Poly specimen preparation

Structure of the Collapsed Monolayers. IR spectra of specimens prepared from air dried collapsed monolayers were typical of specimens in the a-helical conformation with no indication of any p conformation. Electron diffraction patterns gave a similar result. The patterns for poly-(L-leucine) and poly(L-norleucine) are similar to poly(L-norvaline) (12) with low crystallinity. A strong equatorial reflection at 10.94 0.10 A is observed in poly(L-leucine). If we assume as previously (5) that this is the 100 reflection from a hexagonal cell, the calculated area per residue in the monolayer is 17.3 A, assuming the molecular separation is the same as in the collapsed film. This figure is in agreement with the observed area of 16 A in view of the difficulties encountered in spreading the monolayer. 

EN 922 Pipes and fittings of unplasticised poly(vinyl chloride) (uPVC) - specimen preparation for determination of the viscosity number and calculation of the K-value. 

The specimen preparation required for atomic force microscopy of polymers is nunimal. The ability to examine a wet specimen eliminates artifact formation due to drying and the effect of vacuum. In the case of latex samples, the measurement of the particle diameter and distribution is also enhanced by the ability to resolve fine details and to easily make digital measurements. Issues with AFM imaging relate to instrumental parameters, especially whether the AFM is in the contact or non-contact mode (see Chapter 6). Two images are shown in Fig. 5.79 of polystyrene and poly(ethyl methacrylate) (PS/PEMA) latex, imaged in the non-contact mode with a Park Autoprobe AFM. Figure 5.79A... 

The microdomain model of crystallinity in poly(vinyl chloride) (PVC) by TEM has provided a controversy that is noted here simply to highlight the topic of image interpretation and specimen preparation issues that continue to be important, as the conclusions of Clark and Truss [128] were commented upon by Radzilowski and Thomas [129]. In this case, the HREM is the technique being used, and the issues relate to the microscope conditions, the filtering process, the radiation dose and damage, which with PVC would include loss of chlorine and specimen thickness. The issue here is simply that full disclosure of preparation methods and instrumental techniques are a requirement for research papers on polymers, as they clearly affect the images and interpretation. 

ISO 580 1990 Injection-moulded unplasticized poly(vinyl chloride) (PVC-U) fittings -Oven test - Test method and basic specifications ISO 727-1 2002 Fittings made from unplasticized poly(vinyl chloride) (PVC-U), chlorinated poly (vinyl chloride) (PVC-C) or acrylonitrile/butadiene/styrene (ABS) with plain sockets for pipes under pressure - Part 1 Metric series ISO 727-2 2002 Fittings made from unplasticized poly(vinyl chloride) (PVC-U), chlorinated poly (vinyl chloride) (PVC-C) or acrylonitrile/butadiene/styrene (ABS) with plain sockets for pipes under pressure - Part 2 Inch-based series ISO 1163-1 1995 Plastics - Unplasticized poly(vinyl chloride) (PVC-U) moulding and extrusion materials - Part 1 Designation system and basis for specifications ISO 1163-2 1995 Plastics - Unplasticized poly(vinyl chloride) (PVC-U) moulding and extrusion materials - Part 2 Preparation of test specimens and determination of properties ISO 1265 1979 Plastics - Polyvinyl chloride resins - Determination of number of impurities and foreign particles... 

ISO 2898-1 1996 Plastics - Plasticized poly(vinyl chloride) (PVC-P) moulding and extrusion materials - Part 1 Designation system and basis for specifications ISO 2898-2 1997 Plastics - Plasticized poly(vinyl chloride) (PVC-P) moulding and extrusion materials - Part 2 Preparation of test specimens and determination of properties ISO 3114 1977 Unplasticized polyvinyl chloride (PVC) pipes for potable water supply -Extractability of lead and tin - Test method... 

A unique and considerably more elaborate multiaxial test employs a thick-walled hollow sphere test specimen which may be pressurized internally or externally with a nearly incompressible liquid. Figure 20 illustrates the essential features of the test device as described by Bennet and Anderson (5). The specimen is prepared by casting propellant in a mold fitted with a sand-poly (vinyl alcohol) mandrel inside the sphere which may be removed easily after curing. A constant displacement rate instrument drives the piston to pressurize the chamber and apply large deformations. The piston s total displacement volume is transferred to... 

Preliminary spectra have been recorded very recently on poly-vinylidene chloride specimens and a revised vibrational assignment is in preparation by Hendra, Holliday and Mackenzie. 

Some grafting between polystyrene and polyethylene may occur, but we think not. Substantial amounts of polystyrene (but not all) have been extracted from the blend samples by soaking the specimens in refluxing THF for several days. We suspect that if grafting does occur, it is not a significant contributor to polystyrene mass uptake. All the polystyrene could be extracted from a 50 wt % polystyrene/poly(4-methyl-l-pentene) (PMP) blend that was prepared by essentially the same procedure. The backbone of PMP (with two tertiary C —H bonds per repeat unit) is likely more susceptible to radical grafting than HDPE. 

The additive was added gradually to the polymer fused on a two-roll mill at 170°-174°C. After addition, polymer sheets were taken off the mill and put back on the mill endwise. Several such passes were made until the sample was thoroughly mixed. The specimen was removed from the mill in thin sheets and, while hot, cut into small pieces. The polymer was compression molded at 700 p.s.i.g. and a temperature of ca. 155°C. into a 6 X 6-inch sheet of about 0.045-inch thickness. This sheet was cut into the 5 X 1/2 X 0.045-inch specimens for burning in the modified D635 test. The sample was initially evaluated with 25% additive. If the compound was effective, lower concentrations were used until the additive would not confer fire retardant activity, or until the supply of additive was exhausted. With poly (methyl methacrylate), PMMA, cast samples also were prepared. 

When using poly-L-lysine or Silane-coated slides in enzyme digestion protocols, the method of their preparation determines the success of section adherence. The slides must be clean, and specimens must be heated prior to deparaffimzation. Experimentation can determine the slide coating that provides clean backgrounds with the technique of choice. 

The final latices were prepared for electron microscopy by dilution with xylene to ca. 0.1% polymer followed by distillation to remove the water. The distilled latices were diluted further and dried on the specimen substrates. The electron microscope specimens could not be calibrated with monodisperse polystyrene particles because of the sensitivity of the sodium poly (p-vinylbenzene sulfonate) particles to water. Instead, the magnification was calibrated from one separate exposure of monodisperse spheres which was made on each photographic plate of five ejqjosures. 

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