| Abstract: | Caprolactam was copolymerized with 1,5-dioxo-1-methyl-4-azaphosphepane or methylphosphacaprolactam. The molecular weight of the resulting copolymers decreased with increasing concentration of the thermally labile phosphorus moieties. Copolymers based on ≥40% caprolactam were shown to be crystalline by differential scanning calorimetry and x-ray techniques. As the concentration of the phosphorus structures in the copolymers increased, the glass transition and crystallization temperatures increased while the melting temperatures, crystallinities, and thermal stabilities decreased. Melt blends of nylon 6 and polymethylphosphacaprolactam were shown by differential scanning calorimetry, a selective extraction technique, and elemental analysis to contain appreciable amounts of block copolyamides, and no crystalline random structures were detected. The thermal stabilities of the melt blends were similar to those of random copolymers having comparable concentrations of the phosphorus-containing sequences. |
