Stress-whitening in high-impact polystyrenes

Bucknall, C. B.; Smith, Robert Ross

doi:10.1016/0032-3861(65)90028-5

Cited by 333 publications

(88 citation statements)

References 7 publications

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“…This crazing is often observed in stiff and brittle materials. 41,42 The P(3HB-co-7 mol% 3HH) cast Figure 5 DMTA tand of blend cast films aged for 1 month. (a) P(3HB)/PCL, (b) P(3HB-co-7 mol% 3HH)/PCL and (c) P(3HB-co-11 mol% 3HH)/PCL.…”

Section: Microstructural Modificationmentioning

confidence: 99%

The toughening effect of a small amount of poly(ɛ-caprolactone) on the mechanical properties of the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/PCL blend

Katsumata

Saitō

Fang

et al. 2011

Polym J

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To improve the mechanical properties of bacterial poly(3-hydroxybutyrate) [P(3HB)] and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HH)], the materials were blended with poly(e-caprolactone) (PCL). The P(3HB-co-7 mol% 3HH) cast film and the P(3HB-co-11 mol% 3HH) melt-pressed film show brittleness after aging, although unaged samples show ductile behavior. However, the addition of a small amount of PCL was found to greatly improve the toughness of the P(3HB-co-7 mol% 3HH) cast film and the P(3HB-co-11 mol% 3HH) melt-pressed film. Reduction in the whitening of the elongated P(3HB-co-7 mol% 3HH) film by blending with PCL indicates that a transition in the deformation mechanism of the film was induced. In P(3HB-co-11 mol% 3HH)/PCL melt-pressed films, a cloud of craze initiation created by the dispersed PCL was observed. Differential scanning calorimetry thermograms and scanning electron microscopy images of the blended films indicated that finely dispersed PCL, the crystallization of which was restricted, and/or voids formed during preparation contribute to the delocalization of the applied stress and ductile deformation of P(3HB-co-3HH) films. In conclusion, the transition in the deformation mechanisms and the delocalization of the applied stress are expected to be important for enhancing the toughness of aged P(3HB-co-3HH)s, and blending with a small amount of PCL is a simple way to improve the mechanical properties of P(3HB-co-3HH)s. Polymer Journal (2011) 43, 484-492; doi:10.1038/pj.2011.12; published online 23 February 2011Keywords: blend; mechanical property; polyhydroxyalkanoate; poly(e-caprolactone); tensile test INTRODUCTION Several kinds of polyhydroxyalkanoates (PHAs) are biosynthesized by various bacteria as energy-storage materials. 1-5 They may be produced from renewable natural resources and have biodegradability. Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HH)] is part of the PHA family. 6 Doi et al. 7 have found that the content of the 3HH unit greatly affected the thermal and mechanical properties of P(3HB-co-3HH), but had little effect on the crystalline structure of 3HB-rich P(3HB-co-3HH)s because of the formation of the P(3HB)-homopolymer-type crystalline phase and the exclusion of the 3HH unit from the crystalline lattice. P(3HB-co-3HH) was found to show improved mechanical properties and thermal plasticity over those of known PHAs. 8,9 One of the notable advantages of P(3HB-co-3HH)s is their adjustable mechanical properties, from soft to hard material, depending on the comonomer-unit composition; this allows for the tailoring of P(3HB-co-3HH) to various societal applications, such as in green and sustainable polymeric materials.However, P(3HB-co-3HH) becomes brittle after aging at room temperature, thus restricting its practical applications. Although

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Section: Microstructural Modificationmentioning

confidence: 99%

The toughening effect of a small amount of poly(ɛ-caprolactone) on the mechanical properties of the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/PCL blend

Katsumata

Saitō

Fang

et al. 2011

Polym J

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“…Furthermore, in OG-POSS epoxies, the POSS moieties exist at least partially as nanoscale aggregates strongly bonded to the matrix, obviating traditional cavitation from hard inclusions. [32][33][34][35] Thus, as a result of the initiation of voids in the matrix caused by the presence of POSS aggregates (clearly shown in Fig. 8), plastic shear bands are increasingly initiated with increased DDS content.…”

Section: Hybrid Epoxy-based Thermosetsmentioning

confidence: 99%

Hybrid epoxy‐based thermosets based on polyhedral oligosilsesquioxane: Cure behavior and toughening mechanisms

Kim

Qin

Fang

et al. 2003

J Polym Sci B Polym Phys

144

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Polyhedral oligosilsesquioxane (POSS)-reinforced thermosets based on octaglycidyl epoxy polyhedral oligosilsesquioxane cured with 4,4Ј-diaminodiphenyl sulfone (DDS) were prepared and studied for their cure, thermomechanical, and microstructural characteristics. Particular attention was paid to nanometer-scale deformation processes responsible for toughening, as revealed by transmission electron microscopy (TEM) in conjunction with the thermal properties. A cure analysis investigated with calorimetry and rheometry showed a significant dependence of the cure mechanism and kinetics on the DDS content, but all hybrid thermosets reacted completely below 300°C into rigid solids. A dynamic mechanical analysis of this hybrid resin system showed that increasing the DDS concentration used during cure increased the dynamic storage modulus in the glassy (temperature Ͻ glass-transition temperature) and rubbery (temperature Ͼ glass-transition temperature) states, simply through an increase in the crosslink density. The phase structures revealed by TEM with selective POSS staining were drastically affected by the DDS concentration and manifested as altered nanomechanical deformation structures. It was qualitatively found that the main toughening mechanism in the studied POSS-reinforced thermosets was void formation at the nanometer scale, possibly templated by limited POSS aggregation. As the crosslinking density increased with the DDS concentration, microshear yielding between voids prevailed, providing a balance of stiffness, strength, and toughness.

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“…An interesting feature is the criterion for craze formation. It has been suggested that crazes form in the material when a critical limit is reached in for instance stress [3], stress bias [4], strain [5], distortion strain energy [6], dilatation [7] or strain energy [8]. A method for comparing the various proposed criteria was executed by Wang et al [8].…”

Section: Introductionmentioning

confidence: 99%

The effect of interfacial adhesion on the mechanism for craze formation in polystyrene-glass bead composites

Dekkers

Heikens

1983

J Mater Sci

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The craze formation in polystyrene-glass bead composites subjected to a uniaxial tension has been investigated. To gain insight into the role of interfacial adhesion, the bonding between glass and polystyrene was varied by using different silane coupling agents. The distributions of several craze formation criteria around an isolated adhering glass sphere in a polystyrene matrix have been computed with the aid of the finite element analysis. It was found that the mechanism for craze formation is fundamentally different for adhering and non-adhering glass beads. In the case of excellent interfacial adhesion the crazes form near the poles of the beads in regions of maximum dilatation and of maximum principal stress. With poor interfacial adhesion the crazes form at the interface between pole and equator. It is proposed that in the latter case craze formation is preceeded by dewetting along the phase boundary.

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Stress-whitening in high-impact polystyrenes

Cited by 333 publications

References 7 publications

The toughening effect of a small amount of poly(ɛ-caprolactone) on the mechanical properties of the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/PCL blend

The toughening effect of a small amount of poly(ɛ-caprolactone) on the mechanical properties of the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/PCL blend

Hybrid epoxy‐based thermosets based on polyhedral oligosilsesquioxane: Cure behavior and toughening mechanisms

The effect of interfacial adhesion on the mechanism for craze formation in polystyrene-glass bead composites

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