Pyrolysis of some polyvinyl polymers at temperatures up to 1,200 °C

Abstract

A study was made of t he thermal behavior in a vac uum of polystyrcne, polytetra fluoroethvlcne, poly (a-m et h y 1 s tyrcne), polypropylene, polyisobutylen(', and poly (meth yl methacrylate), when pyrolized at 500, 800, and 1,200 .0C. The v olatile products of degradation were collected and fractionated, and the fractlOns analyzed by mass-spectrometn c and microcryoscopic methods. Generally, the results from 500 °0 pyrolysis resemble those obtained prev ious ly from t he same polymer at lower temperatures. The r es uILs at 800° and 1 :200° indicate a much greater fragmentation of the pyrolys is products than at lower temp~ratures. Thus, for example, at 1,200° polystyrene yields less monomer but co nsidcrable greater amounts of 0 2H2, 0 21 -14, 0 3H" and OsI-Is than at lower te mperatures. Similarly, poly(a-methylstyrcnc) yields 100 percent monomer below 500 °0 , but at 800 and 1,200 °0 t he yields are 88 p ercen t an d 34 percent, res pec t ively. A lso at the higher temperatures, pronounced amounLs of Hz, 0I-I4, OzH 2, 0 21-14, 0 3H" 0 3HS, O,H" 0 6I-I6, O,Hs, and OsT -l s are formed.

Polystyrenes :

“…A decrease in styrene yield with an increase in temperature was found by Straus and Madorsky [23] when a thermally prepared polystyrene was decomposed in a helium atmosphere. This result appears to disagree with those of Knight [11] and Booster et al [16], as discussed previously.…”

“…It is generally agreed that the major volatile component produced from the thermal degradation of polystyrenes under these atmospheres is the styrene monomer [3,[11][12][13][14][15][16][17][18][19][21][22][23]. Other commonly detected products are oligomers of styrene, such as the dimer and trimer [13,[15][16][17]19,20], toluene, benzene, ethylbenzene and a-methylstyrene and, under oxidative conditions, species such as benzaldehyde and benzoic acid [11][12][13][14][15][16][17][18][19].…”

“…Straus and Madorsky [23] studied the decomposition of specially prepared laboratory samples of polystyrene under vacuum. These samples were either heated for 30 minutes at AOO and SOO^C, or for five minutes at 800 and 1200®C in a platinum tube surrounded by a preheated moveable furnace.…”

“…The thermal degradation of polystyrenes under inert atmospheres has been examined by a number of investigators [3,[11][12][13][15][16][17][18][19][20][21][23][24][25]27]. VThile nitrogen (Nj) was the gas most widely used to study polystyrene degradation under inert conditions [11,15,[17][18][19][20][21]24,25], helium (He) and argon (Ar) atmospheres were also used [3,12,13,16,23,27]. Different degradation systems as well as a variety of analytical techniques were employed; for example, pyrolysis-gas chromatography (pyrolysis-GC) , thermogravimetric analysis-gas chromatography (TGA-GC), gas chromatography-mass spectrometry (GC-MS), and thermogravimetric analysis-gas chromatography-high resolution mass spectrometry ( TGA-GC -HEMS )…”

Numerical Investigation on Influence on the Regression Rate of the Inlet Parameters in Solid Fuel Scramjet Combustor

“…Thermodynamic functions of each reaction components were given in the polynomial form. Using the literature [9] , the thermodynamic parameters can be calculated. Through the literature[10]，A = 72.…”