Glass Temperature Of Polymer Research Articles

Viscosity of polydimethylsiloxane–pentamer systems

AbstractViscosities of polydimethylsiloxane–pentamer systems were measured over the whole range of concentration. Twelve samples having molecular weights from about 1000 to 5 × 105 were studied. The empirical reduction scheme, plots of log η versus log cM0.68, suggested by Ferry and co‐workers is applicable to samples of M̄v ≥ 22,000 over the entire concentration. Such satisfying superposition of data may be attributed to the systems being the homologous mixtures in which glass temperatures of polymers are very low. On the basis of the treatment of Fox and Allen, the effects of the number and weight‐average molecular weight on viscosity were examined, and the friction coefficient ζ per chain atom at constant M̄n was calculated over a wide range of M̄n. The value ζ is almost constant (ζ = 7.4 × 10−9 dyne‐sec./cm.) in the region of M̄n ≥ Mc, and where otherwise it decreases rapidly with decreasing M̄n. The length of the chainend segment was tentatively calculated.

A generalized equation of state for polymers

AbstractA simple, generalized equation of state has been developed that describes the pressure–volume–temperature behavior of both addition and condensation polymers. Use of the equation requires only that the polymer's glass temperature and density at 25°C. and one atmosphere be known. The equation applies to both amorphous and crystalline polymers for pressures up to 10,000 atm. It also appears to hold for copolymers. Polymer glass temperatures can also be estimated with the equation.

Effect of the plasticizer structure on the glass temperatures of polymers—I. Plasticization of polystyrene by esters of diphenic and naphthalic acids : A. A. Tager, A. I. Suvorova, L. N. Goldyrev, V. I. Esafov and V. L. Berestova, Vysokomol. soedin. 4: No. 6, 803–808, 1962.

Effect of the plasticizer structure on the glass temperatures of polymers—I. Plasticization of polystyrene by esters of diphenic and naphthalic acids : A. A. Tager, A. I. Suvorova, L. N. Goldyrev, V. I. Esafov and V. L. Berestova, Vysokomol. soedin. 4: No. 6, 803–808, 1962.

Effect of the plasticizer structure on the glass temperatures of polymers—II. Plasticization of polymethylmethacrylate by esters of diphenic and naphthalic acids : A. A. Tager, A. I. Suvorova, L. N. Goldyrev, V. I. Esafov and L. P. Topina, Vysokomol. soedin. 4: No. 6, 809–814, 1962.

Effect of the plasticizer structure on the glass temperatures of polymers—II. Plasticization of polymethylmethacrylate by esters of diphenic and naphthalic acids : A. A. Tager, A. I. Suvorova, L. N. Goldyrev, V. I. Esafov and L. P. Topina, Vysokomol. soedin. 4: No. 6, 809–814, 1962.

Polydimethylpolyphenylsiloxanes by catalytic condensation

THE technical use of organosilicon polymers has brought about the necessity~ of investigating their properties at high temperatures. The properties of po]ydimethylpblyphenylsiloxane {L), obtained by catalytic polymerization from phenyltrichlorosilane and dimethyldichtorosilane, are described in this paper. Polymer I I contained 25 per cent more triiunctional monomer than I. Polymer I I I differed from I in containing 5 per cent of a tetrafunctional component; polymer IV differed from polymer II in the same way. Polymer V contained polya]uminomethylphenylsiloxane. Investigation of the propelX, ies was carried out on the free films and on films on a metal substrate. Experiment has shown that the mechanical properties of polymer films depends on their composition and they va~, markedly with temperature. Polymer II, containing more of the trifunctional monomer, is rather stronger at room temperature than I but the strength of both polymers falls sharply with increasing temperature (Fig. 1, curves I and II). The introduction of 5 per cent of a tetrafunctional crosslinking agent increases the initial mechanical strength a little (polymer II]), lowers the elongation in the original state from 40-50 to 15 per ceut and increases it to 60-70 per cent at high temperatures. The mechanical strength falls considerably more slowly with increase in temperature (curve III). The introduction of a crosslinking agent with polymer II results in a decrease in the elongation at break from 20 to 10 per cent. in the original state, and at 160-180 the elongation is 60-70 per cent. The mechanical strength of polymer IV falls considerably less with increasing temperature than does that of the original polymer II. The addition of polyaluminomethylphenylsiloxanes reduces still fnrther the effect of temperature on mechanical strength (curve V). The elongation at break does not exceed 15-20 per cent. Figure 2 shows the thermomechanical properties of these polymers. The curves indicate that polymer II has a higher glass temperatm~ (T~) than polymer I. The glass temperatures of polymers I I I V are also higher. The deformations found in the study of the thermomechanical properties are in complete agreement

Effect of pressure on the glass temperature of polymers : S. A. Arzhakov, E. E. Rylov and B. P. Shtarkman, Vysokomol. soedin. 1: No. 9, 1438, 1959

Effect of pressure on the glass temperature of polymers : S. A. Arzhakov, E. E. Rylov and B. P. Shtarkman, Vysokomol. soedin. 1: No. 9, 1438, 1959

Influence of molecular weight and degree of crosslinking on the specific volume and glass temperature of polymers

AbstractOn the basis of simple assumptions, equations are derived for predicting the specific volume‐temperature‐molecular weight (v‐T‐M) relationships for a homologous series of polymers from the v‐T curves for the monomer and the polymer of infinite molecular weight. Analogous v‐T‐ρ relationships (where ρ is the degree of crosslinking) are similarly obtained. The result, that v decreases linearly with decreasing 1/M and with increasing ρ, conforms with the picture that either the removal of two chain ends (as M increases) or the introduction of a crosslinkage involves, between two polymer segments, the exchange of a van der Waals bond for a shorter covalent bond. The validity of these equations is illustrated by comparison with the observed data for polymers covering a wide range in M, T, and chemical type. For several polymer series the extrapolated value of v at 0°K (v0) is the same for all members of the series, indicating that at this temperature the average length of the van der Waals and covalent bonds between polymer segments are the same. Assuming that the form of the linear relationship observed for polystyrene between the specific volume (vg) at the glass temperature and the value (Tg) of the latter is valid for other polymer series, equations are derived which predict Tg as a function of M from the limiting value of the glass temperature for a chain of infinite length, and from the v‐T curves in the liquid state for the monomer and for the polymer of M = ∞. Analogous Tg‐ρ relationships are similarly obtained. According to these equations, a linear relationship between 1/Tg and 1/M should be obtained, which reduces at high M to a linear dependence of Tg on 1/M. Similarly, a linear dependence of Tg on ρ is predicted at low ρ. These predictions are in satisfactory agreement with data on polystyrene fractions and on crosslinked copolymers of styrene with divinylbenzene.The conclusion that Tg for polystyrenes represent a state of iso‐free volume irrespective of M is shown to be an approximation that is valid, within experimental error, only for large values of M.