BITS Pilani Hyderabad Campus

Polymer Technology CHE G522

BITS Pilani, Hyderabad Campus

Evaluation

Weightage :20%

Marks 40

Lab Record :2

Viva :1

Lab exam 13M

BITS Pilani, Hyderabad Campus

Number of experiments (10)

1.To find the melting point using melting point apparatus.

2.DSC: To find the melting point of semicrystalline polymer.

3.DSC: To find the glass transition temperature of elastomer.

4.TGA: To study the thermal characteristics of semicrystalline polymer composites.

5.To find TGA of polymer composite.

6.To study the mechanical properties of polymer composites, polymer rubber blends, polymer.

7.To study the impact property of polymer material.

8.To prepare specimen using compression molding machine.

9.To prepare specimen using injection molding machine.

10.To prepare specimen using automated injection molding machine.

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The stress-strain behavior of brittle materials compared with that of more ductile materials

Experiment : To find the mechanical properties of the polymer , polymer composites , elastomeric properties

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Sample according to ASTM D638:

BITS Pilani, Hyderabad Campus

BITS Pilani, Hyderabad Campus

An axial force applied to a specimen of original length (lo) elongates it, resulting in a reduction in the cross-sectional area from Ao to A until fracture occurs.

The load and change in length between two fixed points (gauge length) is recorded and used to determine the stress-strain relationship.

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Tensile Test- Basic Principles

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Basic Principles Step 1: Original shape and

size of the specimen with no load.

Step 2: Specimen undergoing uniform elongation.

Step 3: Point of maximum load and ultimate tensile strength.

Step 4: The onset of necking (plastic instability).

Step 5: Specimen fractures.

Step 6: Final length.

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Yield Point

Break Point

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Impact Test: The Izod Test

Generally used for polymers. Izod test is different from the Charpy test in terms of the configuration of the notched test specimen

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Aim to find the impact strength of polymer sample

Izod impact strength of rectangular bar notched specimens measured following the ASTM D256 test method

Impact fracture from the difference of potential energy before and after the impact.

The impact strength is expressed in terms of the energy absorbed per unit width of the specimen and reported as kg-cm/cm.

Sample dimensions are measured in accordance with ASTM D256 procedure, the notch depth is 2mm and the angle is 45 as shown

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Aim to find glass transition temperature and melting point of

amorphous and semicrystalline polymers

DSC

DSC is a thermal method of analysis to study the thermal

behaviour and thermal properties of materials (typically polymers).

Uses of DSC:

Material Identification (Tm and Hf);

single polymers and blends.

Comparative Analysis of Materials Level of Crystallinity in a

material.

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The material is sealed in a sample pan and subjected to a

controlled temperature programme.

The resulting thermograph can yield much valuable information

about the properties of the material analysed.

Working of DSC

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DSC graphs

Heating rate can be varied

BITS Pilani, Hyderabad Campus

BITS Pilani, Hyderabad Campus

TGA measures the amount of weight change of a material, either as a function of increasing temperature, or isothermally as a function of time, in an atmosphere of nitrogen, helium, air, other gas, or in vacuum.

Thermal gravimetric analysis can be interfaced with a mass spectrometer RGA to identify and measure the vapors generated, though there is greater sensitivity in two separate measurements.

Inorganic materials, metals, polymers and plastics, ceramics, glasses, and composite materials can be analyzed.

Temperature range from 25C to 900C routinely. The maximum temperature is 1000C.

Sample weight can range from 1 mg to 150 mg. Sample weights of more than 25 mg are preferred, but excellent results are sometimes obtainable on 1 mg of material.

Samples can be analyzed in the form of powder or small pieces so the interior sample temperature remains close to the measured gas temperature.

TGA

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Determines temperature and weight change of decomposition reactions, which often allows quantitative composition analysis. May be used to determine water content.

Allows analysis of reactions with air, oxygen, or other reactive gases (see illustration below).

Can be used to measure evaporation rates, such as to measure the volatile emissions of liquid mixtures.

Allows determination of Curie temperatures of magnetic transitions by measuring the temperature at which the force exerted by a nearby magnet disappears on heating or reappears on cooling.

Helps to identify plastics and organic materials by measuring the temperature of bond scissions in inert atmospheres or of oxidation in air or oxygen.

Used to measure the weight of fiberglass and inorganic fill materials in plastics, laminates, paints, primers, and composite materials by burning off the polymer resin. The fill material can then be identified by XPS and/or microscopy. The fill material may be carbon black, TiO2, CaCO3, MgCO3, Al2O3, Al(OH)3, Mg(OH)2, talc, Kaolin clay, or silica, for instance.

Can measure the fill materials added to some foods, such as silica gels and titanium dioxide.

Can determine the purity of a mineral, inorganic compound, or organic material. Distinguishes different mineral compositions from broad mineral types, such as

borax, boric acid, and silica gels.

BITS Pilani, Hyderabad Campus