Related Experiment Video
Updated: Oct 19, 2025
10:22
Designed for Molecular Recycling: A Lignin-Derived Semi-aromatic Biobased Polymer
Published on: November 30, 2020
3.6K
The Characterization of Linear Polyethylene SRM's 1482, 1483, and 1484. I. Introduction
Peter H Verdier1, Herman L Wagner1
1Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234.
Journal of Research of the National Bureau of Standards (1977)
|September 27, 2021
Summary
The National Bureau of Standards released new linear polyethylene Standard Reference Materials (SRMs) with varying molecular weights. These materials are certified for molecular weight and viscosity, aiding polymer research.
Area of Science:
- Polymer Science
- Materials Science
- Analytical Chemistry
Background:
- Standard Reference Materials (SRMs) are crucial for accurate scientific measurements.
- Polyethylene characterization is essential for diverse industrial applications.
Purpose of the Study:
- To introduce and describe the preparation of three new linear polyethylene SRMs.
- To provide certified values for molecular weight and viscosity properties of these SRMs.
Main Methods:
- Preparation of linear polyethylene materials with targeted molecular weights.
- Characterization using membrane osmometry for number-average molecular weight.
- Characterization using light scattering for weight-average molecular weight.
- Capillary viscometry for limiting viscosity numbers in two solvents.
Main Results:
- Three linear polyethylene SRMs (1482, 1483, 1484) were prepared with molecular weights around 10,000, 30,000, and 100,000 g/mol.
- The ratio of weight-average to number-average molecular weight (Mw/Mn) was approximately 1.2 for all materials.
- Certified values for molecular weights and limiting viscosity numbers are provided.
Conclusions:
- The successful preparation and characterization of these polyethylene SRMs provide reliable standards for the scientific community.
- These SRMs will facilitate accurate and reproducible polymer analysis and research.
Keywords:
FractionStandard Reference Materiallimiting viscosity numbernarrow molecular weight distributionnumber-average molecular weightpolyethyleneweight-average molecular weightMore Related Videos
Related Concept Videos
01:14Polymer Classification: Architecture
3.3K
Polymers are classified as linear or branched on the basis of their chain architecture. The polymer chains in linear polymers have a long chain-like structure with minimal to no branching at all. Even if a polymer features large substituent groups on the monomer, which appear as branches to the skeleton, it is not considered a branched polymer. A branched polymer contains secondary polymer chains that arise from the main polymer chain. The branching occurs when the polymer growth shifts from...
3.3K
01:26Polymer Classification: Stereospecificity
2.9K
Polymerization generates chiral centers along the entire backbone of a polymer chain. Accordingly, the stereochemistry of the substituent group has a significant effect on polymer properties. Polymers formed from monosubstituted alkene monomers feature chiral carbons at every alternate position in the polymer backbone. Relative to the predominant orientation of substituents at the adjacent chiral carbons, the polymer can exist in three different configurations: isotactic, syndiotactic, and...
2.9K
01:00Characteristics and Nomenclature of Homopolymers
3.5K
Polymers that are made up of identical monomer units are called homopolymers. Only one repeating unit is involved in the construction of the homopolymer structure. For example, as depicted in Figure 1, polypropylene is a homopolymer constituted of propylene monomers. Here, the only repeating unit in the polymer chain is propylene.
3.5K
02:35Free-Radical Chain Reaction and Polymerization of Alkenes
8.5K
The conversion of alkenes to macromolecules called polymers is a reaction of high commercial importance. The structure of the polymer is defined by a repeating unit, while the terminal groups are considered insignificant. The average degree of polymerization represents the number of repeating units in the polymer molecule and is denoted by the subscript n.
8.5K
01:08Molecular Weight of Step-Growth Polymers
2.5K
Step growth polymerization involves bi or multifunctional monomers. Bifunctional monomers react to form linear step growth polymers, whereas multifunctional monomers react to form non-linear or branched polymers.
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
2.5K
01:17Radical Chain-Growth Polymerization: Chain Branching
2.1K
The skeletal structure of polymers synthesized via radical polymerization is always branched. For example, the polymerization of ethylene by radical polymerization results in a low-density grade of polyethylene with a heavily branched skeletal structure. Here, the radical site abstracts hydrogen from the growing chain, and the radical site shifts from the end (a primary carbon center) to anywhere within the growing chain (a secondary carbon center). Consequently, the part of the chain from the...
2.1K