explain how the properties of polymers are improved by using this approach 4.Describe three methods in which adhesives develop their cured attraction between the substrate and the adherent. 5.What are the three major differences between carbon and graphite fibers? VII Complex questions.(10points) 1.What is a fiber-reinforced composite primary composed of?Use a schematic drawing to indicate the structure ofa fber-reinforced composite and their corresponding interfaces and interphase. 2.Discuss the effect of crystallinity on the toughness,strength and density of polymers and exemplify an approach to improving the crystallinity of polymers? 3.Figure I is the graphical plot of the tensile modulus of a unidirectional composite material loaded under isostrain and isostress conditions as a function of volume fraction of reinforcing fiber.Indicate which curve(A or B)is for isotrain condition?For a given volume fraction of fiber in a composite, which condition is more ininreasing the modulus?If the tensile modulus of the fiber and matrix is known,how can we calculate the tensile modulus of the composite under isostrain condition? A 06 Vea瑞 VIIL.Supplementary questions for extra points added to the total score(20pts). 1.Why is natural rubber used in automobile tires?Why are synthetic rubbers also used? 2.Give examples to explain how the properties of polymers are influenced by the structureor processing methods of polymers. 3.Discuss the factors influencing the properties of fiber-reinforced composites. 4.Define the term of"wind anglefor filament winding.How do the hoop tensile strength and axial tensile strength change with wind angle? 第8而 第 8 页 explain how the properties of polymers are improved by using this approach. 4. Describe three methods in which adhesives develop their cured attraction between the substrate and the adherent. 5. What are the three major differences between carbon and graphite fibers? VII. Complex questions. (10points) 1. What is a fiber-reinforced composite primary composed of? Use a schematic drawing to indicate the structure of a fiber-reinforced composite and their corresponding interfaces and interphase. 2. Discuss the effect of crystallinity on the toughness, strength and density of polymers and exemplify an approach to improving the crystallinity of polymers? 3. Figure 1 is the graphical plot of the tensile modulus of a unidirectional composite material loaded under isostrain and isostress conditions as a function of volume fraction of reinforcing fiber. Indicate which curve (A or B) is for isotrain condition? For a given volume fraction of fiber in a composite, which condition is more efficient in increasing the modulus? If the tensile modulus of the fiber and matrix is known, how can we calculate the tensile modulus of the composite under isostrain condition? VIII. Supplementary questions for extra points added to the total score (20pts). 1. Why is natural rubber used in automobile tires? Why are synthetic rubbers also used? 2. Give examples to explain how the properties of polymers are influenced by the structure or processing methods of polymers. 3. Discuss the factors influencing the properties of fiber-reinforced composites. 4. Define the term of “wind angle” for filament winding. How do the hoop tensile strength and axial tensile strength change with wind angle?