I am working with Low density polyethylene (LDPE)/ ethylene-vinyl alcohol copolymer (EVOH) blend. In DSC heat scan, I found two melting picks. So how can I measure the crystallinity% of the blend?
Crystallinity of a polymer can be calculated by rationing the heat of fusion (area under the melting curve) of the target sample divided by the heat of fusion of the pure homopolymers (usually published for well-known polymer). Do this for both polymers (You need to know which melting peak belong to which polymer). You then need to know the composition of the blend. Multiply the fraction of each component to the crystallinity of each component in your blend sample and add the component normalized crystallinity of each polymer to obtain total crystallinity.