POLYSTYRENE
Polystyrene is a versatile plastic used to make a wide variety of consumer products. It is made by polymerizing styrene, a building-block chemical used in the manufacture of many products. Arkema offers a large range of organic peroxide initiators suitable for the different polystyrene technologies, such as General Purpose Polystyrene (GPPS) and High Impact Polystyrene (HIPS) continuous mass processes and expandable polystyrene (EPS) batch suspension process.
Peroxide Selection Guidelines
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The right selection of peroxides will help the HIPS and GPPS industries to increase productivity, improve molecular weights and lower oligomer residuals. On the other hand, the accurate combination of peroxides in EPS production will contribute to reduce cycle time and minimize residual styrene level guaranteeing benzene free materials.
GPPS and HIPS Applications
Increasing productivity and reducing oligomers residuals
For GPPS production, Arkema proposes di-functional perketals such as Luperox® 531, Luperox® 231 or Luperox® 331 that have the capability to increase productivity while maintaining molecular weights (figure 2). Oligomers residuals are also reduced.
For HIPS production, monoperoxycarbonates like Luperox® TBIC and Luperox® TBEC will increase the grafting and improve the rubber phase efficiency resulting in enhanced impact properties
Luperox® TAEC is used as well to maximize the occluded polystyrene in rubber nodules of HIPS
Luperox® JWEB
Luperox® JWEB is a tetra-functional initiator for mass polymerization of Polystyrene. A unique feature of Luperox® JWEB is its ability to produce branches in the polymer chains, which improves hot viscoelasticity (melt strength) that facilitates resin processing by increasing the thermoforming speed. The quality of PS honeycomb foam produced with this initiator is also improved in terms of strength, structure and uniformity.
This food approved peroxide allows PS producers to increase the productivity and the quality of their food packaging grades (see scheme on the right).
Expended Polystyrene (EPS)
EPS mission : Insulation of houses
Arkema produces high quality benzoyl peroxide Luperox® A75, which enables very fine control of the bead size distribution of EPS resins.
Efficient monoperoxycarbonates such as Luperox® TAEC and Luperox® TBEC are utilized as finishers to increase productivity and decrease styrene residuals. They can contribute to reduce the dosage of recently classified toxic (EU) Luperox® DCP, the synergist of polymeric brominated flame retardants (FR) most use so far for construction insulating boards.
Arkema works on the entire substitution of Luperox® DCP, to propose a safe peroxide performing both as a finisher and FR synergist.