Differential scanning calorimetry (DSC) is one of the most widely used technique for measuring crystallinity in the polymer industry. The major source of error in the crystalline index (CI DSC ) of low crystallinity polymeric articles, is the development of further crystallinity during the DSC scan. Although, this type of cold crystallization is obvious, and thus accounted for in polymers like polyethylene terephthalate, nylons are a difficult class of materials in that respect. The major contributing factors to the failure of DSC in measuring low levels of crystallinity in nylons are identified to be (1) silent crystallization between the glass ( T g ) and melting ( T m ) transitions, (2) extreme difficulties in packing a moisture-free nylon in the sample pan (the response due to traces of moisture being a broad endotherm competing with a broad exothermic crystallization), and (3) a sub-T m exotherm, especially in low crystallinity nylons, due to relaxation of the processing-induced stresses. These factors, specific to nylons, mask the observation of cold crystallization and lead to substantially higher than real crystallinities. This manuscript deals with such complications and corrective actions using commercial nylon 6 films of CI DSC Γ
0-40%. X-ray diffraction measurements have been included to support the validity of our improved DSC methodology.