Identify polyamide polymer from following.

Polyamide identification: A polyamide contains repeating amide linkages ($-\mathrm{CO}-\mathrm{NH}^-$).

SBR is a rubber copolymer without amide groups. Melamine formaldehyde contains $\mathrm{C-N}$ bonds but is an amino resin rather than a polyamide. Bakelite is a phenol-formaldehyde resin lacking amide linkages.

Nylon 6,6 forms through condensation polymerization of hexamethylenediamine and adipic acid, producing characteristic amide bonds. This makes it the polyamide among the options.

Final answer: $\boxed{D}$