Polymer
4-Carboxybenzaldehyde was condensed with malononitrile to afford 1-(2,2-dicyanovinyl)-4-benzoic acid, which was converted to the corresponding acid chloride. The latter reacted with half the molar amount of an aromatic diamine or bisphenol to yield cyano-substituted polymer precursors. Crosslinked polymers were obtained by curing at 300°C for 40-60h, which were stable up to 333-400°C in N 2...
The mean-field theory of formation of triblock copolymer superstructure is developed in the strong segregation limit, taking into account the difference in local characteristics of the blocks (widths, persistence lengths). Special attention was paid to the role of the interfacial tension coefficients at the two interfaces during formation of the triblock copolymer superstructure. It is shown that...
The elastic modulus E 1 of the crystalline regions in the direction parallel to the chain axis was measured by X-ray diffraction for a number of ethylene-vinyl alcohol (EVA) copolymers with various vinyl alcohol (VA) contents. Although the E 1 values of polyethylene (235 GPa) and poly(vinyl alcohol) (250 GPa) are very high, these copolymers possessed much lower E 1 values...
Melting point depression techniques are used to test the compatibility of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA). The novelty of the experimental approach lies in the morphology of the melting lamellae, which is kept constant by using identical single crystals in various mixtures with PMMA. The values obtained for the Flory-Huggins interaction parameter are critically...
Four polyimides and one polypyrrolone derived from 2,2 -bis(p-trimellitoxyphenyl) propane dianhydride were synthesized and the transport properties of H 2 , O 2 and N 2 in these polymers were measured at 30°C and 1 atm (1.01 10 5 Pa). Values of permeability and permselectivity were significantly affected by diffusivity and diffusivity selectivity, respectively...
A means of generating high temperature polymer foams which leads to pore sizes in the nanometre regime has been developed. Foams were prepared by casting block copolymers comprising a thermally stable block and a thermally labile material, such that the morphology consists of a matrix of the thermally stable material with the thermally labile material as the dispersed phase. Upon thermal treatment,...
Various maleimide-containing copolymers have been studied with respect to their miscibility behaviour towards poly(methyl methacrylate) (PMMA) by differential scanning calorimetry (d.s.c.). Poly(styrene-co-N-maleimide)s (NMIs) with maleimide contents between 8 and 21 wt% were shown to be completely miscible with PMMA, whereas a blend containing 45 wt% maleimide in the NMI was not miscible with PMMA...
Ampholytic hydrogels were synthesized by copolymerizing acrylamide with specialty monomers. Two monomers, [(methacrylamido)propyl]trimethylammonium chloride (MAPTAC) and sodium styrene sulfonate (SSS), were copolymerized with acrylamide to form one ampholytic hydrogel. Also, the zwitterionic monomers N-(3-sulfopropyl)-N-methacrylamidopropyl-N,N-dimethylammonium betaine (SB1) and N -(3-sulfopropyl)-N-methacroyloxyethyl-N,N-dimethylammonium...
A new sulfur-containing photosensitive monomer, S-methacryloyl O-ethyl xanthane (MAX), was synthesized and characterized. Attempts to make the corresponding S-acryloyl O-ethyl xanthate (AX) under identical experimental conditions resulted in the formation of S-(3-hydroxypropionyl) O-ethyl xanthate as the major product. The free-radical copolymerization behaviour of MAX with methyl methacrylate (MMA)...
Investigations into the optimization of the structural parameters of the macromolecular matrix with a view to designing efficient polymer supports for peptide synthesis are reported. The dependence on the chemical nature of the monomers, nature and extent of crosslinking, the method of polymerization, hydrophobic-hydrophilic balance of the matrix, its chemical and mechanical stability, ease of functionalization,...
This paper focuses on the secondary relaxation (γ-relaxation) behaviour of a set of polyarylates and of the corresponding model systems composed of a single repeat unit and end-groups. The common feature of the compounds is that they contain short dipolar groups (O, C O, CO-O, SO 2 ) between successive phenyl units. The method of analysis was dielectric spectroscopy. The aim of the investigations...
A molecular simulation technique, combined with X-ray diffraction measurements, was applied to the determination of the crystal structure of poly(4,4 -diphenylene pyromellitimide), a high-modulus aromatic polyimide. Simulation of the crystal structure was carried out with the programs POLYGRAPH and CERIUS (Molecular Simulations Inc.) using the Dreiding force field approach. Initial models optimized...
A recent statistical thermodynamic theory of fluids interacting with strong specific intermolecular and intramolecular forces is extended in order to correlate and predict the glass transition temperatures in polymer mixtures. The Gibbs-DiMarzio approach of zero configurational entropy at the glass transition is adopted. The configurational entropy is composed of three distinct parts: a chain flexibility...
The miscibility of blends of poly(4-vinylpyridine) (P4VP) with blocky copolymers of vinyl alcohol/vinyl acetate (ACA) of different compositions has been investigated and compared to that of the blends with random ACA copolymers. The miscibility window found in both cases is narrower for the blocky ACA blends, indicating the influence of the comonomer sequence distribution. Fourier transform infra-red...
Temperature dependent X-ray diffraction studies of poly(di-n-alkylsiloxane)s substituted with side chains containing 7 to 10 carbon atoms have been carried out in order to elucidate the crystalline structure of these materials. In contrast to their lower substituted homologues, no evidence for the presence of a hexagonal columnar mesophase could be found for the investigated materials. At low temperatures,...
I.r. and high-resolution solid-state 1 3 C n.m.r. spectra, as well as proton relaxation times T H 1 andT H 1 ρ of poly(ethylene oxide) (PEO)/atactic poly(methyl methacrylate) (a-PMMA) blends in the solid state, with PEO weight fractions of 10, 30, 50 and 70% were measured. Infra-red spectra of pure PEO with various molecular weights were also measured. The...
Quaternization of the end-groups of α,ω-(dimethylamino)polyisoprenes with monofunctional, difunctional and trifunctional halides (iodides and bromides) has been undertaken on polymers of different molecular weights (M n = 6000 and 38 000 g mol - 1 ). The thermal stability of the ammonium end-groups is somewhat better when iodide counteranions are present. Quaternization increases...
In a previous paper, a model was developed to calculate energy efficiency and temperature profiles inside a polymer plate undergoing heat treatment. This model links up the radiator characteristics and the crystalline structures together with the material i.r. absorption behaviour. Here, to validate the model, we present a comparison between numerical simulation and experimental results carried out...
An analysis has been carried out of the crystalline structure of a blend consisting of amorphous polycarbonate and semicrystalline isotactic polypropylene (PP) crystallized under pressure. Structure investigations were carried out by means of wide-angle X-ray scattering. The amount of particular phases as well as the degree of crystallinity have been analysed. It was found that during pressure...
The piezoelectric and pyroelectric response characteristics for a variety of polymers and crystalline reference materials were correlated with their refractive index (n) and McGinniss equation x values. A general predictive relationship was developed using these n and x parameters which was then used to estimate the piezoelectric d and g constants for polytrifluorovinyl acetate. The predicted...