Kinetik der radikalischen pfropfung von styrol auf polybutadiene

Abstract

Die Kinetik der radikalischen Pfropfung von Styrol auf Polybutadiene wird mit Hilfe von Fallungsfraktionierungen untersucht. Hierbei ist es moglich, die Abhiingigkeit der Art und Menge der gebildeten Pfropfcopolymeren von der Struktur der Polybutadiene und den Bedingungen der thermischen, initiierten und geregelten Styrolpolymerisation zu beschreiben.Kinetisch abgeleitete Gleichungen erlauben die Auftrennung der Pfropfung in die Anteile der Polymer-und der Initiatorradikale. Fur verschiedene Initiatoren werden stark unterschiedliche Pfropfreaktivitaten gemessen. Bei der thermischen Pfropfpolymerisation wird nur ein Beitrag der Polymerradikale gefunden, der insbesondere mit steigendem 1,P-Vinyl-Gehalt des Polybutadiens und steigender Temperatur zunimmt.Die Liinge der Pfropfiiste wird durch die Kinetik der Styrolpolymerisation bestimmt und ist besonders gut durch Regler einstellbar. Die mittlere Zahl der Pfropfaste je gepfropftes Polybutadienmolekul wird vom Wert 1 ausgehend mit steigendem Monomerumsatz kinetisch beschreibbar erhoht. SUMMARY:The kinetics of the free-radical grafting of styrene on polybutadienes is investigated with the aid of fractional precipitations. It is possible in this way to describe the dependence of the nature and quantity of the graft copolymers formed on the structure of the polybutadienes and the conditions of the thermal, initiated and regulated polymerization of styrene.Kinetically derived equations allow the resolution of the grafting into the polymer-radical and initiator-radical contributions. Different initiators give very different grafting reactivities. Thermal graft polymerization shows only a polymerradical contribution, which increases in particular with increasing 1,2-vinyl content of the polybutadiene and with rising temperature.* Vorgetragen auf dem ,,Makromolekularen Kolloquium" in Preiburg am 9. Marz 1973. J. P. FISCHERThe length of the grafted chains is determined by the kinetics of the styrene polymerization, and can be adjusted particularly readily by chain transfer agents. The average number of grafted chains per grafted polybutadiene molecule increases from a value of one with increasing monomer conversion in a manner that can be described kinetically.

Amphiphilic Graft Copolymers and Hyperbranched Polymers Based on (3-Vinylphenyl)azomethyl-malonodinitrile

“…The resulting polymers were separated as the pure graft copolymer (insoluble in water) and homo-PVP (soluble in water) by stirring the crude product in water at room temperature over 3 d. The absence of ungrafted macroinitiator was proven by means of GPC. The grafting process was characterized with regard to grafting success U g , grafting efficiency e and degree of grafting p. [22] The results are shown in Table 1.…”

“…homo-PS) 6 100%. [22] c) Degree of grafting p = (PVP in PS-g-PVP)/(PS-g-PVP) 6 100%. [22] Scheme 3. methods.…”

“…[22] c) Degree of grafting p = (PVP in PS-g-PVP)/(PS-g-PVP) 6 100%. [22] Scheme 3. methods. Elementary analysis (Table 2), as well as IR spectroscopy showed an increasing amount of nitrile groups with increasing the molar azo/styrene ratio.…”

Mechanism and Kinetics

“…Fischer developed expressions for d [G]/ dt for the " grafting to " mechanism of styrene onto polybutadiene [30] .…”

Solution and quasi‐bulk copolymerizations of styrene and methyl methacrylate in the presence of polybutadiene: Mathematical model

“…Many publications4–47 have investigated on the homopolymerizations of MMA or St in the presence of PB rubbers. In the case of high‐impact polystyrene (HIPS), both experimental15–30 and theoretical31–47 articles have been reported.…”