A highly rigid poly-.epsilon.-caproamide composition containing about 50 to 5000 ppm of barium combined with the poly-.epsilon.-caproamide, and having a .gamma.-type crystal ratio of about 0.3 to 0.7 is disclosed. The polyamide has improved rigidity without loss of other advantageous mechanical properties...http://www.google.com.au/patents/US4290935?utm_source=gb-gplus-sharePatent US4290935 - Highly rigid polyamide composition
