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Determining the molecular weight of a polymer  from intrinsic viscosity measurements

Determining the molecular weight of a polymer from intrinsic viscosity measurements

Item no.: P3010601

Experiment Type: Teacher Experiment, Laboratory Experiment

Difficulty Expenditure of Time print
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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.

What you can learn about

  • 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

 

Device Name Item no. Qty
Water, distilled 5 l 31246-81 1,00
Bath for thermostat, makrolon 08487-02 1,00
Styropor P, 250 g 48492-25 1,00
Rubber tubing, i.d. 6 mm 39282-00 4,00
Pasteur pipettes, 250 pcs 36590-00 1,00
Volumetric flask 100 ml, IGJ12/21 36548-00 4,00
Nitric acid , 65% 1000 30213-70 1,00
Ubbelohde viscosimeter, 0.4 mm 03102-03 1,00
Weighing dishes, square shape, 84 x 84 x 24 mm, 25 pcs. 45019-25 1,00
Right angle boss-head clamp 37697-00 1,00
Volumetric pipette, 20 ml 36579-00 1,00
Spoon, special steel 33398-00 1,00
External circulation set for thermostat Alpha A 08493-02 1,00
Rubber tubing,vacuum,i.d.6mm 39286-00 2,00
Pipettor 36592-00 1,00
Volumetric flask 250 ml, IGJ14/23 36550-00 1,00
Hydrochloric acid 37 %, 1000 30214-70 1,00
Beaker, 250 ml, high-form 46027-00 4,00
Universal clamp 37715-00 1,00
Volumetric pipette, 50 ml 36581-00 1,00
Wash bottle, plastic, 500 ml 33931-00 1,00
Immersion thermostat Alpha A, 230 V 08493-93 1,00
Water jet pump, plastic 02728-00 1,00
Glass rod,boro 3.3,l=200mm, d=5mm 40485-03 1,00
Graduated cylinder 100 ml 36629-00 1,00
Volumetric pipette, 5 ml 36577-00 6,00
Toluene 250 30236-25 3,00
Tubing connector, ID 6-10mm 47516-01 2,00
Rubber caps, 10 pcs 39275-03 1,00
Pipette dish 36589-00 1,00
Funnel, glass, top dia. 80 mm 34459-00 1,00
Acetone, chemical pure, 250 ml 30004-25 1,00
Stopwatch, digital, 1/100 s 03071-01 1,00
Hose clip, diam. 8-16 mm, 1 pc. 40996-02 4,00
Retort stand, h = 750 mm 37694-00 1,00
Volumetric pipette, 10 ml 36578-00 1,00
Precision Balance, Sartorius ENTRIS623-1S, 620 g / 0.001 g 49294-99 1,00
Document     Filesize
p3010601e.pdf Experiment guide, English 274.48 KB

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