Claims
- 1. A method for the preparation of an impact resistant polystyrene resin which comprises copolymerizing a styrene monomer and 1 to 15% of an essentially uncrosslinked natural or synthetic rubber in a bulk-suspension system wherein the reaction in the bulk step is initiated thermally in the absence of any initiator compound but in the presence of a molecular weight modifier and continued to phase inversion, the system then being suspended in water and the reaction continued in the presence of an unsymmetrical peroxy-free azo catalyst of the structure R--N.dbd.N--R' where R and R' are different radicals and the R radical is selected from C.sub.2 or higher alkyls, substituted C.sub.1 or higher alkyls, cycloalkyls, aryl-substituted alkyls and substituted cycloalkyls and substituted aryl-substituted alkyls and being characterized by being capable of initiating styrene monomer polymerization and abstracting hydrogen from a natural or synthetic rubber, and the R' radical is selected from alkyl radicals in which the radical carbon carries a substituent selected from nitrile, nitro, aromatic, substituted aromatic, methoxy and halogen groups and being characterized by a resonance stabilization equivalent to the resonance stabilization in the styryl radical and being capable of initiating the polymerization of styrene but not capable of abstracting hydrogen from a natural or synthetic rubber, said R and R' radicals being further characterized by having reactivities of 2 to 9 and 0.1 to 2 respectively on a reactivity scale in which the benzoyloxy free radical has a reactivity rating of 14 and the isobutyronitrile free radical has a reactivity rating of 0.6.
- 2. The method of claim 1 wherein the polymer is a linear homopolybutadiene-1,4 having a cis content of 25-99.5 in its molecular configuration.
- 3. The method of claim 1 wherein R is 1-t-butyl and R' is 1-cyanocyclohexyl.
- 4. The method of claim 1 wherein R is 2-t-butyl and R' is 2-cyanobutyl.
- 5. The method of claim 1 wherein R is 2-t-butyl and R' is 1-isobutyronitrile.
- 6. The method of claim 1 wherein R is 1-tertiary amyl and R' is 1-cyanocyclohexyl.
- 7. The method of claim 1 wherein the R radical is selected from tertiary butyl and substituted tertiary butyl radicals in which the substituent groups are selected from alkyl, cycloalkyl and aromatic radicals.
- 8. The method of claim 1 wherein the R radical has a reactivity rating of 2-9 and the R' radical has a reactivity rating of 0.1-2 based on a scale where the benzoyloxy radical has a reactivity rating of 14 and the isobutyronitrile radical has a reactivity rating of 0.6.
- 9. A polystyrene composition comprising a matrix of polystyrene resin containing dispersed therein a natural or synthetic rubber of which at least 95% of the molecules are grafted with chains of polystyrene attached at an average of 2-4 sites per rubber molecule, the grafted chains of polystyrene being substantially the same length as the polystyrene molecules in the matrix with the grafted and matrix polystyrenes each having a weight average molecular weight of about 250,000-700,000, said polystyrene composition being essentially uncrosslinked and substantially completely soluble in toluene.
- 10. The polystyrene composition of claim 9 wherein the rubber is a linear homopolybutadiene having a cis-1,4 content of 25-99.5% in its molecular structure and is essentially uncrosslinked.
Parent Case Info
This application is a continuation of application Ser. No. 655,546 filed on Feb. 5, 1976 and now abandoned, which was a continuation-in-part of application Ser. No. 408,172 filed on Oct. 19, 1973, now abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
3925511 |
Loveless |
Dec 1975 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
655546 |
Feb 1976 |
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Continuation in Parts (1)
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Number |
Date |
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Parent |
408172 |
Oct 1973 |
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