Weighted cross-products matrix

Uncured resins are oligomers of relatively low molecular weight that may be a liquid or a solid. Before epoxy resins can become useful products, they must be cured, with the addition of a curing agent. Curing involves the cross-linkage by polymerization of the reactive epoxy groups into a three-dimensional matrix. 

Homopolymer PP exists as a two- and possibly a three-phase system of crystalline and amorphous phases with the amorphous phase being comprised of a crystalliz-able isotactic portion and a noncrystallizable atactic portion. The noncrystalliz-able, gummy, atactic PP phase has small amounts of a low molecular weight oily material at a level of 1% and lower. The latter has been characterized in some products as having some structural inversions of propylene monomers and some branches other than methyl. Typical levels of crystallinity in extruded PP pellets are in the 60-70% range. One way to describe the morphology of PP is to consider it an assemblage of crystallites that act as physical cross-links in an amorphous matrix. 

Sijbesma et al. [69] recently demonstrated a ROMP reaction initiated by compressing imbedded mechanochemically activated catalyst and monomers in a solid matrix with a KBr press. When samples containing the catalyst 102 (34 kDa) and the monomer 106 or the di-functional monomer 107 (Figure 12.23) within a high molecular weight (170 kDa) polymer matrix (PolyTHF) were subjected to mechanical strain (0.8 GPa), up to 25% conversion of monomer 106 was obtained after five compression cycles, while the production of a cross-linked polymer from 107 was proven by solid-state NMR techniques. 

---