Blends specimen preparation

Materials and Specimen Preparation. ABS 2 and ABS 3 were prepared by dry and melt blending of ABS 1 with a rigid polySAN. The styrene/acrylonitrile ratio of the polySAN used for blending was the same as that present in the parent ABS 1. Polydiene contents are in the order ABS 1 > ABS 2 > ABS 3. 

ABSTRACT A rapid and precise X-ray fluorescence method has been developed for the multielement analysis of gypsum and gypsum products. Gypsum specimens are calcined at IOOO°C and then fused with sodium tetraborate flux into flat and transparent disks. The choice of a suitable flux system for the specimen preparation is critical because of a rapid decomposition of anhydrite. CaSO,. in lithium ba fluxes at temperatures above 95O C. This decomposition causes not only visible imperfections in the didi surface but also alters considerably the concentrations of the major elements, calcium and sulfur. The procedure used for a fast setup of ten element analysis of gypsum on the Philips PW-1400 spectrometer utilizing synthetic standards and off-line calculated alpha coefficients is presented. Calibrations carried out with chemically analyzed specimens and their mixtures are compared lo those performed with synthetic standards prepared by blending pure chemicals and anhydrite into the flux. 

To construct the phase diagram, thin blend specimens should be prepared. The preferred method is to cast film from a common solvent. However, it has been observed that the blend thermograms depend on the type of solvent used for casting the film. For example, PVC/PHMT blends cast from toluene had a single T, whereas from... 

Owing to experimental difficulties, there are but few publications on uniaxial deformation of blends. To prepare specimens for testing, samples usually are transfer molded and relaxed, both operations requiring relatively long heating time, during which only well stabilized blends will not coarsen. 

A liquid-solid phase diagram established for blends of iPP/POE by means of DSC and LS is presented at the top left of Fig. 7.12, displaying four distinct regions isotropic (I), coexistence of crystal-isotropic (Ci +1), coexistence of crystal-crystal-isotropic (C1+C2 + I), and crystal-crystal (Ci + C2- -C3). Cj and C2 represent the a- and y-form crystals of iPP, respectively, while C3 is designated for POE crystals (31). The blend preparation is identical to the procedure conducted for sPP/POE blend specimens. These iPP/POE blends are found to be completely miscible in the melt state, showing little or no depression of the melting point with composition. 

Scanning electron microscopy (SEM) can offer a good depth of held, good resolution, and easy specimen preparation. It can be used for immiscible polymer blends, where the phases are sufficiently large and can be easily debonded. Information on surface topography, size, and distribution of the dispersed phase and interfacial interaction between phases can be elucidated with this technique. Elemental analysis on the blend components can also be obtained if the SEM equipment includes an energy dispersion X-ray spectrometer (EDX). 

The molecular characteristics of the polymers used for the present study and the blend compositions explored are collected in Tables 1 and 2 respectively. Details on the processing conditions and on the specimens preparation are given in a previous paper... 

To construct the phase diagram, thin blend specimens should be prepared. The preferred method is to cast film from a common solvent. However, it has been... 

All EXL 4000/polymer blends were prepared on a Werner and Pfleiderer ZSK-30 twin screw extruder with a L/D of 24 and at a screw speed of 200 rpm. The melt was degassed. Polymers, EXL 4000 systems and modifier were all added in the throat of the extruder. After compounding, the blends were dried and injection moulded into test specimen on an Arburg Allrounder injection moulding machine. Properties of the polyamide blends were measured either dry as moulded or after conditioning until eguilibrium at 23°C and 50% RH. 

Figure 2. Electron micrographs of 50% (fig. 2a) and 10% (fig. 2b) blends of HOPE with LDPE quenched from 160 into iced acetone. Specimen prepared by permanganic etching followed by shadowing and...

Table 4.4 includes functional groups and polymers and their respective etchants. Chemical etching, such as with solvents and acids, and ion and plasma etching are conducted in order to reveal selectively structures in polymers that may not be observed directly. In all these methods, interpretation of the structures formed can be more difficult than specimen preparation. Accordingly, the etching methods are best used to complement other methods, such as microtomy, fractography and staining. Controls are essential to any experiment of this type, but, with care, the structures of semicrystalline polymers and polymer blends may be observed. 

More importantly, the SEM images shown in Figure 17.1 provided an insight into the possibility of imaging individual spherulites in the blends of two different polyethylenes due to correct specimen preparation. 

Sample preparation was shown to be a crucial issue for the error-free evaluation of the morphology of polymer blends. Whilst the selection of specimen preparation conditions and specific microscopic techniques depend largely on the nature of the problems at hand, the combination of two or more methods will certainly help in obtaining the most reUable picture of the blend morphologies. 

Plummer [120] provided an excellent review in his reflections on the use of microtomy for materials science specimen preparation, with a table of material classes, references, and comments. The review includes examples of polymer composites, blends, membranes, elastomers, and coatings. Kink bands and shear deformation were shown in polybenzobisoxazole (PBO) fibers microtomed and studied by TEM [121]. Fibers treated to cause compressive deformation were taped to sheet polycarbonate and coated with spray acrylic to fix them to the substrate. Small sections (<5mm) attached to the polycarbonate were cut, trimmed, and microtomed to a thickness of 40-80nm with a new area of a diamond knife and picked up on 400 mesh grids. Ericson and Lindberg [122] showed that when the sample holder of the... 

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