Impact Strength of β-Nucleated Polypropylene

Obadal, Martin; Čermák, Roman; Баран, Н. М.; Stoklasa, Karel; Šimoník, Josef

doi:10.3139/217.1802

Cited by 29 publications

(24 citation statements)

References 13 publications

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“…The first resin, named HPP, was a homopolymer without nucleating agent. The second resin, named NPP, had sodium benzoate as nucleating agent in the concentration up to the critical concentration at which the β-form content reaches the saturation level 19,20,39 . Properties of both resins are shown in Table 1.…”

Section: Methodsmentioning

confidence: 99%

“…In the literature [17][18][19][20][21] was revealed the promising mechanical properties of β-form in i-PP articles and it was also exposed that when special crystallization procedures are used or, in particular, specific nucleators as N,N'-dicyclohexylnaphthalene-2,6-dicarboxamide and sodium benzoate are added, the β-form can become as predominant crystalline form in common i-PP articles. Dong and cowokers 17 demonstrated that the sodium benzoate shows apparently versatile nucleating characteristic on the crystallization behavior of i-PP and that this nucleating activity is highly dependent on processing parameters.…”

Section: Introductionmentioning

confidence: 99%

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A X-ray study of β-phase and molecular orientation in nucleated and non-nucleated injection molded polypropylene resins

2009

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The development of α and β-phases and the molecular orientation of injection molded disks of two isotactic polypropylene (i-PP) resins were studied by wide angle X-ray diffraction (WAXD) and pole figures. A nucleated (NPP) and non-nucleated (HPP) polymers were analyzed. The main proposal of this article was the comprehensive study of the interrelations between the processing conditions, phase contents and PP α-phase molecular orientation of injection molded PP resins. In both resins, it was observed that the α-phase was present in all regions along the thickness while the β-phase was present mainly in the external layers, decreasing from the surface to the core; however this last phase was present in a very small amount in the NPP resin. For both polymers, the orientation of the macromolecules c-axis was higher along the flow direction (RD) than along the transverse direction (TD). The b-axis of the PP α-phase molecules was oriented to the thickness direction (ND). The orientation of the c-axis along RD and b-axis along ND of the NPP samples was considerably higher than of the HPP samples, due to the NPP faster crystallization kinetics. For both polymers, the most influential processing parameters on the molecular orientation were the mold temperature and flow rate. The results indicate that, as the mold temperature increased, the characteristic molecular orientation of PP α-phase, with c-axis along RD and b-axis along ND, decreased. With increase in the flow rate an increase of the c-axis molecular orientation of the samples along RD was observed.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A X-ray study of β-phase and molecular orientation in nucleated and non-nucleated injection molded polypropylene resins

2009

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“…Moreover, flexural properties are not usually described in studies dealing with the properties of b-iPP. Our previous work [12], which focused on the specific b-nucleation effect of the nucleator based on N, N'-dicyclohexylnaphtalene-2,6-dicarboxamide (NU100), has revealed that the concentration of 0.03 wt.% of the nucleator can be rated as a "boundary value", since the application of this amount leads to rapid increase of b-phase content and to the achievement of the maximum impact strength. Thus, the aim of the present study is to prove, on both flexural and tensile properties, enhanced ductility of the material with this particular nucleator concentration.…”

Section: Introductionmentioning

confidence: 99%

Tensile and Flexural Properties of β-Nucleated Polypropylenes

Obadal

Čermák

Habrová

et al. 2004

International Polymer Processing

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Tensile and Flexural Properties of b-Nucleated PolypropylenesResuming our previous work on b-nucleated polypropylenes, namely on their impact strength, our present work directs attention towards a flexural and tensile behavior of b-nucleated polypropylenes (b-iPP). For the purposes of this work, commercially available isotactic polypropylene was modified using various amounts of a specific nucleating agent based on N, N 'dicyclohexylnaphtalene-2,6-dicarboxamide (NU100). From the prepared blends test specimens were prepared by injection molding. Structural characterization (crystallinity and the content of b-phase) was carried out by X-ray diffractometry. A multipurpose mechanical property tester was used for determination of tensile and flexural properties. It was found that b-phase content decreased both tensile and flexural strength; on the other hand, the presence of b-phase dramatically raised cold drawability of the injection-molded specimens; addition of 0.03 wt.% of NU100 in the injection-molded parts led to a more than 800 % increase of the draw ratio of specimens tested at the testing speed of 100 mm/min. Furthermore, tensile testing carried out using various strain speeds (10 and 100 mm/ min) revealed that higher ductility of the material containing b-phase is particularly pronounced by faster deformation processes, such as fast drawing or impact load.International Polymer Processing downloaded from www.hanser-elibrary.com by Kungliga Tekniska on August 18, 2015For personal use only.

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“…[8][9][10] However, only a few papers deal with the microhardness of the skin and the core structure in correlation with the tensile properties.…”

Section: Introductionmentioning

confidence: 99%

Effect of the skin-core morphology on the mechanical properties of injection-moulded parts

Hnatkova¹,

Dvořák²

2016

Mater. Tehnol.

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The presented study deals with the effects of different processing parameters during injection moulding on the morphological structure through the thickness of the injection-moulded samples and, consequently, on their mechanical properties. In this work, tensile bars of an isotactic polypropylene were injected under different conditions such as the flow rate, the melt temperature and the mould temperature. The morphological structure of the samples was investigated with polarized light microscopy using thin cross-sections cut perpendicularly to the flow direction. The fountain flow in the mould cavity influenced the crystallization kinetics and the presence of three distinct crystalline zones was observed; namely, the highly oriented non-spherulitic skin, the shear-nucleated spherulitic intermediate layer and the inner core composed of spherulites with a low orientation. The results showed that the flow rate has the highest influence on the thickness of the oriented skin layer. The mechanical properties of the tensile samples demonstrated that the larger thickness of the two outer skins provides the higher tensile strength. The same effect was also confirmed with a microhardness test where the skin layer was harder than the inner spherulitic core. Keywords: skin-core structure, polypropylene, morphology, tensile strength, microhardness Predstavljena {tudija obravnava vpliv razli~nih procesnih parametrov pri vbrizgavanju na morfologijo strukture, zaradi debeline vbrizganih vzorcev, in posledi~no na njihove mehanske lastnosti. V tem delu so bile natezne palice izotakti~nega propilena vbrizgane pri razli~nih pogojih, kot so: hitrost te~enja, temperatura snovi in temperatura kokile. Morfolo{ka struktura vzorcev je bila preiskovana z mikroskopijo s polarizirano svetlobo, z uporabo tankih rezin, odrezanih pravokotno na smer toka. Lijakasto litje v votlini orodja je vplivalo na kinetiko kristalizacije in opa`ena je bila prisotnost treh razli~nih kristalnih podro~ij, in sicer: mo~no orientirana ne-sferulitna skorja, s stri`enjem nukleirana sferulitna vmesna plast in notranje jedro, sestavljeno iz sferulitov, brez orientacije. Rezultati so pokazali, da ima hitrost toka najve~ji vpliv na debelino skorje. Mehanske lastnosti nateznih preizku{ancev so pokazale, da ve~ja debelina dveh zunanjih skorij zagotavlja vi{jo natezno trdnost. Enak u~inek je bil potrjen tudi s preizkusom mikrotrdote, kjer je bila plast skorje bolj trda kot pri notranjem sferulitnem jedru.

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Impact Strength of β-Nucleated Polypropylene

Cited by 29 publications

References 13 publications

A X-ray study of β-phase and molecular orientation in nucleated and non-nucleated injection molded polypropylene resins

A X-ray study of β-phase and molecular orientation in nucleated and non-nucleated injection molded polypropylene resins

Tensile and Flexural Properties of β-Nucleated Polypropylenes

Effect of the skin-core morphology on the mechanical properties of injection-moulded parts

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