List of top Polymer Science and Engineering Questions

During material testing, stress is applied from time $t_i$ to $t_f$ as shown below:

Choose the option(s) where the strain response is correctly mapped to its material class.

Choose the option(s) that correctly match(es) the Zones with their typical Functions in an industrial extruder.

The ‘unperturbed dimension’ of the polymer chain is represented as, \[ \left( \overline{r^2_0} \right)^{1/2} \propto \overline{\ell}(n)^{1/2} \] where, $\left( \overline{r^2_0} \right)^{1/2}$ = root-mean square end-to-end distance
$\overline{\ell}$ = average length of a segment
$n$ = number of segments in the chain
Using the above information, root-mean square end-to-end distance of a branched polyethylene would be ............. when compared with that of the linear polyethylene of the same molecular weight and the same number of segments.

Injection molding is typically used to make plastic parts. If the pressure at the gate is monitored as a function of time during the injection of a thermoplastic polymer, identify the profile that best describes this event.

Match the Polymer with the most suitable Monomer combinations from which it is synthesized.

Match the Product with the most appropriate Processing Technique employed.

In a polymer recycling plant, polymer “X” was depolymerized by glycolysis in the presence of ethylene glycol and a suitable catalyst. The glycolysis reaction yielded the following compound:

Identify the polymer “X” from the following options.

A unidirectional composite of a resin is prepared with continuous fibers, wherein the volume fraction of the fiber in the composite is 0.7. Assume that the resin has a modulus of 9 GPa and the fiber has a modulus of 90 GPa. A sample of this composite, possessing a breadth of 4 mm and a thickness of 1 mm, is subjected to a uniaxial tensile test along the direction of the fiber.
Corresponding to a strain of 0.5%, the force applied on the sample is ............ N. {(Round off to the nearest integer)}

A rubber contains 70 wt% butadiene (molar mass = 54 g/mol), 20 wt% isoprene (molar mass = 68 g/mol), 5 wt% sulfur and 5 wt% carbon black. Assume that all the sulfur is present in crosslinks. If each sulfide crosslink contains an average of two sulfur atoms, the percentage of possible crosslinks that are joined by vulcanization is ............%. {(Round off to one decimal place)}

The density of an amorphous polymer is $0.77 \, {g/cm}^3$ and that of its crystalline counterpart is $0.99 \, {g/cm}^3$. The density of a semi-crystalline sample of this polymer is found to be $0.88 \, {g/cm}^3$.
The degree of crystallinity (on weight basis) of this semi-crystalline sample is ............ {(Round off to two decimal places)}

Titration was used to determine the molar mass of two linear monodisperse polymers A and B. Both the polymers possess the same repeat unit and contain acid end-groups. First, 10 g of polymer A was titrated with 5 mL of a 0.1 M alkali solution. In a separate experiment, 5 g of polymer B was titrated with 5 mL of a 0.1 M alkali solution. All of the alkali solution reacted with the acid end-groups present in both polymer A and polymer B.\ The ratio of the molar mass of A to the molar mass of B is ............ {(Round off to one decimal place)}

The heat of polymerization of ethylene is 25 Kcal/mol. The amount of heat generated during the polymerization of 5.6 kg polyethylene is ............ Kcal. {(Round off to the nearest integer)}

Crystallization is favored in polymer melts when the chain entanglement is ............. and only polymers with ............. molecular arrangement can crystallize.

Thermoplastic Polyurethane and Polyamide 6 both contain amide linkages, but when compared to Polyurethane, Polyamide 6 shows higher melting point due to ..............

Which one of the following measures of viscosity is dimensionless?

Which one of the following permits the direct determination of intrinsic viscosity of a polymer solution for known molecular weight of the polymer?

Under which combination of conditions does the glass transition of a polymer increase?

Polymer “Z” has a high melting point and it decomposes even before it melts. Hence, it is usually dissolved and subsequently regenerated. Rayon is one such regenerated form. Identify the polymer “Z” from the following options.

What is the correct order of decreasing crystallinity of the given polymers?
P Atactic–Polypropylene
Q Syndiotactic–Polystyrene
R Nylon6
S Polyethylene terephthalate (PET)

From the options given, identify the correct match(es) between the polymer products with the most appropriate processing technique.

Polymer Product	Processing Technique
P	Fishing rods
Q	Soft drink bottles
R	Plastic sheets
S	Plastic trays

Mechanical stress is applied on a polymer. Identify the correct match(es) between the statements (1, 2, 3, 4, 5) that describe the deformations and the regimes (P, Q, R). Regime and Statement

Regime	Statement
P	Rubbery regime
Q	Region around glass transition temperature ($T_g$)
R	Sample under deformed state

Additional Statements:

1. Stress-relaxation takes place and the excess free energy is dissipated
2. The motions of the molecules are long-range
3. Segmental motion of the molecules is important
4. The maximum relaxation time is strongly dependent on the molecular weight
5. The deformations are independent of the molecular weight and primarily depend on the local structure

The molar mass distribution of a polymer is given as:

Number of molecules	Molar mass (g/mol)
100	7500
50	5000

The resulting weight average molecular weight of the polymer is ................ g/mol. (Answer in integer)

A nylon sample of 0.03 m$^2$ cross-sectional area is subjected to a creep load of 10 kN. The load is removed after a duration of 60 s. Young’s modulus and the viscosity for nylon are 1 GPa and 300 Giga Poise. The compliance of the specimen is ______ $\times 10^{-9}$ m$^2$/N.

Density = 0.9 g/cc, melt volume = 10 cc, residence time = 100 s. Find extruder output in kg/h.

PVDF was quenched in one case and slowly cooled at 10$^\circ$C/min in another case. The crystallinity of slowly cooled PVDF = 60%. The heat of fusion of the quenched PVDF = 0.54 $\Delta H_m$ (where $\Delta H_m$ = heat of fusion of slowly cooled PVDF). Heat of fusion of 100% crystalline PVDF = 100 J/g. Find crystallinity of quenched PVDF.