- Name: NOROX® CHP
- Chemical Composition: cis-Isopropylbenzene peroxide
- CAS Number: 80-15-9
- Form: Liquid mixture
- NOROX® CHP is a colorless to pale yellow liquid solution of cis-isopropylbenzene hydroperoxide. It is an economical free-radical initiator for unsaturated polyester resins, ethylene monomers, and alkyd resins.
- NOROX® CHP can be used alone or in combination with other peroxides in both ambient-temperature and high-temperature processes.
- Appearance: Pale yellow to colorless liquid
- Active oxygen content: 8.7%
- cis-Isopropylbenzene peroxide content: 80–85%
- Flash point (Seta C.C.): > 72°C
- Density @ 20°C: 1.05 g/cm³
- Soluble in: alcohols, ketones, esters, hydrocarbons
- Slightly soluble in: water
- Critical Temperature (SADT): 75°C
- Recommended storage temperature: Below 30°C; retains activity for 6 months from the date of delivery
- NOROX® CHP is particularly suitable for initiating the curing of unsaturated polyester resin systems at both room temperature and elevated temperatures.
- The exothermic curve typically exhibited is mild and flat, resulting in gradual and thorough curing. This characteristic minimizes cracking and splitting in thick cross-sections.
- NOROX® CHP is typically used in pre-promoted resin systems that use cobalt and/or manganese compounds as the primary catalysts.
- Note: NOROX CHP must never be mixed with acids or directly with promoters or accelerators. This may cause violent decomposition, leading to fire and/or explosion.
- This combination results in lower peak exothermic heat release, the specific magnitude of which is determined by the mixing ratio. The use of NOROX® CHP in the mixture extends the cure time but does not compromise the final cure.
- At temperatures above 82°C, NOROX® CHP behaves similarly to highly exothermic peroxides.
- At temperatures above 121°C, the use of NOROX® CHP may result in exothermic reactions exceeding those typically expected for dibenzoyl peroxide or methyl ethyl ketone peroxide.
- Resin: Epoxy-vinyl ester resin*
- Temperature: 25°C
- Percentage of initiator: 1.5%
- Accelerator percentage: 0.10% (12% cobalt) + 0.05% DMA
- Initiator gel time (minutes): 935
- Time to Peak (minutes): >236
- Peak exothermic temperature (°C): 28
- Hardness at 2 hours: 0
- 3-hour hardness: 0
- Hardness at 4 hours: 7
- 24-hour hardness: 934
- NOROX® CHP: 56
- NOROX® CHM-50: 16
- NOROX® MEKP-925H: 18
- The standard packaging size for NOROX® CHP is a 25-kilogram polyethylene bottle.