Fracture toughness of polypropylene copolymers: influence of interparticle distance and temperature

Starke, J.U.; Michler, G. H.; Grellmann, W.; Seidler, Sabine; Gahleitner, Markus; Fiebig, Joachim; Nezbedová, E.

doi:10.1016/s0032-3861(97)00219-x

Cited by 106 publications

(70 citation statements)

References 16 publications

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“…We found that the fracture behaviour shown by the nanocomposites was very similar to that of the rubber-toughened PP reported by Karger et al [7], where the yielding-related specific essential work (w e,y ) can be used for plane strain toughness comparison. (Note that the w e,y value was found to agree fairly with the critical J IC values derived from high-speed impact tests [7,15]). On this suggestion, the yielding-related specific total fracture work (w f,y ) vs. ligament length (l) is plotted in Fig.…”

supporting

confidence: 71%

Influence of surface-modified TiO2 nanoparticles on fracture behavior of injection molded polypropylene

Zhang

Zhong

Park

et al. 2008

Front. Mater. Sci. China

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We prepared surface-modified TiO 2 nanoparticle (21 nm)/polypropylene nanocomposites using a twinscrew extruder and an injection molding machine. The TEM (transmission electron microscopy) and SEM (scanning electron microscopy) images showed homogeneous dispersion of nano-TiO 2 at 1 vol.% filler content and weak nanoparticle matrix interfacial adhesion. It was found that the essential work of fracture (EWF) approach, usually characterizing fracture toughness of ductile materials, was no longer applicable to the nanocomposite samples because of the extreme crack blunting and tearing processes observed in the EWF tests. As an alternative approach, the specific essential work-related yield was used for assessment of the plane-strain toughness, as suggested in the literature. The results indicated that the addition of 1 vol.% nano-TiO 2 did not toughen the polypropylene (PP) matrix at all. On the other hand, it was observed from the EWF tensile curves that the nanoparticles enhanced the ductility of the PP matrix greatly, the reason of which was probably ascribed to the high level of molecular orientation of the injection molded samples, as revealed by the polarized optical microscopy (POM). Because of the highly ductile behavior induced by the nanoparticles, the fracture energy achieved two-to three-fold increase, depending on the ligament lengths of the samples. The difference between the toughness and ductility of nanocomposites was discussed.Polypropylene (PP) is a ductile polymer material that develops a geometry-dependent plastic deformation zone around the crack tip, the size of which is comparable to the crack length. This kind of fracture process could not be characterized by linear elastic fracture mechanics, which is usually valid for brittle fracture. As known, one approach to determine toughness of the ductile materials is the essential work of fracture (EWF) approach [1,2]. In recent years, this approach has become popular because of its experimental simplicity in comparison with the Jintegral approach. There are some articles in which the EWF approach was successfully applied to evaluate the fracture toughness of PP and its composites [3][4][5][6][7][8][9][10][11][12], nevertheless it was also found that PP-based composites exhibited highly ductile fracture behavior under some factors, which include, for example, test temperature [5], sample thickness [6] and physicochemical property of the second phases adding to PP matrix [6][7][8]. This kind of highly ductile fracture behavior could not be directly evaluated by the EWF approach because of the difficulty to accurately separate the essential work from the total fracture energy. An attempt to overcome this problem has been proposed by Karger et al. [7], who divided an EWF tensile curve into two parts from the yielding point (i.e. from the peak load in EWF load-displacement curve). The yielding-related specific essential fracture work (w e,y ) appeared to agree well with the plane-strain critical EWF value. Based on this background, it is therefore poss...

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supporting

confidence: 71%

Influence of surface-modified TiO2 nanoparticles on fracture behavior of injection molded polypropylene

Zhang

Zhong

Park

et al. 2008

Front. Mater. Sci. China

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“…Such concepts are used in synthesis of new polymers [25]. Microstructures of polymers are related to toughening brittle polymers [26] and to brittle-to-tough transition when increasing the temperature [27]. Thus, in the tough state of polypropylene-ethylene copolymers one observes only isolated deformation structures (croids or cavitation bands) [27].…”

Section: Resultsmentioning

confidence: 99%

Brittleness and toughness of polymers and other materials

2015

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“…Na literatura são encontrados inúmeros exemplos de aplicação da utilização do impacto instrumentado na caracterização de materiais poliméricos a partir de diagramas de energia de iniciação e propagação da trinca [5][6][7] . O monitoramento de propriedades através dos parâmetros da mecânica de fratura (K 1C ; G 1C e J 1C ) utilizando o impacto instrumentado também têm sido relacionados na literatura [8][9] .…”

Section: Determinação De Parâmetros Materiais a Partir Do Diagrama Deunclassified

Determinação de temperatura de transição dúctil-frágil de plásticos através de testes de impacto instrumentado

Correa¹,

Yamakawa²,

Hage³

1999

Polímeros

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Nesse trabalho é realizada uma análise descritiva do teste de impacto tipo Izod instrumentado e são mostradas suas vantagens em relação ao impacto convencional na obtenção de diagramas de força e energia de fratura em tempo-real. Estes diagramas além de fornecerem dados do material em termos de sua resistência ao impacto tradicional, contém informações detalhadas sobre os mecanismos de fratura e as principais características apresentadas durante a propagação da trinca no corpo de prova. A medida da variação da resistência ao impacto com a temperatura pode ser utilizada como uma forma de se determinar a existência de transições dúctil-frágeis ou alternativamente a suscetibilidade de materiais poliméricos à concentração de tensões, i.e., profundidade e raio da extremidade do entalhe. As curvas de carga e energia, obtidas à várias temperaturas, são utilizadas na determinação de parâmetros do material e da temperatura de transição dúctil-frágil de um copolímero de acrilonitrila-butadieno-estireno (ABS). A análise da superfície de fratura por microscopia eletrônica de varredura, (MEV) permitiu a correlação da forma das curvas de impacto com o modo de fratura observado e detalhes da microestrutura do material.

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Fracture toughness of polypropylene copolymers: influence of interparticle distance and temperature

Cited by 106 publications

References 16 publications

Influence of surface-modified TiO2 nanoparticles on fracture behavior of injection molded polypropylene

Influence of surface-modified TiO2 nanoparticles on fracture behavior of injection molded polypropylene

Brittleness and toughness of polymers and other materials

Determinação de temperatura de transição dúctil-frágil de plásticos através de testes de impacto instrumentado

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