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Bennett, James Cameron, and james bennett@student rmit edu au. "Mathematical Analysis of Film Blowing." RMIT University. Mathematical and Geospatial Sciences, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081128.115021.
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Film blowing is a highly complex industrial process used to manufacture thin plastic films for uses in a wide range of applications; for example, plastic bags. The mathematical modelling of this process involves the analysis of highly nonlinear differential equations describing the complex phenomena arising in the film blowing process, and requires a sophisticated mathematical approach. This dissertation applies an innovative combination of tools, namely analytic, numerical and heuristic mathematical techniques to the analysis of the film blowing process. The research undertaken examines, in particular, a two-point boundary value problem arising from the modelling of the radial profile of the polymer film. For even the simplest modelling of this process, namely the isothermal Newtonian model, the resulting differential equation is a highly nonlinear, second order one, with an extra degree of difficulty due to the presence of a small parameter multiplying the highest derivative. Thus, the problem falls into the category of a nonlinear singular perturbation problem. Analytic techniques are applied to the isothermal Newtonian blown film model to obtain a closed form explicit approximation to the film bubble radius. This is then used as a base approximation for an iterative numerical scheme to obtain an improved numerical solution of the problem. The process is extended to include temperature variations, varying viscosity (Power law model) and viscoelastic effects (Maxwell model). As before, closed form approximations are constructed for these models which are used to launch numerical schemes, whose solutions display good accuracy. The results compare well with results obtained by purely numerical solutions in the literature.
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Fang, Yunli. "Rheological effect in film blowing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0019/MQ48852.pdf.
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Tas, Paul Prudent. "Film blowing from polymer to product /." Online version, 1994. http://bibpurl.oclc.org/web/23861.
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Mayavaram, Ravisankar S. "Modeling and simulation of film blowing process." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2454.
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Film blowing process is a flexible mass production technology used for manufacturing
thin polymeric films. Its flexibility in using an existing die to produce films
of different width and thickness, just by controlling process conditions such as, extrudate
velocity, excess pressure, and line speed, makes it an attractive process with
less capital investment. Controlling the process conditions to obtain a stable bubble,
however, is not a trivial task. It is a costly trial and error procedure, which could
result is a large wastage of material and other resources. Hence, it is necessary to
develop methods to simulate the process and design it using numerical experiments.
This important need of the industry defines the objective of this work. In this dissertation,
a transient, axisymmetric, nonisothermal, viscoelastic model is developed
to simulate the process, and it is solved using finite element method. Material behavior
of polymer melt is described using a modified Phan-Thien-Tanner model in
the liquid??like region, and anisotropic Kelvin??Voight model in the solid zone, and
the transition is modeled using a simple mixture theory. Crystallization kinetics is
described using a modified Avrami model with factors to account for the influence
of temperature and strain. Results obtained are compared with available experimental
results and the model is used to explore stability issues and the role of different
parameters. Software developed using this model comes with a GUI based pre- and
post-processor, and it can be easily adapted to use other constitutive models.
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Muslet, Iyad A. "Computer simulation of the film blowing process incorporating crystallization and viscoelasticity." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85088.
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A comprehensive two-dimensional simulation of the film blowing process is developed based on a mathematical model that incorporates the Phan-Thien and Tanner (PTT) and the Neo-Hookean constitutive equations with crystallization effects. The PTT constitutive equation is employed in the liquid-like region, while the Neo-Hookean constitutive equation is employed in the solid-like region, to describe the rheological behavior of the film. The effects of the process variables and parameters on the stress balance and overall behavior of the film were evaluated. The orientation-induced crystallization is accounted for by incorporating the Nakamura non-isothermal equation along with the Ziabicki equation. The proposed model provides predictions of the bubble shape and dimensions, the position of the freeze-line, and the evolution of temperature, crystallinity, birefringence, stresses and deformation in the blown film. The predictions of the model show good agreement with experimental results reported by various workers.
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Niknezhad, Setareh. "Ultrasonically Assisted Single Screw Extrusion, Film Blowing and Film Casting of LLDPE/Clay and PA6/Clay Nanocomposites." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1363079642.
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Steffl, Thomas. "Rheological and film blowing properties of various low density polyethylenes and their blends." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972028625.
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Payne, Clare Elizabeth Ann. "Novel fabrication techniques for solid oxide fuel cells." Thesis, Brunel University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318427.
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Steffl, Thomas [Verfasser]. "Rheological and film blowing properties of various low density polyethylenes and their blends / Thomas Steffl." Aachen : Shaker, 2004. http://d-nb.info/1170529844/34.
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Guy, Ashley Ray. "Effect of Blowing Ratio on the Nusselt Number and Film Cooling Effectiveness Distributions of a Showerhead Film Cooled Blade in a Transonic Cascade." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/43764.
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This paper investigates the effect of blowing ratio on the film cooling performance of a showerhead film cooled first stage turbine blade. The blade was instrumented with double-sided thin film heat flux gages to experimentally characterize the Nusselt number and film cooling effectiveness distributions over the surface of the blade. The blade was arranged in a two-dimensional, linear cascade within a transonic, blowdown type wind tunnel. The wind tunnel freestream conditions were varied over two exit Mach numbers, Me=0.78 and Me=1.01, with an inlet freestream turbulence intensity of 12% , with an integral length scale normalized by blade chord of 0.26 generated by a passive, mesh turbulence grid. The coolant conditions were varied by changing the ratio of coolant to freestream mass flux, blowing ratio, over three values, BR=0.60, 1.0, and 1.5 while keeping a density ratio of 1.7.
Experimental results show that ingestion of freestream flow into the showerhead cooling plenum can occur below a blowing ratio of 0.6. Film cooling increases Nusselt number over the uncooled case and increasing the blowing ratio also increases Nusselt number. At a blowing ratio of 1.5 and Me=1.01 a large drop in effectiveness just downstream of injection on both the pressure and suction surfaces is evidence of jet liftoff. The blowing ratio of 1.0 was found to have superior heat load reduction over the blade surface at both freestream conditions tested. The blowing ratio of 1.0 reduced the heat load by as much as 39% and 32% at Me=0.78 and 1.01, respectively.Master of Science
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MISHRA, SUMAN. "Single-Hole Film Cooling on a Turbine-Blade Leading-Edge Model." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1205156648.
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Blot, Dorian Matthew. "Aerodynamics of Endwall Contouring with Discrete Holes and an Upstream Purge Slot Under Transonic Conditions with and without Blowing." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/19257.
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Endwall contouring has been widely studied as an effective measure to improve aerodynamic performance by reducing secondary flow strength. The effects of endwall contouring with discrete holes and an upstream purge slot for a high turning (127") airfoil passage under transonic conditions are investigated. The total pressure loss and secondary flow field were measured for two endwall geometries. The non-axisymmetric endwall was developed through an optimization study [1] to minimize secondary losses and is compared to a baseline planar endwall. The blade inlet span increased by 13 degrees with respect to the inlet in order to match engine representative inlet/exit Mach number loading in a HP turbine. The experiments were performed in a quasi-2D linear cascade with measurements at design exit Mach number 0.88 and incidence angle. Four cases were analyzed for each endwall -- the effect of slot presence (with/without coolant) and the effect of discrete holes (with/without coolant) without slot injection. The coolant to mainstream mass flow ratio was set at 1.0% and 0.25% for upstream purge slot and discrete holes, respectively. Aerodynamic loss coefficient is calculated with the measured exit total pressure at 0.1 Cax downstream of the blade trailing edge. CFD studies were conducted in compliment. The aero-optimized endwall yielded lower losses than baseline without the presence of the slot. However, in presence of the slot, losses increased due to formation of additional vortices. For both endwall geometries, results reveal that the slot has increased losses, while the addition of coolant further influences secondary flow development.Master of Science
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Rozati, Ali. "Large Eddy Simulation of Leading Edge Film Cooling: Flow Physics, Heat Transfer, and Syngas Ash Deposition." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/30127.
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The work presented in this dissertation is the first numerical investigation conducted to study leading edge film cooling with Large Eddy Simulation (LES). A cylindrical leading edge with a flat after-body represents the leading edge, where coolant is injected with a 30Ë compound angle. Three blowing ratios of 0.4, 0.8, and 1.2 are studied. Free-stream Reynolds number is 100,000 and coolant-to-mainstream density ratio is unity. At blowing ratio of 0.4, the effect of coolant inlet condition is investigated. Results show that the fully-turbulent coolant jet increases mixing with the mainstream in the outer shear layer but does not influence the flow dynamics in the turbulent boundary layer at the surface. As a result, the turbulent jet decreases adiabatic effectiveness but does not have a substantial effect on the heat transfer coefficient. At B.R.=0.4, three types of coherent structures are identified which consist of a primary entrainment vortex at the leeward aft-side of the coolant hole, vortex tubes at the windward side of the coolant hole, and hairpin vortices typical of turbulent boundary layers produced by the turbulent interaction of the coolant and mainstream downstream of injection. At B.R. = 0.8 and 1.2, coherent vortex tubes are no longer discernable, whereas the primary vortex structure gains in strength. In all cases, the bulk of the mixing occurs by entrainment which takes place at the leeward aft-side of the coolant jet. This region is characterized by a low pressure core and the primary entrainment vortex. Turbulent shear interaction between coolant jet and mainstream increases substantially with blowing ratio and contributes to the dilution of the coolant jet. As a result of the increased mixing in the shear layer and primary structure, adiabatic effectiveness decreases and heat transfer coefficient increases with increase in blowing ratio.
The dissertation also investigates the deposition and erosion of Syngas ash particles in the film cooled leading edge region. Three ash particle sizes of 1, 5, and 10 microns are investigated at all blowing ratios using Lagrangian dynamics. The 1 micron particles with momentum Stokes number St = 0.03 (based on approach velocity and cylinder diameter), show negligible deposition/erosion. The 10 micron particles, on the other hand with a high momentum Stokes number, St = 3, directly impinge and deposit on the surface, with blowing ratio having a minimal effect. The 5 micron particles with St=0.8, show the largest receptivity to coolant flow and blowing ratio. On a mass basis, 90% of deposited mass is from 10 micron particles, with 5 micron particles contributing the other 10%. Overall there is a slight decrease in deposited mass with increase in blowing ratio. About 0.03% of the total incoming particle energy can potentially be transferred as erosive energy to the surface and coolant hole, with contribution coming from only 5 micron particles at B.R.=0.4 and 0.8, and both 5 and 10 micron particles at B.R.=1.2.Ph. D.
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Sibold, Ridge Alexander. "The Effect of Density Ratio on Steep Injection Angle Purge Jet Cooling for a Converging Nozzle Guide Vane Endwall at Transonic Conditions." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/102650.
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The study presented herein describes and analyzes a detailed experimental investigation of the effects of density ratio on endwall thermal performance at varying blowing rates for a typical nozzle guide vane platform purge jet cooling scheme. An axisymmetric converging endwall with an upstream doublet staggered cylindrical hole purge jet cooling scheme was employed. Nominal exit flow conditions were engine representative and as follows: {rm Ma}_{Exit} = 0.85,
{rm Re}_{Exit,C_{ax}} = 1.5 times {10}^6, and large-scale freestream Tu = 16%. Two blowing ratios were investigated corresponding to the upper and lower engine extrema. Each blowing ratio was investigated amid two density ratios; one representing typical experimental neglect of density ratio, at DR = 1.2, and another engine representative density ratio achieved by mixing foreign gases,
DR = 1.95. All tests were conducted on a linear cascade in the Virginia Tech Transonic Blowdown Wind Tunnel using IR thermography and transient data reduction techniques. Oil paint flow visualization techniques were used to gather quantitative information regarding the alteration of endwall flow physics due two different blowing rates of high-density coolant. High resolution endwall adiabatic film cooling effectiveness, Nusselt number, and Net Heat Flux Reduction contour plots were used to analyze the thermal effects.
The effect of density is dependent on the coolant blowing rate and varies greatly from the high to low blowing condition. At the low blowing condition better near-hole film cooling performance and heat transfer reduction is facilitated with increasing density. However, high density coolant at low blowing rates isn't adequately equipped to penetrate and suppress secondary flows, leaving the SS and PS largely exposed to high velocity and temperature mainstream gases. Conversely, it is observed that density ratio only marginally affects the high blowing condition, as the momentum effects become increasingly dominant. Overall it is concluded density ratio has a first order impact on the secondary flow alterations and subsequent heat transfer distributions that occur as a result of coolant injection and should be accounted for in purge jet cooling scheme design and analysis.
Additionally, the effect of increasing high density coolant blowing rate was analyzed. Oil paint flow visualization indicated that significant secondary flow suppression occurs as a result of increasing the blowing rate of high-density coolant. Endwall adiabatic film cooling effectiveness, Nusselt number, and NHFR comparisons confirm this. Low blowing rate coolant has a more favorable thermal impact in the upstream region of the passage, especially near injection. The low momentum of the coolant is eventually dominated and entrained by secondary flows, providing less effectiveness near PS, near SS, and into the throat of the passage. The high momentum present for the high blowing rate, high-density coolant suppresses these secondary flows and provides enhanced cooling in the throat and in high secondary flow regions. However, the increased turbulence impartation due to lift off has an adverse effect on the heat load in the upstream region of the passage. It is concluded that only marginal gains near the throat of the passage are observed with an increase in high density coolant blowing rate, but severe thermal penalty is observed near the passage onset.Master of Science
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Nickol, Jeremy B. "Airfoil, Platform, and Cooling Passage Measurements on a Rotating Transonic High-Pressure Turbine." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1459857581.
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Strater, Kurt F. "Countercurrent cooling of blown film." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66003.
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Majumder, Khokan Kanti, and khokankanti@yahoo com. "Blown Film Extrusion: Experimental, Modelling and Numerical Study." RMIT University. Civil, Environmental and Chemical Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080509.161859.
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Abstract This thesis correlates rheological data into a non-linear blown film model that describes the stress and cooling-induced morphological transformations in the axial and flow profiles of the blown films. This will help to improve the physical and mechanical properties of the films in a cost effective way, which will in turn be of great benefit to the food and packaging industries. In this research, experimental and numerical studies of a blown film extrusion were carried out using two different low-density polyethylenes (LDPEs). In the experiment, the key parameters measured and analysed were molecular, rheological and crystalline properties of the LDPEs. In the numerical study, blown film simulation was carried out to determine the bubble characteristics and freeze line height (FLH). A new rheological constitutive equation was developed by combining the Hookean model with the well known Phan-Thien and Tanner (PTT) model to permit a more accurate viscoelastic behaviour of the material. For experimental verification of the simulation results, resins were processed in a blown film extrusion pilot plant using identical die temperatures and cooling rates as used in the simulation study. Molecular characteristics of both LDPEs were compared in terms of their processing benefit in the film blowing process. Based on the experimental investigation, it was found that molecular weight and its distribution, degree of long chain branching and cooling rate play an important role on melt rheology, molecular orientation, blown film processability, film crystallinity and film properties. Effect of short chain branching was found insignificant for both LDPEs. Statistical analysis was carried out using MINITAB-14 software with a confidence level of 95% to determine the effect of process variables (such as die temperature and cooling rate) on the film properties. Film properties of the LDPEs were found to vary with their molecular properties and the process variables used. Blown film model performance based on the newly established PTT-Hookean model was compared with that based on the Kelvin model. Justification of the use of PTT-Hookean model is also reported here using two different material properties. From the simulation study, it has been found that predictions of the blown film characteristics conformed very well to the experimental data of this research and previous studies using different materials and different die geometries. Long chain branching has been found as the most prominent molecular parameter for both LDPEs affecting melt rheology and hence the processability. Die temperature and cooling rate have been observed to provide similar effect on the tear strength and shrinkage properties of blown film for both LDPEs. In comparison to the Kelvin model, the PTT-Hookean model is better suited for the modelling of the film blowing process. It has also been demonstrated in this study that the PTT-Hookean model conformed well to the experimental data near the freeze line height and is suitable for materials of lower melt elasticity and relaxation time.
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Tang, Zuojian 1967. "Surface morphology of polyethylene blown films." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31072.
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The properties of blown polyethylene (PE) films depend on various factors, including crystallinity, morphology, and orientation, in addition to chemical composition. It has been shown that the optical properties are strongly influenced by surface morphology. In this project, we use non-contact atomic force microscopy (AFM) and polarized light microscopy (PLM) to visualize surface and bulk morphology. Various techniques, such as surface and line roughness, surface and line fractal dimension, pair-correlation function and nearest neighbor distance distribution function, are employed to quantify the description of morphology and to compare the morphological characteristics of a number of polyolefin films of commercial interest. A comprehensive quantitative analysis of surface topography has been performed. The co-monomer of the PE resins was found to play a significant role in the formation and the orientation of spherulite-like domains. The film cross-section microstructure has been evaluated qualitatively by using both AFM and PLM. However, quantitative analysis of bulk morphology cannot be obtained due to knife effects.
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Godshall, David Leonard. "Investigations of Structure–Property Relationships in Semicrystalline Thermoplastic Polymers: Blown Polyethylene Films and Polyacrylonitrile Copolymers." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/25971.
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Blown films of high molecular weight high density polyethylene (HMW-HDPE) were produced from two resins of differing molecular weight (MW) and molecular weight distribution (MWD) using a high stalk bubble configuration. The processing conditions were varied such that three film gauges, each fabricated at three frost line heights (FLH), were produced. Crystalline orientation and tear resistance properties of the films were measured. Under appropriate conditions, the formation of two populations of lamellar stacks with their surface normals orthogonal to one another were observed. Increasing the FLH increased the amount of transverse direction (TD) stacked lamellae. This finding was related to bubble shape and relaxation behavior. Balanced in plane crystalline orientation was noted to give the best dart impact performance. Interestingly, for the lower Mw resin in the study, this could be achieved by down gauging.
In a second project, structure-property-processing relationships were investigated in a series of high density polyethylene (HDPE) blown films. The use of metallocene and chromium oxide based resins allowed the effects of MW and MWD on orientation behavior to be studied. All films possessed Keller-Machin low stress morphologies oriented along the film MD. Under identical processing conditions, the narrower MWD resins produced films with greater orientation than the broader MWD resins of equivalent weight average MW. Greater processing stresses and shorter quench times were noted to produce higher levels of orientation. Moisture vapor transmission rate (MVTR) performance of these films was also measured. Orientation effects were seen to influence MVTR as permeation behavior did not scale directly with the crystalline content in the films.
Additional studies investigated the relationship between comonomer content and the thermal and structural properties of novel poly(acrylonitrile-co-methyl acrylate) materials. Five polymers were studied with methyl acrylate (MA) content varying between 0 and 15 mol%. The MA decreased both the glass transition and melting temperatures. Melting point depression was sufficient in the two highest MA content copolymers to allow for complete melting prior to the onset of thermal degradation using modest heating rates (20 ºC/min). Insight into the heterogeneous structure of poly(acrylonitrile) homopolymer was gained through both conventional and modulated differential scanning calorimetry.Ph. D.
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Wang, Lei 1972. "Morphology and optical properties of polyolefin blown films." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36728.
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Optical properties of polyethylene blown films are of great commercial and scientific interest. An understanding of the relationship between morphology and optical properties will have a significant impact on product and process optimization.In this work, a number of linear low density polyethylene (LLDPE) resins of different molecular and structural characteristics were studied. Intrinsic properties such as refractive index and absorption coefficient were estimated from resin compositions using group contribution models. The refractive indices of sample films were also measured using the method of Transmission Spectrum.
The morphology of polyethylene films was investigated using Atomic Force Microscopy (AFM) and Near-field Scanning Optical Microscopy (NSOM). Both the surface and bulk morphologies were evaluated. The observation shows the dominant spherulitic structure on the surface as well as in the bulk, as the result of nucleation and crystallization during the film blowing process. In addition to qualitative observations and comparisons; quantitative characterization methods were employed to describe the features of the morphology.
Based on the morphology characterization, the surface reflection was described by the Beckmann-Davies theory of reflection of electro-magnetic waves by rough surface. The directional distribution of reflected intensity was computed according to the surface roughness information. The gloss values of sample films were computed accordingly and compared with experimental measurements. Furthermore, the problem of light transmission and scattering was investigated. A scattering geometry was proposed from the observations of the morphology of sample films. The light scattering by the surface of polymer films was analyzed using a model that is based on the Mie theory of scattering. The haze values of sample films were computed and compared with experimental measurements.
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Wang, Lei. "Morphology and optical properties of polyolefin blown films." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0029/NQ64689.pdf.
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BAFNA, AYUSH ASHOK. "OPTICAL PROPERTIES AND ORIENTATION IN POLYETHYLENE BLOWN FILMS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1005857011.
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Dočkalová, Dagmar. "Podnikatelská etika v bankovnictví." Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2008. http://www.nusl.cz/ntk/nusl-221992.
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The diploma work addresses the application of ethical code into banking. It deals with business ethic and ethical code of Československá obchodní banka, Inc. The thesis analyses the original ethical code of the bank and engages in the implementation of the new ethical code which includes, among others, “The Whistle Blowing Policy”. The diploma work brings a cross-sectional survey of the employees of Československá obchodní banka, Inc. about their awareness and ability to fulfil the principles of the ethical code. The bank was recommended possible solutions based on the results of the survey.
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Ivings, Krisandra. "Country Culture and Crossover: Narrative Representations of Gender and Genre Through Lyric, Music, Image, and Staging in Carrie Underwood's Blown Away Tour." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35252.
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This thesis examines the complex and multi-dimensional narratives presented in the work of mainstream female country artist Carrie Underwood, and how her blending of musical genres (pop, rock, and country) affects the narratives pertaining to gender and sexuality that are told through her musical texts. I interrogate the relationships between and among the domains of music, lyrics, images, and staging in Underwood’s live performances (Blown Away Tour: Live DVD) and related music videos in order to identify how these gendered narratives relate to genre, and more specifically,
where these performances and videos adhere to, expand on, or break from country music tropes and traditions. Adopting an interlocking theoretical approach grounded in genre theory, gender theory, narrative theory in the context of popular music, and happiness theory, I examine how, as a female artist in the country music industry, Underwood uses genre-blending to construct complex gendered narratives in her musical texts. Ultimately, I find that in her Blown Away Tour: Live DVD, Underwood uses diverse narrative strategies, sometimes drawing on country tropes, to engage
techniques and stylistic influences of several pop and rock styles, and in doing so explores the gender norms of those genres.
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Gururajan, Giriprasath. "Real-time Raman spectroscopy and wide-angle x-ray diffraction during single-layer and multi-layer blown film extrusion." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1211388756/.
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Arruda, Liliane Cardoso. "Efeitos do extensor de cadeia na morfologia, propriedades reológicas e mecânicas de filme tubular de blendas de poli(ácido) láctico) PLA com poli(butileno-adipato-co-tereftlalato) PBAT." Universidade Federal de Sergipe, 2015. https://ri.ufs.br/handle/riufs/3478.
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This study investigated the effect of chain extender epoxy based additive, Joncryl ADR 4368, on the rheological, thermal and mechanical properties of poly(lactic acid) with poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends in the blown films form. Compositions with 40% and 60% by weight PLA were selected for production of such blown films. These dispersed phase content was chosen because the literature does not present mechanical behavior studies of tubular film blends with high concentration of the dispersed phase. Rheological analysis in dynamic oscillatory regime showed the reaction of epoxy group with end chain in both polymers, and a higher reactivity of the chain extender with PLA. The films produced exhibited different morphologies according to the blend composition and chain extender content. Films containing 40% PLA presented the dispersed phase morphology in a fibrillar form; however in the presence of chain extender, the dispersed phase is presented as ellipsoids. This change in morphology resulted in a reduction in the mechanical properties of these films in tensile tests. Films containing 60% PLA had a coarse morphology with dispersed phase in the ribbons-like form. The addition of extender yielded a refinement of the dispersed phase morphology from ribbon to elongated fibril form, which is responsible for the mechanical properties improvement of these films. Despite the low adhesion between matrix and dispersed phase, the proper setting of the morphology of the blends as a function of additive content, allowed to produce films with mechanical properties quite different from each other.Neste trabalho foi estudado o efeito do aditivo extensor de cadeia à base de epóxi, Joncryl ADR 4368, nas propriedades reológicas, térmicas e mecânicas de filmes tubulares de blendas de poli(ácido láctico) com poli(butileno adipato-co-tereftalato) (PLA/PBAT). Composições com 40% e 60% em peso de PLA foram selecionadas para produção destes filmes tubulares. Estes teores de fase dispersa foram escolhidos pelo fato da literatura não apresentar estudos de comportamento mecânico de filmes tubulares de blendas com alta concentração da fase dispersa. Análises reológicas em regime dinâmico oscilatório evidenciaram a reação do grupo epóxi com finais de cadeia de ambos os polímeros, e evidenciaram uma maior reatividade do extensor com o PLA. Os filmes produzidos apresentaram diferentes morfologias de acordo com a composição da blenda e o teor de extensor de cadeia adicionado. Filmes contendo 40% de PLA apresentaram uma morfologia da fase dispersa na forma fibrilar; já na presença do extensor, a fase dispersa se apresentou na forma de elipsóides. Esta mudança na morfologia acarretou em uma redução nas propriedades mecânicas destes filmes em ensaios de tração. Filmes contendo 60% de PLA apresentaram uma morfologia grosseira com a fase dispersa na forma de fitas. A adição do extensor proporcionou um refinamento na morfologia da fase dispersa com formação de fibrilas alongadas, responsável pelo ganho nas propriedades mecânicas destes filmes. Apesar da baixa adesão entre matriz e fase dispersa, o ajuste apropriado da morfologia das blendas, em função do teor de aditivo, possibilitou produzir filmes com propriedades mecânicas bastante diferenciadas entre si.
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Breese, David R. "Modeling the effects of solid state orientation on blown high molecular weight high density polyethylene films a composite theory approach /." Cincinnati, Ohio : University of Cincinnati, 2004. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1107958634.
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BREESE, DAVID RYAN. "MODELING THE EFFECTS OF SOLID STATE ORIENTATION ON BLOWN HIGH MOLECULAR WEIGHT HIGH DENSITY POLYETHYLENE FILMS: A COMPOSITE THEORY APPROACH." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1107958634.
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Butterfield, Craig. "A novel laboratory dispersive and distributive minimixer and applications : development of a new minimixer that can duplicate mixing which occurs in a large twin screw extruder." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4930.
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The mixing of additives into a plastic is an extremely important step in the plastics industry, necessary for the manufacture of almost every conceivable product. Therefore the costs in developing new products can prove very expensive as the testing is usually carried out using full scale machines, usually using twin screw extruders because they are able to provide good dispersive and distributive mixing. This is particularly important when compounding difficult to disperse additives and nano-additives. What is required is a machine that can replicate the mixing abilities of a twin-screw extruder but on a laboratory scale. There have been attempts by industry to develop smaller machines, such as the Thermo Scientific HAAKE Minilab II Micro Compounder which processes on the scale of 7 cm3 of material volume. This can be too small for some needs and therefore a machine is required to produce material on the 10g to 100g scale. To this end a laboratory mixer of novel design was devised and its mixing performance was assessed using conductive carbon black and compared against the Thermo Scientific HAAKE Minilab II Micro Compounder, a 19 mm co-rotating twin-screw extruder and a 40 mm co-rotating twin-screw extruder. Carbon black was used because mixing performance can be assessed by measuring the minimum carbon loading necessary to induce electrical conductivity. It was found that the minimixer was able to induce electrical conductivity at loading of 5.75% but the comparison with the other machines proved difficult as the achievement of the threshold at which semi-conductivity occurred appeared independent of shear rate and mixing duration.
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Bermingham, Siobhan Clara. "The effect of processing parameters on the properties of blown films produced from blends of a low density and a butene based linear low density polyethylene." Thesis, Queen's University Belfast, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282120.
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Kubíček, Václav. "Charakterizace vyfukovaných fólií z měkčeného polylaktidu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-414128.
Full textAbstract:
The master's thesis focuses on preparation of blown films from polylactid acid (PLA) which was blended with selected polyesteres – poly(butylene adipate-co-terephtalate) (PBAT), polycaprolactone (PCL) and polybutylene succinate (PBS) – and thermoplastic starch (TPS) in amount of 30% in order to soften PLA films. The influence of the aditives on static and mechanical tensile properties, on structure, morphology and thermal properties of the films was determined and the obtained parameters were compared to properties of films prepared from neat PLA and high density polyethylene (HDPE). The results showed that the additives increased crystalinity of PLA and thus significantly influenced the properties of the films. In contrast to the film from neat PLA, softening in terms of lowering glass transition temperature occured only by adding PBS and TPS, in terms of increasing ductility only by adding PBAT. All PLA films showed nearly constant elastic modulus up to the beginning of glass transition enabling their potential application till 50 °C. Preparation of the film with TPS was problematic and the film showed the worst mechanical properties. Preparation of other films was without any problems. The most promising additive from the tested ones was PBAT which showed comparable mechanical properties as the film from HDPE.
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Walha, Fatma. "Elaboration de mélanges à base de Bio-polymères : Etude des corrélations entre structure, propriétés et transformation." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI075.
Full textAbstract:
Cette étude est une contribution à la mise au point d’un nouveau matériau filmogène multiphasique, originaire de ressources naturelles et destiné à l’emballage alimentaire. La voie proposée consiste à élaborer un mélange poly (acide lactique) [PLA]/ polyamide 11 [PA11] à différentes compositions; le principal avantage étant d’offrir un éventail de propriétés difficile à réunir sur un même polymère. Les différentes formulations, PLA/PA11, élaborées à l’état fondu dans une extrudeuse bivis ont été étudiés du point de vue des propriétés rhéologiques, thermique, mécanique et de la morphologie. Différents tiers-corps copolymères de structures diverses ont été utilisés, à différents taux, dans le but de promouvoir l’adhésion à l’interface des composants et améliorer les performances des mélanges ainsi conçus. La finalité est d’appréhender une formulation qui soit filmogène, tout en ayant un comportement en élongation, à l’état fondu, parfaitement compatible avec les conditions de transformation par extrusion gonflage de gaineThis study is a contribution to the development of a new biomaterial with suitable melt strength, stiffness-to-toughness balance, and the required thermal performance for food packaging applications. The proposed approach consists in preparing a mixture of poly (lactic acid) [PLA] / polyamide 11 [PA11] with different compositions; the main advantage being to offer a range of properties that are difficult to combine on the same polymer. The different formulations, PLA/PA11, processed in the molten state in a twin-screw extruder were studied from the side of rheological, thermal, mechanical and morphology. Different copolymers of various structures were used, at different rates, in order to promote the adhesion in the interface of the components and to improve the blend systems performances. The aim is to obtain a formulation that having an elongation behavior, in the molten state, perfectly compatible with the blowing process
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Belyamani, Imane. "Développement d'un matériau thermoplastique biodégradable et hydrosoluble à base d'une protéine du lait." Phd thesis, Université Jean Monnet - Saint-Etienne, 2011. http://tel.archives-ouvertes.fr/tel-00702749.
Full textAbstract:
La biomasse représente l'une des principales alternatives à l'utilisation du pétrole dans la plasturgie. Grâce à leurs propriétés fonctionnelles, les caséinates sont une matière première prometteuse pour la fabrication de films plastiques pour des applications dans l'emballage biodégradable et hydrosoluble. La transformation du caséinate de sodium par les techniques habituellement utilisées dans la plasturgie a été démontrée. Des extrudats de caséinate plastifié au glycérol ont été obtenus au moyen d'une extrudeuse bi-vis corotative. La caractérisation physico-chimique du matériau obtenu a confirmé la thermostabilité de cette protéine et a montré la dépendance du comportement du matériau vis-à-vis de l'humidité ambiante. Pour une variation du taux d'Humidité Relative, de 40 à 90% et une augmentation de la concentration du glycérol, plastifiant hygroscopique, le matériau passe d'un état vitreux (rigide) à un état caoutchouteux (mou). Des films fins ont été ensuite réalisés, à partir des extrudats thermoplastiques, par extrusion gonflage. La perméabilité à la vapeur d'eau des films de caséinate de sodium a été étudiée et a montré que ces matériaux sont de mauvaises barrières à l'humidité. La deuxième partie a été consacré à l'étude de mélanges caséinate de sodium/caséinate de calcium d'un côté et caséinate de sodium/PBAT de l'autre. Le mélange des deux caséinates a permis d'augmenter la tenue mécanique du mélange, à partir de 50% de caséinate de calcium, et de retarder le transfert hydrique à travers le film. Dans le même sens, l'ajout du PBAT, a augmenté jusqu'à deux fois plus, le module d'Young des mélanges mais a baissé la résistance au transfert d'humidité du film à cause de l'incompatibilité des deux polymères.
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Liu, Kuo-Chun. "Blowing Ratio Effects on Film Cooling Effectiveness." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-08-2927.
Full textAbstract:
The research focuses on testing the film cooling effectiveness on a gas turbine
blade suction side surface. The test is performed on a five bladed cascade with a
blow down facility. Four different blowing ratios are used in this study, which are
0.5, 1.0, 1.6, and 2.0; mainstream flow conditions are maintained at exit Mach
number of 0.7, 1.1 and 1.3. Nitrogen is injected as the coolant so that the oxygen
concentration levels can be obtained for the test surface. Based on mass transfer
analogy, film cooling effectiveness can be computed with pressure sensitive paint
(PSP) technique. The effect of blowing ratio on film cooling effectiveness is
presented for each testing condition. The spanwise averaged effectiveness for
each case is also presented to compare the blowing ratio and mainstream effect on
film cooling effectiveness. Results show that due to effects of shock, the optimum
blowing ratio is 1.6 for exit Mach number of 1.1 and 1.3; however; without the
effects of shock, the optimum blowing ratio is 1.0 for exit Mach number of 0.7.
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Henrichsen, Lars Krister. "Steady state modeling and dynamic analysis of film blowing /." 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3223615.
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Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006.Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3951. Adviser: Anthony J. McHugh. Includes bibliographical references (leaves 127-130) Available on microfilm from Pro Quest Information and Learning.
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Benkreira, Hadj. "Radiant heating of plastics: Application to film blowing processes." 2003. http://hdl.handle.net/10454/2227.
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YU, CHIH-CHUN, and 游智鈞. "Preparation of Liquid Crystalline Polymer Films by Coextrusion Film Blowing and Discussion on the Effect of Orientation on Properties of Films." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/81718620375053329892.
Full textAbstract:
碩士國立高雄應用科技大學
模具工程系
105
In recent years, portable mobile is popular, including smart phones, tablet PCs, it’s a big market value in world. With the development of high-tech electronic products, the quality of parts in mobile is more and more important ,the main film material of flexible printed board in mobile is PI(Polyimide) until now, but the Water absorption and Dielectric properties of PI is poor in high frequency. the other material”Liquid Crystal Polymer” ,it’s Water absorption and Dielectric properties is better than PI,but it’s price is also higher than PI. Cause the molecular structure of LCP is ramdomly and have rigid rod molecular, make LCP have extremely low melt viscosity,this characteristic make LCP difficult to process in film laminating and blowning. Since the molecule of LCP is rigid, the rigid-rod molecules are easily aligned in the same direction of the shear stress, and be strongly oriented in one direction(Anisotropic), Anisotropic make LCP flim strength have a big difference between transverse(TD) and machine direction(MD),therefore, making biaxially-oriented LCP film and stably has became trend. This study use Extrusion to make LCP film, because the Anisotropic, this study use film blowing which processing have transverse direction extension, LCP have extremely low melt viscosity, it’s hard to blowing nd become film, therefore, this study use Three-layer co-extrusion blown film machine, use A/B/A method, let HDPE be inside and outside layer、LCP be middle layer, HDPE has high melt viscosity can carry LCP and support LCP become film, he HDPE layer can reduce the cooling speed of LCP layer, make the processing easy, by the way, LCP and HDPE is incompatible, so the 3 layer film can separate easily, than get the LCP film. This study use Inflate(blowing)、Thermoforming, make the LCP film Biaxially, the result shows Inflate is not very effective,； Thermoforming transform the orient angle,the bigger of the angle,the MD tensile strength smaller, the TD tensile strength bigger,if the orient angle become 90∘,MD and TD tensile strength close to the same。
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Liu, Cheng-Chien. "Studies of Mathematical Modelling and Experimental On-line Measurement for the Tubular Film Blowing Process." 1991. http://trace.tennessee.edu/utk_gradthes/764.
Full textAbstract:
An experimental and analytical study of the process of blown film extrusion was carried out. On-line measuring techniques were used to follow the dynamics and temperature profiles occurring in the process. The applicability of a mathematical model which includes a non-isothermal crystallization rate equation was tested. Subsequently, a new simplified model derived from a modified force balance was proposed and examined.
Linear low density polyethylene, LLDPE, (melt flow index 1.0) provided by Dow Chemical Company was used in the experimental part of the study. On-line measurements for radius, thickness, velocity and temperature as a function of distance from the extrusion die were carried out, and their reliability was examined. The results indicated that these measuring techniques were sufficiently accurate to make the collection of on-line data a useful analytical tool. The measured profiles of radius, thickness, velocity and temperature were used to test the theoretical model for the tubular film blowing process.
The apparent elongational viscosity, a key parameter for the theoretical simulation, was estimated and calculated from experimental data taken on a melt spinline and an inversion procedure developed for obtaining apparent elongational viscosities for melt spinning. This gave a Newtonian, temperature-dependent apparent viscosity equation. The heat transfer coefficient was estimated from measured temperature profiles on the blown film process.
A computer simulation for semi-crystalline materials was carried out using the mathematical analysis for film blowing which appears in the literature plus a non-isothermal crystallization rate equation. The analysis was carried out by using the fourth-order Runge-Kutta method to solve the resulting differential equations. The predicted results were in qualitative agreement only with the experimental data. At the same time, several unexpected phenomena appeared in the simulation. Some of them have also been reported in the previous literature, but still no satisfactory interpretation is available.
A modified physical approach based on a force balance led to the derivation and proposal of a new simplified model. From this modified analysis, an important and useful relationship between the external forces (i.e., the net takeup force and the inflation pressure) and the variation of radius and thickness of the bubble were determined. Based on the same initiaI conditions as that of the original model, the new model gave predictions which were in fair quantitative agreement with the on-line measurements.
Finally, it was also found that the development of crystallinity strongly influences the final values of radius and thickness of the tubular film, two of the important specifications in industrial film processing. In other words, the effect of crystallization is so significant that it should not be neglected in modelling the tubular film blowing process.
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Steffl, Thomas [Verfasser]. "Rheological and film blowing properties of various low density polyethylenes and their blends / vorgelegt von Thomas Steffl." 2004. http://nbn-resolving.de/urn:nbn:de:bvb:29-opus-732.
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Modhien, Naeemah. "The effect of suction and blowing on the spreading of a thin fluid film: a lie point symmetry analysis." Thesis, 2017. http://hdl.handle.net/10539/23512.
Full textAbstract:
A thesis submitted to the Faculty of Science, University of the Witwatersrand in
fulfillment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 3 April 2017.The effect of suction and blowing at the base on the horizontal spreading under gravity of a two-dimensional thin fluid film and an axisymmetric liquid drop is in- vestigated. The velocity vn which describes the suction/injection of fluid at the base is not specified initially. The height of the thin film satisfies a nonlinear diffusion equation with vn as a source term. The Lie group method for the solution of partial differential equations is used to reduce the partial differential equations to ordinary differential equations and to construct group invariant solutions. For a group invari- ant solution to exist, vn must satisfy a first order linear partial differential equation. The two-dimensional spreading of a thin fluid film is first investigated. Two models for vn which give analytical solutions are analysed. In the first model vn is propor- tional to the height of the thin film at that point. The constant of proportionality is β (−∞ < β < ∞). The half-width always increases to infinity as time increases even for suction at the base. The range of β for the thin fluid film approximation to be valid is determined. For all values of suction and a small range of blowing the maximum height of the film tends to zero as time t → ∞. There is a value of β corresponding to blowing for which the maximum height remains constant with the blowing balancing the effect of gravity. For stronger blowing the maximum height tends to infinity algebraically, there is a value of β for which the maximum height tends to infinity exponentially and for stronger blowing, still in the range for which the thin film approximation is valid, the maximum height tends to infinity in a finite time. For blowing the location of a stagnation point on the centre line is determined by solving a cubic equation approximately by a singular perturbation method and then exactly using a trigonometric solution. A dividing streamline passes through the stagnation point which separates the flow into two regions, an upper region consisting of fluid descending due to gravity and a lower region consisting of fluid rising due to blowing. For sufficiently strong blowing the lower region fills the whole of the film. In the second model vn is proportional to the spatial gradient of the height with constant of proportionality β∗ (−∞ < β∗ < ∞). The maximum height always decreases to zero as time increases even for blowing. The range of β∗ for the thin fluid film approximation to be valid is determined. The half-width tends to infinity algebraically for all blowing and a small range of weak suction. There is a value of β∗ corresponding to suction for which the half-width remains constant with the suction balancing the spreading due to gravity. For stronger suction the half-width tends to zero as t → ∞. For even stronger suction there is a value of β∗ for which the half-width tends to zero exponentially and a range of β∗ for which it tends to zero in a finite time but these values lie outside the range for which the thin fluid film approximation is valid. For blowing there is a stagnation point on the centre line at the base. Two dividing streamlines passes through the stagnation point which separate fluid descending due to gravity from fluid rising due to blowing. An approximate analytical solution is derived for the two dividing streamlines. A similar analysis is performed for the axisymmetric spreading of a liquid drop and the results are compared with the two-dimensional spreading of a thin fluid film. Since the two models for vn are still quite general it can be expected that general results found will apply to other models. These include the existence of a divid- ing streamline separating descending and rising fluid for blowing, the existence of a strength of blowing which balances the effect of gravity so the maximum height remains constant and the existence of a strength of suction which balances spreading due to gravity so that the half-width/radius remains constant.
MT 2017
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Peng, Ya-Chen, and 彭雅珍. "The Applications of the FMEA and FTA in PE Plastic Film Blowing Loss-an Example of Z Company in Taiwan." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/54767513213222909179.
Full textAbstract:
碩士國立雲林科技大學
工業工程與管理研究所碩士班
101
Because of global economic turbulence, enterprises face an intensely competitive environment. Quality assurance and rapid delivery have become inadequate in satisfying customer needs. Customers currently require low-costing products in addition to rapid delivery and good quality. When a system fails to perform its functions, products are damaged as a result of feed failure, scorching, thickness or width discrepancies, sharkskin, bubbling, poor printing, abrasions, and uneven winding. This damage can generate losses for suppliers. This study used a reliability block diagram to construct a system and function relation diagram. Because of the limited resources, the study executives, cross-functional team, and experts elected to simulate “feed failure,” which causes the most serious damage, as the primary event for analysis. Fault tree analysis (FTA) that involved drawing a causal fault tree with event and logic symbols was performed to identify the causes of faults. The results were then incorporated into failure mode and effects analysis (FMEA) to identify the causes of failure and potential failures, and evaluate the severity of outcomes. Based on the results, the executives, cross-functional team, and experts proposed preventive measures and strategies for a sequence of improvements, which were prioritized to control manufacturing processes and reduce risks. The cross-functional team collaborated to implement failure prevention measures and mitigate or eliminate the failure modes. Therefore, the manufacturing processes can be completed simultaneously, and the damage resulting from feed failure (the supply of low-density polyethylene blow-film material) can be prevented. The strategies for improvement were recorded and provided to other interested parties. Thus, manufacturing processes can be improved, the cost of failure can be reduced, and enterprises’ competitiveness can be enhanced. This study used Company Z as an example to demonstrate the feasibility of the measures for preventing the failure mode caused by a system failure, which would otherwise result from feed failure (low-density polyethylene blow-film material). The results obtained in this study can be provided as a valuable reference to related industries.
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Καρακώστα, Νικολίτσα. "Προσομοίωση διεργασιών μορφοποίησης πολυμερών : η επίδραση ψυχρού εξωτερικού αέρα στην εκβολή πολυμερούς με εμφύσηση." Thesis, 2006. http://nemertes.lis.upatras.gr/jspui/handle/10889/1454.
Full textAbstract:
Το αντικείμενο της παρούσας εργασίας είναι η μαθηματική μοντελοποίηση της εφαπτομενικής ροής του ψυχρού αέρα, ο οποίος παρέχεται εξωτερικά της διεργασίας εκβολής πολυμερούς με εμφύσηση (film blowing) και η αριθμητική επίλυση των εξισώσεων που προκύπτουν. Η διεργασία εκβολής πολυμερών με εμφύσηση είναι η βασική μέθοδος παραγωγής φύλλων πλαστικού μεγάλης επιφάνειας τα οποία χρησιμοποιούνται κυρίως ως υλικά συσκευασίας και σε θερμοκήπια.
Στην παρούσα εργασία αναπτύχθηκε μεθοδολογία η οποία επιτρέπει την μοντελοποίηση της ροής και της μεταφοράς θερμότητας του αέρα καθώς και του πολυμερούς και μας δίνει τη δυνατότητα να μελετήσουμε την επίδραση που έχει τόσο η ροή όσο και η ψύξη που προκαλεί ο αέρας στο φιλμ που σχηματίζει το πολυμερές. Αρχικά οι διέπουσες εξισώσεις του αέρα και του πολυμερούς απλοποιήθηκαν με την βοήθεια της θεωρίας των διαταραχών. Η μαθηματική ανάλυση και οι παραδοχές που έγιναν είχαν ως αποτέλεσμα i) η ροή και η παραμόρφωση του πολυμερούς να περιγράφεται από τις εξισώσεις του “λεπτού φιλμ” και ii) η ροή του αέρα να προσομοιάζεται με συνοριακό στρώμα, του οποίου η λύση προκύπτει με την μέθοδο ομοιότητας. Η επίδραση της θερμοκρασίας του αέρα στο πολυμερές μελετήθηκε θεωρώντας την αρχικά σταθερή, ενώ στην περίπτωση που και ο αέρας θεωρείται ότι θερμαίνεται από το πολυμερές, η κατανομή της θερμοκρασίας του προσεγγίζεται με ένα πολυώνυμο 4ου βαθμού στην ακτινική διεύθυνση.
Τα αποτελέσματα που προκύπτουν εξαιτίας της ψύξης του φιλμ δείχνουν ότι οι παραμορφώσεις και οι μεταβολές του πάχους μειώνονται επιτρέποντας στο φιλμ που σχηματίζει το πολυμερές να αποκτά σωληνοειδή μορφή. Η λύση της εφαπτομενικής ροής του αέρα κατά μήκος του φιλμ έδειξε ότι στο φιλμ ασκούνται τάσεις οι οποίες μετατοπίζουν το φιλμ προς τον άξονα συμμετρίας και έτσι λαμβάνονται πιο ομοιόμορφα σχήματα σε σχέση με τα σχήματα που λαμβάνονται χωρίς την επίδραση του αέρα. Η επίδραση της ροής του αέρα φαίνεται να συμβαίνει στο χαμηλότερο τμήμα του φιλμ και κυρίως μέχρι ύψους . Τέλος, η σύγκριση μεταξύ του θεωρητικού μοντέλου που αναπτύχθηκε με πειραματικά αποτελέσματα δείχνει ότι υπάρχει, τουλάχιστον ποιοτικά, συμφωνία.The object of present work is the mathematical modelling of tangential flow of cold air, which is provided externally to the polymer film produced in the well-known industrial process for manufacturing biaxial stretched films, Film Blowing Process, and the numerical solution of equations as well. In the present work was developed methodology which describes the flow and heat transfer of air as well as polymer. This analysis gives us the possibility of studying the effect of the flow as well as refrigeration that causes the air in the film of the polymer. Initially the governing equations of air and polymer were simplified with the help of theory of perturbations. The mathematic analysis and the assumptions that became had as result i) the flow and deformation of polymer described with the equations of "thin film" and ii) the flow of air simulated as a boundary layer, which its solution obtained by method of similarity. The effect of temperature of air in polymer was studied considering initially constant, while in the case where also the air is considered that is heated from polymer, the temperature distribution is approached with a polynomial of 4th degree in the radial direction. The results that arise because of refrigeration of film show that the deformations and the changes of thickness are decreased allowing in the film makes solenoids shape. The solution of tangential flow of air along the film showed that stresses in the film shift the film to the axis of symmetry and thus are received more uniform shapes in regard the shapes which are received without the air effect. The air flow effect appears to happen in the lower part of film and mainly until height . Finally, the comparison between the theoretical model that was developed with experimental results shows that exists qualitatively agreement.
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Luo, Dah-Woei, and 羅大偉. "Computer aided design of extrusion blown film die." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/23832717614982963083.
Full textAbstract:
碩士國立交通大學
應用化學研究所
85
The blown film die , which is also called the spiral mandrel die , is widely used in the production of tubular products , such as pipes , plastic bags and so on . In order to produce the beautiful and durable products , helicalgrooves cut on the mandrel surface are designed to increase flow uniformity and eliminate welding lines . They are the main characteristics of the spiral mandrel die . There are six parameters in designing the spiral mandrel die , which are the diameter of the mandrel , the number of the helical groove , the initial width of the helical groove , the initial depth of the helical groove , the helical angle and the gap , respectively . This study analyzed the isothermal-non-Newtonian flow , based on the two-dimensional flow simulation , in a die with a mandrel of 11 cm diameter and four helical grooves . Then , the Taguchi method was used to determine the optimal values of the rest of four parameters by considering the performance of the die . The performance of the die was examined from flow uniformity , degree of mixing and total pressure drop . Finally , the optimal geometry of the die was determined . Sequentially , the performance of the die was examined under the nonisothermal condition and the discrepancy between the isothermal and the nonisothermal condition was compared . The results show that it is enough to determine the elementary shape of the die according to the isothermal assumption .
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WANG，CHIA-CHAN and 王家榐. "Development of Toughening and Blown Film of Polylactic Acid." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/7cw457.
Full textAbstract:
碩士亞東技術學院
材料與纖維系應用科技碩士班
107
This study is divided into two parts to discuss, the first part: polylactic acid (PLA) toughening and upgrading. First, PBAT, PBS and PLA biodegradable plastics were mixed in different proportions to prepare PmCn and PLA1(PmCn)1 composite plastics. The thermal, mechanical, SEM type, film formation and heat resistance of the film were analyzed and discussed. The thermal properties show that the melting exothermic peak belonging to P disappeared in P1C4 plastic, P was dispersed in the main phase of C, and the other mixing ratios were found to be the melting exothermic peaks of P and C. It was also found in the PLA1(P1C4)1 plastic that the melting exothermic peak belonging to P completely disappeared. P1C4 is blended into an alloy-like composite plastic. When blended with PLA, the P1C4 alloy is dispersed in the PLA main phase. The mechanical properties show that P1C4 plastic has the highest tensile strength. Compared with 100% C, the strength decreases by 20.9% and the elongation increases by 39.8%. PLA1(PmCn)1 plastic with PLA1(P1C4)1 plastic has the highest tensile strength and elongation at break. Compared with PLA, the tensile strength decreased by 52.6% and the elongation increased by 9465%. The increased elongation is of great help in blown film processing. The mechanical properties of the film showed that the PLA1(P1C1)1 plastic had an average tensile strength (X-axis: 17.3 MPa; Y-axis: 17.3 MPa) and elongation at break (X-axis: 45.9%; Y-axis: 218%). The heat resistance stability of the film shows that the PmCn and PLA1(PmCn)1 plastics are tested at 95 ° C, and the deformation amount falls between 0 and 3 mm, and the heat resistance is good. The type properties show that the P1C4 and PLA1(P1C4)1 plastics have a smooth and flat surface. In summary, PmCn and PLA1(PmCn)1 plastics are partially compatible composite plastics. P1C4 is alloyed with PLA. Compatible formulations P1C4 and PLA1(P1C4)1 plastics have the best physical properties, and blown film forming has excellent results. Part II: The first part of the successful development of PLA1(P1C4)1 plastic, mixed with oyster shell powder, fatty acid guanamine dispersant in different proportions, prepared TPLAxOy and TPLAxOyDz composite plastic. The thermal, mechanical, SEM type, film forming properties and heat resistance properties of the composite plastics were analyzed and discussed. The thermal properties show that the TPLAxOy plastic part has a large increase in crystallinity with the increase of oyster shell powder content. In TPLA85O15 plastic, the crystallinity is 80.2%, and the crystallinity is increased by 20.6 wt% compared with TPLA. The mechanical properties show that the TPLAxOy plastic part, with the addition of oyster shell powder, the Young's coefficient value increased significantly, with TPLAO1 plastic 464MPa highest. In the plastic part of TPLAxOyDz, with the increase of the content of oyster shell powder, the value of Young's coefficient increased greatly, with TPLA of TPLAO5D3 plastic being the highest. Compared with TPLA plastic, the Young's coefficient was increased to 884%. The addition of oyster shell powder and dispersant destroys the toughening properties of TPLA, and the stiffness of the plastic increases. The heat resistant properties of the film show that the TPLA95O5D3 film can be heat resistant to 100 ° C when the film thickness is ≧ 0.05 mm. The type properties showed that most of the oyster shell powder was broken up in the TPLA95O5 test piece, and the size was less than 1 μm, which was uniformly dispersed in the continuous phase TPLA plastic. In summary, the oyster shell powder is added to the TPLA plastic to increase the crystallinity of the PBS, and the oyster shell powder is a nucleating agent for PBS. Adding a dispersant to the TPLA plastic increases the stiffness of the plastic. Further, in the blown film forming process, when the oyster shell powder is added in an amount of 10%, the blown film forming process has an excellent effect. Keywords: Polylactic acid、Oyster shell powder、Toughening、Film
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Tao, Wen-Yu, and 陶文鈺. "Optimal Design of Spiral Mandrel Die for Blown Film Process." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/28458438614523602582.
Full textAbstract:
碩士國立交通大學
應用化學系
90
Spiral mandrel dies are widely used in the production of tubular products and polymeric films. The feature of the die is several helical grooves cut on the mandrel surface, and the melt flow from groove leak to clearance gradually. Proper die design can improve flow uniformity and to avoid occurring the weld line. Geometrical parameters in designing the spiral mandrel die are: diameter of the mandrel, the number of helical groove, initial width and initial depth of the helical groove, the groove helix angle, overlap of helical groove, the initial gap, and the taper angle, which we introduce two-sectional design. In this article we analyze non-Newtonian fluid flow in the die. Two-dimension mathematical model is utilized, and the viscosity of polymer melt is assumed to be Power-Law model. Associated with Taguchi method, several optimal sets of die geometric parameters is searched by assessing the flow uniformity and mixing degree respectively. We consider more geometric parameters and different targets during searching process to attain both good flow uniformity and mixing degree. Finally, performance of dies under nonisothermal condition is compared with those determined on isothermal condition. Die lips is discussed at the same time.
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Xie, Wei-Xian, and 謝維賢. "Optimal Design of Spiral Die for Metallocene Polyethylene Blown Film." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/18798002837631228667.
Full textAbstract:
碩士國立交通大學
應用化學系
89
Metallocence polyethylene(m-PE) is a fully potential material with well mechanical properties. But the poor melt strength and high shear rate viscosity are disadvantages in polymer application. Mathematic model combined with Taguchi method is a method for optimal design of spiral mandrel die to avoid the poor melt strength and the overheat of melt. There are seven parameters in designing the spiral mandrel die, which are the diameter of the mandrel, the number of the helical groove, the initial width of the helical groove, the initial depth of the helical groove, the helical angle, the taper angle, and the gap. With m-PE as a processing material, two-dimensional flow simulation and Taguchi method are combined to determine the optimal geometry value, and the performance of the die was discussed. In addition, the performance of the die was examined with die lips. Finally, the performance of the die was examined under nonisothermal condition and compared with under isothermal condition.
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Ohlendorf, Friedrich [Verfasser]. "Vorhersage der mechanischen Folieneigenschaften bei der Schlauchfolienextrusion = Predicting the mechanical film properties in blown film extrusion / vorgelegt von Friedrich Ohlendorf." 2004. http://d-nb.info/971334374/34.
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Chang, xein-min, and 張憲民. "Optimal Design of Spiral die for Physical Foaming and blown film extrusion Process." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/94313729520286970079.
Full textAbstract:
碩士國立交通大學
應用化學系所
92
The purpose of the present study is to establish an analytical program for spiral die with physical foaming agent. First, we predict the viscosity of melt polymer with foaming agent mathematically, and establish the flow model by fluid dynamics. Applying the Sanchez-Lacombe equation, we can calculate the weight percentage of foaming agent in melt polymer at any pressure and temperature. As predicted, more foaming agent can be dissolved into melt polymer at a high pressure or low temperature. The parameters of spiral die include DEPTH, WCHAN, GIBC, HBC, NOSEC, θ and α. Second, we use the Tguchi method to search several optimal sets of die geometric parameters by assessing the flow uniformity(UNI) and mixing degree(MD) isothermally and create ANOVA tables. From ANOVA tables, we realize that the seven parameters can totally describe the flow situation in spiral die. At the same time, we find that whatever the number of channels is, the most relevant parameters with respect to MD are DEPTH,WCHAN and GIBC; with respect to UNI, WCHAN and NOSEC are the most relevant parameters; furthermore, with respect to pressure gradient, GIBC及ALFAR are the most relevant. During polymer foaming, if the local die pressure cannot reach the critical pressure, prefoaming occurs. Therefore, at the outlet of spiral die, we narrow down the channel depth to increase the local pressure, which is thus greater than critical pressure. Finally, with die lip being attached to spiral die, we examine the non-isothermal condition, so that an analytical program for spiral die with physical foaming agent can be established.
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蔡文淵. "Optimal Design of Side-Feed Spiral Mandrel Die for Blown Film Extrusion Process." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/39812762482349170024.
Full textAbstract:
碩士國立交通大學
應用化學系所
93
Abstract Side-feed spiral mandrel die was designed to overcome the disadvantage of central-feed spiral mandrel die. The production rate can be improved and the possibility of forming the poor surface appearance and the warp problem can also be avoided using this type of die. Especially, the possibility of material degradation, which causes the decrease of mechanical properties, can be eliminated via this type of die when the layers of film increase. In addition, this type of die possesses the characteristics of small metal body, which results in a decrease of die cost, and easily taking apart of the die or changing the processing material. Recently, this type of die, thus, has attracted the attention of the foreign equipment suppliers. Therefore, this thesis first employees a flow model of two dimensional control volume method to simulate the flow behavior in the side-feed and spiral mandrel sections. Under this circumstances, the non-Newtonian fluid is assumed to be in the isothermal condition and the flow behavior in these sections will be simulated. In addition, we use the Taguchi method to search several optimal sets of die geometric parameters by assessing the flow uniformity and mixing degree. Finally, under non-isothermal condition, the geometry of die will be extended. This will allow us to simulate the flow behavior and performance of entire die.
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吳祐任. "Optimal disign of side-feed spiral mandrel die for the blown film extrussion process." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/09197149086822723722.
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