The Depolymerization of Polymethylene and Polyethylene

Abstract

cording to some recent theories of the osmotic second virial coefficient in the limit of large excluded volumes, i.e., for high molecular weight polymer molecules in thermodynamically "good" solvents, the ratio A2M%,/(Rl,)'/* should attain an essentially constant value. Qualitatively the constancy of this ratio is an expression of the expectation that the interactions of polymer molecule pairs in such media resemble collisions of spheres whose volumes are proportional to (7?2W)V2. If, then, the volumes of the equivalent hydrodynamic spheres observed viscometrically are also proportional to (i?2w)'/' the ratio AtMw/[rj] should be another constant. _The ratio is plotted against log Mw in the center graph of Fig. 7 for the ten polyvinylacetate fractions in methyl ethyl ketone. Over this molecular weight range the ratio is a constant equal to 4.4 X 1024.A plot of A-iM^I [77] against log M-w for the samesystem in the lower graph of Fig. 7 reveals a remarkably constant value, 1.39, for this ratio over the molecular weight range 246,000 to 3,460,000.Here again data of Howard19 have been used to extend the observations to lower molecular weight polymer fractions.It may therefore be stated empirically that the thermodynamic interaction of a pair of high molecular weight polyvinylacetate molecules in methyl ethyl ketone is similar to the collision of spheres having effective volumes proportional to (A!2W) This observation, coupled with the validity-of the equivalent hydrodynamic sphere treatment of limiting viscosity numbers, yields an empirical relation among the quantities AMw and [17]. It has been found40 that this relation is valid for several polymers in thermodynamically good solvents, and similar magnitudes for the ratio A2MW/ [77 ] are observed.

Thermal degradation of polymers at low rates

“…Prepared according to the method described by Buckley and Ray [6] by decomposing diazomethane, using trimethyl borate as catalyst. Its molec ules are unbranched without methyl groups, and of high molecular weight [7].…”

“…All these polymers, except number 4, are the same materials as those used previously in work on rates of thermal degradation at higher temperatures in the tungsten spring balance apparatus [1,2,7,8,9]. As in previous work, the samples were heated in a vacuum at 100° C to a constant weight before they were used in the rate experiments.…”

“…It r ecords co ntinuously and automatically time, temperature, and weight of the polymer sample undergoing decomposition. This new apparatus was used in a study of thermal degradation at I P aper presented at the 134th National Meeting of the American Ohemical Society in Cbicago, Ill., Sept. [7][8][9][10][11][12]1958.…”

Environmentally Harmful Low Density Waste Plastic Conversion into Kerosene Grade Fuel

“…With respect to present trends in finding cost-effective energy sources, recent research efforts have focused on the utilization of waste polymeric materials in reacting directly with coal [12,13]. This becomes possible since it is well established that waste plastics undergo depolymerization and degradation above 380˚C by a free radical chain reaction [14]. Although a variety of waste plastics processing methods for obtaining hydrocarbons have been developed in the recent past, there is still a great deal of interest for the mentioned co-liquefaction process due to the fact that coal is an abundant fuel resource [15].…”

“…Although a variety of waste plastics processing methods for obtaining hydrocarbons have been developed in the recent past, there is still a great deal of interest for the mentioned co-liquefaction process due to the fact that coal is an abundant fuel resource [15]. Hence, this case seems to be quite promising since earlier studies indicated that positive synergism was achieved by processing coal and waste plastics targeting oily yields [14]. This process became achievable due to the fact that waste plastics are characterized by high hydrogen content and molecular structures that are suitable for this transformation [16].…”