Casting and curing

Curing is often done under sealed conditions, as this minimises drying and carbonation. The vessel should be water vapour tight, which could be achieved using a vessel with a screw cap and sealed with Parafilm, like 

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Flares. A flare compn is described in Refs 15 16 contg powd Mg, Na perchlorate, and a binder which can be cast and cured, and which has a luminous intensity of 50,500 candle-secs/g Incendiaries. A mixt of 1 OOg of Na perchlorate and 58.7g of powd Al has a Qr of 2751cal/g and can be used as a filler for incendiary bombs (Ref 6). A proc is described in Ref 14 for coating Na perchlorate with Al, and the use of the coated material in incendiaries Photo flash Compositions. Mixts of 80% Ca metal and 20% Na perchlorate and 80% Ca, 10% Na perchlorate, and 10% Na nitrate have been examined as expl photoflash compns for both sea level and high altitude use (Ref 13) Refs 1) Gmelin, System No 21 (1928), 408 Supp Part 1 (1964), 180 2) H.H. Willard ... 

Quartz fine aggregate and normal Portland cement were used to prepare mortar with a w/c of 0.5. A cylindrical specimen, 43 mm in diameter and 50 mm long, was cast and cured under sealed conditions for 3 days at 23 °C. The specimen was then oven dried at 105 °C for 1 day prior to exposure to lithium nitrate solution. The specimen was then placed such that the bottom of the cylinder was submerged approximately 1-2 mm into a lithium nitrate solution with Teflon tape applied to the curved surface. 

Additional drawbacks to the use of polyimide insulators for the fabrication of multilevel structures include self- or auto-adhesion. It has been demonstrated that the interfacial strength of polyimide layers sequentially cast and cured depends on the interdiffusion between layers, which in turn depends on the cure time and temperature for both the first layer (Tj) and the combined first and second layers (T2) [3]. In this work, it was shown that unusually high diffusion distances ( 200 nm) were required to achieve bulk strength [3]. For T2 > Tj, the adhesion decreased with increasing T. However, for T2 < Tj and Tj 400 °C, the adhesion between the layers was poor irrespective of T2. Consequently, it is of interest to combine the desirable characteristics of polyimide with other materials in such a way as to produce a low stress, low dielectric constant, self-adhering material with the desirable processabiHty and mechanical properties of polyimide. 

First, discussing the established production methods, the steps in propellant processing are oxidizer preparation, fuel preparation, propellant mixing, cast, and cure. A standard practice in industries handling... 

Materials. The materials are described in detail in the studies summarized in Table I. Most of these results are based on kraft lignin. The NCO/OH ratio of all of these networks were high greater than 1.5. All of the networks were prepared from homogeneous solutions of the lignin-based polyol, added (soft segment) polyol, and diisocyanate. Films were cast and cured under mild conditions with a controlled loss of solvent. The films were post-cured to insure complete reaction (25). 

The mixture leaving the apparatus must be de-aerated. The air is removed from the solid s-liquid dispersion by a centrifugal separator before the propellant is vacuum cast and cured. 

Elastic-gel comp proplnt is prepd by milling oil-extended GR-S rubber (contg 100 parts rubber 30 ps oil) with 5 ps RPA No 3 (A 36.5% soln of xylyl mercaptan in a hydrocarbon solvent), 5 ps ZnO 1 part stearic acid. Then 300 ps oil is added, in small increments, followed by Captax 12, Tuads 6, diphenylguanidine 18, C black 20, sulfur 6 and finally AN (50-100 mesh) 1892 parts. The batch is mixed 60 mins, deaerated, cast and cured for 24 hrs at 220°F] DD)C.C.Rice W.B.Reynolds, USP 2993769 (1961) CA 55, 27891 (1961) [Comp proplnt prepd by mixing petroleum pitch with a polymer, a phase -stabilized Amm nitrate Amm dichromate. 

It was found that 5-nm-thick resist-mask polysilane films worked well in a direct lithography process on silicon substrates, resulting into a line width of 40 nm prepared by scanning probe microscope lithography, using a carbon nanotube tip.57 Thin PMPS films of 6—8 nm, with a molecular weight of 30,000 were prepared by spin casting and cured at 150°C to obtain a smooth surface. It has been interpreted that moisture was essential for the oxidation of the polysilane. The proposed mechanism involved dissociation of Si-Si bonds in polysilane by the electron injection from the carbon nanotube tip catalyzed by moisture. 

A few papers dealing with silicone latex IPNs have appeared. Frisch et al. [ 111 ] patented a process whereby two emulsions were prepared the first contained a hydroxyl-terminated PDMS and stannous octoate, the second a crosslinked polyurethane, poly(urethaneurea) or polyacrylate latex. The two lattices were blended and a film was cast and cured at 120 °C. The mechanical properties were found to be enhanced, especially in the case of the polyacrylate/PDMS IPN. Noteworthy is the fact that semi-IPNs such as the thermally stable... 

Rocket compositions of both double base and composite type are shaped into the desired form (e.g., star-shaped configurations) on extrusion or screw-type presses through a die or by casting and curing. 

Eighteen 2-in. (50-mm) diameter steel balls were included to provide impact to the concrete cubes in addition to the free fall that occurs when the drum is rotating. The number of specimens per batch was eighteen 2-in. (50-mm) cubes, which were cast and cured in a moisture chamber for 28 days according to ASTM C 192-90a. 

Films containing the diamic acid additives were prepared by dissolving 3-15 weight percent (based on resin solids) of the additives into the polyamic acid solutions, then casting and curing as above. 

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