Pressure–volume–temperature dependencies of polystyrenes

Equations of state for polyamide‐6 and its nanocomposites. 1. Fundamentals and the matrix

“…The molecular weight dependence of the characteristic parameters and L-J quantities was reported for PS. 30 It is noteworthy that the larger value of T*f o r1 0 2 2 Bm e a n s that in this polymer the free volume content (at the same P and T) is smaller than that in 1015B 13 ; this could be expected for higher molecular weight.…”

“…It is evident that increased molecular weight and possibly change of molecular configuration resulted in higher values of L-J interaction coefficients, e* and v*; for PS, these coefficients linearly increased with logarithm of M w . 30 The dynamic shear behavior of 1022B is also different than that from that of 1015B. 27 For example, the reported strong polycondensation at 513 K for 1015B was found to be greatly reduced for 1022B, possibly because of high molecular weight.…”

Free volume dependence of polymer viscosity

“…It incorporates the Huggins and Flory configurational entropy of mixing (Flory 1953), and the Lennard-Jones (L-J) intersegmental interactions (Lennard-Jones 1931;Lennard-Jones and Devonshire 1937) with the characteristic segmental energy, ɛ*, and volume, v*, per statistical segment, the latter defined as M s =M n /s, where M n is the number-average molecular weight (Utracki 2005). The authors also introduced the number 3c of the external, volume-dependent degrees of freedom (Prigogine et al 1953a(Prigogine et al ,b, 1957, which for linear, flexible molecules is (Simha 1977):…”

“…The theory also expresses the molecular weight of statistical segments as: M s ò RT*/ P*V* (see below). For most vinyl polymers M s ≈1/2M 0 , where M 0 is molecular weight of the mer (Utracki 2005), i.e., statistically vinyl mer with two C-atoms in the main chain occupies two lattice cells. Thus, replacing P*b yP* R =κP* reduces M s by a factor of κ.…”

“…However, for polymers this strategy is dangerous. There are many polymer grades, and the commercial resins contain plethora of different additives (Utracki 2005)-taking data from different sources may lead to serious errors. Furthermore, initially the method used to fit the PVT data to S-S eos was sequential (first, determine T* and V* from data at ambient pressure, and then compute P* from data at P>0), resulting in a T and P dependence of P*; the current simultaneous fit of data eliminates this ambiguity.…”