The change of molecular weights at peroxide initiated degradation of polypropylene

Abstract

A simple and universal relation between the mutual change of weight and number average molecular weight at random degradation of polymers has been derived. A good agreement has been found between this relation and the experimental results obtained at peroxide initiated degradation of polypropylene. ZUSAMMENFASSUNG:Eine einfache und allgemeine Beziehung zwischen der gegenseitigen h d e r u n g des Gewichts-und Zahlenmittels des Molekulargewichts bei statistischem Abbau von Polymeren wurde abgeleitet. Es wurde eine gute Ubereinstimmung zwischen dieser Beziehung und den experimentellen Ergebnissen beim peroxidisch initiierten Polypropylenabbau gefunden.

Course of degradation and build-up reactions in isotactic polypropylene during peroxide decomposition

“…The peroxide-impregnated powder was then divided into test tubes and evacuated and sealed in a nitrogen atmosphere. The sealed ampules were annealed for particular times (5,10,20,30,40,55,70, 100, 150, and 210 min) at 129°C in an oil bath. The chosen time of annealing was 2.5 min.…”

“…On the other hand, the approximate stoichiometric efficiency of degradation was measured during the decomposition of 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane (0.4 -4 mmol/kg) in i-PP in the presence of the antioxidant 2,6-di-tert-butyl-4-methylphenol (4 -9 mmol/kg) at the temperature zones of the extruder between 160 and 230°C. 5 At the peroxide concentrations used, the average molecular mass (number and mass) of the degraded polymer constantly decreases with an increasing amount of the peroxide decomposed. As degradation proceeds, polymolecularity of PP is narrowed.…”

Impact of stabilization additives on the controlled degradation of poly(propylene)

“…The model is based on free radical kinetic mechanism for the degradation reaction and on conventional plasticating extrusion theory [11][12][13] . Despite the great industrial importance of the controlled rheology process, only a few studies have been published that address the influence of stabilization additives on the process 14) and effectiveness in the final application 15) .…”

Sustainable Development Through Feedstock Recycling of Plastic Wastes

“…Gasification of plastic wastes by treatment with oxygen, air, steam or mixtures of these agents is an effective degradation method that yields synthesis gas and a solid residue as the main products. Gasification can be viewed as a feedstock recycling process for plastic wastes provided that the synthesis gas produced is used in the preparation of methanol, ammonia, hydrocarbons, oxygenated compounds, etc., instead of being used as a fuel gas . The major advantage of gasification is the possibility of treating complex mixtures without any previous separation step.…”