Efficiency of Chemical Cross-Linking of Polypropylene

Borsig, Eberhard; Fiedlerová, Agnesa; Lazár, M.

doi:10.1080/00222338108058488

Cited by 72 publications

(26 citation statements)

References 9 publications

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“…The mechanism to increase cross-linking efficiency with these coagents has been explained by their ability to react with polypropylene radicals. 18,30,31 The chain scission could be retarded if the new radical located on a coagent molecule is stabilized against fragmentation. The radical thus decays preferably by recombination with another polymer radical, giving rise to cross-linking.…”

Section: Introductionmentioning

confidence: 99%

“…26 The efficiency of cross-linking depends on the decomposition rate of peroxide and the reactivity of the radicals formed. Poly-functional monomers, such as vinylsilanes, 27 diallyl maleate, 28 and triallyl cyanurate 29 and ethers of pentraerythritol 30 have been used to accelerate the cross-linking of polypropylene with peroxide. The mechanism to increase cross-linking efficiency with these coagents has been explained by their ability to react with polypropylene radicals.…”

Section: Introductionmentioning

confidence: 99%

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Chemical modification of polypropylene with diisocyanates for improved gas barrier and mechanical properties

2009

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ABSTRACT:In this investigation, modification of polypropylene (PP) with an objective to obtain packaging film with improved gas barrier properties has been studied. The chemical reaction of PP resin with hexamethylene diisocyanate and toluene diisocyanate was monitored by Fourier transform infrared spectroscopy, wherein the appearance of new peaks at 3333 cm −1 for N H stretching, 1620-1641 cm −1 for (C O) NH stretching and 1552-1578 cm −1 corresponding to N H bending in an amide moiety was observed for both the modified PP films. Films of excellent clarity and uniform thickness were obtained by the extrusion of cross-linked polypropylene. The barrier, mechanical, optical, and thermal properties of the modified PP films were studied. The results clearly indicated significant changes in gas barrier and mechanical properties. Food

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chemical modification of polypropylene with diisocyanates for improved gas barrier and mechanical properties

2009

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“…Because the species of peroxide has an important part in both steps (i) and (ii), many researchers have studied the effect of peroxide type on the crosslinking behavior of polymers such as polyethylene 15 and polypropylene. 16,17 For example, Chodak and Lazar 17 demonstrated that the reactivity of primary radicals and their diffusion rate significantly influenced the efficiency of crosslinking in polypropylene.…”

Section: Introductionmentioning

confidence: 99%

Molecular characterization and crystallization behavior of peroxide-induced slightly crosslinked poly(L-lactide) during extrusion

Takamura

Nakamura

Kawaguchi

et al. 2010

Polym J

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Reactive extrusion of poly(L-lactide) (PLLA) was carried out in the presence of a small amount of various peroxides with relatively slow decomposition rates. The resulting crosslinked, four-armed randomly branched PLLA (v-PLLA) was characterized by size exclusion chromatography equipped with multiangle laser light scattering (SEC-MALS), and the results were interpreted according to the type of peroxide used. A new component with a higher molecular weight than the original PLLA was observed in the SEC-MALS chromatograms of the v-PLLA. The weight-averaged molecular weight (M w ) of the v-PLLA was found to increase with increasing effective radical number per PLLA precursor (n), where n is the overall hydrogen abstraction ability of peroxide times the mole ratio of radical to PLLA precursor molecule. This implies that the hydrogen abstraction ability is a good index for the crosslinking efficiency of PLLA. The extent of branching of v-PLLA was estimated by the shrinking factor, g¼/R g 2 S b //R g 2 S l , and rationalized with n, where /R g 2 S b and /R g 2 S l are the mean square radii of gyration of branched and linear polymers with the same molecular weight, respectively. The nucleation and overall crystallization rate of v-PLLA in the nonisothermal crystallization from the melt was discussed from the viewpoints of branching and entanglement density.

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“…Melt grafting and solution grafting require high reaction temperature over 100 °C. The degradation of PP via β hydrogen elimination occurs at such a high temperature[28,29]. In addition, organic solvents used in these reactions pose a threat to the environment.…”

Section: Introductionmentioning

confidence: 99%

Study of suspension grafting process of polypropylene

Liang

Yuan

Shao

et al. 2018

Designed Monomers and Polymers

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Grafting efficiency is an important indicator of polypropylene grafting reaction. A series of studies have been accomplished, including the conditions of free radical presence on PP backbone during peroxide initiation, the effect of preheat treatment and reaction time on PP suspension grafting results, and the effect of peroxide residue on properties of modified PP. An optimized grafting process was proposed by mixing and preheating polypropylene (PP) and the initiator benzoyl peroxide (BPO) before adding the grafting monomer glycidyl methacrylate (GMA),resulting in an increase in grafting efficiency from 50.0% to 78.2%. With initiator residue removed by alternating temperature treatment, the suspension grafting reaction time could be substantially reduced.

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Efficiency of Chemical Cross-Linking of Polypropylene

Cited by 72 publications

References 9 publications

Chemical modification of polypropylene with diisocyanates for improved gas barrier and mechanical properties

Chemical modification of polypropylene with diisocyanates for improved gas barrier and mechanical properties

Molecular characterization and crystallization behavior of peroxide-induced slightly crosslinked poly(L-lactide) during extrusion

Study of suspension grafting process of polypropylene

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