A systematic investigation to determine the importance of molecular weight on the isothermal crystallization kinetics of PEEK across a broad temperature range is presented for three commercial PEEKs (Victrex 150G, 450G, and 650G). The Avrami crystallization model is fit to the isothermal crystallization kinetics of PEEK as a function of crystallization time. To describe the secondary crystallization kinetics, a modified Avrami model is suggested by introducing a second Avrami exponent. The primary and secondary Avrami exponents of PEEK are 3.3 ± 0.4 and 2.3 ± 0.3. Using both standard differential scanning calorimetry (DSC) and fast scanning chip calorimetry (FSC), isothermal PEEK crystallization kinetics are investigated in a wide range of crystallization temperatures (158°C < T c < 336°C). As the molecular weight is increased, the crystallization kinetics decrease. The crystallization half‐times from DSC and FSC are well described by the Hoffman‐Lauritzen model over the entire range of possible crystallization temperatures.

A potent mutagenic compound, 2-amino-3-methylimidazo-[4,5-f]quinoline (IQ), isolated from broiled sardines, cooked beef and beef extract was tested for carcinogenicity in CDF1 mice of both sexes. Mice were given diet containing 0.03% IQ or control diet for up to 675 days. Tumors were observed mainly in the liver, forestomach and lung. In the mice given IQ, the incidences of these tumors were as follows: liver tumors - 41% in males and 75% in females; tumors of the forestomach - 41% in males and 31% in females; lung tumors - 69% in males and 42% in females. In the control mice, incidences of these tumors were as follows: liver tumors - 9% in males and 8% in females; tumors of the forestomach - 3% in males and 0% in females; lung tumors - 21% in males and 18% in females. The incidences of tumors in the liver, forestomach and lung were significantly higher in mice given IQ than in control mice.

2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), which is a mutagenic compound present in fried beef and beef extracts, was given orally to CDF1 mice at a concentration of 0.06% in the diet for 84 weeks. Liver tumors were induced in 43% of males and 91% of females fed MeIQx. The incidences of liver tumors in mice of both sexes were significantly higher in groups fed MeIQx than in control groups. The incidences of lung tumors in females fed MeIQx and of lymphomas and leukemias in both sexes fed MeIQx were also significantly higher than in the respective controls.

Carcinogenicity of 2-amino-3,8-dimethylimidazo[4,5-f]-quinoxaline (MeIQx), which is a potent mutagen first isolated from fried beef and widely present in various cooked foods, was tested in both sexes of F344 rats. Rats were continuously given a diet containing 0.04% MeIQx or basal diet and the experiment was finished on day 429. In experimental animals, the incidence of liver, Zymbal gland, clitoral gland and skin tumors was significantly higher than in control animals. The incidence of liver tumors was 100% in males and 53% in females; most liver tumors of males were hepatocellular carcinomas and all liver tumors of females were neoplastic nodules. The incidence of Zymbal gland tumors was 75% in males and 53% in females. Clitoral gland tumors were induced in 63% and skin tumors were observed in 35% of males and 5% of females. Most of these three types of tumors were diagnosed as squamous cell carcinoma. In the control rats, liver, Zymbal gland, clitoral gland and skin tumors were not observed in either sex.

Carcinogenicities of mutagenic heterocyclic amines in cooked foods have been tested in CDF, mice and F344 rats of both sexes. Eight heterocyclic amines-Trp-P-1, Trp-P-2, Glu-P-1, Glu-P-2, MeAaC, AaC, IQ, and MeIQ-were given to mice and/or rats at 0.02 to 0.08% in the diet continuously. In mice, all heterocyclic amines tested were demonstrated to be carcinogenic. Hepatocellular carcinomas were induced in a high incidence in all groups treated with heterocyclic amines. Hemangioendothelial sarcomas were also induced by Glu-P-1, Glu-P-2, MeAaC, and AaC. Most hemangioendothelial sarcomas were located in the interscapular brown adipose tissue. In mice given IQ, forestomach and lung tumors were also observed in a high incidence. Carcinogenicity tests on MeIQ are ongoing, and interim data by week 83 show that MeIQ also induces forestomach tumors in addition to liver tumors.In rats, hepatocellular carcinomas were induced by Trp-P-1, Glu-P-1, Glu-P-2, and IQ. In rats given Glu-P-1, Glu-P-2, and IQ, adenocarcinomas in the small and large intestines, squamous cell carcinomas in the Zymbal gland and clitoral gland were also observed in a high incidence.