Polypropylene carbonate

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Polypropylene carbonate (PPC), also called poly(propylene carbonate), is a polycarbonate plastic material, a copolymer of carbon dioxide and propylene oxide. It is made by reacting the monomers in presence of eg. a zinc glutarate catalyst. Its CAS number is [50862-75-4] [1] or [25511-85-7] [2].

Polypropylene carbonate is soluble in polar solvents, eg. acetone, methyl ethyl ketone, ethyl acetate, dichloromethane and chlorinated hydrocarbons. It is insoluble in ethyl alcohol, ethylene glycols, water, and aliphatic hydrocarbons. Stable emulsions in water are available commercially.

Polypropylene carbonate is used eg. as a binder, and to increase the toughness of some epoxy resins. It is unsuitable as an oxygen barrier, and therefore is used in applications where diffusion of oxygen through the plastic is desired.

In ceramics industry, polypropylene carbonate and polyethylene carbonate are used as sacrificial binders, especially alumina and silicon carbide; the polymers get burned during sintering as they decompose completely above 300 °C. Together with plasticizers they account for the most of the volumes of the ceramic clay additives; a typical amount of binder in the clay is 2-3 weight %. Due to their low content of sodium they are suitable for preparation of dielectric materials, piezoelectric ceramics, and other special electroceramics. As a binder, PPC is available eg. under trade name QPAC-40; polyethylene carbonate is QPAC-25. [3]

Polypropylene carbonate binders are amorphous, with glass transition temperature of 40 °C. Polyethylene carbonate has glass transition temperature of 25 °C.

Monomeric propylene carbonate is used as an organic solvent. It can be used as a plasticizer, to lower the glass transition temperature of polypropylene carbonate and polyethylene carbonate. It is also a byproduct of manufacture of PPC.

Composites of polypropylene carbonate with starch (PPC/starch) can be used as a biodegradable plastic.