Slip agents, analysis

The use of the particle-beam interface for introduction of samples into a mass spectrometer (PB-MS), without chromatographic separation, was shown by Bonilla [55] to be a useful method for analysis of semi-volatile and nonvolatile additives in PC and PC/PBT blends. The method uses the full power of mass spectrometry to identify multiple additives in a single matrix. The usefulness, speed and simplicity of this approach were illustrated for AOs, UVAs, FRs, slip agents and other additives. 

U V fluorescent sulfur detection and chemiluminescent nitrogen methods have been developed for total sulfur only, nitrogen only or simultaneous sul-fur/nitrogen analysis. These systems provide quick automated analysis to estimate the type and amount of sulfur and nitrogen-containing additives present in a polyolefin sample, i.e. slip agents, antistatics. 

The methodology of laser-assisted mass spectrometry is particularly a useful tool in the development and analysis of materials with surface-related capacities, such as slip agents, lubricants, surfactants, etc. 

The analysis of changes of the coefficient of ffiction, caused by the presence of slip agent, is complicated by the multiplicity of methods used as discussed in the previous chapter. For methods which analyze diffusion of additive into the sample (mass sorption), the amount of absorbed substance at any given time is described by the following equation ... 

If a sample is transported in a plastic bag it may become contaminated with surface material from the bag. A PVC bag may transfer plasticizer to the sample. For PE, it may be transfer of surface slip agent, like erucamide, or mold release agent, like calcium stearate. One may be misled in an analysis if transfer of contaminants is not considered. Sometimes we have analyzed the bag to see if that is the source of material found by analysis. To prevent such problems it is best to wrap samples in thin aluminum foil. Also, polyester bags are available that do not transfer anything to contents [5]. 

Cells are plated at the desired density, either on sterile glass cover-slips for microscopic examination, or directly into multiwell plates (prepare each point at least in tripUcate) for population analysis by ELISA. After treatment of the cells with the desired growth agents, BrdU is added, following the same criteria already discussed for thymidine labeling (short pulse, or long term). Cells are then washed free of residual BrdU by rinsing with PBS, and fixed in ethanol. Fixed cells can be stored at 4°C for further analysis. BrdU... 

In the present analyses, prismatic dislocation loops distributed on different slip planes are used as agents for dislocation generation. For copper, sources length of about 0.60 p,m are used. It is worthy to mention that the boundary conditions of the computational cell sides are different in FE and DD parts of the code. In DD, periodic boundary condition for the representative volume element RVE is used to ensure both the continuity of the dislocation curves and the conservation of dislocation flux across the boundaries, by that we take into account the periodicity of single crystals in an infinite media. In FE analysis however, the sides are constrained to move only in the z direction so that a imiaxial strain consistent with the shock experiment is achieved. In order for the boundary conditions in FE and DD to be consistent, periodic FE bormdary condition is implemented as well. The result of this implementation is discussed in the next section. 

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