Blending powder preparation

Solution blends of 20-25% by weight were formed in DM Ac, with conventional dry spinning and film casting techniques used to produce blend fiber and film, respectively. Blend powders were prepared by precipitating the dope with a non-solvent (water). All materials were extensively washed in methanol or water to reduce residual solvent to less than 1 wt %. Neat resin tensile bars and plaques were compression molded from both powder and fiber. 

Composition An extruded powder prepared from two types of nitrocellulose, blended to give average nitrogen content of 13.15 per cent and a solubility in ether-alcohol of 40 per cent or greater. Components Pyro-cotton, 12.6 0.1 per cent Guncotton, 13.2 per cent or greater. 

After precipitation, the resultant powder is dried (100-110°C) and then milled to reduce the size of the agglomerates. Depending on the dopant concentration, calcination at 850°C yields a fully (cubic) or partially stabilized (cubic, tetragonal, etc.) powder with an average crystallite size of 40 nm (0.04 pm). After compaction, these powders can be sintered to near-theoretical density at 1450°C, a temperature 400°C lower than that possible with powders prepared from mechanically blended component oxides. 

Preparation of mixed spices for testing. A testing mixture of spice blend was prepared by mixing powdered spices purchased from local trading company. The formulation is shown in Table IV... 

Dry blends (powder blending) or blends of plasticized polymers are commonly prepared in a single-shaft mixer, such as ribbon blenders or paddle mixers. 

Blends were prepared with cellulose or silk as soon as a common solvent was available [63, 69-71]. Recently, ionic liquids were used. The solvent l-ethyl-3-methyl-imidazolium acetate completely dissolves raw crustacean shells allowing to recover high purity chitin powder or films and fibres by direct spinning [72]. Films of poly(e-caprolactone) (PCL) blends with a-chitin and chitosan were produced. They are completely biodegradable and the crystallinity of PCL is suppressed in the blends due to hydrogen bond interaction between PCL and polysaccharides [73]. Blends were also realized with poly (3-hydroxybutyric acid) (PHB) and chitin or chitosan. They show faster biodegradation than the pure-state component polymers [74,75]. 

Powder preparation for pressing consists of four phases homogenization blending precompaction and granulation and spheroidization and lubrication. 

In order to confirm that hydrogen sulphide (H2S) was not emitted from the developed blended powder, paste samples were prepared using the original blended powder with 10 and 20% (by weight) extra paper added to the mix. Specimens were kept in airtight plastic bottles to trap any hydrogen sulphide released (Figure 62). Samples were stored at 20 C in a similar manner to other paste specimens. 

In another approach, XRF analysis was carried out on a sample of original blended powder and paste samples prepared with 5, 10 and 20% extra paper at 1, 14 and 28 days after casting. 

In order to fulfil the requirements for concrete, stabilised soil and paste for the site trial, over 100 tonnes of blended powder was prepared at Ryder Point Processing in Matlock in Derbyshire (www.thebgs.co.uk/foundation-web). The blended powder consisted of 80% ground BOS, 15% giound PG and 5% BPD supplied as blended powder. 

Pre-blending the material facilitates its use in ready-mix plants or with other types of mixing methods. The pre-blended powder was easy to use, like ordinary cement, with no further work or preparation required. 

Figure 15. Variation of the glass transition temperature, Tg, against weight % composition for spray-dried, low moisture powders prepared from aqueous solution blends of Lodex 10 (10 DE maltodractrin) and Maltrin M365 (36 DE com syrup solids) SHPs. (Reproduced with permission from reference 26. Copyri t 1989 Elsevier.)...

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