General solutions for the oxidation kinetics of polymers
The simplest general kinetic schemes applicable to the oxidation of polymers are presented, discussed and analyzed in terms of the underlying kinetic assumptions. For the classic basic autoxidation scheme (BAS), which involves three bimolecular termination steps and is applicable mainly to unstabilized polymers, typical assumptions used singly or in groups include (1) long kinetic chain length, (2) a specific ratio of the termination rate constants and (3) insensitivity to the oxygen concentration (e.g., domination by a single termination step). Steady-state solutions for the rate of oxidation are given in terms of one, two, three, or four parameters, corresponding respectively to three, two, one, or zero kinetic assumptions. The recently derived four-parameter solution predicts conditions yielding unusual dependencies of the oxidation rate on oxygen concentration and on initiation rate, as well as conditions leading to some unusual diffusion-limited oxidation profile shapes. For stabilized polymers, unimolecular termination schemes are typically more appropriate than bimolecular. Kinetics incorporating unimolecular termination reactions are shown to result in very simple oxidation expressions which have been experimentally verified for both radiation-initiated oxidation of an EPDM and thermoxidative degradation of nitrile and chloroprene elastomers.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 273806
- Report Number(s):
- SAND-96-1480C; CONF-9606247-1; ON: DE96011687; TRN: 96:004709
- Resource Relation:
- Conference: 18. annual international conference on advances in the stabilization and degradation of polymers, Luzern (Switzerland), 19-21 Jun 1996; Other Information: PBD: 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Miscibility Evaluation Of The Next Generation Solvent With Polymers Currently Used At DWPF, MCU, And Saltstone
New method for predicting lifetime of seals from compression-stress relaxation experiments