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Showing papers on "Glass transition published in 1974"


Journal ArticleDOI
TL;DR: In this article, the dependence of the glass transition temperature Tg on heating or cooling rate |q| is given to a high degree of approximation by d In \\q\\/ATg = Ah*/RTr2 or alternatively, d In | q | /d(l/Tg) = — Ah */R, where Tr is a temperature in the middle of the transition range and Ah * is the activation enthalpy for the relaxation times controlling the structural enthalhip or volume relaxation.
Abstract: It is shown that under certain conditions the dependence of the glass transition temperature Tg on heating or cooling rate |q| is given to a high degree of approximation by d In \\q\\/ATg = Ah*/RTr2 or alternatively by d In | q | /d(l/Tg) = — Ah */R, where Tr is a temperature in the middle of the transition range and Ah * is the activation enthalpy for the relaxation times controlling the structural enthalpy or volume relaxation. The conditions necessary for the validity of these relations are that the structural relaxation be describable by a temperature-independent distribution of relaxation times and that the glass be cooled from a starting temperature well above the transition region and subsequently reheated at the same rate starting from a temperature well below the transition region. Experimental measurements of Tg vs. |q| are presented for As2Ses, B2O3, potassium silicate, and borosilicate crown glasses. Ah* is found to be equal within experimental error to the activation enthalpy for the shear viscosity.

874 citations


Journal ArticleDOI
H.S Chen1
TL;DR: In this article, the formation and stability of glassy alloys of compositions (Pd1−xMx)0.835Si0.165, Pd 1−xTx)1−xpPxp and (Pt 1 −xNix) 1−expPxp, have been investigated.

460 citations


Journal ArticleDOI
TL;DR: In this article, the concept of glassy state is extended to liquid crystalline and even to crystalline materials which have any type of disorder, and the fact that glass should be considered as one of the states of aggregation of matter, irrespective of either the method of formation or the existence of three-dimensional periodicity in molecular arrangements, is stressed.
Abstract: The present review deals primarily with glass transition phenomena in pure simple compounds and pays special attention to the thermodynamic aspects of the vitrification process. The concept of glassy state is extended to liquid crystalline and even to crystalline materials which have any type of disorder. Thus the familiar supercooled liquid-glass transition is shown to be just one example of a class of ‘glass transitions’ due to loss of equilibrium which must occur quite frequently in condensed matter. Evidence of several glass transition phenomena in one and the same compound is given. The fact that glass should be considered as one of the states of aggregation of matter, irrespective of either the method of formation or the existence of three-dimensional periodicity in molecular arrangements, is stressed.

298 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured the heat capacities of hexagonal ice with an adiabatic calorimeter and found that the anomalous temperature drifts and the corresponding C s T hump were observed around 100 K.

191 citations



Journal ArticleDOI
TL;DR: PVT measurements were made on liquid and glassy poly(vinyl acetate) over ranges of -30 to 100 °C and 0 to 800 bar (gage pressure); the values of dT g /dP are in close agreement with those obtained from dynamic mechanical and dielectric time-temperature-pressure superposition.
Abstract: PVT measurements were made on liquid and glassy poly(vinyl acetate) over ranges of -30 to 100 °C and 0 to 800 bar (gage pressure). The data were obtained by three different thermodynamic histories: (a) variable formation pressure, (b) constant formation pressure at one atmosphere, and (c) constant formation pressure at 800 bar. In all of these the glass was formed by isobaric cooling at 5 °C/h. The salient characteristics resulting from the different histories are the following. History (a) produces a glass of structure varying with formation pressure and, hence, does not necessarily give the proper thermodynamic properties of a "single physical substance." However, the liquid-glass intersection temperature, Tg (P), is an important kinetic, or relaxational, property which approximates an isoviscous state. Accordingly, the values of dTg /dP are in close agreement with those obtained from dynamic mechanical and dielectric time-temperature-pressure superposition. Constant formation histories (b) and (c) give proper thermodynamic properties of the glasses, but very little information with respect to kinetics. Increasing the pressure at which the glass is formed increases the density of the glass (at the given cooling rate) considerably in contrast to the entropy (from other work), which appears to be essentially independent of formation pressure. A considerable part of the paper is definitional. The results are related to other PVT, dynamic mechanical, dielectric, and thermodynamic measurements. Interpretations are given in terms of both phenomenological and molecular models.

135 citations


Journal ArticleDOI
TL;DR: In this paper, the shear and longitudinal Brillouin shifts, longitudinal linewidth, Pockel's coefficient, and the Landau-Placzek ratio were measured in fused silica from room temperature, through the glass transition temperature (1200°C), and up to near the melting temperature of quartz (∼1700°C).
Abstract: Thermal Brillouin scattering has been studied in fused silica from room temperature, through the glass transition temperature (1200°C), and up to near the melting temperature of quartz (∼1700°C). The shear and longitudinal Brillouin shifts, the longitudinal linewidth, Pockel's coefficient, and the Landau‐Placzek ratio are measured. From these the behavior of the elastic moduli and absorption coefficient with temperature are obtained. A significant change in the temperature dependence of the moduli and Pockel's coefficient is found to occur above 500°C. In addition, by using the Landau‐Placzek ratio the first measurement in fused quartz of the equilibrium static compressibility above the glass transition has been obtained. Surprisingly little temperature dependence is observed.

126 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of molecular weight on the glass transition temperature of low polydispersity polystyrene (anionically prepared) has been studied by differential scanning calorimet...
Abstract: The influence of molecular weight (900 to 1.8 × 106) on the glass transition temperature of low polydispersity polystyrene (anionically prepared) has been studied by differential scanning calorimet...

96 citations


Journal ArticleDOI
H.S Chen1
TL;DR: The glass transition temperature T g of glassy systems (Pd 1− x M x ) 0.835 Si 0.20 for N = Ni, Co and Fe has been investigated in this article.

80 citations


Journal ArticleDOI
TL;DR: In this article, simple theory and techniques are explored and developed to utilize the dif-ferential scanning calorimeter for the determination of heat capacities, glass transition and enthalpies of transition between two thermodynamic states of substances.

79 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured the thermal expansion and density of (Pd1−xNix)0.80P0.20 and (Pt1−yNiy) 0.75P 0.25 alloys in their various states from room temperature to the glass transition temperature Tg.
Abstract: Thermal expansion and density of (Pd1−xNix)0.80P0.20 and (Pt1−yNiy)0.75P0.25 alloys in their various states have been measured from room temperature to the glass transition temperature Tg. The thermal expansion of the glassy alloys at room temperature varies linearly with x and y and is 10 to 20% higher than that of corresponding pure metals. The thermal expansion of the undercooled alloy liquids near Tg as well as the molar volume v deduced from the density of glasses in contrast exhibits a negative deviation with composition x and y. This behavior is in line with the previously reported negative deviation of the glass transition temperature of these glassy alloys with metal content and may be explained in terms of excess volume associated with a mixture of hard spheres.

Journal ArticleDOI
TL;DR: In this paper, a study of the curing reactions of a cycloaliphatic epoxy resin/anhydride system by torsional braid analysis showed the existence of two critical isothermal temperatures - namely, the maximum glass transition temperature of the thermoset system and the glass transition ratio of the material at its gel point.
Abstract: A study of the curing reactions of a cycloaliphatic epoxy resin/anhydride system by torsional braid analysis showed the existence of two critical isothermal temperatures - namely, the maximum glass transition temperature of the thermoset system and the glass transition temperature of the material at its gel point. Two rheologically active kinetic transitions occur during isothermal cure which correspond to gelation and vitrification. Three types of isothermal behavior occur. Methods for determining the time to gel and the time to vitrify, and also the two above-mentioned critical isothermal temperatures, have been developed. The time to gel obeyed the Arrhenius relationship, whereas the time to vitrify passed through a minimum. Application of these results to thermosetting systems in general is discussed in terms of the influence of molecular structure on the values of the critical isothermal temperatures.

Journal ArticleDOI
TL;DR: In this paper, two component topologically-interpenetrating polymer networks were made of the SIN type composed of two polyurethanes (a polyether-based and a polyester-based) in combination with an epoxy resin, a polyacrylate and two unsaturated polyesters.
Abstract: Two component topologically-interpenetrating polymer networks were made of the SIN type (simultaneous interpenetrating network) composed of two polyurethanes (a polyether-based and a polyester-based) in combination with an epoxy resin, a polyacrylate and two unsaturated polyesters. The linear polymers and/or prepolymers were combined in solution and in bulk together with the necessary crosslinking agents and catalysts. Films were cast and chains extended and crosslinked in situ. All of the IPN's exhibited one glass transition (Tg) intermediate in temperature to the Tg's of the component networks, and as sharp as the Tg's of the components. This suggests that phase separation may not occur and thus some chain entanglement (interpenetration) of the two networks is involved. The observed Tg's are always several degrees lower than the arithmetic means of the component Tg's. A theory based on interpenetration is developed to account for this.

Journal ArticleDOI
TL;DR: In this paper, the equilibrium penetrant content of polystyrene, poly(phenylene oxide), and blends of these homopolymers was studied over a significant range of penetrant activity and temperature.
Abstract: The equilibrium sorption of n-hexane vapor and n-hexane liquid in solution cast films of polystyrene, poly(phenylene oxide), and blends of these homopolymers was studied over a significant range of penetrant activity and temperature. These equilibrium sorption measurements were supplemented by density determinations, refractive index measurements, differential scanning calorimetry and differential thermal analysis. A seemingly complicated pattern of results emerged when the equilibrium penetrant content was plotted as a function of blend composition. At relatively low activity and temperature the equilibrium concentration of n-hexane in these films monotonically increased with poly(phenylene oxide) content in the blend. Conversely, at high activities and in unit activity liquid, the equilibrium penetrant concentration exhibited a distinct minimum when plotted as a function of blend composition. At higher activities, solvent induced crazing accompanied the sorption of penetrant. These results were explained consistently by considering the nature of the sorption isotherm over an activity range sufficient to lower the glass transition temperature, of the equilibrated and swollen blend, below the temperature of the sorption experiment. Most importantly, the interpretation and explanation of these data are based upon phenomena common to all glassy polymer-organic penetrant systems and no special properties of this blend system were included in the analysis. The results, therefore, reflect the apparent homogeneity of polystyrene-poly (phenylene oxide) blends and are useful in considering the equilibrium of penetrant sorption in glassy polymers as a general class of materials.

Patent
Jr. Paul H. Pettit1
24 Dec 1974
TL;DR: A thermosetting polymer powder coating composition comprising finely divided powder particles that have a diameter of about 1-100 microns wherein the powder particles are a blend of A. Hard acrylic polymer having a high glass transition temperature; B. Soft acrylic polymer with low glass transition temperatures; C blocked organic polyisocyanate; D. Hydroxy functional plasticizer; and E. catalytic amount of an organometallic compound is particularly useful as an exterior finish for automobile and truck bodies as mentioned in this paper.
Abstract: A thermosetting polymer powder coating composition comprising finely divided powder particles that have a diameter of about 1-100 microns wherein the powder particles are a blend of A. a hard acrylic polymer having a high glass transition temperature; B. a soft acrylic polymer having a low glass transition temperature; C. a blocked organic polyisocyanate; D. a hydroxy functional plasticizer; and E. catalytic amount of an organometallic compound; The thermosetting powder coating composition is particularly useful as an exterior finish for automobile and truck bodies.

Journal ArticleDOI
L. A. Utracki1
TL;DR: In this paper, a new dependence based on the free volume concept and cell-hole liquid theory is proposed, which permits linearization of the viscosity-temperature data in the range (Ti, Ti+1), where the Ti's are the liquid-liquid transition temperatures.
Abstract: Least squares programs were used to evaluate the correlation between recent experimental results and theoretical, semi-theoretical, or empirical relations between liquid viscosity and temperature. It was found that none of these describes the experimental dependence in the whole range of temperature. A new dependence based on the free volume concept and cell-hole liquid theory is proposed. The theory permits linearization of the viscosity-temperature data in the range (Ti, Ti+1), where the Ti's are the liquid-liquid transition temperatures. It was demonstrated that these transitions, both in small molecular and in polymeric liquids, occur in discrete steps: Ti = aiTg, where Tg is the glass transition temperature and the ai's are numerical parameters. Not all the transitions Ti were apparent in all liquids. Transition T2 = 1.26Tg was observed for most polymeric liquids. On the basis of thermal analysis it was demonstrated that the Ti's coincide with the temperatures at which small changes in the a...

Journal ArticleDOI
TL;DR: In this article, the glass transition temperatures of linear and four-and six-branched regular star polystyrenes are measured by penetration, differential scanning calorimetry, and a density gradient technique.
Abstract: The glass transition temperatures of linear and four- and six-branched regular star polystyrenes are measured by penetration, differential scanning calorimetry, and a density gradient technique. The results of the three methods show that the glass transition temperature depends on the concentration of chain ends in the polymer sample. An attempt is made to assess the influence of the presence of the branch point on the glass transition temperature using a series of four-branched polystyrenes containing varying amounts of isoprene near the branch point. However, any effect of the central branch point on the glass transition temperature is obscured by plastification of polystyrene by polyisoprene.


Patent
07 Feb 1974
TL;DR: In this paper, the hair holding compositions are disclosed comprising solutions of water-insoluble block copolymers of the type A-B-(A-B)n-A.
Abstract: Hair holding compositions are disclosed comprising solutions of water-insoluble block copolymers of the type A-B-(A-B)n-A, where the A segment is a polymer having a glass transition temperature above room temperature, the B segment is a polymer having a glass transition temperature below room temperature, and n is zero or an integer from 1 to 5. The compositions provide excellent ''''feel'''' and set retention characteristics.

Journal ArticleDOI
TL;DR: In this article, the formation and thermal properties of glassy Ni-Fe based alloys were investigated and a wide range of glass-forming compositions and could be quenched to the glassy state with relative ease and reproducibility.
Abstract: The formation and thermal properties of glassy NiFe based alloys were investigated. The NiFePBSiAl alloys were found to exhibit a wide range of glass-forming compositions and could be quenched to the glassy state with relative ease and reproducibility. The variation of the glass transition temperature with a change in the ratio of Ni to Fe and with variations in the P, B, C, Si and Al content are reported.

Journal ArticleDOI
TL;DR: In this article, photochromic 3,3-dimethyl-6′-nitroindolinospirobenzopyran methacrylic derivatives have been synthesized.
Abstract: Three photochromic 3,3-dimethyl-6′-nitroindolinospirobenzopyran methacrylic derivatives have been synthesized, namely, 1-methyl 8′-methacryloxymethyl (A), 1-(β-methacrylamidoethyl) (B), and 1-(β-methacryloxyethyl) (C). They have been copolymerized with methyl, isobutyl, and n-propyl methacrylates. The photochromic behavior of these copolymers in the solid state has been compared to that of the homologous isobutyric compounds dissolved in corresponding polymeric matrices. The kinetics of decoloration were resolved in three simultaneous first-order reactions with rate constants k1, k2, and k3. The influence of the polarity of the polymeric matrix and of the photochrome incorporation has been examined. The rates of decoloration of the copolymers with isobutyl and n-propyl methacrylate are very sensitive to the glass transition temperature Tg; the activation energy of decoloration increases markedly above Tg, from 19.8 to 36.5 kcal; below Tg the entropy of activation is strongly negative (around -20 e.u.), above Tg strongly positive. These effects are interpreted on the basis of an increasing chain segment mobility above Tg.

Journal ArticleDOI
TL;DR: In this paper, the glass transition region of crosslinked polymers prepared from poly(1,2-propylene phthalate fumarate) and styrene was studied using a torsion pendulum.
Abstract: The glass-transition region of crosslinked polymers prepared from poly(1,2-propylene phthalate fumarate) and styrene was studied using a torsion pendulum. The glass-transition temperature and the modulus in the rubbery region of these polymers were analyzed in terms of the crosslink density. The styrene concentration at which the maximum crosslink density occurs, as estimated from the viscoelastic data, is found to be in agreement with estimates made by other workers using chemical methods.

Journal ArticleDOI
TL;DR: In this article, the shear creep behavior of polymethylmethacrylate, PMMA, samples has been studied in the neighborhood of and above their glass temperatures, and the glass temperatures were found to be 106 and 117 °C respectively.
Abstract: The shear creep behavior of polymethylmethacrylate, PMMA, samples has been studied in the neighborhood of and above their glass temperatures. One of the materials studied was “ideally” atactic with equal numbers of random isotactic and syndiotactic placements, while the other was a commercial or “conventional” PMMA which was about 76% syndiotactic. The glass temperatures,T g , were found to be 106 and 117 °C respectively. Evacuation above the glass temperature for several weeks was necessary before reproducible creep compliance,J (t), curves could be obtained. It is believed that absorbed water plasticized the polar materials and its removal led to the shifting of theJ (t) curves to longer times. For both materials apparently successful temperature reduction was found to be possible within the temperature range of our investigations, i.e. up to 200 °C. Retardation spectra were calculated from the reduced curves and are compared. The temperature dependences, as described by the time scale shift factors,a T , were similar when allowance is made for the different glass temperature. Botha T curves could not be fitted to theWilliams, Landel, andFerry, WLF, free volume expression. These are the first examples of such a deviation for amorphous high polymers. It is proposed that the primary softening dispersion has two distinctly different groups of viscoelastic mechanisms contributing to it. On this basis the primary dispersion was decomposed into the two contributions. Both of the resulting temperature dependences were satisfactorily fitted to the WLF equation. Differences in the retardation spectra are noted. The glassy compliance of the commercial PMMA appears to be about twice that of the atactic PMMA.

Journal ArticleDOI
TL;DR: The synthesis and properties of polyamides, polyimides and polyamide-imides based on 4,4′-[sulfonylbis(p-phenyleneoxy)] dianiline are presented in this article.
Abstract: Novel aromatic diamines have been prepared which contain an ordered sequence distribution of thermally stable, flexible, or rigid units. The synthesis of these materials involves a nucleophilic displacement reaction in aprotic solvent with, for example, the alkali metal salt of p-aminophenol, optionally, the salt of a bisphenol and an activated aromatic halide. Such monomers are useful “building blocks” for various polymeric systems but are of special interest in those which can benefit from the high glass transition temperature imparted by polar or rigid moieties, together with improved impact properties conveyed by either groups. Polyimides and polyamide-imides are examples and display high heat distortion temperatures, good solvent resistance, excellent mechanical properties, high thermal and oxidative stability and depending on diamine structure and molecular weight, thermoplastic characteristics. The synthesis and properties of polyamides, polyimides and polyamide-imides based on 4,4′-[sulfonylbis(p-phenyleneoxy)] dianiline are presented in this paper.

Journal ArticleDOI
TL;DR: In this article, the authors measured changes in microhardness, small-angle X-ray scattering and heat capacity with time of annealing at several temperatures ranging from room temperature to 413 K.
Abstract: The heats of formation of amorphous (1− x )As 2 Se 3 · x Sb 2 Se 3 ( x = 0 to 0.4) referred to crystalline As 2 Se 3 and Sb 2 Se 3 were measured by liquid metal solution calorimetry. The values of heats of formation of amorphous (1− x )As 2 Se 3 · x Sb 2 Se 3 decreased from 1.39 ± 0.03 kcal · (g-at) −1 at x = 0 to 1.27 ± 0.04 kcal · (g-at) −1 at x = 0.4. The glass transition temperature and the temperatures of the maximum rates of crystallization and fusion were measured by differential scanning calorimetry. The glass transition temperature increased and the temperatures of the maximum rates of crystallization and fusion decreased with increasing Sb 2 Se 3 content. The relaxation process in amorphous (1− x )As 2 Se 3 · x Sb 2 Se ( x = 0.3) was investigated by measuring changes in microhardness, small-angle X-ray scattering and heat capacity with time of annealing at several temperatures ranging from room temperature to 413 K. With increasing annealing time the microhardness, the height and the temperature of the glass transition peak increased whereas the intensity of small-angle X-ray scattering decreased. These changes reflect relaxation towards a more stable structure of smaller molecular mobility. The changes in the enthalpy with annealing time and the activation energy spectra for relaxation were derived from the heat capacity data. The effects of temperature and time of annealing on the various properties are explained in terms of structural changes and relaxation kinetics.

Journal ArticleDOI
TL;DR: In this paper, light scattering from boron trioxide has been studied as a function of temperature in the melt near the glass transformation temperature and in the solid, and both polarized and depolarized spectra were obtained.
Abstract: Light scattering from boron trioxide has been studied as a function of temperature in the melt near the glass transformation temperature and in the solid. Both polarized and depolarized spectra were obtained. At all temperatures (20–516°C) the scattering consists of a polarized contribution associated with density fluctuations and a depolarized component presumably connected with the anisotropic nature of the B2O3 glass network. Quantitative results are presented confirming that the polarized scattering from density fluctuations in the solid is determined by the equilibrium compressibility of the melt at the fictive temperature. It is shown that the anisotropic scattering also appears to be ``frozen‐in'' at the fictive temperature.


Journal ArticleDOI
TL;DR: Heat capacities of two high density linear polyethylene samples were measured and spontaneous adiabatic temperature drifts were observed in both samples, attributed to the enthalpy relaxation phenomena occurring in the glass transformation region.
Abstract: Heat capacities of two high density linear polyethylene samples were measured from 2 to 360 K. By incorporating the results from the previous work of this series, thermodynamic properties of completely crystalline linear polyethylene may be estimated. Cp , H - H0, S and - (G - H0) at 298.15 K for crystalline linear polyethylene are estimated to be 22.60 J K-1 mol-1, 3544 J mol-1, 23.02 J K-1 mol-1 and 3319 J mol-1, respectively. Spontaneous adiabatic temperature drifts were observed in both samples near 240 K. These drifts may be attributed to the enthalpy relaxation phenomena occurring in the glass transformation region.

Journal ArticleDOI
TL;DR: In this article, the compressive stress relaxation modulus of a container glass composition was investigated over a wide range of strain, time, modulus, and temperature, and it was shown that the glass behaves in a linear viscoelastic manner up to a 2% strain level.
Abstract: The compressive stress relaxation modulus of a container glass composition was investigated over a wide range of strain, time, modulus, and temperature. It is shown that the glass behaves in a linear viscoelastic manner up to a 2% strain level, and that the relaxation modulus is a smooth function of time, with no pseudo-rubbery plateau apparent down to a modulus of 108 dyn/cm2. The data cover roughly five decades of modulus, five decades of time, and a temperature range of 150° C above the glass transition, Tg = 536°C. Within experimental error, the effect of temperature on the stress relaxation behavior is to simply shift the modulus-time curves along the time axis with no change in shape. Temperature dependent shift factor data are expressed in terms of the WLF relation, and are shown to be in good agreement with data found in the literature for other silicate compositions. Viscosity data derived from the generated stress relaxation data agree well with data obtained by more direct methods.

Journal ArticleDOI
TL;DR: In this article, the effect of drawing on the glass transition temperature of amorphous poly(ethylene terephthalate) has been studied in terms of the configurational entropy and the rate of molecular motion in local mode relaxation.
Abstract: The effect of drawing on the glass-transition temperature of amorphous poly(ethylene terephthalate) has been studied. The Tg decreases to a minimum at a draw ratio of 1.5, then increases to a maximum at a draw ratio of about 2.0, and again decreases with increasing draw ratio. The relationship between the change of structure and Tg is discussed in terms of the configurational entropy and the rate of molecular motion in local-mode relaxation. On the basis of configurational entropy, the decrease of Tg at the beginning of drawing depends on the increase of configurational entropy, while at draw ratios above 2.0 it depends on the increase of entropy associated with intermolecular interaction. From the point of view of molecular motion, it is concluded that the change of Tg is determined by local oscillations in the amorphous region.