Influence of the Processes Parameters on the Properties of The ...

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Chapter 3. Analytical Methods and Designs <strong>of</strong> Experiments Linear Graph: <strong>the</strong>y are used to verify that <strong>the</strong> selected table is equipped to represent <strong>the</strong> problem (can you represent all factors and all interactions) and specify how to assign <strong>the</strong> columns <strong>of</strong> <strong>the</strong> Taguchi’ table. Interaction Table: it allows to precise in which columns are <strong>the</strong> influent interactions. When a non linearity <strong>of</strong> <strong>the</strong> response is assumed, <strong>the</strong>re are tables <strong>of</strong> experiments configured according to a finite number <strong>of</strong> experiments. For example, <strong>the</strong> chosen table L 9 (3 4 ) need to perform nine experiments to study 4 factors at 3 levels. In Taguchi’ notation, it is important to note that <strong>the</strong> three levels do not correspond to <strong>the</strong> American notation (-1, 0, 1) but an increasing variation (1, 2, 3). By consulting tables which respect <strong>the</strong> principle <strong>of</strong> orthogonallity, which means that all factors vary evenly on each level (cf. Table 3.3). Table 3.3: Table Taguchi L 9 . Experiment Nr 1 2 3 4 1 1 1 1 1 2 1 2 2 2 3 1 3 3 3 4 2 1 2 3 5 2 2 3 1 6 2 3 1 2 7 3 1 3 2 8 3 2 1 3 9 3 3 2 1 To determine <strong>the</strong> effect <strong>of</strong> one factor, we calculate <strong>the</strong> average response <strong>of</strong> each factor in a given level (e.g. a 1 corresponds to <strong>the</strong> demi-difference between <strong>the</strong> average responses when <strong>the</strong> A factor is at <strong>the</strong> up and down levels) and plot <strong>the</strong> evolution <strong>of</strong> this factor when it goes from low (1) to high (3). The variation factor between <strong>the</strong> extreme levels 1-3 will be aware <strong>of</strong> <strong>the</strong> influence factor (little variation for a neglectable factor) and to compare <strong>the</strong> effects <strong>of</strong> each factor. Similarly, interactions between factors are obtained by calculating <strong>the</strong> system response when <strong>the</strong> factors are in certain levels (for example a 1 b 1 it counts only <strong>the</strong> values corresponding to low levels <strong>of</strong> two factors A and B). By convention, <strong>the</strong> interaction effects are taken equal to half <strong>the</strong> difference between <strong>the</strong> two effects. 8 Conclusion The purpose <strong>of</strong> this chapter was to describe <strong>the</strong> analytical methods that are available for detecting, and/or measuring, and/or monitoring surface, physical and mechanical properties <strong>of</strong> <strong>the</strong> polymers and foams. The main intention was to identify well-established methods that are used as standard methods <strong>of</strong> analysis. The glass transition temperature <strong>of</strong> <strong>the</strong> materials used is determined by <strong>the</strong> DSC principle, which fur<strong>the</strong>r gives results about <strong>the</strong> physical and chemical nature <strong>of</strong> <strong>the</strong> polymeric material. Granulometery gives particle morphology <strong>of</strong> polymer, fillers and modifier used. Brazilian test is a parameter to calculate <strong>the</strong> structural aspects <strong>of</strong> <strong>the</strong> raw material. Molecular weight <strong>of</strong> <strong>the</strong> polymer is determined by taking into account intrinsic viscosity. Scanning electron microscopy, image analysis, mercury porosimetry, microtomography, compression test provides information about <strong>the</strong> morphology and structural properties <strong>of</strong> <strong>the</strong> end product. Experimental designs were used with <strong>the</strong> aim <strong>of</strong> minimizing number <strong>of</strong> experiments when we are confronted to a great number <strong>of</strong> variables. The experiment, based on a statistic plan that was inferred from research, must be repeatable. - 86 -
Chapter 4 Chapter 4 Experimental Procedures and Protocols for Analyses This chapter will be devoted to <strong>the</strong> description <strong>of</strong> various experimental procedures and techniques applied for <strong>the</strong> raw materials and products used in <strong>the</strong> entire <strong>the</strong>sis. Procedures such as mixing <strong>of</strong> materials, pre-grinding by knife mill, co-grinding by tumbling ball mill and preparation <strong>of</strong> pellets by wet and dry methods will be laid down step by step. The specific conditions <strong>of</strong> various analysis techniques used to characterize <strong>the</strong> properties <strong>of</strong> <strong>the</strong> raw materials, intermediate products and final products will be presented. Procedures for laser granulometry to verify particle size, scanning electron microscopy (SEM) for observing <strong>the</strong> pore morphology and SCION ® Image analysis for pore structure and <strong>the</strong>ir distribution will be explained extensively. Finally, Brazilian test to identify <strong>the</strong> mechanical properties <strong>of</strong> <strong>the</strong> raw materials and compression test will be revealed with <strong>the</strong> help <strong>of</strong> schematic diagrams. 1 Procedure for Size Reduction Reduction <strong>of</strong> size <strong>of</strong> polymers and composites was realized in <strong>the</strong> laboratory: "Laboratoire de Génie Chimique". Biopolymers, adjuvants and fillers mixtures were prepared by two different methods, called dry and wet method. Some initial steps were common for both methods, such as size reduction, cogrinding and mixing. 1.1 Size Reduction 1.1.1 Size Reduction by Knife Mill Since some polylactides were supplied in <strong>the</strong> form <strong>of</strong> granules <strong>of</strong> one to several millimeters or in <strong>the</strong> form <strong>of</strong> long fibres, <strong>the</strong>y were first fragmented and reduced to powders or small fibres with a laboratory knife mill (Janke and Kunkel IKA A-10 (115 Volts), Labortechnik, Staufen, Germany). The mill in Figure 4.1 was used for rapid, high-speed grinding <strong>of</strong> small samples from 10 to 25 gms. This apparatus can grind samples down to few hundreds <strong>of</strong> μm in seconds depending upon <strong>the</strong> nature <strong>of</strong> material. Stainless steel or hard-faced blade rotates at speeds up to 20000 rpm. Temperature is maintained by means <strong>of</strong> built-in heat exchangers and <strong>the</strong> control panel has an overload protection reset button and a pilot light. Tubing connections 6.4 mm on <strong>the</strong> cover and housing accept tubes for circulating water.
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Institut National Polytechnique de
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pleased I was to work with all memb
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Publications and Conferences The wo
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ρ p Pellet density Splitting (Bra
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Chapter 2 .........................
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iological performance. Biocompatibi
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