Showing papers in "Polymer in 1979"

TL;DR: In this paper, the historical development of polyglycolic acid (PGA) and polylactic acid (PLA) polymers and copolymers for use in surgery is set down.

TL;DR: In this article, a rapid estimation technique is proposed for the determination of the kinetic parameters describing the autocatalytic reaction of epoxy cure, which utilizes information from a single characteristic point, namely, the point of maximum rate of cure.

TL;DR: In this paper, the authors present a unified picture in which differences between concepts and theories are given secondary importance and the agreements between them are emphasized, and the judgement of the importance of details is a subjective matter and not everybody may agree with the author's treatment.

TL;DR: Theories of rubber elasticity are reviewed and compared in this article and principal differences center on the connection between the locations of network junctions and the macroscopic strain, and experimental evidence in support of theory developed using this hypothesis is discussed.

TL;DR: In this paper, phase transitions and critical behaviour of covalently crosslinked polyacrylamide gels were described and analyzed in terms of the Flory-type mean field theory and the mode coupling theory.

TL;DR: In this article, the crystal structure of poly(trimethylene terephthalate) was determined by a combination of electron diffraction, X-ray diffraction and packing analyses.

TL;DR: In this paper, a triclinic unit cell is proposed for the structure with approximate dimensions a = 5.2 A, b = 4.8 A, c = 35.0 A, α = 115°, β = 121° and γ = 85°.

TL;DR: In this article, it was established that the incorporation of an impact modifier altered the superstructure of the polypropylene matrix by decreasing the average size of spherulites through which the impact strength of the composite may be influenced.

TL;DR: In this paper, the DGEBA/TETA (diglycidyl ether of bisphenol-A/triethylene tetramine) system was examined in postcuring conditions at 100°C for 3 and 6 days.

TL;DR: The determination of the crystalline structure of oriented fibres of poly(trimethylene terephthalate) is described in this article, where the unit cell is triclinic with the following parameters: a = 4.6 A, b = 6.2 A, c = 18.3 A, α = 98°, β = 90°, γ = 112°.

TL;DR: In this article, the spectrum of Nafion cation exchange membranes was made possible by use of i.r. absorption and reflectance (ATR) spectroscopy.

TL;DR: The dimensions of both cyclic and linear poly(dimethyl siloxanes) in dilute solution in benzene-d 6 have been measured by small-angle neutron scattering as mentioned in this paper.

TL;DR: In this article, a die-drawing process was used to make oriented polypropylene rods with room temperature Young's moduli up to 20.6 GPa. The advantages of this process compared with conventional tensile drawing and hydrostatic or ram extrusion are discussed.

TL;DR: In this paper, a commercial sample of polyacrylamide (CALGON) has been carefully purified, analysed and fractionated, and the molecular characterization can be carried out by light scattering and viscosity measurements, without disturbances arising from microgels or aggregates.

TL;DR: In this article, stress and strain crosslinking systems reflecting the thermomechanical history are seen from shrinkage experiments, where a stress crosslink is formed on cooling the deformed material, thus stabilizing the deformation.

TL;DR: In this paper, the synthesis of a series of biodegradable polymers based on the copolymers of polyethylene oxide (PEO) and polyethylenes terephthalate (PET) is described.

TL;DR: In this paper, a linear angular dependence of Dapp towards zero scattering angle has been derived for pre-gel samples in the pregel state, which resembles that of randomly branched chain molecules, where Г is the decay constant of the time correlation function.

TL;DR: In this article, it was shown that an equation first derived for describing the Newtonian viscosity of suspensions of rigid spheres is also applicable to describing the relative viscosities of dilute to moderately concentrated polymer solutions.

TL;DR: In this article, various bulk epoxy resin formulations, based on diglycidyl ether of bisphenol A (DGEBA) and cured with diethylene triamine (DETA), were studied.

TL;DR: Amorphous poly(ethylene terephthalate) has been isothermally annealed in a wide range of temperatures from Tg to Tm and the effects of temperature and time of thermal treatment on density, melting curve and WAXS have been systematically explored as discussed by the authors.

TL;DR: In this paper, an empirical equation relating the glass transition (measured dynamically) of mixed systems to their pure components Tgs can be fitted by the following relationship: in T g =m 1 In T g 1 + m 2 In t g 2 where m is either volume or wt % of each component.

TL;DR: In this paper, single edge notch fracture tests have been carried out on rigid polyurethane foam in the density range 32 to 360 kg/m 3, and fracture properties were characterized in terms of the fracture toughness parameter (K Ic ), the critical strain energy release rate (G Ic ), and crack opening displacement (c.o.d.).

TL;DR: The presence of microvoids in aramid fibres has been suspected for some time as discussed by the authors and their detection together with an investigation of their distribution and size in Kevlar 29 and 49 by electron microscopy and X-ray diffraction techniques.

TL;DR: In this article, the molar enthalpy for gas sorption in glassy polymers at a fixed concentration, often called the isosteric enthalpies of sorption, exhibits a clearly discernable minimum when plotted as a function of penetrant concentration.

TL;DR: In this paper, the shape of the craze at the tip of a crack has been studied using optical microscopy on polycarbonates of various molecular weights at −30°C.

TL;DR: In this article, four new series of comb polystyrenes were prepared and characterized, and the observed θ temperature depression of the combs can be described by Benoit's three parameter theory with Ψ 1 = 0.32 and ( 1 3 − χ 2 ) = 0.045.

TL;DR: In this paper, the bands of stretching and deformation vibrations of CH 2, CCH 3 and OCH 3 groups in the infrared and Raman spectra were assigned.

TL;DR: In this paper, a physical model describing the swelling kinetics of glassy polymers in liquids is presented, using a thermodynamic argument, the stress induced by the penetrant on the glassy matrix is evaluated in terms of the penetration concentration.