Synonyms | carbomer, carboxypolymethylene; carbomer homopolymerDefinition | High-molecular mass polymers obtained by polymerisation of acrylic acid and crosslinking with allyl pentaerythritol. The polymers are synthesised in ethyl acetate using a peroxide to initiate free-radical polymerisation.CAS No | 9007-20-9 (primary CAS), 9003-01-4 (secondary CAS)Chemical name | Carbomer homopolymer, allyl pentaerythritol cross-linkedChemical formula | -(CH2-CH)m-(XM)pCOOHm: number of monomer units; XM: crosslinker, p: number of crosslinker units, with m>>pWeight average molecular weight |Assay | Carboxylic acid content not less than 56 % and not more than 68 % (on dried substance)Description | White or almost white, fluffy, hygroscopic powder or granulesIdentification |Attenuated total reflective infra-red spectroscopyProton nuclear magnetic resonance spectroscopy | Characteristic of the compoundViscosity (Brookfield viscosimetry, 20 rpm) 25 °C | Type B | Type A | Type A29400-39400 mPa.s | 4000-11000 mPa.sPhysical form | powder | powder | granulesPass through 40 mesh, % 425 μm | - | - | 95 minPass through 100 mesh, % 150 μm | - | - | 10 maxSolubility | Insoluble in water. Water-swellable and forms hydrogels in aqueous dispersions.Purity |Residual monomers | Acrylic acid not more than 100 mg/kgResidual crosslinker | tri and tetra-allyl pentaerythritol not more than 1000 mg/kgResidual solvant | Ethyl acetate not more than 0,5 % w/w2-ethylhexanol | not more than 100 mg/kg2-ethylhexylacetate | not more than 100 mg/kgLower molecular weight fraction < 1000 Da | Not more than 0,75 % w/wLoss on drying | Not more than 2 %Sulphated ashes | Not more than 2,5 %