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1.0 Content 1
2.0 Literature Review
2.1 Extruder 2-4
2.2 Polystyrene (PS) 5-6
3.1 Material 7
3.2 Equipment 7
3.3 Procedure 8
3.4 Testing and characterizations 9-10
4.0 Result and discussion
4.1 Effect of screw design on temperature at each temperature zones 11-12
4.2 Effect of screw speed on flow rate in extrusion 13-15
4.3 Effect of temperature on heat transfer in extrusion 16-18
5.0 Conclusion 19
6.0 References 20
7.0 Appendix 21-26
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This experiment was constructed to study the relationship between processing parameter and heat
and mass transfer in twin screw extruder. Productivity, homogeneity and quality of product can be
alternating by using heat and mass transfer concept.
There are 3 types of heat transfer which are convection, conduction and radiation heat transfer .
Convection heat transfer happen when thermal energy density differences which is caused by particles
themselves due to heating. However, forced convection do not occur in this experiment since cooling
down with water bath is a free convection heat transfer. Radiation heat transfer occur only when emit or
absorb radiative energy by lowering or raising their molecular energy levels. However, radiation heat
transfer do not involved in this experiment. Lastly, conduction radiation heat transfer happen between
wall surfaces to molecular particle.
Fourier's law is the main equation used in calculation of heat transfer. This law involved the idea
that the heat flux is proportional to the temperature gradient in any direction 𝑛, where 𝐴 is area of system,
𝑘 is thermal conductivity of material and 𝑇 is temperature involved.
𝐻𝑒𝑎𝑡 𝑓𝑙𝑢𝑥, 𝑞𝑥 = −𝑘𝐴 𝑑𝑇
By deriving Fourier's law, other equations can be obtained and used in this experiment and it will
show in testing and characterization part.
There are several important factors that affecting heat and mass transfer in twin screw extruder.
These factors including processing temperature, screw rotational speed (hopper screw speed and side
feeder screw speed), chemical and physical nature of material used (viscosity and degree of polymer
branching) and shear rate . Some factors are used to manipulate experiment and explained the result.
It was predicted that processing temperature increase will improve productivity by boosting flow
rate. Increasing screw speed will not increase productivity but increasing defects such as present of air
bubbles in extruded material and probability of die swell happen will be increase too. To investigate this
hypothesis, objectives was set and experiment was carried out. 3 set of trials were used to study the
relationship by using different combination of processing temperature and screw speed.
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3.0 LITERATURE REVIEWS