Experimental Study of Sorption and Diffusion of n-Pentane in Polystyrene

Abstract

Polystyrene (PS) foams are widespread heat insulation and impact absorption materials, but many blowing agents used in their production are harmful to the environment. Pentane is a less harmful alternative and is commonly used in the manufacturing of expandable PS, but there are inadequate diffusion data of pentane in PS available in the literature at conditions relevant to PS impregnation and foaming. We conducted gravimetric measurements of sorption dynamics of n-pentane in PS particles and thin films at temperatures from 45 to 110°C and pressures from 0 to 4.8 bar. The measured data were fitted using the Fick's and case II diffusion models and the obtained transport parameters are presented together with an analysis of the dominant diffusion mechanism. We also present the Flory−Huggins interaction parameter for the PS + n-pentane system and show that it can be used to accurately predict the sorption equilibria. This paper thus provides important parameters for the optimization of PS foam production.

Liquid CO2 processing of solid polylactide foam precursors

“…Consistent with the previous observations on similar systems, e.g. PS/ n -pentane, 18 the diffusion profile showed some of the qualitative features associated with “case II” diffusion, i.e. steady advance of a well-defined step-like diffusion front.…”

“…To maintain simplicity, no attempt was made to account explicitly for changes in the specimen dimensions due to swelling of the PLA by the CO 2 , implying a systematic error in the absolute values of D of up to 10% for the largest c considered here (assuming volume swelling to be approximately commensurate with the CO 2 content). 18,19 There was also significant experimental uncertainty at short times, mainly owing to loss of CO 2 during transfer and temperature equilibration), resulting in an experimental error of about 2 % in the initial CO 2 content, although the numerical simulations indicated this to have little influence on X(t) for t greater than a few minutes under the present conditions. Figure 2 shows the values of D[0] and A used to fit the data in Figure 1, plotted as a function of 1/T.…”

Equilibrium Sorption of Propane and 1-Hexene in Polyethylene: Experiments and Perturbed-Chain Statistical Associating Fluid Theory Simulations

“…In order to obtain correct solubilities, several phenomena must be considered: the time drift of the balance, buoyant forces, and polymer swelling. If all necessary corrections are applied, the uncertainty of the obtained solubilities is well below 3% …”

Swelling of polyethylene particles and its relation to sorption equilibria under gas‐phase polymerization conditions

“…The maximum error caused by neglecting the polymer swelling for this sample and temperature is 4.2% for ethylene sorption and 12% for propylene sorption, respectively. Because the standard error of gravimetric measurements is lower than 1%, neglecting the swelling would significantly increase the experimental error. On the other hand, the influence of swelling on the evaluation of 1‐hexene solubility is insignificant and results in errors lower than 1%, see Figure .…”