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dc.contributor.authorLee, Tiehongen_US
dc.date.accessioned2014-03-14T21:41:31Z
dc.date.available2014-03-14T21:41:31Z
dc.date.issued1992-02-05en_US
dc.identifier.otheretd-07292009-090250en_US
dc.identifier.urihttp://hdl.handle.net/10919/43974
dc.description.abstract

In this thesis, the miscibility behavior of blends of polypropylene (PP) and poly(l-butene) (PB1) will be reexamined. The driving force for this study is the fact that contradictory conclusions on this subject exist in the literature. In this thesis, the glass transition behavior, morphology, spherulite growth rate and melting behavior of PP/PB1 blends with different molecular weights and tacticities have been investigated. Dynamic mechanical analysis on the melt blends of isotactic polypropylene and poly(1-butene) (it-PP/it-PB1), made of commercial high molecular weight materials, indicates a single but broad, composition dependent glass transition temperature. Crystallization studies of the a phase of it-PP in these blends show that the spherulitic growth rate of it-PP decreases with increasing it-PBl content. The melting behavior of the it-PP also depends on blend composition. However, polarizing optical microscopy reveals morphologies strongly indicating phase separation in these blends. These seemingly conflicting results are explained by further studies performed on the blends of the same it-PP with an atactic poly(i-butene) of lower molecular weight and blends of the atactic poly(1-butene) with an atactic polypropylene. From studies of the glass transition behavior, morphology and growth rate, it was found that the it-PP and the at-PP are definitely miscible with the low molecular weight at-PB1. Since commercial isotactic polypropylene and isotactic poly(1-butene) always contain a certain amount of low molecular weight fractions, it can be concluded that the single composition-dependent T g, the growth rate depression and the changes in the melting behavior of the it-PP/it-PB1 blends arise from the miscibility of the low molecular weight fractions (both isotactic and atactic) of the it-PB1 and it-PP. Theoretical calculations utilizing the Flory-Huggins-Hildebrand theory (7) supports the above conclusions and suggests the phase separation phenomena in the it-PP/it-PB1 blends is caused by the high molecular weight it-PB1.

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dc.format.mediumBTDen_US
dc.publisherVirginia Techen_US
dc.relation.haspartLD5655.V855_1992.L443.pdfen_US
dc.subjectPolypropyleneen_US
dc.subject.lccLD5655.V855 1992.L443en_US
dc.titleA study of miscibility, morphology, crystallization and melting behavior of isotactic poly(propylene) in blends of poly(propylene) and poly(1-butene)en_US
dc.typeThesisen_US
dc.contributor.departmentChemistryen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-07292009-090250/en_US
dc.date.sdate2009-07-29en_US
dc.date.rdate2009-07-29
dc.date.adate2009-07-29en_US


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