### Abstract

Velocity-of-copolymerization data available in the literature were reinterpreted on the basis of the current notions that the penultimate-unit effect with respect to absolute values of propagation rate constant (but not with respect to the monomer reactivity ratios) is a general rule, and that the termination step is diffusion-controlled, i.e., normal. By making a few simplifying approximations, a new velocity equation was derived, which was found to describe experimental data generally better than the classical equation based on the terminal propagation model with a single adjustable parameter φ, the cross-termination factor. The single adjustable parameter s included in the new equation, which measures the penultimate-unit effect, was found to have a strong correlation with the monomer reactivity ratios such that the smaller r1r2, the smaller is s, i.e., the more significant is the penulimate-unit effect. This result is in support of the relation r1r2=s1s2 suggested by the phenomenological theory [T. Fukuda et al., Makromol. Chem., Rapid Commun., 8, 495 (1987)].

Original language | English |
---|---|

Pages (from-to) | 1003-1009 |

Number of pages | 7 |

Journal | Polymer Journal |

Volume | 21 |

Issue number | 12 |

DOIs | |

Publication status | Published - Dec 1989 |

Externally published | Yes |

### Fingerprint

### All Science Journal Classification (ASJC) codes

- Polymers and Plastics
- Materials Chemistry

### Cite this

*Polymer Journal*,

*21*(12), 1003-1009. https://doi.org/10.1295/polymj.21.1003