William J. MacKnight

The sodium salts of sulphonated poly(aryl-ether-ether-ketone) (PEEK): preparation and characterization

Two complementary methods were developed to produce sulphonated poly(oxy-1,4-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene) (SPEEK) with random, homogeneous compositions over the range of zero to one sulphonate group per repeat unit. The sodium salts (Na-SPEEK) were prepared from about 5 to 100% sodium sulphonate. They displayed excellent thermal stability. The behaviour of Tg, ΔTg and ΔCp at the glass transition as a function of composition suggested the onset of ionic clustering below 25 to 30% sodium sulphonate—an observation confirmed by preliminary SAXS studies. In particular, Tg increased sigmoidally from about 150°C for 5% Na-SPEEK to 415°C for 100% Na-SPEEK. No evidence of crystallinity was observed by d.s.c. in melted and quenched samples above 9% sodium sulphonate. The equilibrium water content at room temperature and 58% relative humidity was four molecules of water per sodium sulphonate group for all compositions. For immersed films, this value increased from 8 molecules of water per sodium sulphonate group for 38% Na-SPEEK to an indeterminably large number for 100% Na-SPEEK, which slowly dissolved. Upon re-equilibration at 58% relative humidity, the water content of the films decreased to about 5.5 molecules per sodium sulphonate group. A low temperature (−80°C to −60°C) mechanical relaxation peak was present in the films conditioned at 58% relative humidity.

Fourier transform infra-red spectroscopy on the thermo-oxidative degradation of polybenzimidazole and of a polybenzimidazole/polyetherimide blend

Abstract The thermo-oxidative degradation of the polybenzimidazole material, poly[2,2′-m-phenylene)-5,5′-bibenzimidazole] (PBI), and of a blend of PBI with the polyetherimide, poly[2,2′-bis(3,4-dicarboxyphenoxy) phenylpropane-2-phenylene bisimide] (Ultem 1000), was investigated by Fourier transform infra-red (FTi.r.) spectroscopy. An experimental protocol and the necessary instrumentation were developed for real-time monitoring of the molecular changes occurring during the process. The spectroscopic data provided information about the mechanism and the kinetics of the thermo-oxidative degradation in its early stages. The FTi.r. spectra of the PBI/Ultem 1000 blend were analysed by subtraction spectroscopy, and the application of this technique allowed us to selectively follow the fate of the two components in the blend. No chemical interaction between PBI and Ultem 1000 was detectable by FTi.r. spectroscopy during the degradation process.

Poly(ethylene oxide)/poly(methyl methacrylate) blends: Influence of tacticity of poly(methyl methacrylate) on blend structure and miscibility

Abstract The influence of different configurations of poly(methyl methacrylate) on the miscibility and superstructure of poly(ethylene oxide)/poly(methyl methacrylate) (PEO/PMMA) blends was examined using small-angle X-ray scattering and differential scanning calorimetry. The blends prepared by solution casting were isothermally crystallized at 48°C. The miscibility, the melting behaviour, the glass transition temperature and the structural parameters of the blends were strongly dependent on the tacticity and blend composition. The small-angle X-ray intensity profiles were analysed using a recently developed methodology. For the poly(ethylene oxide)/atactic poly(methyl methacrylate) (PEO/APMMA) and poly(ethylene oxide)/syndiotactic poly(methyl methacrylate) (PEO/SPMMA) blends, the long period and the amorphous and transition region thicknesses increased with increase of PMMA content, whereas for the poly(ethylene oxide)/isotactic poly(methyl methacrylate) (PEO/IPMMA) blends they are independent of composition. The structural properties of the blends were attributed to the presence of non-crystallizable material in the interlamellar or interfibrillar regions, depending on PMMA tacticity. From the glass transition and melting temperatures, it has been supposed that one homogeneous amorphous phase is present in the case of PEO/APMMA and PEO/SPMMA blends and that the PEO/IPMMA amorphous system is phase-separated. The free-volume contribution to the energy of mixing for the various tactic PMMAs is hypothesized to be responsible for the difference in mixing behaviour.

Microphase separated structure, surface composition and blood compatibility of segmented poly(urethaneureas) with various soft segment components

Properties, surface composition, and blood compatibility of segmented poly(urethaneureas) (SPUUs) with various soft segment components were investigated. The microphase separated structure between hard and soft segments improved with an increase in molecular weight (Mn) of polyether diol in soft segment. The amount of absorbed water depended on the nature of the polyether component. X-ray photoelectron spectra of the surface of SPUU revealed that the surface composition depended on Mn and surface free energy of polyether component. Blood compatibility of SPUU depended on the state of microphase separated structure and surface composition.

Hydrogen bonding in polybenzimidazole/polyimide systems: a Fourier-transform infra-red investigation using low-molecular-weight monofunctional probes

Abstract To elucidate the nature of the specific interactions occurring in polybenzimidazole/polyimide (PBI/PI) miscible blends, a Fourier-transform infra-red investigation on these polymers in the presence of low-molecular-weight monofunctional compounds was undertaken. In the case of PBI the probe compounds were proton-accepting molecules (aliphatic ketones) able to form hydrogen-bonding interactions with the polymeric substrate. In the case of the two investigated polyimides, poly([2,2′-bis(3,4-dicarboxyphenoxy)phenylpropane]-2-phenylenebisimide) (Ultem 1000) and the condensation product of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride and 5(6)-amino-1-(4′-aminophenyl)-1,3,3′-trimethylindane (XU 218), the carbonyl functional group in the probes was replaced by a hydroxyl group. This approach allowed us to conclude that in PBI/PI blend systems a hydrogen-bonding interaction occurs between the polymeric components.

Properties of Ethylene‐Methacrylic Acid Copolymers and their Sodium Salts: Mechanical Relaxations

A study has been made of the mechanical‐relaxation behavior of an ethylene‐methacrylic acid copolymer containing 4.1 mole % acid units and its partially ionized sodium salts. Degrees of ionization, estimated from infrared analysis, ranged from 0% to 78%. The weight‐percent crystallinity of the samples, determined by differential‐scanning calorimetry, varied from about 15 for the acid copolymer to about 7 for the 78% ionized copolymer. Four relaxation regions have been observed. They are labelled α, β′, β and γ, and each has been assigned to motions within the amorphous phase of the polymer. In plots of the logarithmic decrement against temperature (at 1 cps), the α peak for the annealed acid copolymer occurs at 50°C and shifts to higher temperatures with increasing degree of ionization. This trend is consistent with the increase in melt flow viscosity with increasing ionization and, on this basis, the α process is attributed to the long‐range diffusional motions of chain segments. The β′ peak occurs at 23...

Microphase separated structure and blood compatibility of segmented poly(urethaneureas) with different diamines in the hard segment

Abstract The properties, structures and blood compatibility by platelet adhesion and deformation of segmented poly(urethaneureas) (SPUUs) with various aliphatic diamine chain extenders were investigated. The SPUUs containing diamines with an odd number of methylene units showed a remarkable degree of phase mixing between the hard and soft segments. I.r. spectra of SPUUs indicated that the state of hydrogen bonding depended on the number of methylene units in the diamine. XPS measurements revealed that the surface concentration of soft segment was independent of diamine structure but the state of microphase separation strongly depended on the number of methylene units in the diamine. The SPUUs with an even number of methylene units in the diamines showed less platelet adhesion and deformation than those with an odd number of methylene units in the diamines.

Miscible blends of aromatic polybenzimidazoles and aromatic polyimides

SummaryA new family of high performance, miscible polymer blends based on aromatic polybenzimidazoles and aromatic polyimides has been discovered. Preliminary evidence, obtained with commercially available, soluble polymers suggests that polymers of these generic types may be miscible over a wide range of compositions and structural variations. Blend miscibility was evidenced in the form of single Tg1s and well-defined single tan δ relaxations intermediate to those of the component polymers, the formation of clear films and, in one case, enhanced solvent resistance.

Thermal and mechanical properties of solution polymerized segmented polyurethanes with butadiene soft segments

Abstract A series of HTPBD containing polyurethanes of high molecular weight have been synthesized in solution. The value of the soft segment Tg is very close to that of the free HTPBD and independent of hard segment content indicating complete or very nearly complete phase segregation. Since the hard segments of TDI/BDO are amorphous, the driving force for phase segregation must arise from the large degree of incompatibility between the polar hard segment and nonpolar soft segment. Furthermore, in these samples there is also no opportunity for hydrogen bonding between hard and soft segments to enhance compatibility. The values of the hard segment glass transition increase with the average hard segment length following a Fox-Flory type relationship. In contrast to the segment Tg observed in bulk polymerized samples, only a single hard segment Tg occurred in the present study. This indicates that the double Tg behaviour is a result of the heterogeneous nature of the bulk polymerization. With increasing hard segment content, the properties vary from soft to rigid elastomers, and rubber roughened plastics. This variation in properties is caused by changes in the sample morphology which depends upon the relative fractions of hard and soft segments. Mechanical properties show marked improvement over the corresponding bulk polymerized samples. Unlike polyester and polyether urethanes, these materials evidence no change in the soft segment Tg following thermal treatment and no effect of thermal history on the mechanical properties.

Structure and morphology of segmented polyurethanes: 1. Influence of incompatability on hard-segment sequence length

Abstract Separation of three polybutadiene/toluene diisocyanate/butane diol segmented polyurethanes by means of solvent extraction and the characterization of their fractions indicate that the molecules of the original polyurethanes are quite dissimilar in chemical composition and average hard-segment length. These polyurethanes are just blends of two fractions of segmented copolymer with very different average hard-segment content and average hard-segment length. For these polyurethanes, in addition to the segregation of the hard and soft segments, as expected usually for segmented copolymers, the segregation of macromolecules as a whole according to their composition should be considered in the interpretation of their morphology and properties and has been proved to be the origin of the existence of two hard-segment T g s. This ind of compositional non-uniformity is the result of the poor compatibility between the components of the system. It should be a common phenomenon for segmented copolymers, but is especially obvious in the case of polybutadiene-containing polyurethanes owing to the extremely poor compatibility between their components.