The typical strategy used to control the degradation of a thermoplastic during u
ID: 1010494 • Letter: T
Question
The typical strategy used to control the degradation of a thermoplastic during use is to: use prepolymers to initiate oxidation mix it with thermosets increase the molecular weight lower the melting temperature increase the amount of monomers use a variety of protective additives During crevice corrosion, oxygen-rich areas act as the anode while oxygen depleted areas act as the cathode. True False The size of an internal crack that can tolerated at a stress of 100 MPa for a material with K_Ic of 100 MPa.m^1/2 is: Uranium with a PBR of 3.05 is likely to develop a protective oxide on the surface. True FalseExplanation / Answer
The typical strategy used to control the degradation of a thermoplastic during use is to:
use prepolymers to initiate oxidation
mix it with thermosets
increase the molecular weight
lower the melting temperature
increase the amount of monomers
use a variety of protective additives –answer
thermal degradation polymers is sub-atomic weakening as an aftereffect of overheating. At high temperatures the segments of the long chain spine of the polymer can start to partitioned (atomic scission) and respond with each other to change the properties of the polymer. Warm corruption can exhibit a maximum breaking point to the administration temperature of plastics as much as the likelihood of mechanical property misfortune. For sure unless accurately avoided, huge warm debasement can happen at temperatures much lower than those at which mechanical disappointment is liable to happen. The substance responses required in warm corruption lead to physical and optical property changes in respect to the at first determined properties. Warm corruption by and large includes changes to the atomic weight (and sub-atomic weight appropriation) of the polymer and run of the mill property changes incorporate lessened flexibility and embrittlement, chalking, shading changes, splitting, general decrease in most other alluring physical propertie
Question 8
During crevice corrosion, oxygen-rich areas act as the anode while oxygen depleted areas act as the cathode.
® False ----answer
The most widely recognized structure is oxygen differential cell consumption. This happens on the grounds that dampness has a lower oxygen content when it lies in a cleft than when it lies on a surface. The lower oxygen content in the cleft structures an anode at the metal surface. The metal surface in contact with the segment of the dampness film presented to air frames a cathode
Question 9
The size of an internal crack that can tolerated at a stress of 100 MPa for a material with KIC of 100 MPa.m1/4 is:
65mm answer
By using the modulus of elasticity formulae
Stress = 2 p(a /p)^1/2
Question 10
Uranium with a PBR of 3.05 is likely to develop a protective oxide on the surface.
True answer
The Pebble Bed Modular Reactor (PBMR), like most new reactor thoughts, is a resurrection of an old reactor thought. For this situation the old thought is the "high temperature gas reactor" or HTGR, that then was proposed in a secluded variant, known as the MHTGR. The PBMR is a variation of the HTGR.
In the PBMR, the hot helium drives a turbine straightforwardly, decreasing the odds for water-graphite contact. There is an auxiliary water circle, nonetheless. The water is utilized to cool the helium gas before it is sent back to the reactor. The water utilization would be lower than in light water reactors, since the anticipated productivity of the PBMR is higher.
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