What is a Polymer?
A polymer
is essentially the result of organic building blocks called monomers linked
together by means of a solvent. Depending on the mix and proportions of crude
materials and diverse response conditions, numerous sorts of polymers can be created,
for example, polystyrene, polycarbonate, polyethylene and PMMA. Composition of
principle crude materials and added substances also result in polymers of
different grades. SMM (Polymer) is presently producing 6 distinctive PMMA
grades: MH, EX, EXN, MG, LG and LG2.
What is Viscosity?
Viscosity
is a property of a fluid that offers resistance to its flow. Viscosity is due
to the internal friction of molecules and mainly depends on the nature &
temperature of the liquid.
The polymerisation reaction is conducted within specific conditions and boundaries. The quality of the PMMA polymer thus developed can be evaluated by viscosity, which is a significant characteristic for all materials, especially polymers. For liquids, viscosity determines flow characteristics, heat transfer and mass transfer. For polymers, viscosity is often a measuring stick. Viscosity data is crucial as it helps in predicting behavioural properties of the polymer. Also, measurement of viscosity is very important in monitoring the SMM (Polymer) process.
The polymerisation reaction is conducted within specific conditions and boundaries. The quality of the PMMA polymer thus developed can be evaluated by viscosity, which is a significant characteristic for all materials, especially polymers. For liquids, viscosity determines flow characteristics, heat transfer and mass transfer. For polymers, viscosity is often a measuring stick. Viscosity data is crucial as it helps in predicting behavioural properties of the polymer. Also, measurement of viscosity is very important in monitoring the SMM (Polymer) process.
Determining Viscosity
How do you
determine the viscosity of a solid cube of polymer?
Polymer viscosities can range from 103 to 107 Poise so one testing method cannot cover them all. So, two common testing methods are used: melt and solution.
Polymer viscosities can range from 103 to 107 Poise so one testing method cannot cover them all. So, two common testing methods are used: melt and solution.
Melt Viscosity
The melt
index is a common testing technique that studies parameters like compression
weight and testing temperature, predominantly in higher viscosity polymers. Of
course, the results depend on the type of polymer. For instance, for the melt
viscosity test of polyethylene, the study parameters include a temperature of
190˚ C and weight of 10 kg. After a certain time (say 10 minutes), the extruded
polymer is weighed. The melt index is then expressed as grams of polymer/10
minutes and this value corresponds to the average molecular weight of the
polymer. Polyethylene has an average molecular weight of 150,000 g/mole and a melt
index close to 0.3 / 10 minutes.
For processes or final products where ease of processing is required, melt indices above 15 g/ 10 minutes are desirable. Where mechanical properties are needed, melt indices below 1 g/10 minutes are preferred.
For processes or final products where ease of processing is required, melt indices above 15 g/ 10 minutes are desirable. Where mechanical properties are needed, melt indices below 1 g/10 minutes are preferred.
Solution Viscosity
Solution
viscosity testing involves dissolving the polymer in a solvent, usually
accompanied by gentle heat. The solution is then allowed to travel through an
apparatus like a pipette and the travel is timed. The time for the pure solvent
to flow through the same apparatus is also calculated. These two values are
then compared, resulting in a relative viscosity – which is essentially the
ratio of the polymer viscosity to the solvent viscosity.
While melt viscosity
technique is carried out by SMM(P) in regular frequency to ensure the polymer
formed is well under control, solution viscosity is executed by SCASS during
product certification stage as a final confirmation.
Sumitomo
Chemical Singapore is one of leading producers of the polymer - PMMA (Polymethyl
Methacrylate), a polymer of MMA (Methyl Metacrylate Monomer). Visit us to learn
more about polymers, PMMA and MMA.
For
more information kindly visit pmma
thermoplastic
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