The influence of phosphorus- and nitrogen- containing groups on the thermal stability and combustion characteristics of styrenic polymers

Abstract

The effects of covalently bound phosphorus (P-) and nitrogen (N-) bearing groups on the thermal and combustion attributes of polystyrene have been investigated. The necessary chemical modifications were achieved through co- and ter-polymerisation reactions, in a suitable solvent, under radical initiation conditions. The influence of P–N cooperative interactions on the combustion properties of styrenic polymers was studied. The co-monomers of interest included: diethyl(acryloyloxymethyl)phosphonate (DEAMP), diethyl-p-vinylbenzylphosphonate (DEpVBP), acrylic acid-2-[(diethoxyphosphoryl)methyl amino]ethyl ester (ADEPMAE) and maleimide (MI). For the first time, the ter-polymers of styrene containing both P- groups, DEAMP or DEpVBP, and N- groups, MI, were prepared via solution polymerisation. It was found that the thermal stability and combustion characteristics of polystyrene were significantly altered by the presence of nominal amounts of P- and N- containing groups, and, in certain cases, cooperative interactions of these groups were also evident. For instance, the extents of char formation post-degradation of the prepared ter-polymers, as revealed by thermogravimetric investigations in an inert atmosphere (nitrogen), were found to be enhanced by more than 20%, as compared to the unmodified polystyrene. The heat release rates and heat release capacities of the ter-polymers, as measured using the pyrolysis combustion flow calorimetric (PCFC) technique, were reduced by almost 50% in comparison to the same parameters obtained for the unmodified counterpart.

The Effects of Nitrogen‐Containing Monomers on the Thermal Degradation and Combustion Attributes of Polystyrenes Chemically Modified With Phosphonate Groups

“…Figure 8 represents a comparison of the HRC and EHC values measured on the samples of PS, co-polymers containing either DEAMP or MI units (reported previously [19] ), and the ter-polymer, poly(S-ter-DEAMP-ter-MI). It is clear from Figure 8 that the incorporation of only DEAMP into the polymeric chains reduced the HRC and EHC moderately.…”

“…[13][14][15][16][17] As reported previously, several organophosphorus groups were found to be effective in reducing the ignition propensities and suppressing the extents of combustion of PS-based polymers. [3,[16][17][18][19] In most of the previously reported studies, the organophosphorus compounds were incorporated into the PS chains via a co-polymerization technique. [17,[19][20][21] For example, as reported in ref.…”

“…[3,[16][17][18][19] In most of the previously reported studies, the organophosphorus compounds were incorporated into the PS chains via a co-polymerization technique. [17,[19][20][21] For example, as reported in ref. [19], the incorporation of unsaturated P monomer, diethyl(acryloyloxymethyl)phosphonate (DEAMP), into PS had led to a 14% decrease in the heat release capacity (HRC) and peak heat release rate (pHRR), measured through PCFC, at a low level of P loading (0.10 mol).…”

“…[17,[19][20][21] For example, as reported in ref. [19], the incorporation of unsaturated P monomer, diethyl(acryloyloxymethyl)phosphonate (DEAMP), into PS had led to a 14% decrease in the heat release capacity (HRC) and peak heat release rate (pHRR), measured through PCFC, at a low level of P loading (0.10 mol). In other studies, a similar unsaturated P monomer, diethyl(methacryloxymethyl)phosphonate (DEMMP), was introduced into PS, which increased the limiting oxygen index (LOI) of the corresponding co-polymer to 22.5% from 17.9% for PS.…”

Characterisation of biochar from various carbon sources

“…It is also noteworthy that the impact of temperature on the reduction of volatile matter a ppears to be more pronounced between 400°C and 500°C than between 500°C and 600°C f or all substrates. This could imply that a significant portion of the volatile matter is released at the lower end of the temperature spectrum, and that the remaining material is more ther mally stable [19].…”