Question

1. In your final year group research work, you did a gel permeation chromatography (GPC) and Differential Scanning Calorimetric (DSC) analysis of two freshly synthesized Polyethylene terephthalate (PET) polymers, labeled as PET1 and PET2. Use the information given in Table to answer the following questions; Table 1. GPC analysis of two synthesized PET PET samples Density(g/cm) PET1 2.122 PET2 2.222 Percentage crystalline (%) 40 70 a. Determine the following parameters; i. Density of completely amorphous phase ii. Density of completely crystalline phase b. A tensile test was run on PET 1 and PET2 to examine their strength. i. Which of the polymers will show higher tensile strength and why? ii. Which of these two polymers will be relatively suitable for storing carbonated Beverages and why? iii. State and explain two methods for improving the poor gas permeability performance of such polymers.

Answer 1


Given that So- density of Amorphous phase Be- density of crystalline phase Is = density of Sample §c (Ps Pa) to C2 fs (Sc-sa) X 100 PET-1 '/.C= 400) Ss=2.1229/cm? loc: 70% = 2,212 31 cum PET-2 Fil PETT? Pc (2,122-pa) 40 = X 100 2,122 (Pe-pa) -> 0.8488C8c-Sa) = 2.12287 Solar0 0.8488fa -) Sc Pa- 1.2732 2 For PET-2 fc (2,222-fa) 702 2.2228-la 0,7 XOO => 1.5554 Cle-Pa) = 2,222 Pe-fla - n(3) Put se from the equation (2 to eqh

=> 1.5554 54 CE - SA) 2.31–2.40*20.00 Pa Pa 2 2 -> 1,5554(0,84888a-să +12732 Sa Pa-1,2732 fa][1660 1,8860336 la -0,84888 fa-12732 2 2 6 => 3,300568a-1,55548a 1,88603368a-0,8488Pá =) Pa (0.706686-1.4145252) = 1.4145252 ga 0.7066 qa=2.001879/cm3 So from eqr6 0, 8488 X 9.00187 lo Ice 2.33291 cm 2,00187-1,2732 sea 2,332 91 cm?

b). Tensile strength Coystallinety will leads to increase in the Tensile stength '. In the crystalline phase, the bonds are Stronges & deformation can leads to increase Strength for the oriented chains PET - It is higher 7 for polymers, the gas permiability increases as the coystallinily decreases So to minimize the loss of cop from beverges, we use polymer with high crystallinity is suitable i) Increase the poor gas permeability improve poos gas pereability have to increase the crystallinity, So i By increasing the crystalline phase percentage s. By slowly cooling of molten polymer PET- To the
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