The use of CO2 for substituting volatile organic compounds in polymer processing

i.e.

supercritical CO2-assisted polymer processing

has attracted increasing attention in recent years. Dissolution of CO2 in polymer could swell

plasticize and deliver small molecules into the polymer matrixes. Consequently

the structure and morphology of the polymer would change

as well as the fundamental properties

including polymer crystallization

interfacial tension between polymer and gas

and rheology of CO2/polymers melt.CO2-induced changes in these properties could be used to realize the supercritical CO2-assisted polymer processing

e.g.

CO2-assisted polymer grafting

CO2-assisted penetrating of small molecules into polymer and CO2-assisted polymer foaming.Several cases from the authors' laboratory are presented for elucidating how to use the changes to manipulate the CO2-assisted polymer processing.The cases include CO2-induced crystallization of isotactic polypropylene and syndiotactic polypropylene

CO2-induced crystal phase transition of isotactic poly-1-butene

and how to use CO2-induced crystallization to manipulate melt strength of three linear polymers

i.e.

isotactic polypropylene

poly(lactic acid)and poly(ethylene terephthalate)

to prepare the polymer foams with different structures.