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crystalline structures

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Published: 15 May 2022
Fig. 2 Schematic diagrams of (a) halloysite crystalline structure and (b) halloysite nanotubes. Images of halloysite nanotubes by (c) transmission electron microscopy (TEM) and (d) atomic force microscopy (AFM). Source: Ref 17 More
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Published: 01 December 1992
Fig. 3 SEM micrographs of the solder surface in the demo unit. Note the melted and resolidified crystalline structure in (a). (a) 1000×. (b) 100×. More
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Published: 15 May 2022
Fig. 32 Differential scanning calorimetry thermogram comparison of first heating results for the (a) molding resin and (b) failed part. An endotherm is present in the results obtained on the failed window material. The endotherm is characteristic of the melting of crystalline structure within More
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001132
EISBN: 978-1-62708-214-3
.... Surface Examination Scanning Electron Microscopy/Fractography The demo unit, after being intentionally actuated using a propane torch, exhibited a resolidified crystalline structure in the solder of the copper cups when examined by scanning electron microscopy (SEW ( Fig. 3 ). The failed unit...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006933
EISBN: 978-1-62708-395-9
... is important because it impacts the mechanical, physical, and chemical resistance properties of the molded article. In general, rapid or quench cooling results in a lower crystalline state. This is the result of the formation of frozen-in amorphous regions within the preferentially crystalline structure...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006931
EISBN: 978-1-62708-395-9
...; the particular state—whether amorphous, semicrystalline, or crystalline; and the nature of any network structure. These elements, by which all polymers can be classified, are illustrated in Fig. 2 and described with examples in Table 1 . Clearly, there should be no network structure or cross-linking...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006922
EISBN: 978-1-62708-395-9
... materials in which all of the molecules are randomly oriented with no molecular alignment are classified as amorphous. Because there is no crystalline structure, amorphous materials will not truly melt, but they will soften as they approach their glass transition temperature (T g ). Some of the key...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006925
EISBN: 978-1-62708-395-9
... of the changes produced in such structural factors as intermolecular bonding and crystallinity. For example, an atactic polymer tends to be a rubbery amorphous material, while an isotactic polymer is more crystalline with more stiffness and melting temperatures. Fig. 6 Stereoisomers in a simple vinyl...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.matlhand.c9001474
EISBN: 978-1-62708-224-2
... with the notches cut in the same relative position as the defect seen at the origin of the fracture, and these gave the following results: The central regions of the former specimens showed a completely crystalline structure, but the normalised specimens revealed, in the main, tough fractures having a silky...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006915
EISBN: 978-1-62708-395-9
... a crystallinity of 30%, for example. Amorphous polymers exhibit a T g that is the temperature at which the amorphous regions become mobile. Semicrystalline polymers exhibit both a T g and a T m at which the crystallites melt. Because chain mobility is required to form ordered structures, polymers...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.matlhand.c0048091
EISBN: 978-1-62708-224-2
... Abstract A section from a stop-block guide fell to the floor on a crane runway after it failed. A brittle crystalline-type break was disclosed by examination of the fracture surface. The point of initiation was in a hardened heat-affected layer that had developed during flame cutting...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003543
EISBN: 978-1-62708-180-1
... of an overload failure. It also presents examples of thermally and environmentally induced embrittlement effects that can alter the overload fracture behavior of metals. atomic structure brittle cracking crack propagation crystalline structure ductile cracking ductility environmentally induced...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c9001188
EISBN: 978-1-62708-235-8
... Abstract A short fracture section of a forged and normalized Ck 35 (DIN 17200) steel slide showed three distinct zones: a dark colored crystalline area, an incipient crack propagating into a far advanced, rubbed fracture surface, and a fine crystalline final break. Metallographic examination...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006923
EISBN: 978-1-62708-395-9
... polymer crystals. These amorphous regions bind the crystalline elements of the solidified polymer into a solid structure in much the same way as mortar holds together bricks in a brick wall. While these intercrystalline regions may, at times, be areas of weakness in a solid semicrystalline polymer...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006944
EISBN: 978-1-62708-395-9
..., which produce differences in fracture appearances. Sometimes there is more complexity due to the parameters of the material, such as the type of polymer, molecular weight, crystallinity, microstructure (spherulitic structure), the presence of fillers and additives, and other considerations. Behavior...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.conag.c9001449
EISBN: 978-1-62708-221-1
..., cracked in a brittle manner at a bend angle of 30° to give a crystalline fracture. A second notched test piece, normalised at 900°C. before testing, broke at A an angle of 45° but gave a fibrous fracture, showing that some improvement in notch ductility resulted from this treatment. The temperature...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006934
EISBN: 978-1-62708-395-9
... for homogeneous polymers. The word homogeneous is used to exclude copolymers and blends that undergo microphase separation or phase changes. However, the differences between crystalline and amorphous polymers are identified. The application of this review to the practical problems of failure analysis...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006917
EISBN: 978-1-62708-395-9
... regions. Crystalline regions result from greater intermolecular forces that lead to tightly knit and organized structures called lamellae ( Fig. 2 ) ( Ref 3 ). These lamellar structures are comprised of polymer molecules that have created organized folding patterns upon cooling. As the polymeric molecules...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006778
EISBN: 978-1-62708-295-2
... behavior Ductile behavior Structural engineer Applied stress at failure is less than the yield stress Applied stress at failure is greater than the yield stress By eye (1×) No necking, shiny facets, crystalline, granular Necked, fibrous, woody Macroscale (<50×) “Low” reduction...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003525
EISBN: 978-1-62708-180-1
... center on the techniques used to evaluate the composition and structure of the material. Unlike metals, polymers have a molecular structure that includes characteristics such as molecular weight, crystallinity, and orientation, and this has a significant impact on the properties of the molded article...