Poly-as-triazines

Two high molecular weight (η_inh > 1.0) soluble poly-as-triazines have been prepared by the solution polycondensation in m-cresol of 2,6-pyridinediyl dihydrazidine with p,p′-oxybis(phenyleneglyoxal hydrate) and with p,p′-oxydibenzil. Thermal characterization of the poly-as-triazines by TGA showed polymer decomposition temperatures of ～400°C after a 300°C cure in argon. Poly-as-triazines exhibited weight losses <8% after aging in static air at 316°C for 200 hr. Clear yellow films cast for m-cresol solutions exhibited good flexibility and toughness even after aging at 316°C for 200 hr in air and after refluxing in 10% aqueous potassium hydroxide solution for 24 hr.     

Piezoelectric properties of oriented films of poly(γ-methyl D-glutamate)

The dynamic piezoelectric stress constant e^*₂₅ of drawn films of poly(γ-methyl D -glutamate) (PMDG) cast from solutions in α-helix-promoting solvents 1,2-dichloroethane (DCE) and chloroform and from the nonhelicogenic solvent dichloroacetic acid (DCA) was measured from ?180°C to 200°C at 110 Hz. The drawn and annealed films cast from chloroform show a small peak for the real part of piezoelectric stress constant ?e′₂₅ in the temperature range of the mechanical α₂-crystalline relaxation, which is caused by the distortion motion of the backbone chain of the α-helix. On the other hand, drawn films cast from DCE show the peak of the real part of the piezoelectric stress constant, whose magnitude decreases in the range of the mechanical α₁-crystalline relaxation or the β-relaxation processes, which were previously ascribed, respectively, to mutual slipping of α-helices and to the micro-Brownian motion of disordered regions. Also, ?e′₂₅ becomes virtually zero near 180°C where the α₂-relaxation is located. These results suggest that the polarization change induced by applied strain is caused by distortion of the backbone chains in the α-helix. Near 0°C, the temperature range of the side-chain mechanical relaxation, ?e′₂₅ exhibits a marked peak both for films cast from chloroform and from DCE. The maximum value of ?e′₂₅ and the orientation function of the α-helix axis are linearly related and extrapolation of ?e′_25,max to unit orientation function gives 1.3 × 10⁴ cgs esu which corresponds to 2.4 Debye per residue. This value corresponds reasonably to the value of 3.71 Debye for the permanent dipole moment of NHCO bond if the correction for crystallinity is made. This result also indicates the piezoelectric properties of PMDG arise from distortion of the backbone chain of the α-helix induced by applied strain.     

Drawing of poly(p-phenylene sulfide) by solid-state coextrusion

The effects of drawing temperature on the physical and mechanical properties of poly(p-phenylene sulfide) have been studied. A melt-quenched film was drawn by solid-state coextrusion both below (75°C) and above (95 and 110°C) the glass transition temperature T_g (85°C) of PPS. The maximum extrusion draw ratio (EDR_max) increased from 3.4 to 5.6 with increasing extrusion temperature T_e from 75 to 110°C. It was found that extrusion drawing just above the T_g of PPS (95°C) produced more stress-induced crystals. A high efficiency of draw in the amorphous region was achieved by extrusion at T_e-75°C. The tensile modulus at EDR_max decreased from 5.1 to 3.5 GPa with increasing T_e from 75 to 110°C. The low efficiency of draw for the samples extruded at 110°C is explained in terms of disentanglement and chain slippage during drawing due to a less effective network.     

Phase Diagram of the System NaF-KF-AlF3

The phase diagrams of the binary system KF-AlF₃ as well as the ternary system NaF-KF-AlF₃ in the range up to 50 mol% AlF₃, were measured using the thermal analysis method. In the system KF-AlF₃ the coordinates of the eutectic points are: E ₁: 8.0 mol% AlF₃, 821.2°C, and E ₂: 45.5 mol% AlF₃, 565.0°C. In the investigated concentration range of the ternary system 2 eutectic points have been found with the calculated coordinates: E ₁: 36.3 mol% NaF, 62.7 mol% KF, 1.0 mol% AlF₃; t=711.2°C; and E ₂: 51.9 mol% NaF, 27.4 mol% KF, 20.7 mol% AlF₃; t=734.5°C. Other eutectic points lie most probably beyond the investigated part of the system. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development of high ductility and tensile properties by a two-stage draw of poly(acrylonitrile): Effect of molecular weight

Ultradrawing of atactic poly(acrylonitrile) (PAN) was investigated for a M_v series, ranging 8.0 × 10⁴–2.3 × 10⁶. Samples for the draw were prepared from 0.5–30 wt % solutions of PAN in N,N′-dimethylformamide. The solutions were converted to a gel by quenching from 100 to 0°C. The dried gel films were initially drawn uniaxially by solid-state coextrusion (first-stage draw) to an extrusion draw ratio (EDR) of 16, followed by further tensile draw at 100–250°C (second-stage draw). The maximum total draw ratio (DR_t,max) and tensile properties achieved by two-stage draw increased remarkably with sample M_v. Other factors affecting ductility were the solution concentration from which gel was made and the second-stage draw temperature. The effects of these variables became more prominent with increasing M_v. The temperature for optimum second-stage draw increased with sample M_v. Both the initial gel and the drawn products showed no small-angle X-ray long period scattering maximum, suggesting the absence of a chain-folded lamellae structure, which had been found in our previous study on the drawing of nascent PAN powder. The chain orientation function (f_c) and sample density (ρ_s) increased rapidly with DR_t in the lower range (DR_t < 30) and approached constant values of f_c = 0.980–0.996 and ρ_s = 1.177–1.181 g/cm³, respectively, at higher DR_t > 30–100. The tensile modulus also showed a similar increase with DR_t. The tensile strength increased linearly with DR_t, reaching a maximum, and decreased slightly at yet higher DR_t. The highest modulus of 28.5 GPa and strength of 1.6 GPa were achieved with the highest M_v of 2.3 × 10⁶. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 629–640, 1998     

The liquid-phase oxidation of 2,4-dimethylpentane

The initiated oxidation of 2, 4-dimethylpentane in the neat liquid phase at 100°C with 760 torr O₂ gives more than 90% of a mixture of 2,4-dihydroperoxy-2,4-dimethylpentane and 2-hydroperoxy-2, 4-dimethylpentane in a ratio of 7:1. The rate of oxidation depends closely on the [initiator]^1/2, consistent with a mechanism in which chain termination occurs mostly by interactions of two 2-hydroperoxy-2, 4-dimethyl-4-pentylperoxy radicals. 2, 4-Dimethylpentane oxidizes only one sixth as fast as isobutane at the same rate of initiation at 100°C. In cooxidations of the same hydrocarbons, it is 0.71 as reactive as isobutane toward any of the peroxy radicals involved. 2, 4-Dimethylpentane oxidizes 7.5 times as fast at 1.25°C as at 50°C for the same rate of initiation, but the ratio of dihydroperoxide to monohydroperoxide increases only from 5 to 7, corresponding to a difference in activation energy between intramolecular and intermolecular abstraction of 1 kcal/mole. The overall activation energy (E_p – E_t/2) is 10.7 kcal/mole, close to the value of 12 kcal/mole found for isobutane. Absolute values for E_p, E_t, k_p, k_r, and k_t were derived. Ring closure of 2-hydroperoxy-2, 4-methyl-4-pentyl radicals to oxetane, not detected during oxidation, was observed when this radical was generated at 100°C in the near-absence of oxygen. The ratio of rate constants for oxetane formation and addition of oxygen to the 2, 4dimethyl-2-hydroperoxy-4-pentyl radical is about 5.4 × 10^?5 M at 100°C. Thus, ring closure to oxetane is too slow to compete with addition of oxygen above ?200 torr. At 100°C, 2, 3-dimethylbutane gave no evidence of any intramolecular abstraction. However, 2, 3-dimethylpentane did give at least 12% 2, 4-glycol or hydroxyketone.     

Effect of Solvent on the Radical Copolymerizability of Styrene with Acrylonitrile

Radical copolymerization of styrene (St, M₁) with acrylonitrile (AN, M₂) has been carried out using azobisisobutylonitrile as an initiator in benzene, dimethylsulfoxide, acetonitrile, and ethanol at 60 and 80°C. Good linear correlationships were obtained by plotting the values of log r₁, log r₂, Q₂, and e₂ against those of vC[dbnd]N and vC[dbnd]C determined in the solvents: the increase in the interaction between AN and the solvent was found to decrease the values of log r₁ and e₂ but to increase those of log r₂ and Q₂. The results are discussed in terms of the solvation both in the ground state and in the transition state.     

A Thermodynamic Study of Bromo-Lanthanum (III) Complexes from EMF Measurements

The stability constants (for the formation) of LaBr²⁺ and LaBr₂⁺ ions were obtained potentiometrically at various ionic strengths at 20°, 25°, 30°, and 35°. The molal free energy was given by ΔG°=-2,444.04+2.67T log T+1.39T. The thermodynamic quantities for the formation of LaBr²⁺ were evaluated as ΔH_f° = ?207.9, ΔG_f° = ?199.1 kcal mole^?1 and S° = ?29.5 cal. deg^?1 mole^?1 at 25°.     

Increasing Reduction Potentials of Type 1 Copper Center and Catalytic Efficiency of Small Laccase from Streptomyces coelicolor through Secondary Coordination Sphere Mutations

The key to type 1 copper (T1Cu) function lies in the fine tuning of the Cu^II/I reduction potential (E°′_T1Cu) to match those of its redox partners, enabling efficient electron transfer in a wide range of biological systems. While the secondary coordination sphere (SCS) effects have been used to tune E°′_T1Cu in azurin over a wide range, these principles are yet to be generalized to other T1Cu-containing proteins to tune catalytic properties. To this end, we have examined the effects of Y229F, V290N and S292F mutations around the T1Cu of small laccase (SLAC) from Streptomyces coelicolor to match the high E°′_T1Cu of fungal laccases. Using ultraviolet-visible absorption and electron paramagnetic resonance spectroscopies, together with X-ray crystallography and redox titrations, we have probed the influence of SCS mutations on the T1Cu and corresponding E°′_T1Cu. While minimal and small E°′_T1Cu increases are observed in Y229F- and S292F-SLAC, the V290N mutant exhibits a major E°′_T1Cu increase. Moreover, the influence of these mutations on E°′_T1Cu is additive, culminating in a triple mutant Y229F/V290N/S292F-SLAC with the highest E°′_T1Cu of 556 mV vs. SHE reported to date. Further activity assays indicate that all mutants retain oxygen reduction reaction activity, and display improved catalytic efficiencies (k_cat/K_M) relative to WT-SLAC.     

Application of zone-drawing and zone-annealing method to poly(p-phenylene sulfide) fibers

A zone-drawing and zone-annealing treatment was applied to poly(p-phenylene sulfide) fibers in order to improve their mechanical properties. The zone-drawing (ZD) was carried out at a drawing temperature of 90°C under an applied tension of 5.5 MPa, and the zone-annealing (ZA) was carried out at an annealing temperature of 220°C under 138.0 MPa. The differential scanning calorimetry (DSC) thermogram of the ZD fiber had a broad exothermic transition (T_c = 110°C) attributed to cold-crystallization and a melting endotherm peaking at 286°C. The T_c of the ZD fiber was lower than that (T_c = 128°C) of the undrawn fiber. In the temperature dependence of storage modulus (E′) for the ZD fiber, the E′ values decreased with increasing temperature, but increased slightly in the temperature range of 90–100°C, and decreased again. The slight increase in E′ was attributable to the additional increase in the crosslink density of the network, which was caused by strain-induced crystallization during measurement. The resulting ZA fiber had a draw ratio of 6.0, a degree of crystallinity of 38%, a tensile modulus of 8 GPa, and a tensile strength of 0.7 GPa. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1731–1738, 1998     

Ultimate tensile properties of elastomers. VII. Effect of crosslink density on time–temperature dependence

Data on tensile strength and elongation at break for a series of Viton A-HV vulcanizates are discussed. The data were obtained at various extension rates at temperatures from ?5 to 230°C (25 ? T — T_g ? 260°C) on seven vulcanizates having crosslink densities v_e (estimated from C₁ in the Mooney-Rivlin equation) from 0.46 × 10^?5 to 24.4 × 10^?5 mole/cm³. At an extension rate of 1 min^?1, an increase in v_e affects the tensile strength σ_b (based on the undeformed cross-sectional area) and the true tensile strength σ_bσ_b (based on the cross-sectional area of a deformed specimen) as follows: σ_b is essentially constant at a low temperature; it passes through a decided maximum at intermediate temperatures; and it increases to a plateau at elevated temperatures. In contrast, λ_bσ_b decreases markedly at all temperatures, an exception being the most lightly crosslinked vulcanizate(s). Application of time—temperature superposition to the ultimate-property data gave log a_T; its temperature dependence is that typical of nonpolar rubbery polymers. Data on the vulcanizates were compared in corresponding temperature states by plotting log 273σ_b/T, log 273λ_bσ_b/T, and (λ_b — 1)/(λ_b — 1)_max against logt_b/(t_b)_max, where t_b is the temperature-reduced time to break and (t_b)_max is the value at which the ultimate extension ratio λ_b attains its maximum, (λ_b)_max. Except for the most lightly crosslink vulcanizate, the comparison shows that 273λ_bσ_b/T and (λ_b — 1)/(λ_b — 1)_max are substantially independent of (or only weakly dependent on) crosslink density, that 273λ_b/T increases with v_e, and that 273λ_b/T ∝? v_e^0.6 and λ_b ∝? v_e^?0.4 at a large value of t_b/(t_b)_max.     

Ab initio studies of structural features not easily amenable to experiment. 25. Conformational analysis of methyl propanoate and comparison with the methyl ester of glycine

The molecular geometries of three conformations of methyl propanoate (MEP) (C? C? C?O torsions of 0°, 120°, and 180°) and the potential-energy surfaces of MEP (C? C? C?O torsions) and of the methyl ester of glycine (MEG) (N? C? C?O torsions) have been determined by ab initio gradient calculations at the 4-21G level. MEP has conformational energy minima at 0° and 120° of the C? C? C?O torsion, while the 60–90° range and 180° are energy maxima. For MEG there are two minima (at 0° and 180°) and one barrier to N? C? C?O rotation in the 60–90° range. The N? C? C?O barrier height is about twice as high (4 kcal/mol) as the C? C? C?O barrier. The 180° N? C? C?O minimum is characteristically wide and flat allowing for considerable flexibility of the N? C? C?O torsion in the 150–210° range. This flexibility could be of potential importance for polypeptide systems, since the N? C? C?O angles of helical forms are usually found in this region. The molecular structures of the methyl ester group CH₃OC(?O)CHRR′ in several systems are compared and found to be rather constant when R ? H and R′ ? H, CH₃, CH₃CH₂; or when R ? NH₂ and R′ ? H, CH₃, or CH(CH₃)₂.     

Synthesis and properties of eighteen-arm polybutadienes

A series of eighteen-arm regular star polybutadienes with molecular weights between 9.9 × 10⁴ and 1.9 × 10⁶ were prepared and characterized. Evidence is presented for the expanded configuration of the large eighteen-arm stars in a θ solvent. The intrinsic viscosities of the eighteen-arm stars gave g′ = [η]/[η]_l = 0.28₄ in dioxane at 27°C (θ solvent) and 0.22₅ in toluene at 35°C (good solvent). The linear viscoelastic properties of the melts were also determined. The plateau modulus, G_N°, is the same as for linear polybutadiene. The zero-shear viscosities (η₀) and the longest relaxation times (T_max) increase exponentially with the arm molecular weight M_a and are identical to those of four-arm polybutadienes with the same M_a. The zero-shear recoverable compliance (J_e°) increases linearly with molecular weight. v′ in J_e°G_N° = v′N_a, where N_a is the number of entanglements per arm, is 0.95 slightly larger than 0.66 for four-arm polybutadienes. Similarly, g₂ is higher than calculated from the Rouse–Ham theory.     

Kinetics and mechanism of the thermal decomposition of methyl isocyanate

The kinetics of gas-phase decomposition of methyl isocyanate have been investigated in the range of 427–548°C. Two decomposition routes are followed; the predominant one is a radical-chain process giving CO, H₂, and HCN as major products, which has an order of 1.5 and an Arrhenius equation given by log k(L^1/2/mol^1/2·s) = (13.12 ± 0.06) ? (56,450 ± 1670) cal/mol/2.303 RT. The minor route is the bimolecular formation of N,N′-dimethylcarbodiimide and CO₂, which from the low activation parameters E_a = 31.6 kcal, A = 10^5.30 L^1/2/mol^1/2·s, and the reaction order of 1.57 appears to be heterogeneous.     

NMR of enaminones. Part 7 1H-, 13C-, and 17O-NMR and X-ray structure determinations of 1,2-disubstituted conjugated 3-[(tert-Butyl)amino]enones

¹H-, ¹³C-, and ¹⁷O-NMR spectra for the 2-substituted enaminones MeC(O)C(Me)?CHNH(t-Bu) ( 1 ), EtC(O)C(Me)?CHNH(t-Bu) ( 2 ), PhC(O)C(Me)?CHNH(t-Bu) ( 3 ), and MeC(O)C(Me)?CHNH(t-Bu) ( 4 ) are reported. These data show that 3 exists mainly in the (E)-form, 4 in (Z)-form, and 1 and 2 as mixtures of both forms. Polar solvents favour the (E)-form. The (Z)- and (E)-forms exist in the 1,2-syn,3,N-anti and 1,2-anti,1,N-anti conformations A and B , respectively. The structures of the (E)- and (Z)-form are confirmed by X-ray crystal-structure determinations of 3 and 4. The shielding of the carbonyl O-atom in the ¹⁷O-NMR spectrum by intramolecular H-bonding (Δλ_HB) ranging from ?28 to ?41 ppm, depends on the substituents at C(l) and C(2). Crystals of 3 at 90 K are monoclinic. with a = 9.618(2) Å, b = 15.792(3) Å, c = 16.705(3) Å, and β = 94.44(3)°, and the space group is P2₁/c with Z = 8 (refinement to R = 0.0701 on 3387 independent reflections). Crystals of 4 at 101 K are monoclinic, with a = 16.625(8) Å, b = 8.637(6) Å, c = 11.024(7) Å, and β = 101.60(5)°, and the space group is Cc with Z = 4 (refinement to R = 0.0595 on 2106 independent reflections).     

Controlled radical polymerization of styrene mediated by the C‐phenyl‐N‐tert‐butylnitrone/AIBN pair: Kinetics and electron spin resonance analysis

Kinetics of the free radical polymerization of styrene at 110 °C has been investigated in the presence of C‐phenyl‐N‐tert‐butylnitrone (PBN) and 2,2′‐azobis(isobutyronitrile) (AIBN) after prereaction in toluene at 85 °C. The effect of the prereaction time and the PBN/AIBN molar ratio on the in situ formation of nitroxides and alkoxyamines (at 85 °C), and ultimately on the control of the styrene polymerization at 110 °C, has been investigated. As a rule, the styrene radical polymerization is controlled, and the mechanism is one of the classical nitroxide‐mediated polymerization. Only one type of nitroxide (low‐molecular‐mass nitroxide) is formed whatever the prereaction conditions at 85 °C, and the equilibrium constant (K) between active and dormant species is 8.7 × 10^?10 mol L^?1 at 110 °C. At this temperature, the dissociation rate constant (k_d) is 3.7 × 10^?3 s^?1, the recombination rate constant (k_c) is 4.3 × 10⁶ L mol^?1 s^?1, whereas the activation energy (E_a,diss.), for the dissociation of the alkoxyamine at the chain‐end is ～125 kJ mol^?1. Importantly, the propagation rate at 110 °C, which does not change significantly with the prereaction time and the PBN/AIBN molar ratio at 85 °C, is higher than that for the thermal polymerization at 110 °C. This propagation rate directly depends on the equilibrium constant K and on the alkoxyamine and nitroxide concentrations, as well. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1219–1235, 2007     

Regioselective Dialkylations of N‐(tert‐Butyl)iminocyclopentane via Deprotonating One‐Pot Procedures

The title compound ( 1 ) was chosen as a model for the α/α′‐regioselectivity of deprotonation and subsequent alkylation adjacent to the C=N bond. With the bulky base lithium N,N‐diisopropylamide (LDA) as a catalyst, the one‐pot deprotonation steps can be performed through titration with methyllithium, using gas‐volumetric observation of the liberated methane. In the first step with ensuing methylation by iodomethane, the primary product is born at −40 °C in its metastable (Z) configuration (kinetic control) and may be either isolated or converted in situ at 30 °C into its thermodynamically favored (E)‐isomer via cis to trans stereoinversion at the N‐atom. Being slow enough on the laboratory time scale, this stereoinversion process can serve to control the regioselectivity of the second deprotonation/alkylation sequence as follows. The α,α′‐products are formed from the intermediate (Z)‐imine, whereas α,α‐products result from the intermediate (E)‐imine; in either case, syn deprotonation (cis to ^tBu at nitrogen) by LDA is apparently disfavored by the ^tBu group, so that anti deprotonation becomes obligatory. If a third one‐pot deprotonation step is too slow with LDA, it may be performed with the stronger base butyllithium/HMPA which, however, reacts regio‐unselectively. Regioselective one‐pot, LDA‐catalyzed deprotonation with alkylation by oxiranes (alone, or alternatingly with iodomethane) opens a short access to spiro‐[2.4]heptan‐4‐ones.     

Initiator efficiency of 2,2′‐azobis(isobutyronitrile) in bulk dodecyl acrylate free‐radical polymerizations over a wide conversion and molecular weight range

An Erratum has been published for this article in J. Polym. Sci. Part A: Polym. Chem. (2004) 42(21) 5559 . The initiator efficiency, f, of 2,2′‐azobis(isobutyronitrile) (AIBN) in dodecyl acrylate (DA) bulk free‐radical polymerizations has been determined over a wide range of monomer conversion in high‐molecular‐weight regimes (M_n ? 10⁶ g mol^?1 [? 4160 units of DA)] with time‐dependent conversion data obtained via online Fourier transform near infrared spectroscopy (FTNIR) at 60 °C. In addition, the required initiator decomposition rate coefficient, k_d, was determined via online UV spectrometry and was found to be 8.4 · 10^?6 s^?1 (±0.5 · 10^?6 s^?1) in dodecane, n‐butyl acetate, and n‐dodecyl acetate at 60 °C. The initiator efficiency at low monomer conversions is relatively low (f = 0.13) and decreases with increasing monomer to polymer conversions. The evolution of f with monomer conversion (in high‐molecular‐weight regimes), x, at 60 °C can be summarized by the following functionality: f^{60 °C} (x) = 0.13–0.22 · x + 0.25 · x² (for x ≤ 0.45). The reported efficiency data are believed to have an error of >50%. The ratio of the initiator efficiency and the average termination rate coefficient, 〈k_t±, (f/〈k_t〉) has been determined at various molecular weights for the generated polydodecyl acrylate (M_n = 1900 g mol^?1 (? 8 units of DA) up to M_n = 36,500 g mol^?1 (? 152 units of DA). The (f/〈k_t〉) data may be indicative of a chain length‐dependent termination rate coefficient decreasing with (average) chain length. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5170–5179, 2004     

Thermal degradation of polyisobutylene studied using factor-jump thermogravimetry

The overall activation energy of the thermal degradation of polyisobutylene has been measured using factor-jump thermogravimetry to be 206±1 kJ/mole over the range 365 to 405° in N₂ at 800 mm Hg pressure and flowing at 4 mm/s over the sample. This is consistent with some values reported for thermal degradation in vacuum and in solution. In 5 mm Hg of N₂, an apparent activation energy of 218±2 kJ/mole was found, and in vacuum the apparent activation energy is 238±13 kJ/mole. Troublesome bubbling made the vacuum values difficult to measure. Substitution of reasonable values for the activation energies of initiation,E _i , termination,E _t , and the activation energy,E _a , for vacuum degradation in the equationE _a =E _i /2E _d -E _t /2 yields an activation energy E_d=84 kJ/mole for the unzipping reaction. This equation presupposes a degradation mechanism of random initiation, unzipping, and bimolecular termination. Substitution of reasonable values for the heat of polymerization, ΔH, in the definition ΔH=E _p ?e _d suggests that the activation energy of the polymerization reaction at 375° is approximately 30 kJ/mole.     

An oxyluminescence investigation of the auto-oxidation of nylon 66

The kinetics of the thermal oxidation of stabilised and unstabilised nylon 66 fibres and films have been studied by photon counting oxyluminescence methods from 50°C to 150°C. The activation energies for initiation (E₁), propagation (E₃) and termination (E₅) over this temperature range are: E₁ = 16 kcal mol^?1, E₃ = 17·5 kcal mol^?1 and E₅ ≈ 12 kcal mol^?1. The extent of orientation of the polymer does not change the nature of the oxyluminescence curve or E₃ and E₅ above 110°C.Significant losses of critical mechanical properties of the fibres occur in the induction period at 100°C and non-stationary kinetics are described to enable this region to be studied by oxyluminescence. The oxidation rate in the induction period and the limiting rate region in air is one-third the rate in oxygen at atmospheric pressure. Non-stationary methods show that alkyl radical reactions are competitive with alkyl peroxy radical formation in air over the temperature range 100°C to 140°C. This affects the course of the oxidation reaction and the stabiliser efficiency and explains the observation of unsaturated oxidation products by phosphorescence spectroscopy.