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molecular structure

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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
... analyses are performed on metal and plastic materials center primarily 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 polymer functional groups, molecular weight, molecular weight...
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
... functional groups Molecular information, chemical analysis Attenuated total reflectance (ATR) Surface functional groups Molecular information Nuclear magnetic resonance (NMR) spectroscopy Chemical shift of nuclei Molecular structure, functional group determination, sequence distribution Mass...
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
...? Environmental stress cracking is a mechanism of fracture that results from the simultaneous and synergistic exposure of a plastic to chemical and stress. To properly understand the mechanism, it is important to have a basic knowledge of the molecular structure of plastics and how they can crack. As shown...
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...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006918
EISBN: 978-1-62708-395-9
... weight, crystallinity, degree of cross linking, and backbone molecular structure of the polymer ( Ref 26 – 60 ). Polymers are also prone to time-dependent behavior, and fatigue characterization must incorporate viscoelastic effects; such effects may include sustained loading, sensitivity to peak stress...
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
... properties by looking at a structure on paper is an active area of research ( Ref 11 ). Molecular Structure Polymer molecules are chains of repeat units called mers. The length of the chain (number of mers) affects the thermal, mechanical, and rheological properties of plastics, as shown in Table 3...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.petrol.c9001179
EISBN: 978-1-62708-228-0
... at 530 deg C. The connectors were made of SAE 4140 Cr-Mo steel. The material for the rod pipes was Fe-0.4C-1Mn steel. Structural stresses played a role in the cracking. Iron sulfide formed on the fracture planes and flake-like stress cracks occurred in the steel. The hydrogen sulfide content of the gas...
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
... The mer unit defines the chemical composition of a polymer, but complete information about the chemical structure of a polymer has several variations of how the mers combine to form a polymer. These variations in structure within the molecule may involve stereoisomerism, branching, molecular weight...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.auto.c0090442
EISBN: 978-1-62708-218-1
... degradation of the failed part material, and the thermograms supported this. The conclusion was that the failed sleeves had cracked due to embrittlement associated with severe degradation and the corresponding molecular weight reduction. The reduction in molecular weight significantly reduced the mechanical...
Image
Published: 15 May 2022
Fig. 21 Structure of a phenol formaldehyde. (a) Two phenol rings join with a formaldehyde molecule to form a linear chain polymer and molecular by-product. (b) Excess formaldehyde results in the formation of a network thermosetting polymer due to cross linking. Source: Ref 4 More
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
... review of thermoplastic and thermoset plastics is in order. Since the molecular structure and arrangement plays such an important role in how the material will process and function, the reader is encouraged to do a thorough investigation ( Ref 2 ). Additionally, the article “ Engineering Plastics...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003550
EISBN: 978-1-62708-180-1
... into the polymer, do not alter the molecular structure irreversibly. Their effects can be reversed if the chemical is removed from the material, for example, by evaporation. Environmental stress cracking occurs without significant absorption of an environmental reagent by the polymer but will promote brittle...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006916
EISBN: 978-1-62708-395-9
.... Since no two unique molecular structures produce the same infrared spectrum, the resulting spectra can be compared with known material spectra, and the material is thereby positively identified. FTIR is also a useful tool for identifying the presence of contaminant materials within a failed part...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006867
EISBN: 978-1-62708-395-9
... behaviors. Plasticization, solvation, and swelling, which involve diffusion of chemicals into the polymer, do not alter the molecular structure irreversibly. Their effects can be reversed if the chemical is removed from the material, for example, by evaporation. Environmental stress cracking occurs without...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.petrol.c0048698
EISBN: 978-1-62708-228-0
... Abstract Wet natural gas was dried by being passed through a carbon steel vessel that contained a molecular-sieve drying agent. The drying agent became saturated after several hours in service and was regenerated by a gas that was heated to 290 to 345 deg C in a salt-bath heat exchanger...
Book Chapter

Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003541
EISBN: 978-1-62708-180-1
... as a fiber, plastic, or elastomer ( Fig. 1 ), depending on the relative strength of intermolecular bonds and molecular structure or geometry. Noncrystalline polymers with weak intermolecular forces are usually elastomers or rubbers at temperatures above the glass transition temperature, T g . In contrast...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006865
EISBN: 978-1-62708-395-9
... and molecular structure or geometry. Non-crystalline polymers with weak intermolecular forces are usually elastomers or rubbers at temperatures above the glass transition temperature, T g . In contrast, polymers with strong hydrogen bonds and the possibility of high crystallinity can be made into fibers...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006945
EISBN: 978-1-62708-395-9
... ultrasonics linear viscoelastic region critical molecular weight number-average molecular weight modulus of toughness weight-average molecular weight polydispersity index Z-average molecular weight 702 / Reference Information MBS methyl methacrylate-butadiene-styrene MDA MDAB methylenedianiline 4,40...
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
... molding. Most processing conditions require materials with high molecular weights. This is especially true for extrusion and blow molding, which require sufficient melt strength for the extrudate to support itself as it exits from the die. Chemical Structure Chemical structure affects the T g...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006849
EISBN: 978-1-62708-395-9
... properties of polymer. This is followed by a section describing molecular weight determination using viscosity measurements. Next, the article discusses the use of cone and plate and parallel plate geometries in melt rheology. It then reviews the processes involved in the analysis of thermoplastic resins...