Hans
One cannot conclude with certanty that the lower Tg material is the prepreg.
Since the core has been through two lamination cycles (at the laminator and
in your press) it is usual to infer that the lower Tg is the prepreg. This is
reinforced by the single peak after heating. One material or the other was
undercured after your lamination cycle. Did the second lab you mentioned heat
the material after DSC as much as the first lab to complete the cure?  If
these data represent real boards I suggest a bake to fully cure them. Hard
top be sure, these are thoughts which I hope will help
Jerry Sallo
Sallo Consulting Services

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