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molecular weight distribution

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Published: 01 June 2012
Fig. 3 Generic illustration of molecular weight distribution More
Image
Published: 15 May 2022
Fig. 14 Typical molecular weight distribution curve. M ¯ n , number-average molecular weight; M ¯ v ⁠, viscosity average molecular weight; M ¯ w ⁠, weight-average molecular weight; M ¯ z , Z-average molecular weight. Source: Ref 14 More
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Published: 15 May 2022
Fig. 13 Narrow versus broad molecular weight distribution More
Image
Published: 15 May 2022
Fig. 14 Typical gel permeation chromatogram showing variation in the molecular weight distribution of polymer samples. The tabular data showing the molecular weight are also presented. mV, millivolts; M n , number-average molecular weight; M w , weight-average molecular weight; M z More
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Published: 15 May 2022
Fig. 15 Frequency sweeps for two similar polymers but with different molecular weight and molecular weight distribution More
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Published: 15 May 2022
Fig. 15 Gel permeation chromatogram from a high-performance liquid chromatograph. MWD, molecular weight distribution. Source: Ref 18 More
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
... Plastics Testing Geometries One important aspect of the rheological testing of polymers is the testing of the materials in their molten state. The rheological properties are greatly affected by the nature of the polymer, its molecular weight and molecular weight distribution, the degree...
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
... and the molecular weight distribution as well as by processing and subsequent environmental exposure, this property is of considerable importance ( Ref 6 ). The melting point ( T m ) of a semicrystalline polymer is measured as the peak of the melting endotherm. A composite thermogram showing the melting...
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
... a particular analytical technique. Practical information derived from polymer analysis methods Table 2 Practical information derived from polymer analysis methods Test method Property Practical information provided Gel permeation chromatography (GPC)⁠; molecular weight distribution...
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
..., molecular weight. Fig. 12 Sensitivity of solution versus melt rheometry to molecular weight A second example of the unique contribution of melt viscosity measurements using dynamic mechanical techniques is the relationship between η* and G ′ and MW distribution. Figure 13 shows...
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 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: 23
Publisher: ASM International
Published: 01 June 2012
DOI: 10.31399/asm.hb.v23.a0005676
EISBN: 978-1-62708-198-6
... a specific polymer family. The molecular weight distribution of thermoplastics can be more fully evaluated using gel permeation chromatography. The molecular weight is described in terms of statistical averages: M n = number average, M w = weight average, and M z = z -average. A typical...
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
... and distribution, end groups and impurities, and copolymerization. Polymer size is quantified primarily by molecular weight, molecular-weight distribution, and branching. These factors are briefly described in this section. Stereoisomers In addition to possible geometric isomers of the mer unit...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 November 1995
DOI: 10.31399/asm.hb.emde.a0003006
EISBN: 978-1-62708-200-6
... of polyisoprene Structure Within the Molecule The structure within the molecule may involve stereoisomerism, branching, molecular weight and distribution, end groups and impurities, and copolymerization. Stereoisomers The polymer structures illustrated in Tables 1 , 2 , 3 , and 4 may appear...
Series: ASM Handbook
Volume: 21
Publisher: ASM International
Published: 01 January 2001
DOI: 10.31399/asm.hb.v21.a0003432
EISBN: 978-1-62708-195-5
... of the solvents in an explosion-proof oven. GPC A chromatograph is used to define and fingerprint the molecular weight distribution of the resin. Reaction advancement can also be determined by this method. Prepreg Tests Resins that have been impregnated onto fibers are placed there via a solvent...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 November 1995
DOI: 10.31399/asm.hb.emde.a0003025
EISBN: 978-1-62708-200-6
..., such as hydrogen bonding, do not require high molecular weight to achieve good mechanical properties. With low molecular weight, viscosity is very low, which is commonly observed for PA. Molecular weight and molecular weight distribution are useful in characterizing plastic properties. In plastics with a broad...
Series: ASM Handbook
Volume: 21
Publisher: ASM International
Published: 01 January 2001
DOI: 10.31399/asm.hb.v21.a0003441
EISBN: 978-1-62708-195-5
..., molecular weight distribution, specific gravity, refractive index, and chlorine content. Of the thermoset systems being considered, only polyesters, vinyl esters, and epoxies require the addition of other ingredients to facilitate polymerization. There are other ingredients in some systems, particularly...
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
... entanglement, and the retention of molecular weight. Molecular Weight Distribution Molecular weight distribution is another material factor that plays a role in ESC failure. For polymers with similar average molecular weights, increased levels of polydispersity decrease the ESC resistance ( Ref 17...
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
... . Polymer size is quantified primarily by molecular weight, molecular-weight distribution, and branching. Effect of molecular weight on polyethylene Table 3 Effect of molecular weight on polyethylene Number of –CH 2 –CH 2 – units Molecular weight Softening temperature Character of polymer...