Thermal and Calorimetric Investigations of Some Phosphorus-Modified Chain Growth Polymers 1: Polymethyl Methacrylate

Abstract

The thermal and calorimetric characterizations of polymethyl methacrylate-based polymers are reported in this paper. The modifying groups incorporated the phosphorus atom in various chemical environments, including oxidation states of III, or V. Both additive and reactive strategies were employed, where the loading of phosphorus was kept at 2 wt% in all cases. The plaques, obtained through the bulk polymerization route, were subjected to a variety of spectroscopic, thermal and combustion techniques. The results showed that the different modifying groups exerted varying nature, degrees and modes of combustion behaviors, which also included in some cases an additive, and even an antagonistic effect. In the case of covalently-bound phosphonate groups, early cracking of the pendent ester moieties was shown to produce phosphoric acid species, which in turn can act in the condensed phase. For the additives, such as phosphine and phosphine oxide, limited vapor-phase inhibition can be assumed to be operative.

Thermal and Calorimetric Investigations of Some Phosphorus-Modified Chain Growth Polymers 2: Polystyrene

“…Therefore, this particular model was subsequently applied in analysing all the modified versions of the styrene polymers. As in the case of PMMA samples [34], a reduction in the average activation energy values can be observed, except for the system containing the phosphite additive (DEHPi); here a relatively higher value (305 kJ mol −1 ) was obtained. Therefore, it is to be inferred here that, except in the case of DEHPi, in all other cases, the modification resulted in decreased thermal stability of the parent polymer.…”

“…As previously reported, the final compositions of the products through the reactive strategy were effectively controlled with a high degree of certainty since the polymerization reactions were driven to near completion, i.e., ca. 99% conversion; the latter was established through 1 H NMR spectra of the obtained plaques [34].…”

“…A proprietary inhibitor column was employed to remove the inhibitor, tert-butylcatechol, from the styrene monomer prior to use. The necessary precursors, comonomers, and the additive, diethylbenzylphosphonate (DEBP), were synthesized by following procedures as given in Part I (i.e., pertaining to polymethyl methacrylate) of our previous work [34]. The other additives and monomers studied included triphenylphosphine (TPP), triphenylphosphineoxide (TPPO), diethylphosphite (DEHPi), triethylphosphite (TEPi), triethylphosphate (TEPa), diethylpropylphosphonate (DEPP), diethyl-1-(acryloyloxyethyl)phosphonate (DE-1-AEP), acrylicacid-2-[(diethoxyphosphoryl)methylamino] ester (ADEPMAE), diethyl-2-(acryloyloxy)ethylphosphate (DEAEPa), and diethyl-p-vinylbenzylphosphonate (DEpVBP).…”

“…The other additives and monomers studied included triphenylphosphine (TPP), triphenylphosphineoxide (TPPO), diethylphosphite (DEHPi), triethylphosphite (TEPi), triethylphosphate (TEPa), diethylpropylphosphonate (DEPP), diethyl-1-(acryloyloxyethyl)phosphonate (DE-1-AEP), acrylicacid-2-[(diethoxyphosphoryl)methylamino] ester (ADEPMAE), diethyl-2-(acryloyloxy)ethylphosphate (DEAEPa), and diethyl-p-vinylbenzylphosphonate (DEpVBP). The chemical structures of both the additives and reactives are also given in our previous work [34].…”

“…Again, a fixed phosphorus loading of 2 wt.% was used. The structures of the additives and comonomers used in the present study are given previously [34]. The required amounts of the modifying compounds relative to the monomer and associated details are given in Table 1.…”