lab 10 report

A polymer has creep behaviour that can be represented as a power law equation: e = 0 (Jo + Jit") where J, is 0.5 GPa1, J1 is 0.45 GPa's 0.3 and n is 0.3 (with t in seconds). A component of this material has the following applied stress history: There is no stress before t = 0 A positive (tensile) stress of 8 MPa is applied from t = 0 for 4 hours From t = 4 hours to 6 hours, the stress is compressive stress of 2 MPa The stress is then removed. What will the strain in the material be at t = 9 hours? Enter your value as a number to 4 decimal places. You have a 2% error margin with this.

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An unknown polymer sample was found to have the following molecular weight distribution: Molecular weight range 8,000 - 20,000 20,000 - 32,000 32,000 - 44,000 44,000 - 56,000 56,000 -68,000 68,000 -80,000 80,000 - 92,000 Having a DP=763, which of the following common polymers is this sample? Xi 0.05 0.15 0.21 0.28 0.18 0.10 0.03 Wi 0.02 0.08 0.17 0.29 0.23 0.16 0.05 Select one: O a. Polymethylmethacrylate with a monomer molecular weight of 100.121 g/mol O b. Polystyrene with a monomer molecular weight of 104.15 g/mol Polycarbonate with a monomer molecular weight of 61.0168 g/mol O c. O d. Polyvinyl chloride with a monomer molecular weight of 62.498 g/mol Polypropylene with a monomer molecular weight of 42.08 g/mol O e.

Question 5: The graph below gives a plot of force versus total sample length in a tensile test of a polymer. The sample is cylindrical, with an initial diameter of 1 cm and an initial length of 10 cm. From the data below, calculate the modulus, yield stress, yield strain, tensile strength, and % elongation. 1200 800 10 12 13 14 15 Lensth (cm) Force (N)

At room temperature, most polymers have similar fracture toughness compared to metals. O True False

Which of the statements below are accurate regarding the stress-strain behavior of polymers: (This question has more than one correct answer) а. Strain softening happens in elastomers where the deformation gradually leads to a decrease in stress under constant strain rate b. As temperature is reduced, the necking behavior of plastic tensile bars completely disappears C- The slope of the stress-strain curve for totally elastic and brittle polymers is always positive d. The stress-strain curve for vulcanized elastomers has a greater slope than unvulcanized polymers throughout

Thermoplastics are stronger than thermoset plastics. True False   Yield strength, ultimate tensile strength, linear coefficient of thermal expansion, modulus of elasticity (E), proportional limit, and rupture strength are all examples of mechanical properties of engineering materials. True False

An unknown polymer sample was found to have the following molecular weight distribution: Molecular weight range xi 8,000 -20,000 0.05 20,000 - 32,000 0.15 32,000 44,000 0.21 44,000 56,000 0.28 56,000 -68,000 0.18 68,000 - 80,000 0.10 80,000 - 92,000 0.03 Having a DP=763, which of the following common polymers is this sample? Select one: wi 0.02 0.08 0.17 0.29 0.23 0.16 0.05 a. Polymethylmethacrylate with a monomer molecular weight of 100.121 g/mol b. Polyvinyl chloride with a monomer molecular weight of 62.498 g/mol c. Polycarbonate with a monomer molecular weight of 61.0168 g/mol d. Polypropylene with a monomer molecular weight of 42.08 g/mol e. Polystyrene with a monomer molecular weight of 104.15 g/mol

The graph below gives a plot of force versus total sample length in a tensile test of a polymer. The sample is cylindrical, with an initial diameter of 1 cm and an initial length of 10 cm. From the data below, calculate the modulus, yield stress, yield strain, tensile strength, and % elongation.

There are 4 classifications of structural molecular characteristics of polymers - Linear, Network, Crosslinked. What is the final type? Answer:

Question Seven (Plastics) The data below is from a fibre reinforced plastic. Would this composite be suitable for use at 400°C? Explain your answer. Temperature (°C) 20 100 200 300 400 500 600 Plastic A Plastic B Plastic C Yield Strength (MPa) 270 350 47 Tensile Strength (MPa) 300 500 52 E (GPa) 130 3 14 115 100 95 Question Eight (Plastics) Identify the thermoplastic, the elastomer and the thermoset. 70 58 0 Young's Modulus (GPa) Elongation (%) 12 3 600

Draw stress-strain graphs for two polymers: one is stiffer than the other and exhibits ayield point and the other shows no clear yield point but is much tougher.

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which test( izod or charpy or fracture toughness) is better for doing impact test on thermset polymers ?and why?

Compression molding is a manufacturing process in which the molding material is preheated then placed in an open mold cavity where the compressive action of the punch forces the polymer into the desired shape as shown in the figure below. Based on your understanding of the behavior of polymers, which of the statements below regarding compression molding of polymers are accurate? Punch Cavity C. -Upper mold half Charge 41 (1) -Lower mold half Knock-out pin V, F |x.F (2) and (3) Molded part a. Lower operating temperatures are more desirable as they reduce viscosity making it easier to fill the cavity b. This process can only be used for thermosets as they can thermally cure from monomer state This process can be used for both thermosets and thermoplastics as they can both be thermally shaped d. This process is suitable for rubber, PVC and polymethyl methacrylate

An unknown polymer sample was found to have the following molecular weight distribution: Molecular weight range Wi 8,000 - 20,000 0.05 0.02 20,000 – 32,000 0.15 0.08 32,000 - 44,000 0.21 0.17 44,000 – 56,000 0.28 0.29 56,000 - 68,000 0.18 0.23 68,000 - 80,000 0.10 0.16 80,000 - 92,000 0.03 0.05 Which of the following common polymers is this sample? (This question has only one correct answer)

For an application of high strength components including gears cams and rollers the desired properties in a plastic would be high tensile and impact strength, stability at high temperature, and machine ability. Potential materials which are suitable for these applications are nylon phenolics, TFE filled acetals, PET, and poly carbonate. True or false.

An unknown polymer sample was found to have the following molecular weight distribution: Molecular weight range 8,000 - 20,000 20,000 - 32,000 32,000 - 44,000 44,000 - 56,000 56,000 - 68,000 68,000 -80,000 80,000 - 92,000 0.03 Knowing that the monomer is methyl methacrylate, which of the below is the number average degree of polymerization for this polymer sample? Select one: O a. O b. DP 476 O C. DP = 338 DP = 664 O d. DP 544 O e. DP = 801 Xi 0.05 0.15 0.21 0.28 0.18 0.10 Wi 0.02 0.08 0.17 0.29 0.23 0.16 0.05

Which statements are correct regarding the mechanical properties of polymers? a. Drawing increases alignment and strength, and decreases ductility (% elongation) b. Annealing increases alignment, strength and elastic modulus c. Increasing temperature results in increased elastic modulus and strength, and decreased elongation d. Decreasing strain rate causes decreased strength and elastic modulus and increased elongation e. A higher degree of crosslinking generally results in decreased percent elongation at break, and increases strength

When a viscoelastic material is loaded and unloaded, the unloading curve is different to the loading curve, i.e. it takes more energy to displace the material than it does to return the material to its original configuration. This is known as: Select one: O a. creep O b. stress relaxation O c. hysteresis d. strain-rate dependance

Based on the graph below, reinforcing plastic with glass fibers results in:   A. An increase in plasticity   B. An increase in inelastic deformation   C, An increase in stiffness   D. A decrease in stiffness

Question 4 Figure 3 shows the impact of temperature and stress on mechanical properties of materials (a) 1200 High temperature or high stress (b) 900 Medium temperature or medium stress Brittle Ductile Low temperature or low stress 600 300 +Transition temperature -80 -40 40 80 Time Temperature (°C) Figure 3 (a) Izod impact test results for nylon thermoplastic polymer. (b) Creep test results Using Figure 3, explain: (a) The dependence of failure modes on temperature. (b) The effect of temperature changes and stress on the creep rate. Impact strength (J/m) Strain

A continuous and aligned fiber-reinforced composite is to be produced consisting of 30% vol aramid fibers and 70% vol of a polycarbonate matrix. Mechanical characteristics from the test are given below. The composite is characterized by mechanical testing in both longitudinal and transverse loading. Calculate the longitudinal and transverse elastic modulus. 30% vol aramid fibers (Modulus of Elasticity - 121.68 GPa) 70% vol of a polycarbonate matrix (Modulus of Elasticity - 3.42 GPa)

An unknown polymer sample was found to have the following molecular weight distribution: Molecular weight range Xi Wi 8,000 – 20,000 0.05 0.02 20,000 – 32,000 0.15 0.08 32,000 – 44,000 0.21 0.17 44,000 – 56,000 0.28 0.29 56,000 – 68,000 0.18 0.23 68,000 – 80,000 0.10 0.16 80,000 - 92,000 0.03 0.05 What would the weight average molecular weight of the sample be if, we had filtered the monomer mixture with a 44 kDa dialysis tubing before preparation? (Hint: a dialysis tubing of a known molecular weight, only keeps molecules larger than that size)

Polymer Engineering question:  Explain doping process and why this process important for conductive polymer?

Kindly solve it completely by hand if possible.