EPDM Rubber

Ethylene Propylene Diene Monomer Rubber which comes under M-class(i.e. the backbone chain is having polymethylene chains) as classified by ASTM D 1418 standard
DESIGNATED BY THE FOLLOWING LETTERS IN THE SAE J200 / ASTM D 2000 LINE CALL OUT’s in the specification as: EPDM RUBBER AA , BA, CA, DA
The properties of the EPDM depends on the composition of ETHYLENE, PROPYLENE percentage in the grade
cure rate depends on the percentage of the Diene content and as well as the Diene type

GENERAL CHARACTERISITCS OF EPDM RUBBER are as follows:

EPDM Rubber is having very good Heat, Weather, Ozone resistance.
Good resistance to Steam, Polar substances, Ketones, diluted acids and alkalines
Excellent insulation properties for the low/Medium voltage range.

Limitations of EPDM:

General Guideline for the PEROXIDE curing of the EPDM Rubber:

Grade choice for peroxide curing apps with better Heat aging property could have
lesser polypropylene percentage, as there is a possibility of chain scission in the Polypropylene, which
could reduce physical props.
Third monomer type (Diene) and its percentage, as the allylic hydrogen (that is adjacent to
double bond of the diene) is easily abstracted to create a radical that is used to create the crosslink and
also act as the co-agent. Note: DCPD type contains 3 allylic hydrogen, whereas ENB contains up to 6
allylic hydrogen.
The proper choice of the EPDM grade is high molecular weight with narrow distribution to have good
physical properties
use of proper Coagents will also give good physicals – Here the CLCB
grades can be useful in balancing the processing and physicals.
Oil should be Paraffinic type (In Naphthenic, the oil will interfere with the peroxide as the
aromatic content is higher).
if acidic fillers (including kaolin clay, calcined clay, ppt. Silica) are used, PEG or TEA or Silanes need to
be used for better cross-link density.
On the usage of Antioxidants TQ or ODPA with MBI can be used for those requirements.

THERMAL PROPERTIES OF EPDM