Abstract:
The objective of this work was to study the possibility of changing a facility used
to measure yellowness index and haze of polycarbonate. A spectrophotometer was
used to measure these values. The existing method utilized for a long time is Ultrascan
Pro. Using this machine, a plastic workplece is needed. The consumption of the plastic
to make the workplece is around 3 kg for 10 tons of the plastic produced. It takes about
25 minutes to measure 1 sample. The cost of the plastic to make the tested sample is
around B2.25 millions per annum. The new machine studied is Labscan XE. This
machine doesn't need any workplece, it can be used to measure from the pellet directly.
Therefore, the cost of the sampled plastic is negligible. The experiment was done on 30
samples for each method. The measuring results for each value were compared
utilizing paired t-test. The comparing results indicated that the values from the two
methods are different significantly (p<0.05). The other 30 samples for each method
were taken and compare. The result was similar to the first comparison. The average
values of yellowness from the old Ultrascan Pro were 1.47 more than the new Labscan
XE. For the haze, the old one was 0.80 less than the new one in average. It could be
concluded that the two machines gave different results. In practice, the yellowness
index could be used by adding each value from the new machine with 1.47 and for the
haze from the new one could be used by deduct 0.80. Doing this way is acceptable by
the customers. According to economic analysis, if the time of this project is 10 years,
the net present value (NPV) could be around ฿11.09 millions with the internal rate
return (IRR) of 250% and the break-even point of 5 months