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Recently, we have investigated a metallocene catalyst system that can produce polyethylene and ethylene/α-olefin copolymers with tailored molecular weight and short chain branching distributions (SCBD). Ethylene/α-olefin copolymers produced with this system have narrow molecular weight distributions as expected from metallocene catalysts. However, these copolymers are quite unique in that their SCBDs...
The physical aging of a poly(methyl methacrylate) (PMMA) copolymer having a small amount of ethyl methacrylate was investigated below its glass transition temperature (T g ) using dynamic viscoelastic measurements. The results were compared with those from homo-PMMAs to investigate how the comonomer in the copolymer affects the physical aging of the glass. Annealing temperatures were classified...
The kinetics modelling of furfuryl methacrylate photopolymerisation using the method of moments has enabled to obtain the concentrations of radicals and pendant groups in the networks formed at different temperatures. The analysis of these results has shown which simple step of the polymerisation mechanism is favoured according to the reaction temperature. For example, at a temperature of 283K, intermolecular...
Results of the study of stability of free radicals using electron spin resonance suggest a close relationship between the glass transition temperature (T g ) and free radical decay. In a detailed study of radicals in polyethylene (PE) [J. Polym. Sci. A2 6 (1968) 1435] in the sixties, it was concluded that the decay of radicals in solid polymers is connected to molecular mobility. In this report...
(+)-p-[{Methyl(1-naphthyl)phenyl}germyl]phenylacetylene, an acetylene with a bulky chiral germyl group, was polymerized with [(nbd)RhCl] 2 -Et 3 N to give a high-molecular-weight polymer in good yield. The CD spectrum of the polymer exhibited very large molar ellipticities [θ] in the UV region in non-aromatic solvents (e.g. THF and CHCl 3 ). In contrast, the CD signals of the...
Intercrosslinked network of siliconized epoxy-1,3-bis(maleimido)benzene matrix systems have been developed. The siliconization of epoxy resin was carried out by using various percentages of (5-15%) hydroxyl-terminated polydimethylsiloxane (HTPDMS) with γ-aminopropyltriethoxysilane (γ-APS) as crosslinking agent and dibutyltindilaurate as catalyst. The siliconized epoxy systems were further modified...
A new kinetic gelation model that incorporates the kinetics of non-linear free radical copolymerization is presented. Copolymerization of bi- and tetrafunctional monomer mixtures is simulated to characterize kinetic effects on polymerization statistics and microstructures. An algorithm for random next step selection in a self-avoiding random walk and efficient mechanisms of component's mobility are...
Results of inverse gas chromatography study of liquid polybutadiene and dihydroxypolybutadiene are presented. The study was motivated by the application of polybutadiene polyols in polyurethane chemistry where miscibility problems are often encountered. The experimental results revealed marked differences in interaction behavior of polybutadiene and dihydroxypolybutadiene, particularly with relation...
High temperature reversion tests have revealed a state of pre-existing molecular orientation in extruded polyethylene sheet. This state is related to differences in stress-deformation behaviour when specimens of the sheet are stretched along different angles with respect to the extrusion direction. An established large deformation, rate-dependent constitutive equation has been developed to model this...
A cross-linked polyurethane acrylate (PUA) was synthesized by end capping 4,4'-methylene bis(cyclohexyl isocyanate), H 12 MDI/poly-(ethylene glycol), PEG based prepolymer with hydroxy ethyl acrylate (HEA). Significant interactions of the Li + ions with the soft and hard segments of the host polymer have been observed for the PUA complexed with lithium perchlorate (LiClO 4...
For the blends of chlorinated polyethylene and copolymer of ethylene with vinyl acetate, the effect of the introducing filler (fumed silica) on the phase behavior of the blends was investigated. It was found that introducing filler in polymer blends depending on its amount lead either to the increase or to the decrease in the temperature of phase separation. At the filler concentration where both...
Dynamic mechanical experiments performed with original conditions allowed the analysis of a solution containing 15% cellulose dissolved in a monohydrate of N-methylmorpholine N-oxide (NMMO) in the amorphous state. The glass transition zone is studied by dynamic tensile experiments, while dynamic torsion technique is used to determine the viscoelastic behavior in the glassy state. A master curve of...
A possible mechanism for cross-tie fibril generation in crazes of amorphous polymers is proposed. Detailed finite element calculations are performed on an axisymmetric model of a single fibril inside the craze. These calculations suggest that the hydrostatic stress inside the fibril is large enough to cause cavitation and subsequent growth of initial imperfections inside the fibril. The calculations...
Poly(acrylic acid) (PAA) and poly(vinyl pyrrolidone) (PVP) were chosen to prepare polymer complex and blends. The complex was prepared from ethanol solution and the blends were prepared from 1-methyl-2-pyrrolidone solution. DSC results show that the T g s of the PAA/PVP blends lie between those of the two constituent polymers, whereas T g of the PAA/PVP complex is higher than both...
The effect of crystallisation on the glass transition temperature and enthalpic relaxation in poly(ether ether ketone) (PEEK) has been investigated. The increase in glass transition temperature and the activation enthalpy of ageing is explained in terms of the amorphous phase being constrained by the crystallites. The extent of enthalpic relaxation with time has been analysed in terms of the Cowie-Ferguson...
Neutral and non-doped poly(3,4-ethylenedioxythiophene), PEDOTh(Ni), and its hexyl derivative, PEDOTh-C 6 (Ni), have been prepared by organometallic dehalogenation polycondensation of 2,5-dichloro-3,4-ethylenedioxythiophene and its hexyl derivative with a zerovalent nickel complex. PEDOTh-C 6 (Ni) was soluble in organic solvents and 1 H NMR data indicated that it had an M ...
The behaviour of antiplasticized epoxy–amine networks was investigated by variable-temperature determinations of 1H NMR free induction decays. Up to 50°C, all antiplasticized resins exhibited a solid-like behaviour. At higher temperatures, resins containing the less polar additives were shown to be phase-separated, in contrast to systems containing polar additives. The temperature dependence of the...
A novel acrylic terpolymer with pendant perfluoropolyether (PFPE) segments has been synthesized and fully characterized. By hexamethylene diisocyanate functional groups PFPE monofunctional macromonomers have been grafted on a poly(butyl methacrylate-co-hydroxyethyl acrylate-co-ethyl acrylate) random terpolymer. Such grafted copolymer behaves like an interface-active material, since the perfluoropolyether...
Polyether–polyester block copolymers having various polyetheramide contents were synthesized. Single glass transition intermediated in temperature between the glass transition temperatures of polyester and polyetheramide components was found for all of polyether–polyesters. The compositional variation of glass transition exhibited a similar trend to the predicted result of thermodynamic theory for...
Radical copolymerization of captodatively (cd) substituted methyl and ethyl 2-acetoxyacrylates (MAA and EAA) with electron-withdrawing olefins including vinylidene cyanide and acrylonitrile is studied using azobisisobutylonitrile as a radical initiator at 60°C, and the structure of copolymers is examined by 13C NMR spectra. It is found that the copolymerization of MAA and EAA with vinylidene cyanide...
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