MISCIBILITY OF HOMOPOLYMER RANDOM COPOLYMER BLENDS .2. SMA/PMMA BLENDS

The miscibility of blends of PMMA with SMA (50 wt% MA) has been investigated by means of NMR, FTIR and DSC techniques. The results indicate that the SMA/PMMA blends are miscible on a molecular level, and there are strong intermolecular interactions between the phenyl groups in SMA and carbonyl groups in PMMA. It is the intermolecular interactions instead of the intramolecular repulsion forces within the SMA copolymer that make the SMA/PMMA blends miscible. It is also found that the strength of the intermolecular interactions to some degree depends on the compositions of the blends.

ARYLIDENE COPOLYETHER SULFONES .2. SYNTHESIS END CHARACTERIZATION OF SOME NEW COPOLYETHER SULFONES CONTAINING DIBENZYLIDENE CYCLOHEXANONE MOIETIES

New copolyether sulfones containing 2,6-bis(p-oxo-benzylidene)cyclohexanone and 2,6-bis(o,p-dioxo-benzylidene)cyclohexanone moieties were prepared in the conventional literature manner by condensing the dipotassium salts of 2,6-bis(p-hydroxybenzylidene)cyclohexanone (III), 2,6-bis(o,p-dihydroxybenzylidene)-cyclohexanone (V), and 2,2-bis(p-hydroxyphenyl)propane (Bisphenol A, VII) with 4,4'-dichlorodiphenyl sulfone (VI), or by condensing the dipotassium salts of III and VII with a new benzylidene cyclohexanone sulfone macromer (X). Finally, the polycondensation reaction of sulfonyl bis(p-benzaldehydeoxo-p-phenylene) (IX) with cyclohexanone leads to an unsaturated copolymer (XVI). The resulting copolyether sulfones were confirmed by IR, H-1-NMR, viscometry, elemental analysis, thermooptical (TOA), x-ray, and thermogravimetric (TGA) measurements.

ARYLIDENE COPOLYETHER SULFONES .1. SYNTHESIS AND CHARACTERIZATION OF SOME NEW COPOLYETHER SULFONES CONTAINING DIBENZYLIDENE CYCLOPENTANONE MOIETIES

New copolyether sulfones containing 2,5-bis(4-oxo-benzylidene)-cyclopentanone moieties were prepared in the conventional literature manner by condensing the dipotassium salts of 2,5-bis(4-hydroxybenzylidene)cyclopentanone (I) and 2,2-bis(4-hydroxyphenyl)propane (Bisphenol A, III) with 4,4'-dichlorodiphenyl sulfone (II), or by condensing the dipotassium salts of I with chlorine-terminated Bisphenol A-4,4'-dichlorodiphenylsulfone copolymers (V). The resulting copolyether sulfones were confirmed by IR, viscometry, DSC measurements, thermooptical analysis (TOA), and thermogravimetric analysis (TGA).

PHASE-BEHAVIOR IN EPOXY-RESIN CONTAINING PHENOLPHTHALEIN POLY(ETHER ETHER SULFONE)

Phenolphthalein poly(ether ether sulphone) (PES-C) was found to be miscible with uncured bisphenol-A-type epoxy resin, i.e. diglycidyl ether of bisphenol A (DGEBA), as shown by the existence of a single glass transition temperature within the whole composition range. Miscibility between PES-C and DGEBA is considered to be due mainly to the entropy contribution. However, dynamic mechanical analysis (d.m.a.) and scanning electron microscopy (SEM) studies revealed that PES-C exhibits different miscibility with four cured epoxy resins (ER). The overall compatibility and the resulting morphology of the cured blends are dependent on the choice of cure agent. For the blends cured with amines (4,4'-diaminodiphenylmethane (DDM) and 4,4'-diaminodiphenylsulphone (DDS)), no phase separation occurs as indicated by either d.m.a. or SEM. However, for the blends cured with anhydrides (maleic anhydride (MA) and phthalic anhydride (PA)), both d.m.a. and SEM clearly show evidence of phase separation. SEM study shows that the two phases interact well in the MA-cured blend while the interface between the phases in the PA-cured blend is poorly bonded. The differences in the overall compatibility and the resulting morphology between the amine-cured and anhydride-cured systems have been discussed from the points of view of both thermodynamics and kinetics.

MISCIBILITY OF POLY(HYDROXYETHER OF PHENOLPHTHALEIN) WITH POLY(ETHER SULFONE)

Blends of poly(hydroxyether of phenolphthalein) (PHP) with poly(ether sulphone) (PES) were prepared by casting from a common solvent; they were found to be miscible and show a single, composition-dependent glass transition temperature. All the PHP/PES blends exhibited lower critical solution temperature behaviour, i.e. phase separation occurred at elevated temperatures. A F.T.-i.r. study revealed that a hydrogen-bonding interaction occurs between these polymers but it is weaker than in pure PHP. The observed miscibility is hence proposed to be the result of specific interactions between the polymers.

PHASE-SEPARATION IN ANHYDRIDE-CURED EPOXY-RESIN CONTAINING PHENOLPHTHALEIN POLY(ETHER ETHER KETONE)

Dynamic mechanical analysis and scanning electron microscopy were used to study phase separation of three blends of anhydride-cure bisphenol-A-type epoxy resin with phenolphthalein poly(ether ether ketone). Phase separation was observed for all the blends. The overall compatibility and the resulting morphology of the cured blends are dependent on the choice of cure agent. The phenomena have been discussed from the points of view of both thermodynamics and kinetics. The effects of the choice of hardener on phase separation are considered to be primarily due to differences between the chemical natures of the hardeners.

THE MISCIBILITY AND MORPHOLOGY OF EPOXY-RESIN POLY(ETHYLENE OXIDE) BLENDS

Poly(ethylene oxide) (PEO) was found to be miscible with uncured epoxy resin, diglycidyl ether of bisphenol A (DGEBA), as shown by the existence of a single glass transition temperature (T(g)) in each blend. However, PEO with M(n) = 20 000 was judged to be immiscible with the highly amine-crosslinked epoxy resin (ER). The miscibility and morphology of the ER/PEO blends was remarkably affected by crosslinking. It was observed that phase separation in the ER/PEO blends occurred as the crosslinking progressed. This is considered to be due to the dramatic change in the chemical and physical nature of ER during the crosslinking.

BLENDS OF PHENOLPHTHALEIN POLY(ETHER ETHER KETONE) WITH PHENOXY AND EPOXY-RESIN

The properties of miscible phenolphthalein poly(ether ether ketone)/phenoxy (PEK-C/phenoxy) blends have been measured by dynamic mechanical analysis and tensile testing. The blends were found to have single glass transition temperatures (T(g)) that vary continuously with composition. The tensile moduli exhibit positive deviations from simple additivity. Marked positive deviations were also observed for tensile strength. The tensile strengths of the 90/10 and 75/25 PEK-C/phenoxy blends are higher than those of both the pure components. Embrittlement, or transition from the brittle to the ductile mode of failure, occurs in the composition range of 50-25 wt% PEK-C. These observations suggest that mixing on the segmental level has occurred and that there is enough interaction between the components to decrease its internal mobility significantly. PEK-C was also found to be miscible with the epoxy monomer, diglycidyl ether of bisphenol A (DGEBA), as shown by the existence of a single glass transition temperature (T(g)) within the whole composition range. Miscibility between PEK-C and DGEBA could be considered to be due mainly to entropy. However, PEK-C was judged to be immiscible with the diaminodiphenylmethane-curved epoxy resin (DDM-cured ER). It was observed that the PEK-C/ER blends have two T(g), which remain invariant with composition and are almost the same as those of the pure components, respectively. Scanning electron microscopy showed that the PEK-C/ER blends have a two-phase structure. The different miscibility with PEK-C between DGEBA and the DDM-cured ER is considered to be due to the dramatic change in the chemical and physical nature of ER after curing.