Thickness effect on fracture in high impact polystyrene

Yap, O. F.; Mai, Yiu‐Wing; Cotterell, B.

doi:10.1007/bf00745563

Cited by 40 publications

(10 citation statements)

References 19 publications

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“…Thus, the plane strain wze is 1.10 k J / m 2 and an equivalent plane strain K1c value of 1.45 M P a v~. This agrees well with a plane strain value of 1.50 MPaCm using thick samples larger than 25 mm [22]. When 1 > 2t, the elliptical craze zone took the shape of a line zone of constant width leading to w/being independent of l as shown in Fig.…”

Section: Rubber-modified Polystyrenessupporting

confidence: 73%

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On the essential work of ductile fracture in polymers

1986

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The essential work of fracture concept has been extended to cover ductile tearing of polymeric materials that neck before fracture. It is shown that the plane stress specific essential fracture work (w e) can be obtained from deeply edge-notched tension specimens, containing either single or double notches, by extrapolating the straight line relationship between the total specific fracture work (Wy) and ligament length (1) to zero ligament. In this way, specific essential fracture works have been obtained for nylon 66 and two polyethylenes. It seems that w e is a material property for a given sheet thickness being independent of specimen geometry. The straight line relationship between w / a n d / breaks down when the ligament length to sheet thickness ratio is less than about three, since the fracture data fall in the plane stress-plane strain transition region. However, a plane strain specific essential fracture work can still be obtained by extrapolating the least squares curve of the data to zero ligament provided the thickness satisfies plane strain condition. If this condition is not satisfied a near plane strain value is obtained which is dependent upon thickness. This method is also appropriate for ductile polymers like the rubber modified polystyrenes that craze rather than neck.JR curves have also been obtained for nylon 66 and the polyethylenes. Under strictly J-controlled crack growth conditions, it is shown that the intercept and slope of the JR curve, i.e. Jc and dJ/da, are related to the intercept and slope of the w/versus l plot. The limited amounts of J-controlled data available have precluded a more definite and general conclusion to be made. But based on what little is available, the comparisons of these two quantities in the J R -Aa and w / -1 plots are. not unreasonable.

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Section: Rubber-modified Polystyrenessupporting

confidence: 73%

“…Only small size samples with approximately 3.6 mm thickness were produced for this work. Figure 12 shows the DENT fracture results for HIPS taken from [22] in which WJlt is plotted against I. There is apparently a straight line relationship for the data when l < 2t (i.e.…”

Section: Rubber-modified Polystyrenesmentioning

confidence: 98%

On the essential work of ductile fracture in polymers

1986

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“…The Essential work of fracture was first applied for the evaluation of low‐rate fracture toughness of very ductile polymers in plane stress,29–33 but can also be applied for the evaluation of polymer toughness at high‐rate and in‐plane strain conditions 9, 25, 34–36. The work of fracture is partitioned into two parts.…”

Section: Methodsmentioning

confidence: 99%

Mechanical evaluation of propylene polymers under static and dynamic loading conditions

Fasce

Pettarín

Bernal

et al. 1999

J. Appl. Polym. Sci.

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ABSTRACT:The present investigation is concerned with the evaluation of the impact toughness of commercial-grade Propylene polymers. Conventional impact static stressstrain and static fracture experiments were carried out. Static stress-strain experiments revealed different pattern behaviors among the materials that were reflected in the fracture behavior. Under static conditions, all materials exhibited ductile behavior and crack grew under J-controlled conditions displaying stress whitening through the whole fracture surface with the sole exception of the homopolymer, which displayed a ductile instability after some stable crack growth. Under dynamic conditions the homopolymer exhibited brittle behavior, the block copolymer exhibited some plastic deformation at the crack tip, and the random copolymer samples exhibited a whitening effect due to voiding and craze formation through the whole fracture surface, indicating that stable crack propagation was occurring. Fracture mechanics tests were analyzed by following different methods, depending on the mode of fracture presented by the polymer. The Normalization J-method was used under static conditions. The elastic method, the corrected elastic method, and the essential work of fracture methodology were used to characterize brittle, semibrittle, and ductile behavior, respectively. Fracture mechanics parameters arisen from both static and dynamic conditions are compared.

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“…Although the essential work of fracture (EWF) model was originally developed to characterise the fracture of deeply notched metal and polymer specimens through large-scale yielding [14][15][16][27][28][29], it can also be used to explain the adhesive thickness effect on the fracture toughness of adhesive joints. For a deeply notched specimen with a small un-cracked area B ¢ .W ¡ a/, full yielding precedes material fracture initiation.…”

Section: Essential Work Of Fracture For Large-scale Yield Of Polymersmentioning

confidence: 99%