8/ What is the principal difference between the two subdivisions of the polymeric composites: therm thermoplastics? 8.1. Thermoset matrix- polyester, epoxide, phenol formaldehyde or other - after curing becomes inso infusible. On the contrary, thermoplastic matrix hardens as a result of cooling of the polymer melts. 8.2. The difference between the two main types polymer matrices is the use of continuous carbon reinforcement of thermosets and chopped glass fibres in the thermoplastic composites. 8.3. The use of reactive and thermoplastic resins for activating of the surfaces of reinforcing fillers. 9/ In what range vary the diameters of the glass fibres in the polymer composites reinforced with them? 9.1. The reinforcing glass fibers for plastics are 0,1 – 0,2 mm. in diameter; 9.2. The diameters of the reinforcing glass fibers for plastics are at about 3 - 4 um. 9.3. The diameters of the reinforcing glass fibers for plastics vary from 8 to 12 un.

How does the degree of cross-linking affect the mechanical properties of a tough polymer?

3. The geometry of the reinforcing phase in a composite greatly determines the overall properties. Polycarbonate has a Modulus of Elasticity=2.2 GPa, Tensile Strength-62.5 MPa. Carbon Fiber has a Modulus of Elasticity=228 GPa, Tensile Strength=3.5 GPa. For a 40 vol% carbon fiber and a 60 vol% polycarbonate matrix composite, compute the Tensile Strength and Young's Modulus for the composite for the following situations. Assume longitudinal loading. a. Continuous and aligned fibers b. Discontinuous and aligned fibers with I> le where 1 = 101, (K = 1). c. Discontinuous and aligned fibers with I< le where I= 0.51, (K = 1). d. Which of these composites is the strongest? Which is the stiffest (has the highest Young's Modulus)?

Question 6. Calculate the average molecular weight Mm for a thermoplastic that has the following weight fractions fi for the molecular weight ranges listed: Molecular Weight _fi 0.01 Molecular Weight Range (g/mol) 20,000-25,000 25,000-30,000 30,000-35,000 35,000-40,000 Range (g/mol) fi 0-5000 0.19 5000-10,000 0.04 0.21 0.15 10,000-15,000 15,000-20,000 0.16 0.17 0.07

Connecting rod (as shown below) is a car part that connects engine piston to crankshaft and converts reciprocating motion into rotating motion. It performs under load at high temperature around 150°C. Long carbon fiber thermoplastic composite (LFT) with 30% carbon fiber has been considered to replace metal (steel or aluminum) rod to improve efficiency.    Based on the data for different polymers listed in the table above, which polymer(s) would you choose as the polymer matrix for the connecting rod? What is your rationale?

Briefly explain how each of the following influences the tensile or yield strength of a semicrystalline polymer and why: (a) Molecular weight (b) Degree of crystallinity (c) Deformation by drawing

Continuous and aligned fiber-reinforced composite with cross-sectional area of 330 mm² (0.51 in.²) is subjected to a longitudinal load of 49200 N (11100 lbf). Assume Vf=0.3, Vm = 0.7, Ef= 131 GPa and Em = 2.4 GPa. (a) Calculate the fiber-matrix load ratio. (b) Calculate the actual load carried by fiber phase. (c) Calculate the actual load carried by matrix phase. (d) Compute the magnitude of the stress on the fiber phase. (e) Compute the magnitude of the stress on the matrix phase. (f) What strain is expected by the composite? Part 1 Calculate the fiber-matrix load ratio. M Save for Later Part 2 What is the load, in N, carried by the matrix and the fibers? (a) What is the matrix load in N? i (b) What is the fiber load in N? i N N Attempts: 0 of 3 used Submit Answer

Why do thermoplastic polymers start to turn white as they are plastically deformed?

Please solve this mechanical engineering materials course question

Molecular weight data for some polymer are tabulated here. Compute (a) the number-average molecular weight, (b) the weight-average molecular weight. (c) If it is known that this material's degree of polymerization is 710, which one of the polymers listed in Table 14.3 is this polymer? Why? Molecular Weight Range g/mol 15,000-30,000 Xi Wi 0.04 0.01 30,000-45,000 0.07 0.04 45,000-60,000 0.16 0.11 60,000-75,000 0.26 0.24 75,000-90,000 0.24 0.27 90,000 105,000 0.12 0.16 105,000-120,000 0.08 0.12 120,000-135,000 0.03 0.05