What are the molecular weight determination methods for polymers?

What are the molecular weight determination methods for polymers?

Molecular weights of polymers can be determined by chemical or physical methods of functional-group analysis. They are measurement of the colligative properties, light scattering, or ultracentrifugation; or by measurement of dilute-solution viscosity.

What are the advantages of light scattering in determination of mol wt?

The addition of light scattering detection online with GPC/SEC systems allows the measurement of true – or absolute – molecular weight of macromolecules, as opposed to the relative values obtained from conventional column cali- bration techniques.

What is the significance of determination of molecular weight of a polymer?

The molecular weight of a polymer is directly related to its properties. As the molecular weight increases, mechanical properties generally increase. Every polymer has an ideal molecular weight at which the balance of different properties (such as processability, strength, brittleness etc.) is optimized.

What is light scattering method in polymer?

Static light scattering is a technique in physical chemistry that measures the intensity of the scattered light to obtain the average molecular weight Mw of a macromolecule like a polymer or a protein in solution.

What is the principle of light scattering?

The basic principle is simple: The sample is illuminated by a laser beam and the fluctuations of the scattered light are detected at a known scattering angle θ by a fast photon detector. Simple DLS instruments that measure at a fixed angle can determine the mean particle size in a limited size range.

Which method is used for determination of molecular weight?

(1) MW can be measured using many different methods including gel permeation chromatography (GPC), osmometry, light scattering, viscometry, cryoscopy, ebulliometry, ultracentrifugation, mass spectrometry, and end-group analysis.

Which method is most suitable for determining molecular mass polymer?

(A) : Osmotic pressure method is the most suitable method to determine the number average molecular masses of polymers.

How is light scattering measured?

Two techniques are used to detect the light scattering of a solution: (1) nephelometry, in which the light-scattering species in solution are monitored by measuring the light intensity at an angle away from the incident light passing through the sample; (2) turbidimetry, in which the light-scattering species in …

Which spectroscopy is light scattering technique?

Raman spectroscopy is a nondestructive light scattering technique that is commonly used for examining the bonding between carbon atoms in DLC films and other carbon-containing solids.

What is the most accurate method to determine molecular weight?

GPC method is the most effective technique to determine molecular weight of your polymer.

Which one is best method for molecular mass determination of polymer?

Osmotic pressure method
(A) : Osmotic pressure method is the most suitable method to determine the number average molecular masses of polymers.

What are the different types of molecular weight of a polymer?

They are high molecular weight polymers with repeating units as monosaccharides….15.3.2.2 Polymer molecular weight (Mi), number average molecular weight (Mn)

Number of polymers Ni Molecular weight of each polymer chain Mi (molar mass)
2 200
3 400
2 500
1 600

What is light scattering process?

Light scattering is a term referring to physical processes involving the interaction of light and matter. Due to this interaction light incident on an ensemble of particles — crystals, aerosols, molecules, atoms etc. — is partially “deflected” in directions deviating from the incident direction.

What is light scattering used for?

Dynamic light scattering (DLS) is a technique in physics that can be used to determine the size distribution profile of small particles in suspension or polymers in solution.