Craze fibril stability and breakdown in polystyrene

Yang, Arnold C.‐M.; Krämer, Edward J.; Kuo, Chia C.; Phoenix, S. Leigh

doi:10.1021/ma00161a039

Cited by 80 publications

(110 citation statements)

References 13 publications

Supporting

Mentioning

105

Contrasting

Order By: Relevance

“…This result is similar to what is observed for homopolymer glassy films where cracks are observed to initiate within crazes due to the breakdown of craze fibril structure in the active zone where polymer is being drawn into the craze. 1,18 The cumulative fraction of the film squares in which crazing has occurred is shown in Figure 4A for annealed samples and in Figure 4B for spun-cast samples. The onset for crazing does not depend significantly on the different thermal history of the samples.…”

Section: Block Copolymer Morphology and Microdomainmentioning

confidence: 99%

Effect of Thermal History and Microdomain Orientation on Deformation and Fracture Properties of Poly(cyclohexylethylene)−Polyethylene Triblock Copolymers Containing Cylindrical PE Domains

et al. 2002

Self Cite

View full text Add to dashboard Cite

We investigate the effects of polyethylene cylinder domain orientation and thermal history on the micromechanical deformation and fracture properties of poly(cyclohexylethylene)-poly(ethylene)-poly(cyclohexylethylene) (CEC) triblock copolymer where the poly(cyclohexylethylene) (PCHE) blocks are unentangled. The properties are assessed using a "fragility" test in which copolymer films are strained in tension using a copper grid as a support. Optical microscopy was used to determine the statistics of deformation and fracture events while transmission electron microscopy (TEM) and scanning force microscopy (SFM) were used to investigate the morphological details of the plastically deformed regions. Films of CEC show much more ductility if the PE cylinders are oriented either randomly (spun-cast films) or parallel to the tensile direction than if the PE cylinders are perpendicular to the tensile direction. In the latter case craze breakdown and crack propagation can proceed within the unentangled PCHE matrix domain without the highly entangled PE cylinders bridging such cracks. For the highest molecular weight CEC physical aging of the PCHE glassy domains is also important in causing embrittlement. Removing such physical aging by quenching from above the glass transition temperature T g of PCHE causes a change in deformation mechanism from crazing in slowly cooled samples to a mixed case where crazing and shear deformation compete. Although the crystal morphology in the PE cylinders may also depend on the cooling rate during crystallization, it can be ruled out as the cause of the embrittlement since films physically aged below T g of PCHE but above the melting temperature of PE show brittle behavior when quenched from the aging temperature.

show abstract

Section: Block Copolymer Morphology and Microdomainmentioning

confidence: 99%

Effect of Thermal History and Microdomain Orientation on Deformation and Fracture Properties of Poly(cyclohexylethylene)−Polyethylene Triblock Copolymers Containing Cylindrical PE Domains

et al. 2002

Self Cite

View full text Add to dashboard Cite

show abstract

“…For comparison, widths have been normalized using midsection (maximum) widths for a given craze. h ) 78 nm (0), h ) 112 nm (O), h ) 112 nm (b), and h ) 188 nm(2).…”

mentioning

confidence: 99%

High-Throughput Craze Studies in Gradient Thin Films Using Ductile Copper Grids

2004

View full text Add to dashboard Cite

Polymer materials are being developed and used for numerous photonic and electronic applications where the polymer is expected to maintain its dielectric properties in confined geometries. In these applications, the initiation or growth of mechanically induced defects, such as crazes, cracks, or shear bands, can significantly alter the intended function of the polymer. In this paper, we introduce a high throughput methodology to facilitate the investigation of craze growth in confined films. Specifically, we extend the previous research conducted on the effects of film thickness on crazing of polystyrene into unexplored thickness regimes of films less than 100 nm. We combine novel techniques of gradient thin film preparation, the established methodology of the copper grid strain test, the automated features of atomic force microscopy, and batch image processing to provide increased throughput and standardization in our quantitative measurements. We demonstrate that the mechanisms of craze widening and micronecking are quantitatively continuous to film thicknesses as thin as 50 nm.

show abstract

“…15 In addition, the fracture toughness of typical craze matter and its connection to the craze structure have also been a subject of study. 16 Whereas these considerations are all of importance, the most effective operational means of improving toughness has proved to be accepting a certain set of adventitious imperfections resulting from highquality material processing practice and to lower the craze flow stress to render them subcritical in TOUGHENING OF GLASSY POLYMERS relation to this lowered stress level.…”

Section: Discussion Rate Mechanisms Of Diluent-induced Tougheningmentioning

confidence: 99%

Toughening of glassy polymers by prepackaged deformation-activated diluents

Qin

Argon

Cohen

1999

J. Appl. Polym. Sci.

View full text Add to dashboard Cite

ABSTRACT:The use of low molecular weight liquid rubber diluents in concentrations of ϳ 1%, dispersed finely in the form of submicron-sized pools, had been demonstrated in the past by Gebizlioglu and colleagues (Macromolecules 1990, 23, 3968) to be an effective source of toughening of brittle glassy polystyrene through deformation-accentuated plasticization effects of craze matter during the development of craze plasticity. Herein, we present results of a study extending the range of this plasticization effect through the development of a new "precipitation-molding" process that can routinely incorporate diluent pools of up to 4 -5% by volume and can increase the tensile toughness by about a factor of 3 over what was achieved before. The experiments demonstrate that the toughening mechanism operates primarily through a substantial reduction of the craze flow stress that promotes an increase in craze plasticity that renders inactive adventitious inclusions that normally initiate fracture. Experiments with all blends at different temperatures and strain rates indicate that the fracture response can be represented by a universal behavior pattern of a single thermally assisted process of fracture of craze matter where the diluent merely modulates the plastic resistance. However, the experimental results show that the sorption of the diluent that controls the plasticization effect during straining competes against the time-dependent fracture process and that the toughening effect decreases monotonically with increasing strain rate and decreasing temperature that limits the effectiveness of the process to a range considerably below what is required for impact response.

show abstract

Craze fibril stability and breakdown in polystyrene

Cited by 80 publications

References 13 publications

Effect of Thermal History and Microdomain Orientation on Deformation and Fracture Properties of Poly(cyclohexylethylene)−Polyethylene Triblock Copolymers Containing Cylindrical PE Domains

Effect of Thermal History and Microdomain Orientation on Deformation and Fracture Properties of Poly(cyclohexylethylene)−Polyethylene Triblock Copolymers Containing Cylindrical PE Domains

High-Throughput Craze Studies in Gradient Thin Films Using Ductile Copper Grids

Toughening of glassy polymers by prepackaged deformation-activated diluents

Contact Info

Product

Resources

About