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Efeito da radiacao ionizante no prolipropileno nacionalMUSICO FILHO, WALTER 09 October 2014 (has links)
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02758.pdf: 10540189 bytes, checksum: 11f088ac718b0e5f521aa64453bc4156 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Efeito da radiacao ionizante no prolipropileno nacionalMUSICO FILHO, WALTER 09 October 2014 (has links)
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02758.pdf: 10540189 bytes, checksum: 11f088ac718b0e5f521aa64453bc4156 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Formation of Giant Single Crystals of Isotactic Polypropylene via Mesophase / メゾ相経由のアイソタクチックポリプロピレンの巨大単結晶の形成Asakawa, Harutoshi 26 March 2012 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16879号 / 工博第3600号 / 新制||工||1544(附属図書館) / 29554 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 金谷 利治, 教授 長谷川 博一, 教授 辻井 敬亘 / 学位規則第4条第1項該当
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A study of miscibility, morphology, crystallization and melting behavior of isotactic poly(propylene) in blends of poly(propylene) and poly(1-butene)Lee, Tiehong 29 July 2009 (has links)
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 <sub>g</sub>, 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. / Master of Science
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A material model for multiaxial stretching and stress relaxation of polypropylene under process conditionsSweeney, John, O'Connor, C.P.J., Spencer, Paul, Pua, H., Caton-Rose, Philip D., Martin, P.J. 03 December 2020 (has links)
No / Polypropylene sheets have been stretched at 160 °C to a state of large biaxial strain of extension ratio 3, and the stresses then allowed to relax at constant strain. The state of strain is reached via a path consisting of two sequential planar extensions, the second perpendicular to the first, under plane stress conditions with zero stress acting normal to the sheet. This strain path is highly relevant to solid phase deformation processes such as stretch blow moulding and thermoforming, and also reveals fundamental aspects of the flow rule required in the constitutive behaviour of the material. The rate of decay of stress is rapid, and such as to be highly significant in the modelling of processes that include stages of constant strain. A constitutive equation is developed that includes Eyring processes to model both the stress relaxation and strain rate dependence of the stress. The axial and transverse stresses observed during loading show that the use of a conventional Levy-Mises flow rule is ineffective, and instead a flow rule is used that takes account of the anisotropic state of the material via a power law function of the principal extension ratios. Finally the constitutive model is demonstrated to give quantitatively useful representation of the stresses both in loading and in stress relaxation.
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The use of fluorescence to probe the morphology changes in complex polymersLe Grange, Marehette Suzanne 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Impact polypropylene copolymers (IPC) are commercially used in a variety of applications. They
are very complex materials and extensive studies have been conducted to understand the
relationship between their chemical structure, morphology and impact properties. The distribution
of ethylene propylene rubber (EPR) within IPC has drawn much attention but visualization of the
morphology is difficult. In this study a fluorescent marker was used to probe the distribution of
EPR within the crystalline and semi-crystalline fraction.
The EPR was removed from a commercial IPC and labelled with a fluorescent marker. In this
study a method utilizing the hydrophilic nature of cellulose nanowhiskers (CNW) was developed to
label the EPR. CNW were labelled with fluorescein-5’-isothiocyanate (FITC) and rhodamine B
(RhB) using a one-step procedure. The labelled CNW were incorporated into the EPR by means
of sonication. The mobility of the labelled CNW within the EPR film was investigated by confocal
fluorescence microscopy (CFM), and showed that the labelled whiskers did not move within the
EPR, thus substantiating the validity of this approach. The labelled EPR was recombined with the
crystalline fraction by means of injection moulding and was analysed by CFM, and the distribution
of the labelled EPR was evaluated. Confocal fluorescence microscopy showed an even distribution
of the labelled rubber throughout the injection moulded sample.
The miscibility of two EPRs within the IPC matrix in the melt was also investigated using this
technique. CFM showed that the technique has promise to prove miscibility or the lack thereof
when chemically similar materials are combined in the presence of morphologically different matrix
materials. / AFRIKAANSE OPSOMMING: Impak polipropileen kopolimere (IPK) word kommersieel gebruik in ‘n wye reeks produkte. Die
samestelling van hierdie kopolimere is baie ingewikkeld en uitgebreide studies is al gedoen om hul
chemiese samestelling op molekulêre vlak te verstaan. Baie studies met betrekking tot die
verspreiding van die etileen-propileen rubber (EPR) binne in hierdie impak polipropileen
kopolimere is al gedoen, maar visualisering van die morfologie is moeilik en beperk. Hierdie kennis
kan bydra tot die verbetering van hul chemiese eienskappe en toepassings. In hierdie studie word
ʼn fluorosserende merker gebruik om die verspreiding van die EPR binne die kristallyne en semikristallyne
fraksie te ondersoek.
Die EPR is verwyder vanuit 'n kommersiële IPK en is gemerk met 'n fluoresserende merker. In
hierdie studie is 'n metode ontwikkel om die EPR te merk deur gebruik te maak van die hidrofiliese
eienskap van sellulose nanovesels (SNV). Die SNV is gemerk met fluoressien-5'-isotiosianaat
(FITC) en rhodamien B (RhB) met behulp van 'n eenstap proses. Die gemerkte SNV is deur middel
van sonikasie in die EPR versprei. Die mobiliteit van die gemerkte SNV binne-in die EPR film is
ondersoek deur gefokusde fluoressensie mikroskopie (GFM) en het getoon dat die gemerkte
vesels nie binne die EPR beweeg nie. Dit bevestig dus die geldigheid van hierdie benadering. Die
gemerkte EPR is herkombineer met die kristallyne fraksie deur middel van spuitgiet en is
geanaliseer deur GFM en die verspreiding van die gemerkte EPR is geëvalueer. GFM het 'n
eweredige verspreiding van die gemerkte rubber regdeur die moster wat gespuitgiet is getoon.
Die mengbaarheid van twee EPRs binne-in die IPK matriks is ook ondersoek deur gebruik te maak
van hierdie tegniek. GFM het getoon dat hierdie tegniek waarde inhou om te bewys dat twee
produkte mengbaar is of nie, al word hulle geherkombineer word met ‘n matriks wat morfologiese
van hul verskil.
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The rheology and processing of glass mat thermoplasticsBland, Jonathan H. January 1997 (has links)
No description available.
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Characterization of the mechanical and moisture absorption properties of kenaf reinforced polypropylene compositesAsumani, Oscar 05 September 2014 (has links)
Great interest has been generated in the use of natural fibres as environmentally
friendly reinforcing materials in polymeric composites, which do not require high
load bearing capabilities. kenaf fibres extracted from kenaf plants (hibiscus
cannabinus) have been identified as an attractive option due to its production cost
and the ability of the kenaf plants to grow in a variety of climatic conditions.
Polypropylene (PP) has a relatively low production cost, excellent corrosion
resistance, good retention of mechanical properties and less recycling challenges
in comparison to other matrix systems such as thermosets. Given the individual
advantages of kenaf fibre and polypropylene, kenaf reinforced polypropylene
composites (kenaf/PP composites) have considerable commercial interest in the
composite industry. However, limitations arise with respect to the mechanical
performance and to the resistance to moisture absorption when natural fibres are
used.
This study focuses on the improvement of the mechanical properties (e.g. tensile,
flexural, fatigue and impact properties) and the resistance to moisture absorption
of kenaf reinforced polypropylene composites by means of fibre treatments (e.g.
alkali and alkali-silane treatments) and the use of filler materials (e.g.
functionalized multi-wall carbon nanotubes). Kenaf reinforced polypropylene
composites are manufactured by a modified compression moulding using the
film–stacking technique. The crux of this technique is that kenaf mats are
impregnated with polypropylene powder in order achieve a uniform material
distribution and to lower the manufacturing temperature, thereby preventing the
thermal alteration of the composite constituents (e.g. kenaf fibres) and silano
functional groups attached to the multi-wall carbon nanotubes. Fibre treatments
including alkali treatments and alkali followed by silane treatments (alkali-silane)
are considered in order to improve the fibre-matrix interfacial adhesion. The
concentrations of the alkali solutions range from 1% to 8% in intervals of 1% by
mass. Fibre contents ranging from 20% to 35% in interval of 5% by mass are
considered for both kenaf and glass fibre reinforced plates. Functionalized multi-wall carbon nanotubes are used as filler material in order to improve the
mechanical properties of the composite plates. The concentrations of the multiwall
carbon nanotube (MWCNT) range from 0.1% to 1.25%.
Mechanical test and microscopic examination results showed that alkali
treatments improve the mechanical properties of kenaf/PP composites. However,
the improvements due to alkali-silane treatments were found to be more
significant because additional silane treatments substantially enhanced the fibrematrix
interfacial adhesion. Material failures in untreated kenaf/PP composites
and alkali treated kenaf/PP composites were mainly characterized by fibre pullouts,
whereas in alkali-silane treated kenaf/PP composites they were characterised
by fibre breakage. Alkali concentrations of 5% and 6% NaOH are found to the
optimum concentrations for both alkali treatment and alkali-silane treatment.
The use of functionalized MWCNTs as filler material improved furthermore the
mechanical properties of kenaf/PP-MWCNT composites in comparison to those
of kenaf/PP and glass/PP composites. The main contributing factors of the
improvements were found to be the enhancement of the interfacial adhesion
between the nanoparticles and the matrix, and also between the nanoparticles and
kenaf fibres. Material failures in kenaf/PP-MWCNT composites were
characterized by fibre breakage and matrix cracks. The optimum MWCNT
concentrations were found to be 0.5% and 0.75%. 30% fibre contents was found
to be the optimum fibre content for both kenaf/PP and kenaf/PP-MWCNT
composites. Test results showed that the fibre treatments, especially alkali-silane
treatment, improved the resistance to moisture absorption of the composites. Test
results also showed that the manufacturing technique, which enables the
manufacturing of composite plates with layers of different moisture diffusion
resistances, has a significant influence on the resistance of kenaf/PP composites.
The addition of multi-wall carbon nanotubes to the polypropylene matrix did not
alter the moisture absorption resistance of kenaf/PP-MWCNT composites. The
impregnation of kenaf and fibre glass mats with polypropylene powder
significantly lowered the manufacturing temperature
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Studies of molecular mobility in oriented polypropylene by vapor diffusion and ESR techniques.January 1983 (has links)
by Ma Tak-lun. / Bibliography: leaves 68-69 / Thesis (M.Phil.) -- Chinese University of Hong Kong, 1983
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Model and analysis of the geometric characteristics of primary carpet backingFord, Allison Elaine 01 December 2003 (has links)
No description available.
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