G.A. Skinner

Inorganic tin compounds as flame retardants and smoke suppressants for polyester thermosets

The fire retardant action of inorganic tin additives in polyester resin thermosets cross-linked with styrene has been investigated. Thermal methods were used to analyse the degradation and oxidation index and smoke measurements were also carried out on the resins with and without tin additives. The interaction between the tin compounds and the halogens introduced into the polymer structure using halogen-containing reactive monomers affects the degradation, fire retardant and smoke suppressant properties. The changes are described and the nature of the fire retardant action is discussed.

Pyrolysis-gas-chromatographic study of a series of polyester thermosets

Abstract Thirteen different unsaturated polyester prepolymers have been synthesised in an attempt to establish a relationship between the structures of the commonly used polyesters and the pyrolysis products of their cross-linked polymers. All the polyesters contained maleic anhydride units as the unsaturated sites and all were cured using styrene as the cross-linking monomer. The variation in structure involved either the glycol component or the aromatic acid. The cross-linked polyesters were pyrolysed at 600°C and the products separated and identified using gas chromatography and gas chromatography–mass spectrometry. Many products were identified as arising from either the styrene cross-links or the polyester chains. The presence of cinnamate esters confirmed that degradation occurred across both distinct parts of the polymer network. The identity of some other products, particularly the phthalate esters, suggested that more than one degradation mechanism was occurring.

The application of 1H nuclear magnetic resonance spectroscopy for the determination of the absolute configuration of chiral carboxylic acids

Abstract A modification of a model, described by Mosher, allows a correlation to be made between the absolute configuration of a range of simple chiral carboxylic acids with the corresponding nmr chemical shifts of their esters derived from (S)-methyl mandelate.

The effects of structure on the thermal degradation of polyester resins

Thermal methods have been used to study the stability and the stages of degradation of unsaturated polyester resins of various structures. The effects of altering the glycol or the aromatic acid and of introducing particular structural units have been investigated. Thermal analysis results are presented for each type of structure and conclusions deduced on the structures likely to be the most stable.

Studies of fire-retardant polyester thermosets using thermal methods

The use of thermal methods in the study of flammability and fire retardant action is discussed and compared with the standard test methods. This paper provides an overview with examples drawn from continuing studies on polyester resins, especially those containing halogenated monomers. Thermal analysis and cone calorimetry results are complemented byanalysis of the gaseous and solid products using a wide range of analytical methods.

The mechanism of action of tin compounds as flame retardants and smoke suppressants for polyester thermosets

The mechanism of the flame retardance of inorganic tin additives has been investigated by examining their effects in three halogenated polyester thermosets, cross-linked with styrene. The techniques used have included oxygen indices, the nitrous oxide index, thermal analysis, pyrolysis-gas chromatography and residue analysis. The residue analysis was carried out on sequentially degraded samples in order to identify the temperature ranges at which volatilisation of both the metal and halogen occurred. Both condensed and vapour mechanisms appeared to be operating. The extent to which either mechanism was observed, depended on both the halogen present and the composition of the polyester. The nature of the interactions between the tin and halogenated polyesters is discussed along with evidence for the formation of the tin halides.

The thermal degradation of polyester resins II. The effects of cure and of fillers on degradation

Abstract The effects of altering the composition, the cure regime and of incorporating different fillers and fibres on the degradation of polyester resins have been studied by thermal analysis and other methods. Results are presented comparing the degradation behaviour of each type of structure, cure, filler and fibre and conclusions are drawn summarising the changes which occur in the thermal stability and in the stages of decomposition of the resins.

A study of flame retarded polymers by thermal methods

Abstract The use of molybdenum trioxide as a flame retardant in halogen-containing polyester resins has been studied. Although oxygen index measurements showed that Sb 2 O 3 is more effective as a flame retardant, MoO 3 formulations produce far less smoke. The thermal degradation of these polyesters has been investigated by TG, DTA and by hot-stage microscopy, and the changes in the decomposition curves caused by the MoO 3 studied in both nitrogen and air atmospheres. MoO 3 has been shown to act predominantly by a condensed phase mechanism, to increase the number of decomposition steps, to produce more char, and to alter the structure of the char. Analysis of the volatiles and solid products has given no evidence for any molybdenum—halogen compound.