If the product of reactivity ratios, r_1 r_2, is about zero, what type of copoly
ID: 526549 • Letter: I
Question
If the product of reactivity ratios, r_1 r_2, is about zero, what type of copolymer would be formed? (A) alternating copolymer (B) block copolymer (C) random copolymer What is the value of r_1 r_2 for an ideal random copolymer? (A) 1 (B) zero (C) Which of the following represent ionic polymerization? (A) step-growth (B) free-radical (C) cationic (D) anionic (E) C & D If reactivity ratios, r_1 and r_2, are greater than one, what type of copolymer would be formed? (A) alternating copolymer (B) block copolymer (C) random copolymer which polymerization mechanism can have termination step by coupling? (A) step-growth (B) free-radical (C) cationic (D) anionic Which of the following can estimate the molecular weight distribution of a polymer? (A) light scattering (B) osmotic pressure osmometric (C) size exclusion chromatography (D) none of the above (E) all of the above What technique would you use to determine crystallinity in a polymer? (A) UV-Visible (B) infrared (C) Raman (d) NMR (E) X-ray diffraction. Above melting point, T_m, what is the physical state of a polymer? (A) Solid (B) liquid (C) gas (D) aqueous (E) none of the above Below glass transition temperature, T_g, a material should behave in what manner? (A) rubbery (B) liquid (C) glassy (D) aqueous Above T_g, a material should behave in what manner? (A) Rubbery (B) liquid (C) glassy (D) aqueous Which of the following bases is not a component of DNA? (A) Guanine (B) Cytosine (C) Uracil (D) Thymine (E) Adenine Which of the following is a deoxyribose sugar? (E) None of the aboveExplanation / Answer
Answer:- 21) (A) Alternating copolymer
Explanation:-
Alternating co-polymerization is characterized by r1r2 = 0, where neither r1 nor r2 is greater than one. As with ideal behavior, there are two types of alternating behavior—extreme and moderate alternating behavior. Both r1 and r2 are zero in extreme alternating behavior, and the two monomers enter into the copolymer in equimolar amounts in a nonrandom, alternating arrangement along the copolymer chain. Each of the two types of propagating species preferentially adds the other monomer, that is, M1 * adds only M2 and M2 * adds only M1.
Answer:- 22) (A) 1
Explanation:-
When r1 and r2 are approximately equal to 1, the conditions are said to be ideal, with a random copolymer produced, in accordance with the Wall equation.
Answer:- 23) (E) C & D
Answer:- 24) (B) Block copolymer
Explanation:-
With both ratios larger than 1, homopolymerization of component M1 is favored but in the event of a crosspolymerization by M2 the chain-end will continue as such giving rise to block copolymer.