Shagufta Zulfiqar

Study of the thermal degradation of polychlorotrifluoroethylene, poly(vinylidene fluoride) and copolymers of chlorotrifluoroethylene and vinylidene fluoride

Abstract A systematic study of the thermal degradation of a series of homopolymers and copolymers of chlorotrifluoroethylene and vinylidene fluoride was carried out using thermogravimetry and thermal volatilisation analysis (TVA). Volatile products were separated by subambient TVA and characterised by means of infrared spectroscopy and mass spectrometry. On degradation, polychlorotrifluoroethylene gives the monomer as the major product and CO 2 , C 2 F 2 Cl 2 , C 3 F 5 Cl and C 2 F 3 Cl 3 in traces. Poly(vinylidene fluoride) forms hydrogen fluoride in appreciable quantity along with the monomer and C 4 H 3 F 3 . The copolymers show a similar type of degradation pattern. The structural changes which take place during degradation have also been studied and mechanisms of formation of the various products are disccused.

Thermal degradation of poly(glycidyl methacrylate)

Abstract The degradation behaviour of poly(glycidyl methacrylate) (PGMA) has been studied using thermogravimetry in dynamic nitrogen and thermal volatilisation analysis (TVA) under vacuum, with programmed heating at 10°C/min. Volatile products have been separated by subambient TVA and identified. The cold ring fraction and partially degraded polymer have been examined by IR spectroscopy. When the polymer decomposes thermally at temperatures up to 500°C, the major product is monomer due to a depolymerisation reaction. Minor products arising from ester decomposition are acrolein, allyl alcohol, glycidol, carbon dioxide, isobutene, propene and carbon monoxide. A mechanism which accounts for all these products has been formulated.

Thermal degradation of blends of PVC with polysiloxane-1

Thermal degradation of blends of PVC with polydiphenylsiloxane (PDPS) and polydimethyldiphenylsiloxane (PDMDPS) has been studied by thermogravimetry (TG) and differential thermal analysis (DTA) over the whole composition range. From the TG and DTA data, curves have been constructed to enable the experimental weight loss behavior to be compared with the component polymers. Activation energy and order of reactions were calculated for the blends and component polymers using TG data. The results show slight destabilization at low loading of PDPS and PDMDPS but for compositions with 50% or more PDMDPS and PDPS, both polymers are stabilized, particularly the PDMDPS blends which show much slower weight loss.

Thermal degradation of glycidyl methacrylate-styrene copolymers

Abstract The thermal degradation of copolymers of glycidyl methacrylate and styrene was studied by thermal volatilisation analysis (TVA), thermogravimetry (TG) and pyrolysis mass spectrometry. The apparent activation energies for the decomposition of copolymers were calculated from the results of TG experiments. The condensable volatile products from the TVA experiments have been identified after separation by subambient thermal volatilisation analysis (SATVA). The cold ring fraction was examined by IR spectroscopy. The copolymers are intermediate in stability between polystyrene and poly(glycidyl methacrylate). The degradation products are mainly those expected by comparison with those obtained from the homopolymers. A mechanism of thermal degradation has been suggested.

Synthesis, characterization and thermal degradation of glycidyl methacrylate-α-methyl styrene copolymers

Abstract Glycidyl methacrylate (GMA) and α-methyl styrene (AMS) were copolymerized in different ratios under vacuum using azobisisobutyronitrile (ABIN) as initiator. The copolymers were characterized by gel permeation chromatography (GPC), IR and 1 H-NMR spectroscopy. Their composition was determined by 1 H-NMR analysis. Thermal degradation of copolymers was studied by thermogravimetery (TG), differential thermogravimetery (DTG) and differential thermal analysis (DTA) under inert atmosphere. The apparent activation energies for decomposition of the copolymers were calculated from their TG data and their thermal stability compared.

Thermal degradation of poly(2-methoxyethyl methacrylate)

Abstract When poly(2-methoxyethyl methacrylate) decomposes thermally at temperatures up to 500°C, two separate reactions occur. The major reaction is depolymerization giving monomer as the only product. The minor reaction is ester decomposition which results in a very small yield of volatile products including carbon monoxide, carbon dioxide, methane, ethylene, isobutene, methyl vinyl ether, methanol and formaldehyde. A mechanism which accounts for all these products has been formulated.

The thermal degradation of poly(allyl methacrylate)

The thermal degradation of poly(allyl methacrylate) has been investigated using thermal volatilisation analysis (TVA), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The main pyrolysis products have been identified and the characteristics of the reactions deduced and discussed. Mechanisms have been proposed to account for the products formed.

The thermal degradation of glycidyl methacrylate-methyl methacrylate copolymers

Abstract Copolymers of glycidyl methacrylate and methyl methacrylate with widely differing compositions have been studied by thermal volatilisation analysis (TVA), thermogravimetry (TG), differential thermal analysis (DTA) and pyrolysis-mass spectrometry (Py-MS) techniques. The apparent activation energies for the decomposition of the copolymers were calculated from the results of thermo-gravimetric experiments. The condensable volatile degradation products have been identified after separation by subambient TVA (SATVA). The cold ring fraction (CRF) and the structural changes in the residue in the course of degradation were examined. Non-condensable products formed during TVA degradation were identified using a mass spectrometer attached to the TVA apparatus. The two monomers are the major products of degradation of the copolymers, which, unlike the PMMA, also yield CRF products. Anhydride rings are detected in the CRF and in the residue from partial degradation to 340 °C. Glycidyl methyl ether is also one of the degradation products. A mechanism of degradation is proposed.

New stabilisers for polymers on the basis of IPDI protected 2,2-thiobis(4-methyl-6-tert-butylphenol) and hindered amines

New thermostabilisers for polymers on the basis of a sterically hindered phenol and several sterically hindered amines (HA) were synthesised by reaction with isophorone diisocyanate (IPDI). Their thermal stability was studied by means of thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA). Antioxidative properties in polypropylene were investigated in oven ageing tests using FTIR spectrometry. The compounds containing both hindered phenol and HA moiety afforded better stabilising performance in thermooxidation than two phenol moieties linked through IPDI.

Thermal degradation studies of copolymers of chlorotrifluoroethylene and methyl methacrylate

Abstract The thermal degradation of the homopolymers and a series of copolymers of chlorotrifluoroethylene (CTFE) and methyl methacrylate (MMA), prepared by emulsion polymerisation, have been studied using thermogravimetry and thermal volatilisation analysis (TVA). The products of degradation have been separated by subambient TVA and characterised by infra-red spectroscopy and mass spectrometry. PCTFE degrades to give monomer as a major product; the emulsion PMMA sample degrades to give a high yield of monomer, but also gives small amounts of additional products, in contrast to PMMA samples previously studied made by bulk or solution polymerisation. In the degradation of the copolymers, monomer formation is predominant, but some lactonisation is observed, with release of methyl chloride: other features of the degradation are explained by various radical reactions.