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.

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.

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

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.

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.

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.

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

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)

Kindly solve it completely by hand if possible.

Which of the following is incorrect regarding the degree of crystallinity of semi-crystalline polymers? (This question has more than one correct answer) a. Increasing the degree of crystallinity generally increases polymer strength, elastic modulus and ductility in semi-crystalline polymers b. Semi-crystalline polymers are heat treated to increase the crystallinity and improve polymer strength c. The tendency of a polymer to crystalize decreases with increasing molecular weight d. Heat treatment always results in enhanced polymer strength, elastic modulus and brittleness

The answer is one of the options below please solve carefully and circle the correct option Please write clear .

a. Determine whether the new biomaterial follows a most closely a linear elastic, neo-Hookean, or Mooney-Rivlin relationship.b. Show manipulation of strain energy density functions and include comparative plots of data showing results for linear elastic, neo-Hookean, and Mooney-Rivlin relationships.c. list any assumptions givens: . Shear moduli: 11 = U2 = 10MPa. Relationship between elastic constants: E = 2u(1 + v)

Polymeric materials are liable to creep at room temperature, stress and time of loading, which one of the following statements is correct? a. the longer the time, the creep strain increase. b. The higher the temperature, the higher the creep limit. c. Reduce the stress increases the strain. d. Increase the temperature increases the creep strain.

Hello Sir.Good Evening I have a question in my home work related materials polimer lesson. The following below is my question. Please advice, thank you so much. "Explain how the relationship between temperature and the tensile strength of polymers ?"

What is an important consequence of time-temperature equivalence for testing of polymer time-dependent elastic moduli?

Which of the following are incorrect regarding the crystallinity and mechanical behavior of polymers? a. As temperature is reduced, necking behavior of plastic tensile bars completely disappears b. Semi-crystalline polymers are heat treated to increase crystallinity and improve strength c. Heat treatment always results in enhanced polymer strength, modulus, and brittleness d. Strain softening happens in elastomers where the deformation gradually leads to a decrease in stiffness under constant strain rate e. Increasing the degree of crystallinity generally increases polymer strength, elastic modulus, and ductility in semi-crystalline polymers f. The stress-strain curve slope for totally elastic and brittle polymers is always positive

When a failure data set for a ceramic material processed in a certain facility is analyzed, it is found that the characteristic strength is 327 MPa and the Weibull modulus is 8.75. A nominally identical batch of material processed in a different facility is also tested and found to have essentially the same characteristic strength, but the Weibull modulus is 6.25. At what stress level is the probability of failure equal to 50% for each set of material? What initial conclusion might you draw about the quality control procedures at the two facilities?