Heterogeneous grafting of maleic anhydride and α‐methylstyrene from atactic polypropylene

Abstract

Atactic polypropylene (PP) is an amorphous short-chained by-product of isotactic polypropylene (iPP). Due to its enhanced solubility, PP is a suited model polymer for kinetic studies of iPP melt reactions. The maleination of PP via radical grafting at high temperatures was investigated. Since maleic anhydride (MAA) produces discoloring oligomers, PP was grafted with a mixture of MAA and a-methylstyrene (MS). Advantageous is that MS cannot homopolymerize at high temperatures and that MAA and MS tend to copolymerize alternatingly (to colorless products). The kinetics of the grafting process is complicated by a phase separation of PP and [MAA+MS] that is caused by the special attractions between the two monomers. As a result, two grafted PP products are obtained, of which the major is only slightly but the minor is heavily grafted. The latter graft copolymer, which is probably created in the interfaces between phase domains, carries one MAAMS graft per PP back bone chain, approximately with three MAA and five MS units. ZUS AMMENFASSUNG: Ataktisches Polypropylen (PP) ist ein amorphes, kurzkettiges Nebenprodukt des isotaktischen Polypropylens (iPP). Wegen seiner erhohten Loslichkeit ist PP ein gunstiges Modellpolymeres fur Studien der Kinetik von iPP-Schmelzereaktionen. Untersucht wurde die Maleinierung von PP durch radikalische Pfropfung in der Schmelze. Da Maleinsaureanhydrid (MAA) verfiirbende Oligomere bildet, wurde PP mit einer Mischung aus MAA und a-Methylstyrol (MS) gepfropft. Von Vorteil ist, dal3 MS bei hohen Temperaturen nicht homopolymerisieren kann und dal3 MAA und MS praktisch alternierende, farblose Copolymere liefern. Die Kinetik des Pfropfprozesses kompliziert sich durch eine Phasenseparation von PP und [MAA+MS], die bei hoheren Monomerkonzentrationen auftritt und von speziellen Wechselwirkungen zwischen den beiden Monomeren ausgelost wird. Deswegen werden zwei gepfropfte PP-Produkte gebildet, ein wenig gepfropftes Hauptprodukt und ein hochgepfropftes Nebenprodukt. Dieses entsteht vermutlich in den Phasengrenzflachen. Es tragt pro PP-Kette einen MAWS-Ast, der ungefahr aus drei MAA-und funf MS-Bausteinen besteht.

Styrene‐assisted grafting of maleic anhydride onto isotactic poly butene‐1

“…The results indicated that in the presence of St, MAH likely activated the reactivity of the double bond to form a CTC [11, 12], which increased G and formed branches of an alternating MAH‐St on iPB‐1. Similar results were presented by Li et al [13].…”

Phosphorylated cardanol prepolymer‐grafted carboxylated styrene–butadiene rubber for better processing with enhancing silica filler dispersion

“…also studied the styrene‐assisted free‐radical graft copolymerization of MA onto PP . Moreover, MA was also grafted with various commercial polymers such as polyethylene, ethylene–propylene copolymer, and polystyrene in the presence of peroxide initiators …”

Melt functionalization of LDPE with thio ester, amino ester, and hydroxy ester by thermolysis method—An FTIR study

“…Grafting of undecylenic acid onto ethylene octene copolymer under molten condition was reported in the literature 4. Poly (ethylene)s are melt functionalized with maleic anhydride,5–9 glycidyl methacrylate,10–13 methacrylic acids and their derivatives,14–16 oxazolines,17, 18 and silane 19. Dokolas et al20 reported the graft copolymerization of methyl methacrylate, styrene and 4‐vinyl pyridine onto LLDPE backbone.…”