Ejection temperature

We have seen that ZTRID can be successfully observed and interpreted for cluster ions. It is of interest to look as well at covalent molecular ions for new thermochemical information. The parent ion of tetraethylsilane illustrates these possibilities. The ion is formed in adequate abundance directly in the FTICR cell by electron impact, and the more abundant triethylsilyl ion is readily removed by ion ejection. Temperatures substantially above room temperature are needed to give measurable ZTRID rates. Figure 10 shows the low-pressure dissociation chemistry at 403 K. At this temperature, some water vapor outgasses in the cell and reacts with the tetraethylsilane parent ion to give the EtjSi(H20) ion, but this competing bimolecular reaction is well behaved and easily allowed for in the kinetic fitting. The parent ion undergoes the ZTRID process. 

Crystallization temperature and the heat of crystallization at various cooling rates (or the ejection temperature of the molded part) ... 

Orientation of filler particles is also important therefore warpage is influenced by processing conditions which tend to orient the filler such as rate of flow, temperature, ejection temperature, and material crystallization conditions. The current literature does not provide much information on this subject. 

Melt viscosity Melt density Thermal conductivity Specific heat Solidification temperature Ejection temperature Ttemperature, shear rate... 

For the design data, the relevant properties that need to be evaluated along with the applicable ISO and ASTM standard methods are summarized in Tables 11.12 and 11.13, respectively. For some of the properties like pvT data, no-flow temperature, ejection temperature, and fatigue in tension, etc., no national or international standards exist today. Efforts are under way to develop industrywide standards for these properties. Suggested test conditions in Tables 11.12 and 11.13 are intended to serve as a guide in establishing specific test conditions for the purpose of developing comparable data. 

In the injection molding process, during the dwell time the cooling and solidification of the melt starts in the mold. To increase productivity, minimization of the cooling time is required. However, minimization of the cooling time leads to parts with higher ejection temperature and poor mechanical properties. 

At the conclusion of the holding phase, and while the mold remains closed for the molding to cool to ejection temperature, the injection unit cycle recommences with the resumption of screw rotation and melt preparation. 

During the cooling of the component, the heat is drawn from it by the mould. The amount of heat involved depends on the component weight, the type of plastic (specific heat content), the ejection temperature, and the cycle frequency. The mould passes this heat to the environment (by heat conduction to the machine and by radiation or convection to the ambient air), if no special temperature control system is connected up. The higher the mould temperature, the greater the amount of heat released to the environment. So, when the machine starts up, the mould initially heats up to the temperature at which the amount of heat supplied by the solidifying and cooling plastic can be released to the environment. 

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