THE FRACTURE-BEHAVIOR OF PHENOLPHTHALEIN POLYETHER ETHER KETONE AT ELEVATED-TEMPERATURE FOR LONG TERMS

The fracture behavior of phenolphthalein polyether-ether ketone (PEK-C) affected by physical aging at 200 degrees C was studied by tensile experiments, scanning electron microscopy, and differential scanning calorimetry observations. The ductile-brittle fracture transition (DBT) caused by physical aging can be considered as a competition between fracture mechanisms of crazing and shear yielding. The aging time required for the DBT is found to be around 400 h, based on the morphological studies and tensile experiments. The shear yielding component of the mechanical deformation could erase the aging effect, thus a deaging phenomenon occurs. We found that the deaging phenomenon has an intrinsic relationship with the extent of aging in the specimen and as a result of the fracture behavior. (C) 1995 John Wiley and Sons, Inc.

YIELD BEHAVIOR AND VISCOELASTIC INTERPRETATION BY ACTIVATION VOLUMEN OF PHENOLPHTHALEIN POLYETHER KETONE

Phenolphthalein polyether ketone (PEK-C) exhibits a marked tensile yield behaviour. The yield stress depends on strain rate and the activation volume V could be evaluated from the data of the yield stress. From the creep and stress relaxation behaviour,

COMPATIBILITY AND CRYSTALLIZATION OF TETRAHYDROFURAN-METHYL METHACRYLATE DIBLOCK COPOLYMER/POLYTETRAHYDROFURAN BLENDS

The compatibility and crystallization of tetrahydrofuran-methyl methacrylate diblock copolymer (PTHF-b-PMMA)/tetrahydrofuran homopolymer (PTHF) blends were studied. Our results showed that the crystallization and morphology of compatible PTHF-b-PMMA/PTHF

TENSILE YIELD IN PHENOLPHTHALEIN POLYETHER KETONE

Uniaxial tension tests to the yield point were performed on phenolphthalein polyether ketone (PEK-C) from room temperature to near the glass transition temperature (T-g) at a constant rate of 0.02 min(-1). At room temperature, some measurements were also

J-INTEGRAL STUDIES OF CRACK INITIATION AND CRACK TIP-BLUNTING OF PHENOLPHTHALEIN POLYETHER KETONE

The J-integral is applied to characterize the fracture initiation of phenolphthalein polyether ketone (PEK-C) for which the concepts of linear elastic fracture mechanics (LEFM) are inapplicable at high temperatures for reasonably-sized specimens due to ex

TEMPERATURE RATE DEPENDENCE OF YIELD AND FRACTURE-BEHAVIOR OF PHENOLPHTHALEIN POLY(ETHER KETONE)

The rate/temperature dependence of yield stress, tensile modulus and crack opening displacement of phenolphthalein poly(ether ketone) (PEK-C) has been investigated. The rate/temperature dependence of crack opening displacement and the correlation establis

GLASS-TRANSITION AND CRYSTALLIZATION OF POLY(VINYL ALCOHOL)-G-POLY(METHYL METHACRYLATE) GRAFT-COPOLYMERS

The glass transition behaviour, microphase separation morphology and crystallization of poly(vinyl alcohol)-g-poly(methyl methacrylate) graft copolymers (PVA-g-PMMA) were studied. A lamellar microphase separation morphology was formed, even for a copolyme

DUCTILE TEARING INSTABILITY IN PHENOLPHTHALEIN POLY(ETHER KETONE)

Phenolphthalein poly (ether ketone) (PEK-C) [GRAPHICS] can fail by tearing instability when the elastic contraction is greater than the plastic extension due to crack growth. Tearing instability (TIS) theory developed by Paris and c

Crystallization Behavior of Poly(tetrahydrofuran-b-methyl methacrylate) Diblock Copolymer

Crystallization behavior of a series of newly synthesized poly (tetrahydrofuran-b-methyl methacrylate) diblock copolymer has been studied by differential scanning calorimetry (DSC) and X-ray scattering and diffraction techniques. The results show that the

EXCIMER FLUORESCENCE STUDY ON THE MISCIBILITY OF POLY(VINYL METHYL-ETHER) AND STYRENE-BUTADIENE STYRENE TRIBLOCK COPOLYMER

The excimer fluorescence of a triblock copolymer, styrene-butadiene-styrene (SBS) containing 48 wt% polystyrene was used to investigate its miscibility with poly(vinyl methyl ether) (PVME). The excimer-to-monomer emission intensity ratio I(M)/I(E) can be used as a sensitive probe to determine the miscibility level in SBS/PVME blends: I(M)/I(E) is a function of PVME concentration, and reaches a maximum when the blend contains 60% PVME. The cloud point curve determined by light scattering shows a pseudo upper critical solution temperature diagram, which can be attributed to the effect of PB segments in SBS. The thermally induced phase separation of SBS/PVME blends can be observed by measuring I(M)/I(E), and the phase dissolution process was followed by measuring I(M)/I(E) at different times.

SYNTHESIS AND MOLECULAR-STRUCTURE OF (CH3CP)2YB.DME AND ITS CATALYTIC ACTIVITY FOR THE POLYMERIZATION OF METHYL-METHACRYLATE

The complex of (CH3Cp)2Yb . DME (DME = dimethoxyethane) has been synthesized by the reduction with metallic sodium of the corresponding chloride (CH3CP)2YbCl. (CH3CP)2Yb . DME crystallized from DME in the monoclinic space group Cm, with cell constants a = 11.068(3), b = 12.338(4), c = 12.479(4) angstrom; beta = 100.51(2)-degrees, V = 1675(l) angstrom3, and D0 = 1.66 g/cm3 for Z = 4. Least-squares refinement of 1420 unique observed reflections led to final R of 0.0487. This complex can be used as a catalyst for the polymerization of methyl methacrylate (MMA).

THE EFFECT OF MOBILITY OF MOLECULES ON RADIATION-INDUCED CHAIN SCISSION AND RACEMIZATION OF ISO-POLY(METHYL METHACRYLATE)

The radiation-induced chain-scission and racemization of isotactic poly(methylmethacrylate)(iso-PMMA) in amorphous and semi-crystalline state as well as in solution have been studied with nuclear magnetic resonance and molar mass deter-mination. It is shown that the chain-scission is dominant for iso-PMMA in dilute solution while the racemization reaction is not favorable in this case. On the contrary, the racemization is favorable when iso-PMMA was irradiated in its crystalline state while chain-scission is not. Such experimental results could be well explained by the mobility of molecules and "cage effect". The hypothesis, we proposed previously that the chain-scission, racemization and recombination are in competition and the final result depends on the state of molecular motion at which iso-PMMA was irradiated, has been verified verified once again.

THE COMPATIBILITY AND CRYSTALLIZATION OF THE MIXTURES OF POLY (TETRAHYDROFURAN-b-METHYL METHACRYLATE) DIBLOCK COPOLYMER WITH POLYVINYL CHLORIDE HOMOPOLYMER

The compatibility and crystallization behaviour of the mixtures of poly (tetrahydrofuran-methyl methacrylate) diblock copolymer (PTHF-b-PMMA) with polyvinyl chloride has been studied. We found that the compatibility of these blends, in which there is special interaction between the homopolymer and the PMMA block of the copolymer, is much better than that of the AB/A type blends; and that the crystallization rate and crystallinity of PTHF microdomain changed greatly due to the swollen by PVC homopolymer. In this paper, these changes in cryatallization are well explained according to the theories of block copolymer blends and the density gradient model presented by JIANG Ming.

SYNTHESIS AND CRYSTAL-STRUCTURE OF NEODYMIUM COMPLEX OF 1-METHYL-1, 4, 7, 10-TETRAAZACYCLODODECANE

The complex [Nd(L)(CH3CN)(CF3SO3)3] has been synthesized. Where L = 1-methyl-1, 4, 7, 10-tetraazacycldodecane. The crystal structure of the complex has been determined by a four-circle X-ray diffractometer to a final deviation factor B value of 0.0370 and R(w) value of 0.0385 respectively. The crystal is triclinic system, space group P1BAR with a = 0.8738(2), b = 1.2870(3), c = 1.2900(3) nm, alpha = 85.63(2), beta = 87.25(2), gamma = 78.30(2)-degrees, V = 1.41571 (60) nm3, Z = 2, D(c) = 1.92 g/cm3. The neodymium ion is eight-coordinated to forming a distorted square antiprism.