Klon - Teckno Polymers Quality Control Trainee Interview Questions and Answers

Vulcanisation of rubber is a chemical process that involves adding sulfur to raw rubber to improve its strength, elasticity, and durability.

• Raw rubber is heated with sulfur in the presence of an accelerator, typically zinc oxide, to initiate the vulcanisation process.

• The mixture is then heated to a specific temperature for a certain amount of time to allow the sulfur to cross-link with the rubber polymer chains.

• This cr...read more

Polymerisation process of synthetic polymers involves the linking of monomer units to form long chains or networks.

• Synthetic polymers are created through a chemical reaction called polymerisation.

• Monomer units, which are small molecules, are linked together to form long chains or networks.

• Polymerisation can be initiated by heat, light, or a catalyst.

• Examples of synthetic polymers include polyethylene, polypropylene, an...read more

Some branches of organic chemistry related to the polymer industry include polymer chemistry, polymer physics, and polymer engineering.

• Polymer chemistry focuses on the synthesis and study of polymer structures.

• Polymer physics deals with the physical properties and behavior of polymers.

• Polymer engineering involves the design and processing of polymers for specific applications.

Chain initiation, propagation, transfer, and termination are key steps in polymerization reactions.

• Chain initiation involves the formation of reactive species that can start the polymerization process.

• Chain propagation is the repeated addition of monomers to the growing polymer chain.

• Chain transfer involves the transfer of a growing polymer chain to another molecule, affecting the chain length.

• Chain termination occurs ...read more

Initiator chemicals used for polymerisation include organic peroxides, azo compounds, and photoinitiators.

• Organic peroxides are commonly used as initiators in polymerisation reactions.

• Azo compounds are another type of initiator chemical used in polymerisation.

• Photoinitiators are used in photopolymerisation processes to initiate polymerisation upon exposure to light.

Instruments commonly used for quality control in the polymer industry include spectrophotometers, rheometers, and thermal analyzers.

• Spectrophotometers are used to measure the color and transparency of polymers.

• Rheometers are used to measure the flow and deformation behavior of polymers.

• Thermal analyzers are used to study the thermal properties of polymers, such as melting point and glass transition temperature.

A tensile testing machine measures the strength of a material by applying a pulling force until it breaks.

• Calibrate the machine before testing to ensure accurate results

• Secure the material in the grips of the machine

• Apply a gradually increasing force until the material breaks

• Record the maximum force applied before failure

• Calculate the tensile strength by dividing the maximum force by the cross-sectional area of the mat...read more

A moisture analyser is operated by placing a sample in the chamber, setting the parameters, and allowing the instrument to measure the moisture content based on the principle of loss on drying.

• Place a sample of the material to be tested in the chamber of the moisture analyser.

• Set the parameters such as temperature and time for the drying process.

• Start the analyser to heat the sample and measure the weight loss as the m...read more

A colour matching cabinet is operated by setting the light source, placing the sample inside, and comparing it to standard colours.

• Set the light source to the appropriate type (e.g. D65 for daylight simulation)

• Place the sample to be matched inside the cabinet

• Compare the sample to standard colours under controlled lighting conditions

• Adjust the light intensity and angle as needed for accurate colour matching

Operating a melt flow indexer involves setting the temperature, loading the sample, and recording the melt flow index.

• Set the temperature of the indexer according to the polymer being tested

• Load the sample into the indexer and allow it to melt

• Measure the melt flow index by recording the time it takes for the polymer to flow through the die

• Some melt flow index parameters for polymers: PVC - 100-450 g/10 min, PP - 0.3-50...read more

An impact testing machine is operated by placing the specimen between the anvils and releasing a pendulum to strike the specimen, measuring the energy absorbed.

• Place the specimen between the anvils of the machine.

• Release the pendulum to strike the specimen.

• Measure the energy absorbed by the specimen during impact.

• The principle of impact testing is to determine the ability of a material to absorb energy during fracture.

• ...read more

Operating a benchtop spectrophotometer involves understanding its principle, calibrating with known standards, and comparing color characteristics of polymers.

• Understand the principle of spectrophotometry - measures the intensity of light at different wavelengths

• Calibrate the spectrophotometer using known standards to ensure accurate readings

• Prepare samples of the specific polymer and the known standard for comparison

• M...read more

A viscometer is operated by filling the sample into the instrument, setting the desired parameters, and measuring the viscosity based on the principle of fluid flow resistance.

• Ensure the viscometer is clean and calibrated before use.

• Fill the sample into the viscometer according to the manufacturer's instructions.

• Set the desired parameters such as temperature and speed of rotation.

• Initiate the measurement and record the...read more

Operating a melting point apparatus involves setting up the sample, heating it gradually, and recording the temperature at which the sample melts.

• Set up the melting point apparatus according to the manufacturer's instructions.

• Place a small amount of the sample in a capillary tube and insert it into the apparatus.

• Gradually heat the sample while observing it through a magnifying lens.

• Record the temperature at which the s...read more

To operate a notch cutter, vernier caliper, and micrometer, one must have knowledge of their functions and proper handling techniques.

• To operate a notch cutter, ensure the material is securely clamped and align the cutting edge with the desired notch location before cutting.

• When using a vernier caliper, gently close the jaws around the object being measured and read the measurement from the scale, taking care not to ap...read more

A notch cutter is required before impact testing to create a standardized defect in the specimen, which helps in determining the material's toughness and resistance to fracture.

• Notch cutter creates a standardized defect in the specimen

• The presence of a notch helps in determining the material's toughness and resistance to fracture

• Without a notch, the impact test results may not accurately reflect the material's behavior...read more

Operating an injection molding machine involves setting up the machine, loading the material, adjusting parameters, and monitoring the process.

• Set up the injection molding machine by connecting it to power and ensuring all safety measures are in place.

• Load the material (such as plastic pellets) into the machine's hopper.

• Adjust parameters like temperature, pressure, and injection speed based on the material being used a...read more

Lubricant is used in injection molding machines to reduce friction, prevent wear and tear, and improve overall machine performance.

• Lubricants such as silicone oil, mineral oil, and grease are commonly used in injection molding machines.

• Proper lubrication should be done at regular intervals to ensure smooth operation and prevent breakdowns.

• Over-lubrication should be avoided as it can lead to contamination of the molded ...read more

Instruments used in quality control for polymers are calibrated using standardized procedures to ensure accuracy and reliability.

• Calibration involves comparing the measurements of an instrument to known standards.

• Adjustments are made to the instrument to minimize any discrepancies between the instrument's readings and the known standards.

• Calibration certificates are often provided by external calibration labs to verify...read more

A glow-wire test apparatus is operated by heating a wire to a specified temperature and then applying it to the test sample to assess its flammability.

• Turn on the glow-wire test apparatus and set the temperature to the specified level.

• Place the test sample under the glow-wire.

• Bring the heated wire in contact with the test sample for a specified duration.

• Observe the sample's reaction to the heat and record the results.

• T...read more

To operate a bunsen burner in a flammability cabinet for checking flame retardants in polymers, follow safety protocols, adjust the flame, place the sample in the cabinet, observe the flame behavior, and record results.

• Ensure proper safety measures are in place before operating the bunsen burner.

• Adjust the air and gas flow to create a blue flame with a well-defined cone.

• Place the polymer sample in the flammability cabi...read more

Ash content can be checked using a muffle furnace and silica crucible by heating the sample to burn off organic material and weighing the residue.

• Weigh the clean and dry crucible before adding the sample.

• Place the sample in the crucible and heat it in the muffle furnace to burn off organic material.

• Cool the crucible in a desiccator before weighing the residue to determine the ash content.

• The principle is based on the f...read more

Young's modulus is a measure of stiffness of a material, while secant modulus is a measure of the material's response to stress. They are used to check the durability of polymers.

• Young's modulus is a measure of the stiffness of a material and is defined as the ratio of stress to strain within the elastic limit.

• Secant modulus is a measure of the material's response to stress and is calculated by drawing a line from the ...read more

Optimizing zonal phases of injection nozzle parameters for different polymers to ensure consistent mold quality.

• Understand the specific requirements of each polymer in terms of temperature, pressure, screw speed, etc.

• Adjust the zonal phases accordingly to meet the optimal processing conditions for each polymer.

• Monitor the mold surface for any signs of bubble formation, excess flash, uneven surface, or polymer residues.

• ...read more

Cleaning and purging the injection molding machine before test molding a different polymer material is important to prevent contamination and ensure product quality.

• Prevents contamination of the new polymer material with remnants of the previous material

• Ensures consistent product quality by removing any residue or impurities from the machine

• Helps prevent defects in the final product caused by mixing different materials

• ...read more