Search

Isotactic and atactic poly(4-methyl-1-pentene) powders were degraded in the presence of pure oxygen at temperatures of 145° and 175°C. The functional groups present in the nonvolatile products were identified using infrared spectroscopy. The volatile products that formed were identified by means of a relativly new technique which combines gas chromatography and mass spectroscopy. In this study, seventeen volatile products were detected and identified and their relative abundance estimated. The results obtained could readily be reproduced. Various oxidation mechanisms for these products are postulated.

A method is described which allows the precise estimation of molecular weight distribution parameters p and A which pertain to free-radical polymerizations. Thus, expressions are developed which allow the estimation of (1 − p) by means of a programmable calculator using molecular weight distribution data derived from GPC. Values of A may subsequently be calculated by means of a plot of one of the expressions given. Values of (1 − p) and A obtained in this paper were checked using theoretical values as well as by a comparison between calculated and observed values. The agreement between calculated and theoretical or experimental values indicates that the method presented for the estimation of (1 − p) and A is both reliable and relatively rapid. Previously reported methods for the estimation of (1 − p) and A have involved curve-fitting trial calculations as well as more precise interpolation procedures. However, the latter are based on single-peak maximum values.

The autoxidation of a film of isotactic polybutene-1 (IPB) containing a large amount of metallic ash (about 0.2%) was studied by means of infrared spectroscopy. Reaction temperatures were varied from 105 to 120C and oxygen concentrations from 25 to 100% by volume. A reaction scheme previously reported for the autoxidation of atactic polybutene-1 (APB) was utilized for the IPB. Various results obtained for IPB were compared with those previously reported for APB. (Author)

A general scheme previously reported for the autoxidation of polyolefins is further substantiated by results obtained for the uncatalyzed and catalyzed autoxidation of various concentrations of atactic polypropylene (APP) (by admixture with polyisobutylene) under various experimental conditions. Thus, rates of maximum carbonyl formation were measured as a function of APP concentration at 120C, oxygen concentrations ranging from 0.5 - 100% by volume and cobaltic acetylacetonate catalyst concentrations (3 and 17) x 0.0000001 mole/7.5 mg sample. Good agreement was found between experimentally observed and theoretical dependencies of the maximum carbonyl formation rate on APP concentration derived from the combined reaction scheme. (Author)

The uncatalyzed, uninhibited thermal oxidation of a film of atactic polybutene-1 was studied by means of infrared spectroscopy. Reaction temperatures varied from 110 to 130°C. and oxygen concentrations from 12.5 to 100% by volume. A reaction scheme previously reported for the oxidation of isotactic polypropylene was utilized for the atactic polybutene-1. It was found that the scheme and the mathematical expressions derived therefrom could satisfactorily explain the experimental results obtained.

Expressions were derived relating changes of intrinsic viscosity to reaction time, based on a scheme previously presented for the uncatalyzed, uninhibited thermal oxidation of polyolefins. A value of the kinetic parameter A may be obtained from these expressions by using an iterative type of procedure and employing data presented by other workers for the oxidation of atactic polybutene-1. This value of A was compared with the corresponding value obtained by the authors from rate of carbonyl formation studies in oxidation of atactic polybutene-1 by means of infrared absorption spectroscopy methods. The good agreement between the values of A obtained from the two different experimental techniques employed lends further support to the validity of the scheme used and the expressions derived therefrom.

Recently the rate constants for the autoxidation of isotactic polypropylene based upon a postulated relatively simple scheme were calculated. Electron spin resonance, volumetric and chemical techniques were employed. This paper demonstrates that similar values of these rate constants could also be calculated from a more general scheme. From this general scheme, expressions were derived which involved the rate constants of interest and other constants which had been previously calculated from experimental data based upon the use of infrared absorption techniques. The values of the calculated rate constants at various temperatures agreed well with those reported earlier where comparison was possible. (Author)

The iron-catalyzed autoxidation of atactic polypropylene has been studied in the solid phase using infrared spectroscopy. The reaction temperature ranged from 110° to 130°C, the ferric acetylacetonate concentration varied from 0.3 × 10−7 to 90.0 × 10−7 mole per 7.5 mg atactic polypropylene, and the oxygen concentration varied from 5 to 100 vol-%. In the region of relatively low catalyst concentrations, the maximum steady rate varied approximately first order in respect to the catalyst concentration and about zero order at relatively high values of the catalyst concentration. Linear relationships between the maximum steady rate and the oxygen concentration, for both low and high concentrations, were obtained. A general scheme and kinetic expressions derived there-from previously reported for the uncatalyzed autoxidation of polyolefins and recently modified to account for cobalt-catalyzed autoxidation of actactic polypropylene has been successfully applied to the experimental results.

A simplified procedure is presented to estimate the two adjustable parameters in a lognormal distribution function. From values of these parameters, the weight distribution function, W(M), as well as various molecular weight averages can be calculated. The method was applied to fractionation data selected at random for several polymers. The agreement between calculated and reported values appears to be good.

The autoxidation of a film of atactic polypropylene was studied by means of infrared spectroscopy. Reaction temperatures varied from 110 to 135C and oxygen concentrations from 5 to 100% by volume. A general reaction scheme previously reported for the autoxidation of polyolefins was utilized for atactic polypropylene. Various results obtained for this polymer were compared with those previously reported for isotactic polypropylene. (Author)

Experimental data on dilute solutions of poly(hexene-1), obtained from viscosity, osmometry, and light scattering in various solvents, previously reported, were treated and compared with various hydrodynamic theories of linear polymers. It was found that poly(hexene-1) can best be described by the model of Flory-Fox. Furthermore, the data were found to conform to the treatment of Kinsinger and Ballard for nonpolar polymers in the α-olefin series in the unperturbed state.

An isotactic polybutene-1 was fractionated, and melting points of several fractions were determined. The fractions were studied by light-scattering and viscosity techniques. The parameters in the Mark-Houwink equation are [η] η 4.73 × 10−5M in heptane at 35°C., [η] = 1.50 × 10−4M in heptane at 60°C., and [η] = 9.49 × 10−5M in decalin at 115°C. The molecular weight range studied was 0.45 × 105 to 0.9 × 106.

The authors had previously reported a general scheme with corresponding kinetic expressions for the uncatalyzed thermal autoxidation of polyolefins, such as atactic polybutene-1 (APB), in the bulk phase. Recently, Bawn and Chaudhri reported that similar kinetic expressions and scheme were also applicable to autoxidation of atactic polypropylene (APP) in solution. These workers did not attempt to correlate their results for the effect of oxidation on the molecular weight of APP as evidenced by intrinsic viscosity. In this paper, we have applied expressions, previously reported for changes in intrinsic viscosity as a function of time during the autoxidation of APB in the bulk phase, to the data provided by Bawn and Chaudhri for the autoxidation of APP in solution. The quantitative evidence obtained indicates that the intrinsic viscosity relationships which were found to be valid for the autoxidation of APB in the bulk phase are also valid for the autoxidation of APP in solution (at polymer concentrations of ca. 1.5M and above).

Utilizing carbonyl formation data previously obtained during the thermal oxidation of unstabilized atactic polypropylene, unstabilized isotactic polypropylene and unstabilized atactic polybutene-1 along with a semi-empirical expression, it was possible to extrapolate and obtain arbitrary induction times at relatively low temperatures. Values of induction times thus obtained were correlated with changes in physical properties, i.e., intrinsic viscosity and the product of ultimate elongation and ultimate tensile strength (a product which is often referred to as the impact index).

Data reported for the autoxidation of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) in solution at relatively long reaction times were analyzed. A relatively simple and a more general kinetic scheme with corresponding rate expressions were used. It was found that the more general scheme gave somewhat more satisfactory agreement between calculated and observed values of several reaction variables. Limitations in the applications of both schemes to PEG and PPG autoxidations are mentioned.

Low molecular weight atactic polypropylene hydroperoxide (APPH), m. (onset) ≈ 80°C, was prepared via oxidation of uninhibited low molecular weight atactic polypropylene (APP). The APPH was thermally decomposed over a temperature range of 115°–125°C in which the APPH was in a neat molten state. The reaction order (n) was found to be close to 2, n = 2.2 ± 0.2, and the activation energy of decomposition (E) was ca. 27 kcal/mole1. In contrast to solid-state decompositions, such values would be anticipated for liquid-phase decompositions due to enhancement of molecule mobility and hydrogen bonding.

This work is a study of some dilute solution properties of polyhexene-1. Results with the following experimental measurements are reported: osmotic pressure, phase equilibrium, viscosity, light scattering, molecular weight, molecular weight distribution, and degree of chain extension. Three good solvents were used, cyclohexane, tetrahydrofuran, and toluene, and one poor solvent, phenetole, in order to obtain theta conditions. The properties of polyhexene-1 are compared with those of other α-olefin polymers reported in the literature.