Question

2. During the acid catalyzed polymerization of terephthalic acid and ethylene glycol, some fraction of methanol (CH-OH) is incorporated, but no more ester bonds can be formed. a. Based on the above, what is the extent of reaction, p? b. How does fav determine whether a linear or network polymer is formed as p nears 1? c. Why do you believe the polymer in this reaction will be a gel-network or linear chains? d. What is fivg, the average number of functional groups per monomer, if the molar ratio of ethylene glycol to methanol to terephthalic acid is 11:1:10? e. Why is it more feasible to remove methanol than ethylene glycol from the reaction? f. If you were to remove all the methanol present based on the stoichiometry given in 2.c, what would the theoretical chain length be? g. If the final X, is 1,000: i. What is r, the final monomer stoichiometry? ii. From the repeat unit shown on the formula sheet, estimate the molecular weight. High transparency is typically associated with a completely amorphous structure, as in polystyrene and acrylic (polymethylmethacrylate or PMMA). Despite this general rule", PET possesses significant crystallinity, though it is optically transparent to the eye. h. Based on the above statement, does crystallinity in a polymer always mean that the polymer will not be transparent? i. What aspects of the PET molecular structure could enhance crystallinity? j. What aspects of the PET molecular structure could reduce crystallinity? Beyond optical transparency, gas permeability is a very important property for carbonated beverages, such as soda pop, where CO2 binds with water in the form of carbonic acid H2CO3. k. Is the density of amorphous or crystalline regions (or domains) higher in general? 1. Would you expect diffusion of CO2 molecules to be higher or lower in amorphous or crystalline regions? Why? On the other hand, milk jugs/bottles are often composed of high density polyethylene, and polyethylene is arguably the lowest cost polymer available. Unfortunately, it not transparent m. Low-density polyethylene (LDPE), however is transparent. What reduces crystallinity in the case of LDPE? What properties might make it unsuitable for carbonated beverage use?

please only do H-M. i have done everything else.

Answer 1

Answer to the first four subparts (H-K):

H. The term cystalline means that intramolecular packing of structure in all directions remains same but this doesnt imply that it reduces the transparet nature of a substance which actually depends on refractive index ,which directly correlates to the density of the substance under a certain temperature,so the statement given is false.

Note:- The degree of polymer crystallinity depends on both intrinsic and extrinsic factors.
high molecular weight, linear polymeric chain structure, are very important conditions for high crystallinity .

We cannot reach 100 percent cystallinity because polymers do not have a uniform molecular weight.

I. Crystallinity of a is directly dependent on its intra-molecular packing .

Improving the purity of a substance and dereasing the surrounding temperature would
decreases space between molecules thus increasing the crystallinity of substance.

J.

The Short branches interfere with crystal formation and reduce the amount of crystallinity ,on the contrary long branches undergo side chain crystallization because they form lamellar crystals of their own.Crystallinity in PET is usually induced by thermal crystallization and by stress or strain induced crystallization.

So conclusion drawn from above statements is adding additives into a substance and increasing the
temperature can decrease the crystallinity of a substance.

K.

The density of crystalline substance is more than that of amorphous because of efficient packing of molecules in all directions .