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Technical data


Determining the molecular weight of a polymer from intrinsic viscosity measurements

Article no: P3010601

Principle

The viscosity of a liquid is effectively determined by the strength of the intermolecular attractive forces. In the case of solutions, the viscosity of the solvent can alter significantly depending on the type and concentration of the solute. Due to their size, macromolecules have a very considerable impact on the viscosity of the solvent. Viscosity measurements can be used to estimate the mean molecular mass of a macromolecule if something is known about its conformation.

Benefits

  • Determination of an important parameter of rheology
  • For both demonstration and student experiments

Tasks

  1. Use a thermostatted capillary viscometer to measure the viscosities of solutions of polystyrene in toluene over a range of five polymer concentrations.
  2. Determine the instrinsic viscosity and from that estimate the molecular weight (relative molecular mass) of the polymer in this solution.

Learning objectives

  • Viscosity of liquids
  • Ostwald capillary viscometer
  • Poiseuilles's equation
  • Macromolecules
  • Mass average and number average molecular weights
  • The Mark-Houwink equation
  • Alternative techniques e.g. osmosis
  • Sedimentation (ultracentrifuge methods)
  • Light scattering

 

Necessary accessories:

This experiment requires a precision balance

Precision balance, Sartorius ENTRIS® II, 620 g : 1 mg (49311-99)

 

Scope of delivery

Immersion thermostat Alpha A, 230 V 08493-93 1
Bath for thermostat, makrolon 08487-02 1
External circulation set for thermostat Alpha A 08493-02 1
Retort stand, h = 750 mm 37694-00 1
Right angle boss-head clamp 37697-00 1
Universal clamp 37715-01 1
Ubbelohde viscosimeter, 0.4 mm 03102-03 1
Digital stopwatch, 24 h, 1/100 s and 1 s 24025-00 1
Weighing dishes, square shape, 84 x 84 x 24 mm, 500 pcs. 45019-50 1
Volumetric flasks, Boro, various sizes 36550-00 1
Volumetric flasks, Boro, various sizes 36548-00 4
Bulb pipettes, various sizes 36577-00 6
Bulb pipettes, various sizes 36578-00 1
Bulb pipettes, various sizes 36579-00 1
Bulb pipettes, various sizes 36581-00 1
Pipettor 36592-00 1
Pipette dish 36589-00 1
Funnels (glass), Boro, various sizes 34459-00 1
Water jet pump, plastic 02728-00 1
Rubber hose for vacuum, various diameters 39286-00 2
Rubber hose, various diameters 39282-00 4
Hose clip, diam. 8-16 mm, 1 pc. 40996-02 4
Beakers, Boro, high form, various sizes 46027-00 4
Graduated cylinders, Boro, various sizes 36629-00 1
Glass rod, boro 3.3, l=200mm, d=5mm 40485-03 1
Spoon, special steel 33398-00 1
Pasteur pipettes, 250 pcs 36590-00 1
Rubber caps, 10 pcs 39275-03 1
Wash bottle, plastic, 500 ml 33931-00 1
Styropor P, 250 g 48492-25 1
Toluene 250 ml 30236-25 3
Acetone, chemical pure, 250 ml 30004-25 1
Hydrochloric acid 37 %, 1000 ml 30214-70 1
Nitric acid , 65% 1000 ml 30213-70 1
Water, distilled 5 l 31246-81 1
Tubing connector, ID 6-10mm 47516-01 2

Necessary accessories

Precision Balance, Sartorius, 620 g : 1 mg 49311-99

PHYWE Systeme GmbH & Co. KG
Robert-Bosch-Breite 10 – 37079 Göttingen – Germany
www.phywe.com