Thesis (M.S. in civil engineering)--Washington State University, December 2008. / Title from PDF title page (viewed on Mar. 10, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2010. / Title from PDF t.p. (viewed June 30, 2010). Additional advisors: R. Michael Banish, Derrick R. Dean, Nasim Uddin, Uday K. Vaidya. Includes bibliographical references (p. 197-202).

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High amylose cornstarch, normal cornstarch and waxy cornstarch were plasticized using water and glycerol as plasticizers in a Haake Rheomix 3000 batch mixer. A two-level factorial experiment design was used to investigate the effects of processing conditions and the water/glycerol ratio on the mechanical properties of the thermoplastic starches. The significances of factors (processing temperature, time, roller rolling rate and ratio of water to glycerol) on the mechanical properties were evaluated. The morphology, thermal properties, average molecular weight and molecular weight distribution of the thermoplastic starches were analyzed using scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and high performance size exclusion chromatography (HPSEC). The mechanical properties and rheological properties of the materials were measured using an Instron tensile testing machine and a Rosand capillary rheometer. The thermoplastic starches were further blended with poly(lactic acid)(PLA) at different composition ratios. The morphology, thermal properties, molecular weight and molecular weight distribution of the thermoplastic starch/PLA blends were analyzed using SEM, DSC, HPSEC. Mechanical and rheological properties of the blends were investigated using the same methods as those used in the investigation of thermoplastic starches. The effects of amylose content in the starches, composition (starch/plasticizer ratio, water/glycerol ratio, starch/PLA ratio), molding methods and molding temperature on structure and properties of thermoplastic starches and thermoplastic starch/PLA blends were also investigated and compared. A power law model and a cross model were used to fit the experimental rheological data of the thermoplastic starches and the thermoplastic starch/PLA blends. The thermoplastic normal starch with starch/plasticizer ratio of 2/1 (wt/wt%) shows a tensile strength of 2.81 MPa, a modulus of 55.09MPa and an elongation at break of 76.0%. The post-extruded thermoplastic normal starch/PLA blend with the starch/PLA ratio of 50/50 (wt/wt) and the starch/plasticizer ratio of 2/1(wt/wt) exhibits a tensile strength of 15 MPa, a modulus of 926 MPa and an elongation at break of 6%. / Thesis / Master of Applied Science (MASc)

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The South African manufacturing industry plays a pivotal role in the growth of its local economy. Modern manufacturing requirements include the ability to respond quickly to product variability, fluctuations in product demand and new process technologies. The reconfigurable manufacturing paradigm has been proposed to meet the demands of the new manufacturing requirements. In order to assess the feasibility of incorporating automated, reconfigurable manufacturing technologies into the production process of thermoplastic fibre-reinforced composite parts, a system, based on the thermoforming process, that implements these technologies was developed and evaluated. The assessment uses a seat pan for commercial aircraft as case study. Aspects that were addressed include the architecture, configuration and control of the system. The architecture and configuration addressed the sheet cutting, fixturing, reinforcing, heating, forming, quality assurance and transportation. The control, implemented using agents and based on the ADACOR holonic reference architecture, addresses the cell control requirements of the thermoforming process. An evaluation of the system’s reconfigurability and throughput is performed using KUKA Sim Pro. The evaluation of the system’s throughput is compared to the predicted throughput of the conventional technique for manufacturing thermoplastic fibre reinforced composite parts in a thermoforming process. The evaluation of the system’s performance show that the system designed in this thesis for the manufacture of a thermoplastic fibre-reinforced composite seat pan sports a significant advantage in terms of throughput rate, which demonstrates its technical feasibility. The evaluation of the system’s reconfigurability show that, through its ability to handle new hardware and product changes, it exhibits the reconfigurability characteristics of modularity, convertibility, integrability and scalability. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse vervaardigingsbedryf speel 'n sentrale rol in die groei van die plaaslike ekonomie. Moderne vervaardiging vereistes sluit in die vermoë om vinnig te reageer op die produk veranderlikheid, skommelinge in die produk aanvraag en nuwe proses tegnologieë. Die herkonfigureerbare vervaardiging paradigma is voorgestel om te voldoen aan die nuwe produksie vereistes. Ten einde die uitvoerbaarheid van die integrasie van outomatiese, herkonfigureerbare vervaardiging-tegnologieë in die produksieproses van veselversterkte saamgestelde onderdele te evalueer, is 'n stelsel, gebaseer op die termo-vormingsproses, wat sulke tegnologieë implementeer, ontwikkel. Die assessering gebruik 'n sitplek pan vir kommersiële vliegtuie as gevallestudie. Aspekte wat aangespreek is sluit in die argitektuur, konfigurasie en beheer van die vervaardigingstelsel. Die argitektuur en konfigurasie spreek aan die sny, setmate, versterking, verwarming, vorm, gehalteversekering en vervoer van n veselversterkte saamgestelde sitplek pan in 'n termo-vormingsproses. Die beheer, geïmplementeer deur die gebruik van agente en gebaseer op die ADACOR holoniese verwysing argitektuur, spreek die selbeheervereistes van die termo-vormingsproses aan. 'n Evaluering van die stelsel se herkonfigureerbaarheid en deurvoer word gedoen met die behulp van KUKA Sim Pro. Die evaluering van die stelsel se deurvoer word vergelyk met die deurvoer van die konvensionele vervaardigingsproses vir termoplastiese vessel-versterkte saamgestelde onderdele in 'n termo-vormingsproses. Die evaluering van die stelsel se prestasie toon dat die stelsel wat in hierdie tesis ontwerp is vir die vervaardiging van 'n termoplastiese vessel-versterkte saamgestelde sitplek pan, hou 'n beduidende voordeel, in terme van deurvloeikoers, in wat die stelsel se tegniese haalbaarheid toon. Die evaluering van die stelsel se herkonfigureerbaarheid wys dat, deur middel van sy vermoë om nuwe hardeware en produk veranderinge te hanteer, die stelsel herkonfigureerbare einskappe van modulariteit, inwisselbaarheid, integreerbaarheid en skaalbaarheid vertoon.

Nanocomposites are a new class of mineral-field plastics that contain relatively small amounts (&lt / 10%) of nanometer-sized clay particles. The particles, due to their extremely high aspect ratios (about 100-15000), and high surface area (in excess of 750-800 m2/g) promise to improve structural, mechanical, flame retardant, thermal and barrier properties without substantially increasing the density or reducing the light transmission properties of the base polymer. Production of thermoplastic based nanocomposites involves melt mixing the base polymer and layered silicate powders that have been modified with hydroxyl terminated quaternary ammonium salt. During mixing, polymer chains diffuse from the bulk polymer into the van der Waals galleries between the silicate layers. In this study, new nanocomposite materials were produced from the components of recycled thermoplastic as the matrix and montmorillonite as the filler by using a co-rotating twin screw extruder. During the study, recycled poly(ethylene terepthalate), R-PET, was mixed with organically modified quaternary alkylammonium montmorillonite in the contents of 1, 2, and 5 weight %. Three types of clays were evaluated during the studies. For comparison, 2 weight % clay containing samples were prepared with three different clay types, Cloisite 15A, 25A, 30B. The nanocomposites were prepared at three different screw speeds, 150, 350, 500 rpm, in order to observe the property changes with the screw speed. Mechanical tests, scanning electron microscopy and melt flow index measurements were used to characterize the nanocomposites. The clay type of 25A having long alkyl sidegroups gave the best results in general. Owing to its branched nature, in nanocomposites with 25A mixing characteristics were enhanced leading to better dispersion of clay platelets. This effect was observed in the SEM micrographs as higher degrees of clay exfoliation. Nearly all the mechanical properties were found to increase with the processing speed of 350 rpm. In the studies, it was seen that the highest processing speed of 500 rpm does not give the material performance enhancements due to higher shear intensity which causes defect points in the structure. Also the residence time is smaller at high screw speeds, thus there is not enough time for exfoliation. In general, the MFI values showed minimum, thus the viscosity showed a maximum at the intermediate speed of 350 rpm. At this processing speed, maximum exfoliation took place giving rise to maximum viscosity. Also, the clay type of 25A produced the lowest MFI value at this speed, indicating the highest degree of exfoliation, highest viscosity, and best mechanical properties.

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Thesis (M.S.)--Cleveland State University, 2007 / Abstract. Title from PDF t.p. (viewed on May 8, 2008). Includes bibliographical references (p. 81-84). Available online via the OhioLINK ETD Center. Also available in print.