Carboxylation of polypropylene by reactive extrusion with functionalised peroxides

Assoun, Laurent; Manning, Steven C.; Moore, Robert B.

doi:10.1016/s0032-3861(97)00584-3

Cited by 46 publications

(65 citation statements)

References 18 publications

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“…This is not surprising, given that the alkoxy radical arising from it can either abstract a hydrogen from the polyethylene or generate by ␤ scission a methyl radical that would react similarly. This observation is in agreement with those of Moore, 12,13 who identified the influence of the alkylperoxy moiety only when the alkyl radical, liberated in the ␤-scission of the t-alkoxy radical, was an ethyl radical.…”

Section: Methodssupporting

confidence: 93%

“…[1][2][3][4][5][6][7][8][9][10][11] To our knowledge, only the articles by Moore et al 12,13 have described the functionalization of polyolefins, polypropylene in this case, carried out by thermal decomposition of peroxyesters in the absence of any additive. Acid and ester functions were introduced onto polypropylene; one of functionalization mechanisms, invoked in the current study, was the combination of the macroradical, formed in the hydrogen abstraction from the polymer by one of the radicals produced in the decomposition of the perester, with the counterradical of this latter.…”

Section: Introductionmentioning

confidence: 99%

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Chemical modification of molten polyethylene by thermal decomposition of peroxyesters

Navarre¹,

Saule²,

Maillard³

2002

J of Applied Polymer Sci

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ABSTRACT:The functionalization of polyethylene was realized by the thermal decomposition of peroxyesters in molten polymer in the absence of any other additive. Ester and acid functions were introduced onto the polymer operating with various peroxyesters. This grafting resulted from the combination of a polymer radical, generated in the abstraction of a hydrogen from polyethylene by an alkoxy radical, with an acyloxy or carbon-centered radical arising from the perester. A complete methodology was set up to identify and to titrate the functions present onto the polyethylene and to determine the extent of crosslinked polymer.

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Section: Methodssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Chemical modification of molten polyethylene by thermal decomposition of peroxyesters

Navarre¹,

Saule²,

Maillard³

2002

J of Applied Polymer Sci

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“…Assoun et al 37 reported ∼17% (and 0.02 mol %) as the largest grafting yield for a series of peroxyesters used for PP functionalization by melt extrusion at 180°C and in an N 2 environment. Saule et al 34 reported a grafting yield of 5% for isotactic PP grafted in a 2.5 h batch process carried out in an inert environment at 160°C using a peroxyester.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Thus, postpolymerization functionalization of PP by melt processing results in dramatic MW reduction. For example, for PP-g-ES samples made by melt processing with asymmetric peroxy derivatives, Saule et al 35 reported weightaverage MW (M w ) reductions of 53−70% with grafting yields of 30−40%, 56 and Assoun et al 37 reported a 24% reduction in M w at only 0.02 mol % grafting level and ∼17% grafting yield. (Grafting yields have a maximum of 100% when grafting is done with asymmetric peroxy molecules.)…”

Section: Scheme 3 Mechanism For β-Scissionmentioning

confidence: 99%

“…34,35 Although they expected greater functionalization of PP relative to PE because the C−H bond dissociation energies are lower for methane hydrogens than for methyl or methylene hydrogens, they found that hydrogen abstraction (needed for functionalization) "hardly occurs" 34 with PP and inferred that PP methyl groups hinder hydrogen abstraction by 1,1-dimethylethoxy radicals. 34 Maillard and co-workers 31−36 and Assoun et al 37 acknowledged the possibility of achieving direct functionalization with an acyloxy radical, • OCOR″−X, i.e., without undergoing decarboxylation to form an alkyl radical, • R″−X. Indeed, this type of termination reaction is possible as long as the alkyl radical is more stable than its acyloxy counterpart.…”

Section: ■ Introductionmentioning

confidence: 99%

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Ester Functionalization of Polypropylene via Controlled Decomposition of Benzoyl Peroxide during Solid-State Shear Pulverization

Diop

Torkelson

2013

Macromolecules

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Polypropylene (PP) is a nonpolar polyolefin that is sometimes functionalized with polar molecules to allow for reactive compatibilization and improve interfacial adhesion. Functionalized PP is conventionally synthesized by melt extrusion at elevated temperature (T) (≥∼180°C) with a radical initiator and polar monomer, e.g., maleic anhydride. A drawback to high T functionalization is that β-scission, which leads to cleavage of C−C backbone bonds, is significant and results in major molecular weight (MW) reduction and property degradation. We present a novel method of functionalizing PP using benzoyl peroxide (BPO) alone by a process called solid-state shear pulverization (SSSP), resulting in ester functional groups (benzoates) grafted at high yield onto PP. Ester functionalized PP (PPg-ES) is synthesized with limited MW reduction because SSSP is done at sufficiently low T to suppress β-scission. Characterization before and after grafting at 0.18 mol % (0.46 wt %) graft level indicates that functionalization (and subsequent purification) is accompanied by only one chain scission event per 12 400 PP repeat units, resulting in 17% and 36% reductions in number-average MW and weight-average MW, respectively. Benzoate grafting levels are tuned from 0.08 to 0.41 mol % (0.22 to 1.14 wt %) by varying the BPO feed level. In addition to limited MW reduction, PP-g-ES exhibits modified interfacial properties, the ability to undergo transesterification reactions consistent with reactive compatibilization, and little to no loss of physical and mechanical properties relative to neat PP. ■ INTRODUCTIONPolyolefins are nonpolar by nature which leads to excellent chemical resistance but poor compatibility with polar molecules. When functionalized with polar moieties 1−15 such as hydroxyl groups, 2,3 itaconates, 4 methacrylate esters, 4,5 and maleic anhydride, 6−12 the modified polyolefins are useful as compatibilizers in blends, 16−18 composites, 19,20 and nanocomposites. 21−23 Commercial, functionalized polyolefins are based on covalent addition of functional monomers to polyolefins in the presence of a radical initiator; the major categories of this type of functionalization are discussed in detail in a recent publication. 12 The most common method used for functionalization is melt extrusion; under the high temperature (T) conditions utilized, functionalization is usually accompanied by undesirable side effects, including chain scission, branching, and cross-linking. 24−28 For this reason, there is ongoing interest to develop improved, commercially scalable methods for postpolymerization functionalization of polyolefins in the presence of both a radical initiator, such as an organic peroxide, and a functional monomer. 12 An alternative method for direct functionalization of polyolefins in the absence of functional monomer was described in a 2005 review by Boaen and Hillmyer, 29 who stated, "An interesting approach that is related but could prove to be more efficient is the direct functionalization with organic peroxides alone." At...

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Comparison of carboxylated and maleated polypropylene as reactive compatibilizers in polypropylene/polyamide-6,6 blends

Bohn

Manning

Moore

2001

J. Appl. Polym. Sci.

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Using reactive extrusion, polypropylene is functionalized with maleic anhydride and compared on an equimolar basis to polypropylene that is functionalized with an asymmetric, carboxylic acid containing peroxide. The grafting efficiency for the asymmetric peroxide is double that obtained for the maleic anhydride system. Moreover, the asymmetric peroxide yields a functionalized material with minimal molecular weight degradation and desirable mechanical properties, relative to maleic anhydride‐grafted polypropylene. In compatibilized blends of polypropylene and nylon 6,6, the polypropylene that was functionalized with the asymmetric peroxide is found to be an improved compatibilizer compared to that of maleic anhydride‐grafted polypropylene. The differences in mechanical properties of the two different functionalized polypropylene materials and their respective blends are rationalized on the basis of the grafting efficiency, molecular weight degradation during reactive extrusion, and effect of free functional species on the ability to form graft copolymers in compatibilized blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2398–2407, 2001

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Carboxylation of polypropylene by reactive extrusion with functionalised peroxides

Cited by 46 publications

References 18 publications

Chemical modification of molten polyethylene by thermal decomposition of peroxyesters

Chemical modification of molten polyethylene by thermal decomposition of peroxyesters

Ester Functionalization of Polypropylene via Controlled Decomposition of Benzoyl Peroxide during Solid-State Shear Pulverization

Comparison of carboxylated and maleated polypropylene as reactive compatibilizers in polypropylene/polyamide-6,6 blends

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