Polymer Initiators

Longchain

Luperox^® JWEB50 organic peroxides has been specifically developed to produce high molecular weight, high-heat, crystal PS at improved productivity and cost efficiency. This peroxide is multifunctional allowing polymerization of branched macromolecules.

A[O] = 3,25 - 3.39wt% 50 % assay in ethylbenzene

Luperox^® JWEB50 organic peroxides is a room temperature stable liquid, 1 hr T = 119°C (in ethylbenzene) peroxide with half-life similar to currently used cyclic 121°C (in dodecane) perketals and is appropriate for use in mass PS processes. Long-Chain branched PS

A unique aspect of Luperox^® JWEB50 organic peroxides is its ability to produce long-chain branching. Changes in melt rheology caused by branches have been used in polyolefins and even PET to improve processing behavior (melt strength). Branching increases low shear viscosity and causes an earlier onset of shear thinning that results in a nearly equivalent high shear viscosity.

wt% Luperox® JWEB50	MFI 5kg/200°C g/10 min	viscosity (Pa.s)
		0.05 s-1	500s-1
0	11.7	4000	180
60	7.9	6000	210

Conditions: A[O] = 26.5 ppm: CSTR: res. time = 1h33min, T = 119°C,for Luperox^® 331 and 123°C for Luperox^® JWEB50: PFR: 42m, T = 137-157°C; Feed rate = 2.61 lb/hr

The table denotes shear rheology of PS prepared in a continuous process with Luperox^® 331M50 and JWEB50 at equivalent A[O].

As shown below the use of a mixture - 40% Luperox^® 331M50 and 60% Luperox^® JWEB50 - increases long chain branching. The result is an increase of the extensional viscosity and melt strength of PS. These features are useful in processing operations that require significant stretching or low sagging.

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Transient extensional viscosity measured using a Rheometrics RME at 160°C.