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Development of surface fluorinated polypropylene fibres for use in concreteTu, Lin 17 February 2014 (has links)
D.Ing. (Civil Engineering) / Polypropylene (PP) fibre is one of the most widely used fibres for reinforcing concrete. Due to its unique material properties such as economic production cost, relatively high melting point and alkaline resistance, PP fibres in concrete are found to increase the toughness, provide restrained plastic and drying shrinkage cracking resistance, increase impact resistance and flexural loading capacity (especially during the post-crack stage) of concrete structures and components. The wettability of PP fibre surfaces is poor due to the hydrophobic surface nature of polypropylene. The bonding between the PP fibre and the concrete matrix is recognized as poor and currently the PP fibre / concrete interfacial bonding depends upon interlocking and keying (mechanical bonding). As the interfacial bond strength between the PP fibre and the concrete is much smaller than the tensile strength of PP fibre and concrete, in order to fully explore the reinforcing effect of PP fibres in concrete, further improvement of interfacial bonding is necessary. In this investigation, the research work was conducted on the surface oxyfluorinated PP fibre newly developed by the Atomic Energy Corporation of South Africa Limited. Examining the feasibility of using this fibre in concrete, as well as evaluating its superiority over unmodified PP fibres, is the key task of this investigation. This new type of oxyfluorinated PP fibre shows a large increase in interfacial bond strength compared to the unmodified PP fibres. The surface free energy concept and Lewis acid-base interfacial interaction theory were innovatively used to examine the interfacial bonding between the PP fibre and the concrete matrix. The purpose of this study was to develop the background of such oxyfluorinated PP fibres, to establish the mechanism of the increase in interfacial bonding and to investigate the basic properties of the concrete incorporating oxyfluorinated PP fibres. The experimental results on the properties of oxyfluorinated PP fibre reinforced concrete compared with those of unmodified PP fibre reinforced concrete and plain concrete are presented, with some field test results focused on the improvement in shrinkage cracking control capacity. It is concluded in this investigation that the surface oxyfluorinated PP fibres possess significantly increased PP fibre / concrete interfacial bonding due to the chemical bond arising from the acid base interfacial interaction and the intimate interfacial contact arising from the improved fibre surface wettability. When combining oxyfluorinated pp fibre with concrete, a general improvement in the physical and mechanical properties of fibrous concrete compared to that created with unmodified PP fibres, is obtained.
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Continuous drawing studies of foam fibrillated yarnChilds, Jack Douglas 12 1900 (has links)
No description available.
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Characterization of fibrillated polypropylene and recycled waste fiber reinforced concreteScott, David Edward 08 1900 (has links)
No description available.
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Optimization of thermoplastic pultrusion process using commingled fibersKamble, Vishal D. January 2008 (has links) (PDF)
Thesis (M.S.)--University of Alabama at Birmingham, 2008. / Additional advisors: Burton Patterson, Derrick Dean, Selvum (Brian) Pillay. Description based on contents viewed Feb. 10, 2009; title from PDF t.p. Includes bibliographical references (p. 80-83).
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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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Development of commercial, sustainable processes for dyeing generic, unmodified polypropylene fiberGupta, Murari Lal. January 2008 (has links)
Thesis (Ph.D)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Cook, Fred; Committee Member: Beckham, Haskell; Committee Member: Bottomley, Lawrence; Committee Member: Carr, Wallace; Committee Member: Etters, Nolan. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Studies on flax/polypropylene-reinforced composites for automotive applicationsBiyana, Nobuhle Yvonne January 2015 (has links)
The use of natural fibers as reinforcement in thermoplastics presents an interesting alternative for the production of low cost and ecologically friendly composites. One of the advantages of using natural fibres is their low specific weight, resulting in higher specific strength and stiffness when compared to glass reinforced composites. Natural fibres also present safer handling and working conditions. They are non-abrasive to mixing and can contribute to significant cost reduction. This work is divided into two phases: Phase 1 deals with developing nonwoven mats composites from flax/polypropylene (PP) and evaluating their properties. Flax/polypropylene fibres (at different weight ratios) were processed by needle-punching technique in order to form nonwoven mats. The mats were compression-molded at a temperature of 180oC to form composite materials. The mechanical, thermal and viscoelastic properties of the composites were analyzed. Composites (untreated and silane-treated) were also subjected to varying conditions of temperature and humidity and the tensile properties of the conditioned and unconditioned composites were investigated. The mechanical properties (tensile, flexural and impact) of flax/PP composites were found to increase and reach maximum values at 30 per cent fibre loading and then decrease at higher fibre content. Thermal studies revealed that the composites were stable up to 320oC and samples containing 40 per cent flax fibres were found to exhibit greater thermal stability than neat PP. The dynamic mechanical analyses of the composites showed that the incorporation of flax in the composites resulted in an increase of the storage modulus with a maximum value exhibited by composite containing 40 per cent fibre loading. Composites containing chemically modified fibres exhibited low tensile modulus after conditioning. Phase 2 is based on the investigation of the effect of nano-calcium carbonate (CaCO3) on the properties of two types of polymer matrices: recycled PP and virgin PP. In this case, composites were prepared by melt-mixing and injection molding. The mechanical and thermal properties of the composites were characterized. The tensile modulus of the nano-CaCO3 filled PP (virgin and recycled) composites were found to increase and reach maximum at 30 per cent nano-CaCO3 loading, while the tensile strength decreased with increasing filler content. Thermal studies showed that the nano-CaCO3 filled PP samples exhibited a one-step degradation pattern and are thermally stable up to 450oC. The thermal stability of the samples was found to decrease following the addition of nano-CaCO3. SEM micrographs of the tensile fractured surfaces of composites of the nano-CaCO3 filled virgin and recycled PP revealed the presence of nano-CaCO3 agglomeration.
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Properties and characteristics of polypropylene fibers spun by the phase-separation techniqueWilliams, Matthew Carl January 1971 (has links)
A spinning apparatus was built for the investigation of the phase-separation technique as applied to the production of polypropylene fibers from naphthalene solutions. The solutions were spun through a single 2.00 millimeter spinneret at compositions of 15 and 22 per cent polymer and at temperatures of 145 and 160°C. Linear velocities in the spinneret and draw ratios ranged from 0.125 to 0.277 meters per minute and from 759 to 2198, respectively.
It was found that naphthalene could be extracted from the fibers by diethyl ether in less than one minute; however, this extraction was not necessary prior to properties testing because all of the naphthalene in the fibers exposed to air was lost by sublimation.
Deniers of 14 selected fiber samples varied inversely with draw ratio and directly with solution composition in a range from 2.5 to 8.0. After the samples were cold-drawn 3:1, tests with a Scott Tensilgraph showed that tenacities, per cent elongations at break, and secant moduli varied directly with draw ratio in ranges from 0.9 to 1.6 grams per denier, from 50 to 150 per cent, and from 17 to 30 grams per denier, respectively. Per cent elongations at break also varied directly with solution composition.
The fibers, in general, exhibited good hand, bulk, tangling, and self-crimping characteristics. Photographs of four of the fiber samples were made to show the tangling and crimp qualities. / Master of Science
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Cracking Control in Mezzanine Floor Slabs using Rice Husk Ash and Polypropylene FibersCano, B., Cano, B., Galarza, J., Rodríguez, J., García, F. 28 February 2020 (has links)
The continuous population increase in recent years requires a greater number of households to be built quickly, with good materials and produced under quality standards that guarantee their manufacturing process. The prefabricated concrete, produced and supplied by concrete plants, is poured into the different structural elements, the mezzanine slabs being the most careful surfaces in the appearance of fissures; because being horizontal and having larger dimensions, the dimensional changes in the concrete appear more frequently due to the rapid loss of water from the surface of the concrete before setting; which generates superior stresses to the resistant capacity of the concrete at early ages, which affect the durability and reduce the resistance of the structures, causing greater economic expenses in maintenance and repairs. In the present investigation, 5%, 10% and 15% of rice husk ash was used as a replacement for cement and 900g/m3 of polypropylene fiber; The results indicate that as the percentage of rice husk ash increases, there is a reduction in the slump and the crack fissures, and that the resistance to compression and flexion decreases, with respect to the concrete pattern.
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Vliv přídavku polypropylenových vláken na vlastnosti betonů / Effect of addition of polypropylene fibers on the properties of concreteSvozil, Jaroslav January 2013 (has links)
The thesis evaluates the influence of the addition of polypropylene fibers on the properties of concrete. One of the major elements is to compare different finishes polypropylene fibers without static functions, including low temperature plasma treatment plasma. The main work is to test the knowledge of the properties of fresh concrete with these fibers, as well as testing volume changes and finally testing these concretes on physical and mechanical properties
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