Chemical modification of isotactic polypropylene by melt blending

Kim, Jun Young; Seo, Eun Su; Park, Dae Soon; Park, Kwang Min; Kang, Seong Wook; Lee, Chang Hyung; Kim, Seong Hun

doi:10.1007/bf02875456

Cited by 11 publications

(5 citation statements)

References 24 publications

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“…Shifts in the crystallization temperature in coagent-modified PPs have been extensively reported in the literature, , but these reports may have potentially overlooked the formation of secondary, insoluble phases, such as gels, in coagent-modified PPs. Kim et al, and more recently Wan et al and Zhang et al, , alluded to the potential effects of gels or other byproducts stemming from the grafting reaction of the coagent. In the present work, in spite of the absence of gel, both PP- g -TAM and PP- g -TMPTMA contained a small population of cross-linked nanoparticles (Figure ) whose dimensions are comparable to those of common nucleating agents. , Given their nature, these particles may influence PP crystallization through heterogeneous nucleation that is independent of long-chain branching effects.…”

Section: Results and Discussionmentioning

confidence: 99%

“…In addition to affecting melt-state rheological properties, coagent-modification has been reported to increase the crystallization temperature ( T c ) and degree of crystallinity of PP, ,,, while also affecting isothermal and nonisothermal crystallization kinetics. − Most accounts of these phenomena focus on branched chains residing in the high molecular weight portion of the molecular weight distribution, − with some researchers proposing that the material’s gel fraction provides a “nucleating” effect on crystallization dynamics. − It should be noted, however, that branched materials prepared by alternate technologies, including LCB-PP prepared by metallocene polymerization, electron beam irradiation, and silane cross-linking, do not show significant shifts in T c . Therefore, crystallization of coagent-modified LCB-PP materials has not been explained unambiguously.…”

Section: Introductionmentioning

confidence: 99%

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Crystallization of Coagent-Modified Polypropylene: Effect of Polymer Architecture and Cross-Linked Nanoparticles

Zhang

Tiwary

Gui

et al. 2014

Ind. Eng. Chem. Res.

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Linear isotactic polypropylene (PP) was chemically modified by solvent-free, peroxide-initiated grafting of trimethylolpropane trimethacrylate and triallyl trimesate. The resulting coagent-modified PP materials possessed bimodal molecular weight and branching distributions, whose populations varied with coagent structure. In addition to changing polymer chain architecture, these chemical modifications generated a small amount of well-dispersed, coagent-derived nanoparticles. When compared with the parent material and PP samples treated with peroxide alone, coagent-modified materials demonstrated significantly higher crystallization temperatures and crystallization rates, as well as a finer spherulitic structure. The importance of a particle-induced, heterogeneous nucleation mechanism is confirmed by comparative analysis of a long-chain branched PP derivative synthesized by homogeneous silane grafting and moisture curing chemistry. Crystallization studies show that whereas branching has a moderate effect on crystallization kinetics, heterogeneous nucleation effects dominate the crystallization of coagent-modified PP materials.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Crystallization of Coagent-Modified Polypropylene: Effect of Polymer Architecture and Cross-Linked Nanoparticles

Zhang

Tiwary

Gui

et al. 2014

Ind. Eng. Chem. Res.

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“…Moreover, the polyfunctional monomers can also combine with the secondary macroradicals, resulting in chain-extension, branching, and crosslinking. [1,2] For polypropylene, the MS is mainly determined by molecular weight and molecular weight distribution, especially the number of the long chain branches and degree of crosslinking. It was found that the MS decreased when DCP was added, and the MFR was obviously higher than that of the original co-PP, indicating the reduction of the mean length and average molecular weight of the macromolecule chains.…”

Section: Melt Behavior and Gel Contentmentioning

confidence: 99%

“…[1,2] It has been reported that the melt strength and the thermal stability of PP can be promoted via introducing long chain branching on the PP main chain or forming a crosslinked structure among the molecular chains. [3−5] Initiating the branching reaction by irradiating with high-energy radiation in the presence of polyfunctional monomers was found to achieve such a goal.…”

Section: Introductionmentioning

confidence: 99%

Structure and Properties of Reactive Extruded Ethylene-block-co-Polypropylene: Influence of Dicumyl Peroxide and Divinylbenzene

Sheng

Xie

Yang

et al. 2008

Journal of Macromolecular Science, Part B

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The reaction of an ethylene-block-co-polypropylene (co-PP) with a polyfunctional monomer-divinylbenzene (DVB)-in the presence of dicumyl peroxide (DCP) was performed in a single screw extruder. It was found that the chain structure of co-PP was significantly influenced by the DVB concentration when the DCP content was fixed. Without DVB, degradation of co-PP chains, induced by DCP, mainly occurred. But when DVB was incorporated, reactions of crosslinking and branching prevailed in the system. The crystallization temperature of the modified co-PP was enhanced and the number of spherulites was increased, accompanied with a decrease of the spherulite size, due to the branched and crosslinked structure. The essential work of the fracture (EWF) method was adopted to characterize the fracture performance of the modified co-PP. The specific essential work of fracture, w e , first decreased gradually to a minimum, and then climbed with increasing DVB concentration, which might be attributed to the variations of the length of the DVB segment (LDS) acting as the crosslinking node and the spherulite size of co-PP. The specific, nonessential work of fracture, βw p , of the modified co-PP was elevated to some extent with an increasing concentration of DVB. It was speculated that the crosslinked and branched structures favored stress transfer among molecular chains and spherulites, which was beneficial to the enlargement of the plastic deformation zone.

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“…As a packaging material, polypropylene (PP) has gained interest in many industrial fields because of its advantages, ie, low cost, good mechanical properties, and low moisture transmittance . Despite these advantages, PP has high oxygen transmittance, and therefore, it does not work well as a packaging material.…”

Section: Introductionmentioning

confidence: 99%

Improvements in the oxygen barrier property of polypropylene nanocomposites

Kim

Ryu

Kim

2018

Polymers for Advanced Techs

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A nanocomposite consisting of polypropylene (PP)/nanoclay (montmorillonite) was prepared by means of a melt-compounding process with the use of a twin-screw extruder. Because of the complex dispersion of polar and hydrophilic clays that have many cations in the nonpolar and hydrophobic PP, amino-silane was introduced to modify the surface of the clays. Also, to improve the compatibility of the modified nanoclay with PP, a PP-graft-maleic anhydride was used as a compatibilizer. From Fourier transform infrared spectroscopy analysis and the mechanical property test results, it was confirmed that the surface of the nanoclay was properly modified, and it was successfully dispersed in the PP matrix. The composite was investigated by electron microscopy to analyze its morphology and the degree of dispersion of the nanoclay. An analysis of oxygen permeability according to nanoclay content was performed, and it was found that the higher nanoclay content makes the decrease in oxygen permeability. In addition, a shelf-life test was carried out to determine the relationship between decreased oxygen permeability and food preservation performance. The preservation performance of the food package prepared with the resin made in this study was improved because of the improvement in mechanical properties and oxygen barrier property.

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Chemical modification of isotactic polypropylene by melt blending

Cited by 11 publications

References 24 publications

Crystallization of Coagent-Modified Polypropylene: Effect of Polymer Architecture and Cross-Linked Nanoparticles

Crystallization of Coagent-Modified Polypropylene: Effect of Polymer Architecture and Cross-Linked Nanoparticles

Structure and Properties of Reactive Extruded Ethylene-block-co-Polypropylene: Influence of Dicumyl Peroxide and Divinylbenzene

Improvements in the oxygen barrier property of polypropylene nanocomposites

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