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Molecular degradation

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Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.homegoods.c0090424
EISBN: 978-1-62708-222-8
... carbonate, which is a common breakdown product produced during the decomposition of polycarbonate. The conclusion was that the most likely cause of the molecular degradation was improper drying and/or exposure to excessive heat during the injection molding process that in turn caused the material...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.auto.c0090451
EISBN: 978-1-62708-218-1
... steel sleeve. The drying process had exposed the resin to relatively high temperatures, which caused substantial molecular degradation, thus limiting the part's ability to withstand the stresses. The drying temperature was found to be significantly higher than the recommendation for the PET resin...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c0090460
EISBN: 978-1-62708-234-1
... as a result of molecular degradation caused by the service conditions. Specifically, the part material had undergone severe chemical attack, including oxidation and hydrolysis, through contact with silver chloride. The source of the silver chloride was not established, but one potential source...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c0090463
EISBN: 978-1-62708-234-1
... contact inserts. Investigation supported the conclusion that the switch housings failed via brittle fracture, likely through a creep mechanism. The failure was caused by severe embrittlement of the housing resin associated with massive molecular degradation produced during the molding process. A potential...
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...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.homegoods.c0090448
EISBN: 978-1-62708-222-8
... importantly, the resin had been degraded, producing a reduction in the molecular weight and reducing both the mechanical integrity and chemical-resistance properties of the parts. Crystallization Electrical appliances Grease Housings Injection molding Molding resins Undercrystallization...
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
... modulus, tan delta Temperature-dependent behavior, aging/degradation, solid-liquid interactions Gel permeation chromatography (GPC) Weight-average molecular weight, molecular weight distribution Degradation, suitability of material for use Melt flow rate (MFR) Melt viscosity Degradation...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.chem.c0090454
EISBN: 978-1-62708-220-4
... initially, and subsequently, circumferentially around the wall. Throughout the examination, no signs of postmolding molecular degradation or chemical attack were found. Fig. 1 Scanning electron image showing features associated with brittle fracture and slow crack growth within the crack initiation...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c9001593
EISBN: 978-1-62708-234-1
..., without molecular degradation. Metal insert molding certainly offers distinct manufacturing and design advantages; however, it has inherent risks. These liabilities include the potential to generate excessive strain on the location of the part surrounding the insert due to a differential...
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
... the macromolecular chains, reducing molecular weight, and diminishing polymer properties as a result. Each of these effects is examined in subsequent paragraphs. Plasticization, Solvation and Swelling Environmental Stress Cracking Polymer Degradation by Chemical Reaction Surface Embrittlement...
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
.... Thus, structural components serving at elevated temperatures or in outdoor applications may undergo degradation if the polymers employed are not properly stabilized. Mechanical stress is known to enhance degradative effects. Degradation usually involves molecular-weight reduction by one of several...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003571
EISBN: 978-1-62708-180-1
.... and Tabor D. , Friction and Wear of Polymers, Chapter 1 , Polymer Surfaces , Clark D.T. and Feast J. , Ed., John Wiley & Sons , 1978 3. Pooley C.M. and Tabor D. , Friction and Molecular Structure: The Behaviour of Some Thermoplastics , Proc. R. Soc. (London...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001767
EISBN: 978-1-62708-241-9
..., such as absorbed water and other low-molecular-weight compounds. The sample went on to experience a primary weight loss of 80.7%, centered at 419 °C, and associated with the decomposition of the polymer. The sample exhibited a 10.2% weight loss due to the combustion of char and noncombustible residue content...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001831
EISBN: 978-1-62708-241-9
... within the motor would be inevitably increased to some extent. Under this condition, the grease used in the bearing suffered two kinds of degradation, i.e., the decomposition and the oxidation. The former one would produce several low-molecular-weight organic compounds, and the latter one would generate...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006788
EISBN: 978-1-62708-295-2
... showing extensive corrosion of weld metal and fusion line with a relatively small opening on the bold metal surface. Source: Ref 116 . Reprinted with permission from NACE International Fig. 12 Water-treatment system characterized at locations 1 to 5 using molecular microbiological method...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006782
EISBN: 978-1-62708-295-2
... on the metal surface or by interfering with either the anodic or cathodic reactions. High-molecular-weight amines retard the hydrogen-evolution reaction and subsequently reduce corrosion rate. Adequate conductivity in both the metal and the electrolyte is required for continuation of the corrosion reaction...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003552
EISBN: 978-1-62708-180-1
..., hydrogen damage of metal manifests itself in one of several ways. The types of interactions between hydrogen and metals include the formation of solid solutions of hydrogen in metals, molecular hydrogen, gaseous products from reactions between hydrogen and alloying or segregated impurity elements...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006784
EISBN: 978-1-62708-295-2
... attack Steels subject to combined high-temperature and high-pressure hydrogen. Also affects copper Irreversible chemical reactions of hydrogen with matrix or alloy elements form high-pressure pockets of gases other than molecular hydrogen. Cracking from hydride formation Transition, rare earth...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003522
EISBN: 978-1-62708-180-1
... chromatography (GPC) Weight-average molecular weight, M ¯ w ; molecular weight distribution (MWD) Low-angle light scattering M ¯ w , MWD Osmometry, membrane Number-average molecular weight, M ¯ n Osmometry, vapor pressure M ¯ n Dilute solution viscosity...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006757
EISBN: 978-1-62708-295-2
... chromatography (GPC) Weight-average molecular weight, M ¯ w ; molecular weight distribution (MWD) Low-angle light scattering M ¯ w , MWD Osmometry, membrane Number-average molecular weight, M ¯ n Osmometry, vapor pressure M ¯ n Dilute solution viscosity...