Reactive processing of polymers: Effect of bifunctional and tri-functional comonomers on melt grafting of glycidyl methacrylate onto polypropylene (2023)

Table of Contents
Polymer Degradation and Stability Abstract Introduction Section snippets Materials Conventional PP-GMA grafting system in absence of comonomer Conclusions References (21) Polym Degrad Stab Polym Degrad Stab Polym Degrad Stab Polym Angew Makromol Chem J Appl Polym Sci Macromol Mat Eng Cited by (19) N-vinyl pyrrolidone-assisted free radical functionalization of glycidyl methacrylate onto styrene-b-(ethylene-co-butylene)-b-styrene Effect of Tea Polyphenols on the Melt Grafting of Glycidyl Methacrylate onto Polypropylene Addition of divinyl benzene comonomer to glycidyl methacrylate grafting to cyclic natural rubber Improvements in the synthesis and characterization of glycidyl methacrylate-grafted EPDM through melt free-radical process Effect of divinylbenzene-assisted maleic anhydride grafted poly(lactic acid) on properties of microcrystalline cellulose/poly(lactic acid) composites Post-polymerization modification by nitroxide radical coupling Recommended articles (6) Assembly of polyamide 6 nanotube arrays with ordered patterns and the crystallization behavior Synthesis of polypropylene nanocomposites using graphite oxide-intercalatedZiegler–Natta catalyst Kinetics of autoepitaxial crystal growth in amorphous films of Cr2O3 Aesthetically textured, hard latex coatings by fast IR-assisted evaporative lithography Polypropylene-grafted nanoparticles as a promising strategy for boosting physical properties of polypropylene-based nanocomposites Editorial for “Recent advances in DNA-based biosensor”

Polymer Degradation and Stability

Volume 95, Issue 3,

March 2010

, Pages 353-362

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Two reactive comonomers, divinyl benzene (DVB) and trimethylolpropane triacrylate (TRIS), were evaluated for their role in effecting the melt free radical grafting reaction of the monomer glycidyl methacrylate (GMA) onto polypropylene (PP). The characteristics of the GMA-grafting systems in the presence and absence of DVB or TRIS were examined and compared in terms of the yield of the grafting reaction and the extent of the main side reactions, namely homopolymerisation of GMA (poly-GMA) and polymer degradation, using different chemical compositions of the reactive systems and processing conditions. In the absence of the comonomers, i.e. in a conventional system, high initiator concentrations of peroxides were typically required to achieve the highest possible GMA grafting levels which were found to be generally low. Concomitantly, both poly-GMA and degradation of the polymer by chain scission takes place with increasing initiator amounts. On the other hand, the presence of a small amount of the comonomers, DVB or Tris, in the GMA-grafting system, was shown to bring about a significant increase in the grafting level paralleled by a large reduction in poly-GMA and PP degradation. In the presence of these highly reactive comonomers, the optimum grafting system requires a much lower concentration of the peroxide initiator and, consequently, would lead to the much lower degree of polymer degradation observed in these systems. The differences in the effects of the presence of DVB and that of TRIS in the grafting systems on the rate of the GMA-grafting and homopolymerisation reactions, and the extent of PP degradation (through melt flow changes), were compared and contrasted with a conventional GMA-grafting system.


In-situ melt grafting reactions of polar functional groups on commercial inert hydrocarbon polymers such as polyolefins and their copolymers has been the subject of intense studies over the last three decades with the aim of producing a new range of specialty materials with targeted properties [1]. Polypropylene, PP, benefits from its low cost and versatile set of properties hence its use in many commercial applications. However, it is an inert hydrocarbon polymer that lacks the presence of reactive functionality and this limits its application in many technologically important fields due to, for example, its low surface energy, poor dyeability and compatibility with polar polymers. Various reactive (vinyl-based) modifiers have therefore been employed to functionalise PP to introduce new properties that would expand its uses in new areas of applications such as in compatibilisation of polymer blends, interfacial coupling to polymers and inorganic substrates, crosslinking and reactive stabilisation [2], [3], [4], [5], [6].

Most attention has been given to free radical melt grafting on PP of two such vinyl-based monomers, maleic anhydride, MA, and glycidyl methacrylate, GMA. These monomers are bifunctional monomers containing an unsaturated function capable of free radical grafting on hydrocarbon polymers and a highly electrophilic moiety that can react with different nucleophilic functions such as carboxylic, hydroxide and amine groups, and this in turn can then be used to promote further reactions, e.g. reactive compatibilisation in blends and alloys [4]. The grafting efficiency of both GMA and MA on different hydrocarbon polymers, however, has been shown to be generally low [2], [3], [7], [8], [9]. In the case of GMA, this is mainly due to its low reactivity towards macroradicals and high tendency towards homopolymer formation.

In our laboratory, we have developed a highly effective and versatile functionalisation strategy that is capable of improving the grafting efficiency of variety of functional monomers on polymers. This approach is achieved through in-situ co-grafting of a small amount of a more reactive (compared to the modifier) comonomer (co-agent) [10], [11], [12], [13], [14], [15]. In earlier work, we have reported the use of the polyfunctional comonomer, trimethylolpropane triacrylate, TRIS, with different reactive modifiers, e.g. with GMA in EPR [13] and with various reactive antioxidants in PP [10], [11], [12], and have shown that these systems give rise to a dramatic increase in the level of grafting of the modifiers on the polymers examined.

We report here our work on the effect of two reactive comonomers, a bifunctional one, divinyl benzene, DVB, and a tri-functional one, TRIS on the characteristics of free radical melt grafting reactions of GMA on PP and to compare these grafting reactions with similar ones but which are carried out in the absence of a comonomer (conventional system).

Section snippets


Granules of polypropylene Apryl-3020 BNI (PP) with melt flow rate of 2.0g/min (at 230°C/2.16kg) were kindly supplied by Elf-Atochem. GMA (97% purity), DVB and TRIS were used as received from Aldrich Chemical Co. The peroxides used were 2,5-dimethyl-2, 5-bis(t-butyl peroxy) hexane (Trigonox 101, T101), 1,1-di(tert-butylperoxy)-3,3,5-trimethyl cyclohexane (Trigonox T-29B90) were kindly donated by Akzo Nobel, dicumyl peroxide (DCP) and benzoyl peroxide (BPO) were purchased from Aldrich and

Conventional PP-GMA grafting system in absence of comonomer

In a conventional peroxide-initiated GMA-PP grafting system (i.e. in absence of a comonomer), in addition to the target grafting reaction, there is typically at least two other competing side reactions involving GMA-homopolymer formation (poly-GMA) and degradation of PP mainly by chain scission, reaction (1).


The peroxide (Trigonox 101)-initiated GMA-PP conventional melt grafting system was examined at different peroxide and initial GMA concentrations and at different processing temperatures.


The incorporation of a small concentration of the highly reactive comonomers DVB or TRIS in PP/GMA free radical melt grafting system has been shown to bring about advantageous changes in the grafting yield of GMA. In the presence of a very small concentration of peroxide a faster rate of grafting is achieved concomitant with a substantial reduction in the main competing side reactions, namely chain scission or comonomer-assisted crosslinking of the polymer and the GMA-homopolymerisation (a

References (21)

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  • N.C. Liu et al.



  • Y.J. Sun et al.

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  • R. Ohnishi et al.

    Macromol Mat Eng


There are more references available in the full text version of this article.

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