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molecular weight distribution

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Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006930
EISBN: 978-1-62708-395-9
... polymers but with different molecular weight and molecular weight distribution Fig. 6 Representative flow curve for a polymer melt Fig. 7 Viscosity and shear stress versus shear rate for PDMS (polydimethylsiloxane) from rotational rheometry Fig. 8 Viscosity versus shear rate...
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
..., viscous 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 Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006849
EISBN: 978-1-62708-395-9
...-density polyethylene Fig. 11 Degree of polymerization of polybutadiene rubber at 25 °C (77 °F). MW, molecular weight. Fig. 12 Sensitivity of solution versus melt rheometry to molecular weight Fig. 13 Narrow versus broad molecular weight distribution Fig. 14 G...
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
... Practical information provided Gel permeation chromatography (GPC)⁠; molecular weight distribution, MWD Weight-average molecular weight, M ¯¯¯¯w … Polymer MWD with soluble polymers … Low-angle light scattering, MWD for homopolymers, interactions polymer/solvent M ¯¯¯¯w M ¯¯¯¯w...
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
... and Crystallinity The primary use of DSC in polymer analysis is the detection and quantification of the crystalline melting process. Because the crystalline state of a polymeric material is greatly affected by properties including stereoregularity of the chain and the molecular weight distribution as well...
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
... transmission MW molecular weight MWD molecular-weight distribution MS mass spectroscopy NBR nitrile-butadiene rubber (or acrylonitrile-butadiene rubber) NBS National Bureau of Standards NDE nondestructive evaluation NDI nondestructive inspection NDT nondestructive testing NFPA National Fire Protection...
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
... Molecular weight Molecular-weight distribution Environmental stress-cracking resistance Decreases Increases Broadens Impact strength Decreases Increases Narrows Stiffness Increases … … Hardness Increases … … Tensile strength Increases … … Permeation Decreases...
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
... property and environmental stress-cracking (ESC) resistance Property Improved ESC resistance Amorphous or semicrystalline Semicrystalline Crystallinity Varies Molecular weight Higher Molecular weight distribution Narrow Polymer molecular fusion/entanglement More Unfilled...
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
... enough heat is applied to relax the induced orientation. Rotomolding and other low-shear processes produce little orientation. The synthesis methods used to make polymers generally give a distribution of molecular weights (MWs). This is important because the presence of short molecules reduces melt...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.9781627083959
EISBN: 978-1-62708-395-9
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
... melting profiles. MW, molecular weight. Source: Ref 53 Fig. 10 Differential scanning calorimetry thermogram of Fiberite 934 epoxy, 4.89 mg (0.075 gr), 10 °C/min (18 °F/min) heating rate. T g , subambient glass transition temperature of uncured resin; T i , initiation temperature or onset...
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
..., it is nearly impossible to determine whether the failure is primarily due to excessive regrind usage. However, MFI, molecular weight distribution (MWD), DSC, and optical microscopy techniques are often employed to determine the cause of failure, with favorable results. To achieve optimal chemical...
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
...Effect of increasing mean stress on fatigue crack propagation Table 1 Effect of increasing mean stress on fatigue crack propagation Increasing High-density polyethylene Nylon High-molecular-weight polymethyl methacrylate (PMMA) Polystyrene Epoxy Polyethylene copolymer...
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
... of the random nature of most polymerization reactions. Thus, polymers are generally characterized by a molecular-weight distribution and the associated averages. This is discussed in more detail in the article “Characterization of Plastics in Failure Analysis” in this Volume. Deformation and Fracture...
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
... is the point at which a crack is first nucleated. It usually coincides with the location of the maximum principal tensile stress or the minimum material resistance to fracture. Strictly speaking, because neither a uniform distribution of stress nor material homogeneity exists throughout an engineered component...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006920
EISBN: 978-1-62708-395-9
...: A Comparison with Low Molecular Weight Compounds , Pure Appl. Chem. , Vol 51 , 1979 , p 233 10.1351/pac197951020233 23. Roger A. et al. , Photochemistry of Aliphatic Polyamides. 4. Mechanisms of Photooxidation of Polyamides 6, 11, and 12 at Long Wavelengths , Macromolecules , Vol 19...
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
... may involve the following methods: Molecular spectroscopy. Infrared (IR) or Fourier transform infrared (FTIR) spectroscopy Nuclear magnetic resonance (NMR) spectroscopy Molecular weight (MW) and molecular weight distribution (MWD) using light scattering as well as other secondary...
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
... Molecular weight (MW) and molecular weight distribution (MWD) using light scattering as well as other secondary methods Methods of thermal analysis Differential scanning calorimetry (DSC) and differential thermal analysis Thermomechanical analysis Dynamic mechanical analysis Thermogravimetric...
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
... ), 1978 , p 220 – 224 , 10.1016/0032-3861(78)90043-5 38. Pitman G. and Ward I. , Effect of Molecular Weight on Craze Shape and Fracture Toughness in Polycarbonate , Polymer , Vol 20 (No. 7 ), 1979 , p 895 – 902 , 10.1016/0032-3861(79)90130-7 39. Mills N.J...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006864
EISBN: 978-1-62708-395-9
... to proportional, integral, and derivative control Check for process heating/cooling issues due to volatilization/vaporization of low-molecular-weight by-products or additives Steady, slow decrease in output Clogged screen pack or leakage along the screw flight Clean screen pack Implement...