Showing papers on "Glass transition published in 1969"
TL;DR: The glass-forming tendency of a given material is determined principally by a set of factors which can be specified to some extent in the laboratory, namely, the cooling rate, - T, the liquid volume, v], and the seed density, ps and depending upon the materials constants: the reduced crystal-liquid interfacial tension, α the fraction, f, of acceptor sites in the crystal surface, and the reduced glass temperature, Trg.
Abstract: Summary Generally substances are more stable in a crystalline than in a glassy state. Therefore, to form a glass, crystallization must be bypassed. Under certain conditions, the melts of many substances can be cooled to the glass state. Whether or not the melt of a given material forms a glass is determined principally by a set of factors which can be specified to some extent in the laboratory, namely, the cooling rate, - T, the liquid volume, v], and the seed density, ps and upon a set of materials constants: the reduced crystal–liquid interfacial tension, α the fraction, f, of acceptor sites in the crystal surface, and the reduced glass temperature, Trg . The glass-forming tendency will be greater the larger are - T and Trg and the smaller are v]. ps, and f. The number and variety of substances which have been prepared in a glassy or ‘amorphous solid’ form have been greatly increased with techniques in which the material is condensed from solution on to a surface held well below its glass temperature. T...
1,896 citations
TL;DR: In this paper, the glass-liquid transition was exhibited thermally by both binary and ternary alloys, and the stability, ease of formation and glass transition temperature, Tg, of the glasses were all increased by the replacement of Pd with small concentrations of the noble metals.
416 citations
TL;DR: In this article, the glass transition temperature, dynamic shear moduli, and bulk viscosities of Phenoxy PKHH (a thermoplastic polymer made from bisphenol-A and epichlorohydrin) filled with glass beads and Attapulgite clay were investigated.
Abstract: The glass transition temperature, dynamic shear moduli, and bulk viscosities of Phenoxy PKHH (a thermoplastic polymer made from bisphenol-A and epichlorohydrin) filled with glass beads and Attapulgite clay were investigated. The glass temperature of the polymer increased with increasing filler concentration and with increasing specific surface area of the filler. The data were interpreted by assuming that interactions between filler particles and the polymer matrix reduce molecular mobility and flexibility of the polymer chains in the vicinity of the interfaces. From the measured moduli and the viscosities of the filled and unfilled materials, the modulus reinforcement ratio in the glassy state and the relative viscosity in the viscous state were obtained as functions of the filler type and concentration. The relative modulus for the glass bead composite system follows the Kerner equation, while the clay-filled systems exhibit slightly greater reinforcement. The relative viscosities are strongly temperature dependent and do not follow conventional viscosity predictions for suspensions. It is suggested that the filler has a twofold effect on the viscosity of the composite materials; one is due to its mechanical presence and the other is due to modifications of part of the polymer matrix caused by interaction. Using the WLF equation to express all modifications of the matrix, one can isolate a purely mechanical contribution to the viscosity reinforcement. This mechanical part is approximately bounded by the theoretical predictions of Kerner,32 Mooney, 36 and Brodnyan,41 for suspension viscosities.
154 citations
134 citations
TL;DR: In this paper, the yield stress behavior of two glassy polymers is studied through the glass transition region over a wide range of strain rates, and it is described as a non-Newtonian flow in agreement with Eyring's theory, excepts a narrow range relating to the slowest strain rates.
Abstract: The yield-stress behavior of two glassy polymers is studied through the glass transition region over a wide range of strain rates. For temperatures below the glass transition temperature, the yield stress behavior could be described as a non-Newtonian flow in agreement with Eyring's theory, if one excepts a narrow range relating to the slowest strain rates. For temperatures above Tg, the yield-stress behavior is still nonlinear but fits the relations based on the concept of free volume.
91 citations
TL;DR: The morphology of solution cast films of butadiene and styrene block polymers in both stretched and unstretched state has been studied by electron microscopy, and has been related to the mechanical behavior of these materials as mentioned in this paper.
Abstract: The morphology of solution cast films of butadiene and styrene block polymers in both stretched and unstretched state has been studied by electron microscopy, and has been related to the mechanical behavior of these materials. These micrographs confirm the indications from dynamic properties that this material consists of a two-phase system in which the relationship between the phases is sensitive to the solvent system used in casting. Although the basic morphological unit is a polystyrene sphere of 100 A diameter dispersed in a matrix of polybutadiene, the interaction between spheres is complex. These spheres are more deformable than would be predicted from their glass transition temperature. The dynamic mechanical properties, stress-strain properties, and stress relaxation properties of block polymers of styrene and dienes can be explained in terms of the morphology and changes of morphology on stretching in the electron microscope.
82 citations
TL;DR: In this article, it was shown that if a solute was used which was a nonsolvent for the polymer, a plot of the logarithm of the specific retention volume as a function of reciprocal temperature showed a marked inflection at a temperature close to the glass transition temperature for the poly.
Abstract: In a recent communication, Smidsrod and Guillet showed that thermodynamic data on the interactions between poly (isopropylacrylamide) and various gaseous solutes could be obtained by making the polymer the stationary phase in a gas Chromatograph It was also shown that if a solute was used which was a nonsolvent for the polymer, a plot of the logarithm of the specific retention volume as a function of reciprocal temperature showed a marked inflection at a temperature close to the glass transition temperature for the polymer We wish to report similar data on several additional polymers which lead us to believe that the phenomenon is a general one and may be used to obtain an estimate of transition temperatures for a variety of polymeric materials
80 citations
TL;DR: In this article, the glass transition temperature of poly(acrylic acid) was found to be of the order of 103C and increases with increasing anhydride content, reaching an extrapolated value of 140C for the pure linear anhydric acid.
Abstract: : The kinetics of dehydration and decarboxylation as well as the glass transition temperature as a function of anhydride content were measured for poly(acrylic acid). It was found that the glass transition of PAA is of the order of 103C and increases with increasing anhydride content, reaching an extrapolated value of 140C for the pure linear anhydride. Anhydride formation is first order reaction, as is also decarboxylation, the latter being much slower than the former. Anhydride formation occurs primarily by an intramolecular process. (Author)
80 citations
TL;DR: In this paper, a gas-flow method of measuring the diffusion, solubility, and permeability of gases and vapors in polymer films is described, and the specific advantages of this system over the time-lag technique are discussed.
Abstract: A novel gas-flow method of measuring the diffusion, solubility, and permeability of gases and vapors in polymer films is described. The specific advantages of this system over the time-lag technique are discussed. Transport data, including activation energies and enthalpies of solutions, for hydrogen and deuterium in poly(vinyl fluoride) are presented, and the effects of the glass transition and of orientation on the observed transport rates are discussed.
57 citations
TL;DR: In this article, the authors present quantitative studies of the time and temperature effects on the production of this endothermal peak during the annealing of PVC homopolymer and an acetate copolymer.
Abstract: Poly(vinyl chloride) displays a normal DSC or DTA curve for the glass transition when quenched from above its T g . However if cooled slowly or annealed near the glass-transition temperature, a peak appears on the DSC or DTA curve at the T g . In this article quantitative studies of the time and temperature effects on the production of this endothermal peak during the annealing of PVC homopolymer and an acetate copolymer are presented. This phenomenon conforms to the Williams, Landell, and Ferry equation for the relaxation of polymer chains, the rate of the peak formation becoming negligible at more than 50°C below T g . The energy difference between the quenched and annealed forms is small. For a PVC homopolymer annealed 2 hr at 68°C, which is T g -10°C, the difference is 0.25 cal/g. For a 13per thousand acetate copolymer of PVC similarly annealed, the difference is 0. 36 cal/g. The measured rates of the process give a calculated activation energy of 13-14 kcal/mole for PVC homopolymer and copolymer. This appearance of a peak on the T* lg*s curve for a polymer when annealed near the glass temperature appears to be a general phenomenon.
33 citations
TL;DR: In this paper, the Adam-Gibbs theory of relaxation processes was applied to derive approximate (configurational) entropy parameters, E (Sc), which exhibit qualitatively the properties of E(V) observed in studies of nonionic liquids.
Abstract: The electrical conductances of calcium nitrate–potassium nitrate solutions have been measured as a function of temperature to 200°C and pressure to 3000 atm, by imposing oil pressure directly on samples held within an externally heated bomb. Log (conductance) varies linearly with pressure at high temperatures, but curvilinearly at low temperatures, the “activation volume” appearing to increase with increasing pressure. “Activation volumes” increase rapidly with decreasing temperature. The observations may be accounted for if the “ideal glass transition temperature” T0 is taken to be the only pressure‐dependent variable in a simple equation previously found to describe temperature and composition‐dependent variations in conductance in this, and other, systems. Within uncertainty limits, T0 varies linearly with pressure and mole fraction, thus pressure equivalents of given composition changes can be simply stated. Using a thermodynamic relation applicable at the glass transition, the observed dependence of T0 on pressure is used to predict the change of heat capacity at the glass transition. The value is confirmed within error by direct measurements. Application of the Adam–Gibbs theory of relaxation processes leads to the derivation of approximate “constant (configurational) entropy” parameters, E (Sc), which exhibit qualitatively the properties of “constant volume” parameters, E(V), observed in studies of nonionic liquids.The electrical conductances of calcium nitrate–potassium nitrate solutions have been measured as a function of temperature to 200°C and pressure to 3000 atm, by imposing oil pressure directly on samples held within an externally heated bomb. Log (conductance) varies linearly with pressure at high temperatures, but curvilinearly at low temperatures, the “activation volume” appearing to increase with increasing pressure. “Activation volumes” increase rapidly with decreasing temperature. The observations may be accounted for if the “ideal glass transition temperature” T0 is taken to be the only pressure‐dependent variable in a simple equation previously found to describe temperature and composition‐dependent variations in conductance in this, and other, systems. Within uncertainty limits, T0 varies linearly with pressure and mole fraction, thus pressure equivalents of given composition changes can be simply stated. Using a thermodynamic relation applicable at the glass transition, the observed dependence of ...
TL;DR: In this article, a study has been made on four chain-extended polyurethan (PU) elastomers differing only in the nature of the flexible segment, namely, poly(butylene adipate) (PBA), poly(tetramethvlene oxide) (PTMO), poly-propylene oxide (PPO), and poly-ethylene oxide (PEO), and the saturation water concentration increases from 1.6 to 3% in the first three samples and jumps to 113% in PEO-PU.
Abstract: A study has been made on four chain-extended polyurethan (PU) elastomers differing only in the nature of the flexible segment, namely, poly(butylene adipate) (PBA), poly(tetramethvlene oxide) (PTMO), poly(propylene oxide) (PPO), and poly(ethylene oxide) (PEO). The saturation water concentration increases from 1.6 to 3% in the first three samples and jumps to 113% in PEO-PU. The flux normalized to 1 mil thickness is nearly the same in the first three samples, whereas an increase of 70% is expected in PPO-PU on the basis of the higher water solubility and a 24-fold increase is expected in PTMO-PU on the basis of the 27°C lower glass transition. For PBA-PU, the upward curvature of the isotherm at higher activities, zero heat of mixing, and linear decrease in diffusion constant D with concentration indicate that immobilization of water in clusters plays an important role in the transport mechanism. Nearly identical behavior is observed in PTMO-PU, suggesting that the lower than expected D in this pol...
TL;DR: A series of polyvinyl alkyl ethers, with the ether side chain ranging in length from methyl to n-decyl, has been studied from ∼60°K to above the glass transition as mentioned in this paper.
Abstract: A series of polyvinyl alkyl ethers, with the ether side chain ranging in length from methyl to n-decyl, has been studied from ∼60°K to above the glass transition A linear variable differential transformer was used to measure the linear expansion coefficient, α, complemented by mechanical loss measurements with a freely oscillating torsion pendulum and dielectric loss measurements In addition to the glass transition, two low-temperature transitions have been observed in these systems The first below Tg, Tgg(1), follows the same trend as the glass transition, ie, as the side chain length increases the temperature at which the transition occurs decreases, until n-octyl, where side chain crystallization is manifested The second transition below Tg, Tgg(2), occurs at ∼100°K irrespective of side chain length Because of their analagous dependence on side chain length, Tgg(1) is thought to be similar to the glass transition, ie, due to main chain motion Δα' at Tgg(2) is of greater magnitude tha
TL;DR: In this paper, internal friction and creep measurements have been used to reveal the mechanism of cure in epoxy resins cross-linked with diethylene triamine (DETA), and the β-relaxation is associated with the main glass transition of the undercured resin network.
Abstract: Internal friction and creep measurements have been used to reveal the mechanism of cure in epoxy resins cross-linked with diethylene triamine (DETA). The β-relaxation is associated with the main glass transition of the undercured resin network. The glass transition temperature (Tg) is about 40° C above the maximum temperature of cure and the curing reaction slows down about 2 h after each increase of the temperature. At 25° C the cure is only about half complete and since in this resin, when fully cross-linked, Tg is at about 140° C, temperatures of 100° C or over are needed to complete cure.
TL;DR: A modification of the Primak analysis for activation energy distributions is presented and compared with the well-known analysis for relaxation time distributions in this article, where mathematical and physical interrelationships between the two analyses are discussed.
Abstract: A modification of the Primak analysis for activation energy distributions is presented and compared with the well‐known analysis for relaxation time distributions. Mathematical and physical interrelationships between the two analyses are discussed. Activation energy spectra are derived from the data of Kovacs for volume relaxation in polystyrene and polyvinyl acetate. The energy spectra are bell shaped and cover the range from 5 to 20 kcal/mole. The concept of a shift factor is introduced to account for changing structure in the glass transition region. The shapes and locations of the spectra are discussed and compared with previous interpretations of volume relaxation data.
TL;DR: In this article, the authors made measurements between 10 2 and 10 10 Hz on samples of polyethylene glycol 200 polyurethane, polypropylene glycol polyurethsane and polyethylen glycol 450 polyurentane elastomers and found that they exhibit low dielectric permittivity and loss factor at temperatures below a transition temperature measured by differential scanning calorimetry, which is best explained by the existence of Maxwell-Wagner two-phase interfacial polarization.
TL;DR: The glass-transition temperature of water (Tg) has been calculated by use of the Tammann-Hesse viscosity equation with the Viscosity equal to 1013 poise at Tg significantly higher than previous estimates.
Abstract: The glass-transition temperature of water (T(g)) has been calculated by use of the Tammann-Hesse viscosity equation with the viscosity equal to 10(13) poise at T(g). The derived value of T(g),162 +/- 1 degrees K, is significantly higher than previous estimates.
TL;DR: In this article, the authors used an adiabatic vacuum calorimeter and a differential scanning (DSC) method to measure the heat capacities of 1,3-dioxolan and poly-1, 3-Dioxolan from 80°K to 390°K.
Patent•
31 Dec 1969TL;DR: An OPAQUE MICROPOROUS FILM SUITABLE AS PAPER and CAPABLE OF BEING PRINTED is described in this paper, where at least two patrolmen are available with each other and one patrolman has a glass transition temperature at least 40*C.
Abstract: AN OPAQUE MICROPOROUS FILM SUITABLE AS PAPER AND CAPABLE OF BEING PRINTED. THE FILM HAS AT LEAST TWO POLYMERS WHICH ARE INCOMPATIBLE WITH EACH OTHER AND ONE POLYMER WHICH IS IN EXCESS HAS A GLASS TRANSITION TEMPERATURE AT LEAST 40*C. LOWER THAN THAT OF ANOTHER POLYMER WITH WHICH IT IS INCOMPATIBLE. DRAWING AT ABOUT THE GLASS TRANSITION TEMPERATURE OF THE POLYMER IS EXCESS RESULTS IN FILM OPACITY.
Patent•
04 Sep 1969
TL;DR: A polymeric binder for magnetic coating exhibiting excellent wear and aging characteristics comprised of a mixture of a high molecular weight vinyl chloride-vinyl acetate or a polyvinylacetal having a glass transition temperature (Tg) in excess of 70 DEG C.
Abstract: A polymeric binder for magnetic coating exhibiting excellent wear and aging characteristics comprised of a mixture of a high molecular weight vinyl chloride-vinyl acetate or a polyvinyl acetal having a glass transition temperature (Tg) in excess of 70 DEG C. and a thermoplastic polyurethane-polyurea, hydroxyl-functional elastomer which is a reaction product of a mixture of a polyesterdiol, a hydrocarbon diol, a diphenyl sulfone diamine and an organic diisocyanate.
TL;DR: In this paper, a study of the relaxation phenomena in three series of polyurethanes in the neighborhood of their glass transition temperatures and above has been made, where the technique of dynamic mechanical relaxation was used in the investigation at various frequencies up to 110 Hz.
Abstract: A study has been made of the relaxation phenomena in three series of polyurethanes in the neighborhood of their glass transition temperatures and above. The technique of dynamic mechanical relaxation was used in the investigation at various frequencies up to 110 Hz. Differential Scanning Calorimetry (DSC) was also used as a supplement to the mechanical measurements. The series are: (1) H series based on polymerization of hexamethylene diisocyanate and various diols, (2) DP series based on polymerization of 4,4′ diphenylmethane diisocyanate and various diols, and (3) 4M series based on polymerization of 4‐methyl meta phenylene diisocyanate and various diols. Four relaxation regions are discernible in the temperature range investigated and these are labelled β, α, αt and αc in order of increasing temperature. The following molecular mechanisms are associated with these relaxations: (1) The β relaxation (DP and 4M series only) arises from phenyl group motion in the chain backbone, (2) the α relaxation (all s...
TL;DR: In this article, the effect of microstructure on the glass temperature T(g) of poly(alpha-methyl styrene) has been investigated, and it has been observed that T increases as the syndiotacticity of the molecule increases.
Abstract: : The effect of microstructure on the glass temperature T(g) of poly(alpha-methyl styrene) has been investigated. It has been observed that T(g) increases as the syndiotacticity of the molecule increases-thus T(g) = 446K for polymer with 67% syndiotactic placements, while a value of T(g) = 453K is found for a sample with 95% syndiotactic placements. Coefficients of expansion for the liquid and glassy states have been calculated and from these a chain stiffness parameter has been estimated using the Gibbs-DiMarzio theory. The result indicates that the flex energy of the alpha-methyl styrene chain is about 20% larger than for the polystyrene chain. (Author)
TL;DR: The deactivation-region onset temperature is quite dependent on the subsequent crystallization conditions and may not be observed in some polymers during crystallization from the melt as mentioned in this paper, and those polymers capable of being quenched directly from the melted to a non-crystalline glassy state and subsequently crystallized by reheating to above the glass transition, do not exhibit any more than a partial melting type melt treatment effect.
Abstract: As discussed in this paper, melt treatment prior to crystallization, apparently proceeds by the following stages: partial melting; an insensitive region; and at higher temperatures, deactivation of nucleation sites. The deactivation-region onset temperature is quite dependent on the subsequent crystallization conditions and may not be observed in some polymers during crystallization from the melt. In addition, those polymers capable of being quenched directly from the melt to a non-crystalline glassy state and subsequently crystallized by reheating to above the glass transition, do not exhibit any more than a partial melting type melt treatment effect. The deactivation regime absence is a result of the homogeneous nucleation that occurs during crystallization from the quenched glassy state at temperatures slightly above the glass transition.
Use of a metal- or glass-constraining medium does mask (at least partially) the effect of melt history upon crystallization from the melt. In addition to the masking effect of a constraining medium, some of the controversy in the literature pertaining to the existence of a melt treatment phenomenon may arise due to degredation of some polymers prior to the onset of the deactivation regime. The crystallization conditions employed are also quite influential on the possible effect melt treatment can have since the melt history phenomenon is noted by its effect on subsequent crystallization.
01 Jan 1969
TL;DR: In this paper, the minimum amount of acid required to obtain resistance to freezing and thawing was determined, and values for the glass temperature, (Tg) and minimum film formation temperature (MFT) of the polymer were correlated with the minimum required acid content.
Abstract: Emulsion polymers and copolymers of ethyl acrylate-methyl methacrylate containing varying amounts of methacrylic acid were subjected to three freeze-thaw cycles, following adjustment to a pH of about 9.5 with NH3. The minimum amount of acid required to obtain resistance to freezing and thawing was determined. Values for the glass temperature, (Tg) and minimum film formation temperature (MFT) of the polymer were correlated with the minimum required acid content, indicating that more acid is required as the glass temperature decreases. If a polymer is exceptionally hard so that its particles resist irreversible contact under large forces, it would be expected that little or no acid would be required to obtain freeze-thaw stability. On the other hand, if the polymer particle is so soft (low Tg) as to readily form aggregates, then very high acid amounts would be required. A plot of minimum weight per cent of acid versus Tg or MFT should, therefore, be hyperbolic approaching zero acid at very high Tg values and approaching very high acid levels at very low Tg values. This is indeed the characteristic of the plot of the experimental data.