Polymer Initiators

Suspension PVC

Polymerization temperature determines molecular weight classified by K value (K-value is the viscosity measurement correlated with molecular weight).

For different K-values, peroxide cocktails of different activities are required to optimize polymerization time (half-life correlated with reaction time and temperature). The concentration of organic peroxides range from 200 to 2000 ppm.

The table below summarizes the properties of organic peroxide recommended for PVC polymerization

	1 hour Half-life (°C)	comments	Resin grade recommendations
Luperox® 610M50 Luperox® 610EN50	54	Maximizes productivity Minimizes color and odor No aromatics	Front end for K-67 and higher High quality grades
Luperox® 188M75	56	Forms aromatic byproducts Compromises odor, color and productivity for cost	Front end for K-67 and higher
Luperox® 546M75	64	Best alternative to peroxydicarbonates for whiter resins	Back end for K-67 and higher Front end for K-57 and lower High quality grades
Luperox® 10 Luperox® 10EN50	66	Alternative to peroxydicarbonates for whiter resin with some productivity loss	Back end for K-67 and higher
Luperox® 223M75 Luperox® 223EN50 Luperox® 223V70	66	Preferred initiator for S-PVC. Cost effective	Back end for K-67 and higher Front end for K-57 and lower
Luperox® 554M75	74	Lower energy radicals, a higher boiling point and faster rates make this peroxide slightly preferable to Luperox 11	Back end for K-57 and lower High quality grades
Luperox® 11M75	76	Cost effective initiator. Due to low boiling point, could build up fisheyes	Back end for K-57 and lower
Luperox® LP Luperox® LPS40	81	Solid peroxide can be handled with minimal cooling requirements but may form emulsifiers that could interfere with the suspension	Back end for K-57 and lower

Initiator Technologies

For closed reactor

Peroxides are charged in liquid form: ·  Solution in hydrocarbons, e.g. Luperox® 10M75 ·  Aqueous suspension, e.g. Luperox® LPS40 ·  Aqueous emulsion, e.g. Luperox® 610EN50

For open reactors

peroxides could be charged in solid form: ·  Solid percarbonates ·  Frozen flakes (frozen emulsions)