Crazing in semicrystalline thermoplastics

Kausch, H. H.; Gensler, R.; Grein, C.; Plummer, C. J. G.; Scaramuzzino, P.

doi:10.1080/00222349908248140

Cited by 65 publications

(44 citation statements)

References 10 publications

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“…This mixed fracture behaviour is shown in Figure 7a where the shear bands and the crystalline regions are clearly visible. Another fracture mechanism frequently seen in thermoplastic polymers is crazing [7,8]. Crazing associated with fibrillated structure occurs at very localized plastic deformation areas (Figure 7b).…”

Section: Resultsmentioning

confidence: 99%

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Failure behavior of PA12 based SLS lattice structure with macro-porosity

et al. 2018

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Abstract. Nowadays the demands of high reliability, high mechanical properties under fatigue loading and ultra-light-weight design are topics of pressing needs in different industry applications. Additive manufacturing technique has great potential to meet such demands and Selective Laser Sintering (SLS) is the dominantly used one due to its versatility in material design, construction and the much higher achievable mechanical strength compared to its competing technologies like fused filament fabrication. In this study, it is aimed to give an insight to the fracture behaviour of SLS produced lattice structure with macro-porosity under compression load. The stress type and distribution on the lattice structure under compression load are anisotropic because of the unit cell topologies and the anisotropic processing condition. Therefore, different kinds of fracture types are evident depending on the region of the fractured struts.

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Section: Resultsmentioning

confidence: 99%

“…A crystal lamella is connected by amorphous regions which contain non-entangled chains, dangling chain ends and/or loops and more or less taut tie-molecules [7]. A lamella will be deformed in shear or in tension or stack rotation depending on the relative orientation of a lamellar bundle with respect to the principal stress direction.…”

Section: Resultsmentioning

confidence: 99%

Failure behavior of PA12 based SLS lattice structure with macro-porosity

et al. 2018

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“…At the beginning of macroscopic stretching, the lamellae are displaced rigidly, and the ensuing interlamellar separation leads to strong hydrostatic tension within the constrained amorphous network. The tie molecules become more extended and transfer locally concentrated elastic stresses to the lamellae [35]. Stress relief can occur in two ways, through cavitation within the amorphous network and/or through crystal plastic deformation.…”

Section: Mechanism Of Chevron Folding In Semicrystalline Polymersmentioning

confidence: 99%

Chevron morphology in deformed semicrystalline polymers

Krumova¹,

Henning²,

Michler³

2006

Philosophical Magazine

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International audienceChevron morphology was observed using transmission electron microscopy in various semicrystalline polymers deformed in tensile experiments. The morphological and mechanical prerequisites for chevron structure formation in semicrystalline polymers were revealed. It was demonstrated that chevron folding is a common deformation mode which can appear in real, i.e. globally unoriented or partially oriented samples, in areas where the lamellar stacks are oriented perpendicular to the deformation direction. Similarities with the behaviour of other layered systems were found. The mechanisms of chevron formation is discussed in the light of the fundamental statements of the folding theories and is related to the specific microstructure of the polymers. The effect of the boundary conditions, deformation temperature and macroscopic strain on the characteristics of the chevron structure is described

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“…The influence on the triaxial stress field is a change of the position of maximum tensile values. Under high tensile triaxial stress, craze-like features, as interlamellar separation and voiding of amorphous regions (Kausch et al, 1999), may be initiated in the semi-crystalline matrix material, and upon extension and coalescence of cavities, true crazes may be formed. The highest negative hydrostatic pressures are found at the particle equators for the large scale, isotropic material.…”

Section: Effect Of Radial Anisotropy On Mechanisms Of Failurementioning

confidence: 99%

“…Therefore, the initiation of crazing may, for the particle-modified system with radially oriented anisotropy, be expected to occur at the particle poles, rather than in the equator region. The growth of initiated crazes is likely to occur along planes which are perpendicular to the direction of maximum principal stress (Kausch et al, 1999). In Fig.…”

Section: Effect Of Radial Anisotropy On Mechanisms Of Failurementioning

confidence: 99%

Micromechanical modeling of particle-toughening of polymers by locally induced anisotropy

Dommelen

Brekelmans

Baaijens

2003

Mechanics of Materials

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The impact strength of several semi-crystalline polymers can be improved by the dispersion of second-phase rubber particles. A criterion for the effect of this practice is based on the average interparticle matrix ligament thickness. The critical interparticle distance is considered to be an intrinsic material property of the matrix. A toughening mechanism has recently been suggested which considers a layer of transcrystallized material around well dispersed particles, having a reduced yield strength in certain preferentially oriented directions. In this work, the potential of local anisotropy for the toughening of semi-crystalline polymeric material is investigated. The matrix material is modeled within the framework of anisotropic Hill plasticity with a rate dependent and hardening yield stress. The applicability of different two-dimensional micromechanical models is assessed by comparison to fully three-dimensional simulations with irregularly dispersed particles. A reduced plastic shear resistance of percolating transcrystallized material is found to be very effective in inducing extensive delocalized shear deformations and alters the location of the peak tensile hydrostatic stresses.

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Crazing in semicrystalline thermoplastics

Cited by 65 publications

References 10 publications

Failure behavior of PA12 based SLS lattice structure with macro-porosity

Failure behavior of PA12 based SLS lattice structure with macro-porosity

Chevron morphology in deformed semicrystalline polymers

Micromechanical modeling of particle-toughening of polymers by locally induced anisotropy

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