Chemistry, 25.09.2019 01:30 gabelawson6996
The structure formation upon cooling of the quiescent melt of a nearly defect-free isotactic poly(propylene) (ipp) homopolymer is investigated in this study. this ipp has a molecular weight of 1 x 10° g/mol and a narrow molecular weight distribution. information about the crystallization kinetics is collected in a broad range of cooling rates. standard differential scanning calorimetry is used at cooling rates in the range 3-100c/min. the near absence of regio- and stereo-defects allows this ipp to crystallize at significantly higher temperatures and to form crystals at higher cooling rates than commonly observed for standard ipp. the data reveal that the ipp homopolymer with close-to-perfect stereo-regularity forms crystals at high cooling rates. the defect-free polymer chain allows the formation of relatively thick lamellar crystals having a relatively high tensile modulus of 20888 mpa. macromolecular chemistry and physics, 216(22), 2171-2178 (2016) a) provide a rough sketch of a dsc plot comparing the heat evolution of a sample of "defect free" ipp versus 'normal' ipp. normal polypropylene has a tm of 130°c b) why does the near absence of defects allow this ipp to crystallize at higher temperatures than for 'normal' ipp? c) why does the near absence of defects allow this ipp to crystallize thicker crystals than observed for 'normal' ipp? provide a rough quantitative estimate of crystal thickness d) why is the tensile modulus of these crystals higher than that of crystals formed from 'normal' ipp?
Answers: 1
Chemistry, 22.06.2019 04:00, tifftifftiff5069
You encounter a solution that is acidic and you decide to test it by adding a small amount of a strong acid. the ph lowers slightly but is approximately unchanged, and still remains acidic. what can you say about the solution? a. it is a buffer solution. b. it is not a buffer solution it is a strong acid solution. d. the solution has been neutralized. e. the solution has excess acid present
Answers: 1
Chemistry, 22.06.2019 09:00, tbiles99
What type of energy do chemical bonds have? what type of energy is it converted to during chemical reactions? question 15 options: chemical bonds have kinetic energy, which is converted to potential energy during chemical reactions. chemical bonds have electric energy, which is converted to potential energy during chemical reactions. chemical bonds have heat energy, which is converted to kinetic energy during chemical reactions. chemical bonds have potential energy, which is converted to heat energy during chemical reactions.
Answers: 1
Chemistry, 22.06.2019 10:00, paynedeforest2596
According to the tide table below what time of day will the highest tide occur? (2 pt) the highest tide will occur at
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The structure formation upon cooling of the quiescent melt of a nearly defect-free isotactic poly(pr...
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