Production uniformity

Aerospace and nuclear reactor appHcations of graphite demand high reHabiHty and reproducibiHty of properties, physical integrity of product, and product uniformity. The manufacturing processes require significant additional quaHty assurance steps that result in high cost. 

A higher level of product uniformity than can be achieved with natural rubber. 

Mixing in the smaller reactor is generally better. Improved mixing may improve product uniformity and reduce by-product formation. 

The grafting through approach involves copolymerization of macromonomers. NMP, ATRP and RAFT have each been used in this context. The polymerizations are subject to the same constraints as conventional radical polymerizations that involve macromonomers (Section 7.6.5). However, living radical copolymerization offers greater product uniformity and the possibility of blocks, gradients and other architectures. 

Major applications of modern TLC comprise various sample types biomedical, pharmaceutical, forensic, clinical, biological, environmental and industrial (product uniformity, impurity determination, surfactants, synthetic dyes) the technique is also frequently used in food science (some 10% of published papers) [446], Although polymer/additive analysis takes up a small share, it is apparent from deformulation schemes presented in Chapter 2 that (HP)TLC plays an appreciable role in industrial problem solving even though this is not reflected in a flood of scientific papers. TLC is not only useful for polymer additive extracts but in particular for direct separations based on dissolutions. 

When we injection mold small plastic items, it is standard practice to mold several identical parts simultaneously in a mold containing multiple cavities. In order to insure product uniformity, we must design runners that distribute the molten polymer evenly to each cavity. 

Chi-Square Distribution For some industrial applications, product uniformity is of primary importance. The sample standard deviation s is most often used to characterize uniformity. In dealing with this problem, the chi-square distribution can be used where %2 = s2/a2) (df). The chi-square distribution is a family of distributions which are defined by the degrees of freedom associated with the sample variance. For most applications, df is equal to the sample size minus 1. 

The bulk density of the flakes is typically between 250 and 450kg/m3. Compared to pellets, with a typical bulk density of between 750 and 850kg/m3, this has a negative effect on equipment sizing and product handling. Further comminuting the PET flakes increases the bulk density and improves product uniformity, but also creates additional product loss to dust. 

In general the required performance criteria and product uniformity parameters stipulated in shotcrete specifications are as follows ... 

Uniformity of temperature distribution across the shelves is important in order to maintain product uniformity. 

Prescott JK, Hossfeld RJ. Maintaining product uniformity and uninterrupted flow to direct-compression tableting presses. Pharm Technol 1994 18(6) 98-114. 

Make volume to 1.0 L with purified water and mix well under vacuum for at least 15 minutes to ensure product uniformity and to deaerate the product. 

Purification. Unsubsliluled di-p-xylylene (DPXN) is readily purified by recrystallization front xylene. It is a colorless, highly crystalline solid. The principal impurity is polymer, which is insoluble in the recrystallization solvent and easily removed by hot filtration. In purifying DPXC and DPXD, care is taken not to disturb the homologue composition, so that product uniformity is maintained. 

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