Process for preparation of monodispersed crystalline particles from amorphous polymers
AssigneeXerox Corporation
InventorsCharles L. Beatty, John M. Pochan
Life of this patent
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Abstract
Process for preparation of monodispersed crystalline particles from amorphous crystallizable polymers. In this process, an amorphous polymer of an inorganic glass, such as selenium, or of organic polymer, such as a polyester, is initially contacted with a crystal inducing fluid under certain specified conditions. Concurrent with such contact the crystallizable polymer is subjected to physical and/or ultrasonic forces. This combination of steps results in the substantially complete conversion of the amorphous polymer to monodispersed crystalline particles. In the case of crystallization of amorphous selenium, this process is directive for preparation of the corresponding triclinic crystalline form of this material.
Claims26
A process comprising:
- (a) contacting a sample comprising amorphous selenium with a crystal inducing fluid at temperatures in excess of the T.sub.g but below the T.sub.m of the sample, thereby promoting triclinic crystal formation on the surface of said sample;
- and
- (b) subjecting said sample to attrition concurrent with step (a), whereby said triclinic crystals are removed from the surface of said sample and fragmented to monodispersed particles, the rate of removal of crystalline particles from the surface of the sample being approximately equivalent to or greater than the rate of crystal formation on said sample.
A process comprising:
- (a) contacting a sample comprising amorphous, crystallizable inorganic polymer with a crystal inducing fluid at temperatures in excess of the T.sub.g but below the T.sub.m of the polymer, thereby promoting crystal formation on the surface of said polymer;
- and
- (b) subjecting said sample to attrition concurrent with step (a), whereby said crystals are removed from the surface of said sample and fragmented to monodispersed particles, the rate of removal of crystalline particles from the surface of the sample being approximately equivalent to or greater than the rate of crystal formation of said sample.
A process comprising:
- (a) contacting a sample comprising amorphous, crystallizable organic polymer selected from the group consisting of vinyl polymer, poly(olefin) polymer and poly(ether) polymer with a crystal inducing fluid at temperatures in excess of the T.sub.g but below the T.sub.m of the polymer, thereby promoting crystal formation on the surface of said polymer;
- and
- (b) subjecting said sample to attrition concurrent with step (a), whereby said crystals are removed from the surface of said sample and fragmented to monodispersed particles, the rate of removal of crystalline particles from the surface of the sample being approximately equivalent to or greater than the rate of crystal formation of said sample.
Dependencies are inferred from the claim text.