| 摘要 |
<p>The present invention is a rubber modified monovinylaromatic polymer composition comprising:
a) a monovinylaromatic polymer matrix having an average molecular weight in weight Mw above 155,000 g/mol,
b) rubber particles dispersed therein, said particles having :
a volume median particle size (RPS volume) of about 8.5 µm,
a monomodal distribution with essentially no shoulder,
a low-to-moderate crosslinking of the rubber expressed as a swell index (SI) above 14,
a rubber phase volume fraction (RPVF) of at least 39%,
c) a moderate amount of low- Mw plasticizers, defined as the weight fraction of solubles in methanol, and such that the weight ratio c/(a+b+c) ranges from 0 to 5%. The present invention is also a process for preparing the above composition comprising :
a) forming a polymerizable mixture comprising at least one monovinylaromatic monomer and optionally one or more comonomers,
b) dissolving at least a viscous rubber of essentially linear structure in said polymerizable mixture to form a rubber containing polymerizable solution,
c) contacting a free radical initiator and a chain transfer agent with the polymerizable mixture at conditions whereby phase inversion subsequently occurs,
wherein the chain transfer agent is capable to produce an increase of the rubber to PS phase viscosity ratio within the inversion reactor,
d) continuing the polymerization of the solution obtained at step c), optionally in the presence of a free radical initiator, until a monovinylaromatic polymer matrix having rubber particles dispersed therein is obtained.</p> |
