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HW _4 Solutions

# HW _4 Solutions - ANS Using the given values for E glass...

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CEE 3020 Civil Engineering Materials SOLUTIONS Question 1 See your course notes for a sketch of the linear polyvinylchloride molecule with isotactic structure. Question 2 Calculate the degree of polymerization for polyvinylchloride which has the following weight fractions, f i , for the molecular weight ranges listed. Molecular Weight Range, g/mol f i 0-5,000 5,000-10,000 10,000-15,000 15,000-20,000 20,000-25,000 25,000-30,000 30,000-35,000 35,000-40,000 0.02 0.07 0.16 0.22 0.26 0.14 0.09 0.04 ANS. f i M i Σ f i M i 0.02 2500 50 0.07 7500 525 0.16 12,500 2000 0.22 17,500 3850 0.26 22,500 5850 0.14 27,500 3850 0.09 32,500 2925 0.04 37500 1500 329 )] 5 . 35 ( 1 ) 1 ( 3 ) 12 ( 2 [ / 20550 = + + = Σ = mol g m M f DP i i i Question 3 A unidirectional hybrid composite contains 50% E glass fibers and 10% carbon fibers (v f =0.60) in an epoxy matrix. Calculate: (a) the strength and elastic modulus in the fiber direction.

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Unformatted text preview: ANS. Using the given values for E glass fibers, High Strength carbon fibers, and average values for epoxy resin: ( 29 ( 29 ( 29 ( 29 psi V V psi V V m m f f c m m f f c 000 , 000 , 8 40 . 000 , 375 1 . 000 , 000 , 29 1 5 . 000 , 000 , 10 1 000 , 297 40 . 9400 1 . 000 , 435 1 5 . 000 , 500 1 = × + × × + × × = Ε + Ε = Ε = × + × × + × × = + = ∑ ∑ η σ ησ (b) the strength and elastic modulus in the transverse direction. ANS. Using given values for E glass fibers, High Strength carbon fibers, and average values for epoxy resin: ( 29 ( 29 ( 29 ( 29 psi V V psi V V m m f f c m m f f c 000 , 150 40 . 000 , 375 1 . 000 , 000 , 29 5 . 000 , 000 , 10 760 , 3 40 . 9400 1 . 000 , 435 5 . 000 , 500 = × + × × + × × = Ε + Ε = Ε = × + × × + × × = + = ∑ ∑ η σ ησ...
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