Polymer Plasticization Using Supercritical Carbon Dioxide:  Experiment and Modeling

Abstract

The most important effect of sorption of compressed gases and supercritical fluids into glassy polymers is the reduction of the glass transition temperature (T g). This plasticization effect causes changes in mechanical and thermophysical properties of the polymers. In this work, a thermodynamic study based on experimental and theoretical results is addressed. New data were carried out for poly(2,6-dimethylphenylene oxide) (PPO), poly(acrylic acid) (PAA), and the copolymer vinylpyrrolidone−vinyl acetate [P(VP−VA)] using an inverse gas chromatographic technique. To model the T g behavior of diluent−polymer systems, a model that couples the lattice-fluid equation of state and the Gibbs−DiMarzio criterion was used. A parametric study of the influence of the physical properties (lattice coordination number, molecular weight, and binary interaction parameter) on the T g behavior is presented. The thermodynamic model fairly describes the experimental data measured in this work and gives a phenomenological representation of the retrograde vitrification for the systems PPO−CO2, PVP−CO2, and P(VP−VA)−CO2.

Effect of Pressure on the Melting Point of Pluronics in Pressurized Carbon Dioxide

“…Their melting behaviour was comparable to Pluronics® in the pressure range of 0.1 to 40 MPa 34,35 . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 A u t h o r ' s a c c e p t e d m a n u s c r i p t The melting point depression is widely accepted to occur due to the increase in polymer free volume and segment mobility caused by the dissolution of CO 2 in the matrix 36 . The degree of depression is dependent on CO 2 's ability to interact with CO 2 -philic functional groups present in an excipient 37 .…”

The sorption behaviors in PLLA-CO2 system and its effect on foam morphology

“…A number of techniques such as creep compliance, stepwise differential scanning calorimetry (DSC) and solubility measurements have been utilized to establish the retrograde behavior [15][16][17][18]. The technique of systematic solubility measurement has been used to demonstrate the unique retrograde behavior in amorphous poly(methyl methacrylate) (PMMA)-CO 2 [18,19], acrylonitrile-butadiene-styrene copolymer (ABS)-CO 2 [20], and syndiotactic PMMA (sPMMA)-CO 2 [20] systems.…”

Room‐Temperature, Near‐Instantaneous Fabrication of Auxetic Materials with Constant Poisson's Ratio over Large Deformation

“…[ 23 ] This aspect results in a substantial solubility of CO 2 , generates additional free volume and greatly enhances the polymer chain mobility, leading to a signifi cant reduction of the glass transition temperature in a variety of polymers containing these groups. [24][25][26][27] It is therefore plausible that by employing carbon dioxide to reduce the glass transition temperature of SAN copolymers, which contains a substantial amount of nitrile groups, the required processing temperatures would be decreased to a level that issues stemming from the poor thermal transport properties of the PU foams can be alleviated or overcome. Carbon dioxide also has an added benefi t due to its attractive properties such Since the fi rst report of artifi cial auxetic materials in 1987, [ 1 ] signifi cant effort has been made to developing auxetic polyurethane (PU) foams, [2][3][4][5][6][7][8][9][10][11][12][13][14][15] due to their novel properties and numerous potential applications including increased indentation resistance and energy absorption for applications in protective equipment, [ 7,8,15 ] improved acoustic and dielectric properties for damping applications and wave absorption, [ 16 ] and controlled porous structure for fi lters.…”