Hardness Test

Material and Equipments Material : High Density Polypropylene (HDPP)

Manufacturer:

Titon

(Pasir

Gudang)

/

Petronas (Kratan, kawasan perindustrian Gebong) Molecular Structure:

Chemical Resistance Acids-concentrated Acids-dilute Alcohols Alkalis Aromatic hydrocarbons Greases and Oils Halogenated Hydrocarbons Halogens Ketones

Good-Fair Good-Fair Good Good Fair Good-Fair Fair-Poor Poor Good

Electrical Properties Dielectric constant @ 1MHZ Dielectric strength (kV mm-1) Dissipation factor @ 1 MHz Surface resistivity (Ohm/sq) Volume resistivity (Ohmcm)

2.2-2.6 30-40 3-5 x10-4 1013 1016-1018

Mechanical Properties Coefficient of friction Elongation at break (%) Hardness- Rockwell Izod Impact strength (Jm-1) Abrasive resistance-ASTM D1044 Tensile modulus (GPa) Tensile strength (MPa)

0.1-0.3 150-300 R80-100 20-100 13-16mg/1000cycles 0.9-1.5, for biax film 2.2-4.2 25-40, for biax film 130-300

Physical properties Density (g cm-3) Flammability Limiting oxygen index (%) Radiation resistance Resistance to Ultra-violet Water absorption – equilibrium(%)

0.90 HB 18 Fair Poor 0.03

Thermal properties Coefficient of thermal expansion (x10-1K-1) Heat-deflection temperature – 0.45 MPa (°C) Heat-deflection temperature – 1.8 MPa (°C) Specific heat (JK-1kg-1) Thermal conductivity @ 23 °C (Wm-1K-1) Upper working temperature (°C) Lower working temperature(°C) Equipment : 1. Plastic Injection Machine

100 – 180 100-105 60-65 1700-1900 0.10-0.22 90-120 -10 to -60

System Control

Hopper

Mold design

Temperature Controller

Mold

Lubricator 2. Universal tensile tester – INSTRON

3. Desktop type Scanning Electron Microscopic

3. Micro Hardness tester

4. Mini Saw

4. Minitab 15 Software

Procedure:

(A) Injection Moulding Process Machine Specification: Model: 820 D 850-210 Serial No: 148404 Manufacture: 1996 Weight: 2400 kg Clamp force: 850 kN tons

Operating Voltage: 380V 50 Hz Heating: 5.56 kW Pump motor: 16.5 kW Total Load: 24.1 kW

Procedure: 1. The mould is clamped to ensure the mould is held properly. 2. The safety guard is closed. 3. The polyproplyene pellets are poured into the feeding hooper. 4. The injection speed is input in V1 and pressure is input in P on the system control while temperature for the injection is input using the temperature controller according to the parameters level for experiment 1 as shown in the table 1. Parameters Temperature(oC

A 210

B 230

) Pressure(bar) 100 125 Speed(rpm) 200 300 o Exp Temperature( C Pressure(bar) 1 2 3 4 5 6 7 8 9

) 210 210 210 230 230 230 250 250 250

100 125 150 100 125 150 100 125 150

C 250 150 400 Speed(rpm) 200 300 400 300 400 200 400 200 300

Table 1 Parameters of injection moulding 5. The start button is switched on. 6. The cooled product is then ejected from the mould and the safety guard is open to remove the product. 7. This process is repeated until 3 pairs of samples are produced for each experiment. (B) Universal Tensile Tester (C) Hardness Test Purpose: To perform hardness test on injection moulded products. Theory : The Rockwell hardness test defines hardness as “a value calculated by substracting an indentation depth from a constant value”. The unit of Rockwell hardness “1” corresponds to 2µm. The Rockwell hardness test calculates the hardness of a specimen based on the indentation depth. With this method, loading operation is performed in two steps; the preliminary test force of 98N is applied first, and then the total force depending on the Rockwell scale is applied. With a soft specimen, the indentation is deep. Since the Rockwell hardness test is based on the indentation depth under a preliminary test force, the measurement result is hardly affected by the finished surface condition of the specimen, and the indentation depth can be directly converted into a hardness value. Therefore, this method can reduce the measurement time. For this experiment the scale that we have choose is P, Preliminary force : 98.07N Total test force : 1471N Indenter : Steel ball or hard metal ball with diameter 12.7mm Applicable materials: Plastic, light alloy and lead.

Procedure:

1. The specimen surface is inspected to ensure it is smooth and flat, free from a foreign substance and also oil. 2. The specimen is placed on an anvil that has a screw threaded base. 3. The anvil is turned and raised by the screw threads until the TEST light is activated. 4. The start lever is activated and the load is slowly applied to the indenter. 5. The load is released and after a beep sound, the result is recorded. 6. The procedure above is repeated for all specimens. (D) Scannning Electron Microscope Purpose: To conduct morphology analysis on to the specimens. Theory: The surface of the specimen to be examined is scanned with an electron beams and the reflected beam of electron is collected and then display at the same scanning rate on a cathode ray tube. The image on the screen which may be photographed represents the surface features of the specimens. Magnification ranging from 10 to 50000 times is possible and permits qualitative and semi-qualitative analysis of the surface area. Procedure: 1. The Main Switch on the Control Unit is turned on. 2. The Exhange Switch on the Main Unit is pressed and the evacuation will start when Exchange Switch is lit in green. 3. The specimen from experiment 1 is cut into a small piece using a mini saw. 4. A conductive double-sided tape is sticked on a specimen stub and the specimen is taped on to the tape. 5. The specimen stub is attached to the height adjustment screw and the holder height is adjusted so that the clearance between the topmost point of the specimen and the lowest face of the gauge becomes about 1mm. 6. Exhange Switch is pressed to break the vacuum and the specimen stage is drawn out slowly to place the specimen holder into the holder base of the stage. 7. The stage is set to be centre by adjusting the X and Y knobs. 8. Holding the specimen stage, Exchange Switch is pressed to start the evacuation. “READY” light will be lighted up. 9. “Start” button on the operation window is clicked and “Auto Start Mode” will be activated to turn on the electron beam. An image is displayed and adjusments are done to get the required images. 10. Image is captured and saved, the “Stop” button is clicked to stop the electron beam.

11. Exchange Switch is pressed to break the vacuum of the specimen chamber and “AIR” will be lit in red. 12. The specimen stage is withdrawn and the specimen holder is pulled out from the base of the stage. 13. Specimen is removed. This steps are repeated for the next 2 specimens. 14. The images are then analyse on their morphology.