(DE4038043-A)      Polymers comprise (a) a styrene polymer, (b) 1-10 wt. % w.r.t. (a) of a satd. 3-6 C hydrocarbon as blowing agent and (c) opt. conventional assistants in effective amts.. The benzene content is less than 1 ppm and the styrene content is less than 2000 ppm.    The expandable styrene polymer is prepd. e.g. by polymerisation of styrene, opt. together with other comonomers, in aq. suspension in the presence of 0.1 - 1 wt. % of a styrene-soluble peroxy cpd. with a half life of 1 hour at 120-135 deg. C. opt. in combination with a peroxy cpd. with a half life of 1 hour at 85-95 deg. C as catalyst, carrying out the polymerisation such that 30-90 % of the styrene is polymerised in the temp. range 120-150 deg. C and the residual styrene content in the polymer is less than 0.2 %, and before, during or after the polymerisation, adding the blowing agent and any other assistants.    USE/ADVANTAGE -   Styrene polymers with a greatly reduced benzene content can be made using a benzoyl gp.-free peroxy cpd. with a half life of 1 hr at 120-135 deg. C as polymerisation catalyst. The resulting styrene polymers have improved expandability and give expanded polystyrene foams with a very low benzene content and which are therefore suitable for use e.g. in medical applications and foodstuff packaging.    (US5266602-A)      Prepn. of an expandable styrene polymer comprises polymerising styrene in the presence of 1-10 wt.% of a satd. 3-6C-hydrocarbon as blowing agent opt. in the presence comonomers, in aq. suspension and opt., conventional additives added before, during or after the polymerisation. The catalyst (pref. in an amt. of 0.2-0.7 wt.%) used is a benzoyl-free peroxy cpd. having a half life of 1hr. at 85-95 deg.C. The polymerisation is so that 30-90% of the styrene polymerises at 120-150 deg.C and the residual styrene content in the polymer is less than 0.2%.    USE/ADVANTAGE -   The prepn. yield, benzene-free expandable styrene polymers useful in medicine and for the packaging of foodstuffs.    (EP488040-A3)      Polymers comprises (a) styrene polymer, (b) 1-10 wt% w.r.t. (a) of a satd. 3-6C hydrocarbon as blowing agent and (c) opt. conventional assistants in effective amts. The benzene content is less than 1 ppm and the styrene content is less than 2000 ppm.    The expandable styrene polymer is prepd. e.g. by polymerisation of styrene, opt. together with other comonomer, in aq. suspension in the presence of 0.1-1 wt% of a styrene-soluble peroxy cpd. with a half life of 1 hour at 120-135 deg.C opt. in combination with a peroxy cpd. with a half life of 1 hour at 85-95 deg.C as catalyst. carrying out the polymerisation such that 30-90% of the styrene is polymerised in the temp. range 120-150 deg.C and the residual styrene content in the polymer is less than 0.2% and before, during or after the polymerisation adding the blowing agent and any other assistants.    USE/ADVANTAGE -   Styrene polymers with a greatly reduced benzene content can be made using a benzoyl gp.-free peroxy cpd. with a half life of 1 hr. at 120-135 deg.C as polymerisation catalyst. The resulting styrene polymers have improved expandability and give expanded polystyrene foams with a very low benzene content and which are therefore suitable for use e.g. in medical applications and foodstuff packaging5    (EP488040-B1)      An expandable styrene polymer which comprises a) a styrene polymer; b) from 1 to 10% by weight, based on a), of a saturated C3- to C6-hydrocarbon as blowing agent, and, if desired, c) conventional assistants in effective amounts.    (EP488040-B2)      Polymers comprises (a) styrene polymer, (b) 1-10 wt% w.r.t. (a) of a satd. 3-6C hydrocarbon as blowing agent and (c) opt. conventional assistants in effective amts. The benzene content is less than 1 ppm and the styrene content is less than 2000 ppm.    The expandable styrene polymer is prepd. e.g. by polymerisation of styrene, opt. together with other comonomer, in aq. suspension in the presence of 0.1-1 wt% of a styrene-soluble peroxy cpd. with a half life of 1 hour at 120-135 deg.C opt. in combination with a peroxy cpd. with a half life of 1 hour at 85-95 deg.C as catalyst. carrying out the polymerisation such that 30-90% of the styrene is polymerised in the temp. range 120-150 deg.C and the residual styrene content in the polymer is less than 0.2% and before, during or after the polymerisation adding the blowing agent and any other assistants.    USE/ADVANTAGE -   Styrene polymers with a greatly reduced benzene content can be made using a benzoyl gp.-free peroxy cpd. with a half life of 1 hr. at 120-135 deg.C as polymerisation catalyst. The resulting styrene polymers have improved expandability and give expanded polystyrene foams with a very low benzene content and which are therefore suitable for use e.g. in medical applications and foodstuff packaging5