Precise measurement of the PVT of polypropylene and polycarbonate up to 330�C and 200 MPa

Abstract

An apparatus for measuring the pressure-volume-temperature (PVT) properties of polymers using a metal bellows has been developed at temperatures from 313 to 623 K and pressures up to 200 MPa. A calibration of the device was performed by measuring PVT of mercury and water. The experimental uncertainty of specific volumes was estimated to be within {0.2%, while that of temperatures was within {0.1 K below 300ЊC and {0.3 K above 300ЊC. The estimated uncertainty of pressures was {0.1 MPa below 100 MPa and {0.25 MPa above 100 MPa. The PVT properties of polypropylene and polycarbonate were measured by the apparatus in the temperature ranges from 40 to 300ЊC and from 40 to 330ЊC, respectively, and pressures from 10 to 200 MPa. The effects of a sample cup and sample forms were investigated. The use of the sample cup showed a little effect on the measurments of PVT properties for both samples. The shape (pellet and pillar) of the samples caused a small difference in the specific volumes only under high temperatures and low pressures. The PVT properties in a melt state were correlated by the Simha-Somcynsky equation of state, showing a good agreement with measurements.

Pressure relaxation of polystyrene and its comparison to the shear response

“…The piston diameter is 3.16 mm; considering the backlash of the gear and the temperature stability, a conservative resolution of 7 3 10 À6 cm 3 can be achieved, which is much better than other PVT instruments. [21][22][23][24] The piston position is measured by a linear variable differential transducer (LVDT, from Omega Engineering) mounted at the end of the piston. The instantaneous pressure of the system is monitored by a commercial pressure transducer (up to 60,000 psi, from Sensotec).…”

Influence of cooling rate on pVT‐data of semicrystalline polymers

“…Consequently, these standard techniques (confining fluid and piston die) can only be used for amorphous polymers or at low cooling rates for semi-crystalline polymers. Specific volume measurements at low cooling rates were done by Douillard [3] [17] measured the specific volume of a semi-crystalline polypropylene and studied the effect of a sample cup holder and the sample form. Because crystallization kinetics were not included, direct and quantitative conclusions on the influence of the crystallization kinetics on the specific volume could not be drawn.…”

PVT Properties of Polymers for Injection Molding

“…PVT testing setup developed by Barlow (1978). Sato et al (1997) developed an apparatus (Fig. 6) using a metal bellows at temperatures from 40 to 350 °C and pressures up to 200 MPa.…”

“…The shape (pellet and pillar) of the samples caused a small difference in the specific volumes only under high temperatures and low pressures. Sato et al (1997).…”

“…It has been shown that differences between the piston-die and confining-fluid technique in methods or measurement principles do not lead to differences in measured values bigger than 4% (Sato et al, 1997).…”