobility of crystal/amorphous interphase is highly temperature-dependent. In order to study the temperature relaxation behavior of crystal/amorphous interphase, the author has used thermal analyses, dielectric and dynamic mechanical relaxation, wide and small angle x-ray scattering, and [sup 13]C solid state NMR. Thermal analysis heat capacity measurement was the first tool used to identify the crystal/amorphous interphase. The amount of interphase strongly depends on the polymers themselves and thermal treatments. Dielectric relaxation was used to probe the motion of dipoles in different environments through a wide range of temperature and frequency. The results indicate that the interphase of PPS and PEEK has mobility between crystal and amorphous phases, and relaxes gradually from the glass transition temperature to the melting point. NEW-TPI shows little interphase by thermal analysis and small angle x-ray scattering (SAXS), and relaxes immediately above the glass transition temperature. [sup 13]C solid state NMR had been used to probe the local motion of PPS, and to separate the different phase by different chain mobility. NMR results are consistent with those obtained by the thermal analysis and dielectric relaxation spectroscopy. Flory interaction parameter has been derived from the melting point depression for PBT/PAr blends. Two glass transition temperatures are due to interphase, which is a mixture of amorphous PBT and amorphous PAr, and a region primarily consisting of amorphous PAr. Three different morphologies, namely interlamellar, interfibrillar or interspherulitic, are observed by SAXS for PBT/PAr blends depending on the composition.

• Research Organization: Massachusetts Inst. of Tech., Cambridge, MA (United States)
• OSTI ID: 7017501
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ORGANIC POLYMERS
CRYSTAL-PHASE TRANSFORMATIONS
RELAXATION
AMORPHOUS STATE
BUTENES
CRYSTAL LATTICES
IMIDES
POLYETHYLENE GLYCOLS
TEMPERATURE DEPENDENCE
TEREPHTHALIC ACID
ALCOHOLS
ALKENES
CARBOXYLIC ACIDS
CRYSTAL STRUCTURE
DICARBOXYLIC ACIDS
GLYCOLS
HYDROCARBONS
HYDROXY COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHASE TRANSFORMATIONS
POLYMERS
360602* - Other Materials- Structure & Phase Studies