Specific volume vs. temperature

Fig. 4. Specific volume vs temperature for a crystallizahle polymer. The dashed line represents amorphous material (6). Numbers refer to individual states.

Figure 3 Curves of specific volumes vs. temperature for poly(vinyl acetate) measured on cooling. Equilibrium values measured 0.02 h and 100 h after cooling, as indicated. Tg and Tg are glass transitions respectively at fast and slow cooling rate. Reproduced from Ref. [2] with permission of John Wiley Sons, Inc.

The specific volume vs. temperature data were obtained by using capillary dilatometers. Specific volumes at 25°C., determined in a pycnometer, were used as reference. 

The existence of regions of excess a suggests that there is a loosening of the membrane s polymer network, which implies an increase in specific volume. Since the and excess a plots demonstrated that the region between T/Tg = 0.83 and 0.87 was reasonably constant, this portion of the specific volume vs. temperature curves could be fitted quite well with straight lines. When these lines are extrapolated to higher temperatures, an excess specific volume term can be arrived at by subtracting from the measured values of V8 the extrapolated values of the lines. 

Fig. 1.5a Specific volume vs. temperature plot for a crystalline solid and a glassy material with a glass transition temperature (Tg).

FIGURE 82 MELT SPECIFIC VOLUME VS TEMPERATURE FOR NEAT XYDAR 300 SERIES LOWER MELTING POINT RESIN... 

Figure 12.8 shows a plot of specific volume vs. temperature for the poly(vinyl acetate)/acetonyl acetone system at a solvent volume fraction of 0.14 (Kokes etal., 1952). By comparing these data with your results for Problem 1, discuss the effect of solvent addition on the specific volume and T. ... 

Figure 1.39 Tg estimate from the change in specific volume vs. temperature for a commercial PES.

Figure 7.15 Specific volume vs. temperature and pressure (PVT) for Basell Polyolefins PE resins [2].

Figure 8.72 Specific volume vs. temperature for Arkema Pebax 3533 SN 01—Shore hardness 35 TPEs—PEBA resin.

Tig. 28. Specific volume vs temperature plot for PBFP. The volume coefficient of thermal expansion 2.48x lO in crystalline state (below 60 °C) 6.99 x IQ- °C- in the mesomorphic... 

FIG. 11 -8. Specific volume vs. temperature for poly(vinyl acetate), measured after cooling quickly from well above Tg. Black points, equilibrium values half black, values measured 0.02 hr and 100 hr, after quenching the sample is indicated. (Kovacs. )... 

Sketch the variation of the specific volume vs. temperature for an amorphous polymer. Indicate regions of free volume, occupied volume, the Tg and the T . Give the correct names for the Tg and the T... 

Fig. 4.27 Specific volume vs. temperature for semicrystalUne polyethylene. The degree of crystallinity, c, in percent can be obtained from.

Here v is the velocity of sound, and it is assumed to be a function of temperature and pressure. oc is the specific volume vs temperature (thermal expansion) coeffident If there are no relaxation effects, then ... 

The cubic thermal expansion coefficient, determined from the specific volume vs. temperature plot, both before and after the densification process, (run II), is ap = 2.0 10 " (7), typical of that for glassy polymers. 

A classic method for determining Tg is dilatometry, in which the specific volume of the polymer is measured as a function of temperature. Figure 1 compares the specific volume vs. temperature curves for two idealized samples a 100% amorphous material and a 100% crystalline material. Both materials follow the same path as their liquids are cooled from the melt. At the melting temperature, Tm.the crystallizing material orders into its crystal habit and exhibits a discontinuous decrease in specific volume. Below Tta, this solid has a reduction in specific volume with decreasing temperature, but the slope of this line, the volmnetric thermal expansion coefficient, is less than the slope of the Uquid line. 

The temperature dependence of the specific volume of proteins outside the range of thermal stability (usually outside the linear range between 4 and 45 °C) is complex and nonlinear. A plot of specific volume vs. temperature may display several sections, the thermal effects depending on the protein under investigation and the environmental conditions (e.g., pH, solvent, presence of additives). For example, a... 

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