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Glass Transition Temperature and Molecular Motion
List the order of the glass transition temperatures for polyethylene, polypropylene, polyvinyl chloride, and polystyrene. PE (-80), PP (-20), PVC (85), PS (100).
Define the glass transition temperature in polymer materials. –
Describe the reason for this vast range of glass temperatures among these 4 materials.
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In general, condensation polymers have higher monomer feedstock costs but lower capital costs to synthesis. False or True.
Above the critical degree of polymerization, molecular weight largely governs the mechanical properties of the polymer. True or False.
A and B are monomers polymerized to form the following copolymer:
A-A-B-A-B-B-A-A-A-B-A-B-A-A-B-B-B-B. This is an example of a block copolymer. True or False
Engineering Thermoplastics are a class of polymers which are generally more expensive than commodity polymers. True or False.
The processes of crystallization occurs at temperatures below the Tg (glass transition) True or False.
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How does conventional oven cooking different from boiling cooking in respect of conduction, convection, and radiation of heart transfer
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Differentiate Nusselt and Biot number amidst almost the same formula.
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The Henry’s law constant for CO2 dissolved in dichloromethane (DCM) at 25 °C is 153 bar.
a) If the vapor pressure of dichloromethane at this temperature is 56.6 kPa, what is the solubility of CO2 if the total pressure is 1 bar?
b) 100 mole/s of a mixture 17 mole% CO and the rest DCM is fed to a Flash unit operating at 25 °C and 1 bar. Determine the molar flow rates of the exiting vapor and liquid streams and their compositions.
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(ii) Briefly outline methods for BNCT beam production and
their
advantages and disadvantages. Explain advantage of epithermal
neutron BNCT and the method of epithermal neutron beam production
on a reactor .
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What factors inform the choice of the economic or optimum reflux ratio within a distillation column?
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What Happens to the bottom and top products if the feed point to a distillation column is switched from the designed optimum to
1. A tray closer to the reboiler?
2. A tray closer to the condenser?
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rank the top 5 best reactor from best to less best that can deal with high temperture reaction ?
Batch, CSTR, PFR , PBR other ??
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3. As a substitute non-chlorinated solvent for dry cleaning fabrics, bromopropane (C3H7Br) demand has increased. Bromopropane can be synthesized by reacting propanol (C3H8O) with hydrogen bromide (HBr), with water as the second product. A reactor is fed 20 kg/min propanol and 20 kg/min hydrogen bromide. (a) If one of the reactants is completely consumed, what is the composition of the reactor outlet stream? (b) What is the fractional conversion of the excess reactant? (c) What is the extent of reaction? (d) If 60% of the limiting reactant is consumed, what is the yield of bromopropane?
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Which of the following statements explains why oil has a greater viscosity than water? |
1. Oil molecules always move slower than water molecules 2. Oil molecules have more space in between them than water molecules 3. Oil molecules have a more complicated shape than water molecules 4. Oil molecules are less dense than water molecules |
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Which of the following statements is incorrect? |
1. A catalyst does not alter the state of equilibrium in a chemical reaction 2. A catalyst remains unchanged at the end of a chemical reaction 3. A catalyst is highly specific in its action 4. A catalyst initiates a reaction. |
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White phosphorous is stored under water, because |
1. it does not react with water 2. it is poisonous 3. it is unstable 4. its kindling temperature in dry air is very low |
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With increase in the number of shell passes, the value of FT(Temperature correction factor) |
1. remains same 2. remains same, only if the number of tube passes does not change. 3. decreases 4. increases |
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Use of baffles in agitators help in minimizing the __________ tendency. |
1. both swirling and vortex 2. vortex 3. swirling 4. neither swirling nor vortex |
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In liquid-liquid equilibrium studies, a system is called type II if |
1. the A-C pair is immiscible 2. the B-C and A-B pairs are partly miscible 3. the B-C pair is completely miscible 4. A-B miscible |
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The cross over frequency of the process which is having the transfer function of G(s) = 5/(2s+1)4 |
1. 20 2. 0.1 3. 0.5 4. 0.05 |
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Molecularity of an elementary reaction P + Q = R + S is |
1. 1 2. 2 3. 3 4. 4 |
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Cavitation in centrifugal pumps is caused by |
1. High fluid velocity at suction 2.low barometric pressure 3.low suction pressure 4.high suction pressure |
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Cavitation in centrifugal pumps may be eliminated by maintaining |
1.suction pressure higher than vapor pressure of the liquid at the suction temperature. 2. suction pressure sufficiently lower than vapor pressure of the liquid at the suction temperature. 3.liquid velocity at the suction less than 0.3 ft/s 4.suction pressure less than 1 atm. |
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consider distribution of the solute C in two partially miscible solvents A(carrier) and B(solvent). What is the selectivity of separation at the plait point? |
1. 1 2. very large 3. Zero 4. less |
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Cooling water fouling factors vary in the range of 0.001 to 0.003. What is the SI unit? |
1. (kcal/hr. m. °C)-1 2. (W/m2.°K)-1 3. (BTU/hr.ft2. °F)-1 4. (kcal/hr.m2.°C)-1 |
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Industrially, the process of sedimentation is conducted on a large scale in equipment called |
1.sorting classifiers 2.cyclones 3.thickeners 4.filters |
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The Schedule number is an indication of |
1.material density 2.pipe wall thickness 3.pipe size 4.pipe roughness |
Answer all the MCQs correctly with proper explanation.
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Identify a “multicomponent, soft material” that you find interesting, and would like to discover how it works.
To be acceptable, the material you choose must have a multicomponent formulation with non-trivial mechanical properties.
1. Identify the product or material. You can be as specific as you like – Crest pro-health, Kirkland signature natural peanut butter, “Great Stuff” rodent- blocking foam, whatever.
2. Identify the primary pupose of the product or material – what is it supposed to do, what problem is it solving for its user?
3. Identify the mechanical aspects involved in the product’s function. Must it be sprayable? Must it pour? Spread? Wet a particular material? Must it cling to something? Scrub? Sit without flowing? As best you can, connect these properties to the non-Newtonian flow phenomena we’ve discussed.
4. What chemical tasks must the product perform? Stability (how could it go unstable?) Clean a surface? React with a substrate? Absorb or dissolve a deposit? Coat a surface? Deposit a substance? Kill microbes? Absorb something or release something? Buffer against environmental changes?
5. Does the material undergo any transformations during use? (Phase transitions, does it harden, does it evaporate, …)
6. Identify constraints on the specific product. Must it be edible? FDA- compliant for pharma space? Toxicity? Environmental impact? Cost and availability of ingredients? These limit specific choices from the various classes of “building blocks” used to achieve the rheology, performance, etc.
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According to Sparrow's Syria: Death from Assad’s Chlorine there is good chlorine, bad chlorine and deadly chlorine. How would the same characterizations made in Syria be applied to chlorine use and homeland security in the U.S.?
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When designing a bottle such as a ketchup bottle wirh
outermost and innermost shells, that is, how to choose a proper
material to be used for each of the inner and the outer?
pleass provide proper materials with the prove.
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