Quick setting

Precipita.tlon. An ink may also be caused to dry by precipitation of its binder rather than by evaporation of solvent. This can be accompHshed by a dding a diluent, such as water in the form of steam or humidity, to a hygroscopic solvent ink system, which causes the solubiHty of the resin in the ink film to decrease sharply and causes it to precipitate when its tolerance for the diluent is reached. Eurther drying is accompHshed by absorption of the solvents into the stock and then by evaporation. Another form of precipitation setting is the quick-set mechanism. This utilizes resins held in solution in a relatively poor solvent, by means of a small amount of an exceUent solvent (called a sweetener) blended with it. When the ink film is printed on the paper, an amount of the solvents is absorbed reducing the content of the sweetener solvent to a point which causes the resins to precipitate and the ink to set. 

Fumaric acid occurs naturally in many plants and is named after Fumaria officinalis, a climbing aimual plant, from which it was first isolated. It is also known as (E)-2-butenedioic acid, aHomaleic acid, boletic acid, Hchenic acid, or /n j -l,2-ethylenedicarboxylic acid. It is used as a food acidulant and as a raw material in the manufacture of unsaturated polyester resins, quick-setting inks, furniture lacquers, paper sizing chemicals, and aspartic acid [56-84-8]. 

A useful mnemonic device for quickly setting down the HMOs for cyclic systems is Frosts circle.If a regular polygon of n sides is inscribed in a circle of diameter 4/3 with one comer at the lowest point, the points at which the comers of the polygon touch the circle define the energy levels. The energy levels obtained for benzene and cyclobutadiene with Frost s circle are shown in Fig. 1.12. 

High-alumina cement is very quick setting, but its acid resistance is only slightly better than Portland cement, and it is rapidly attacked by alkalis. Super-sulfated cement is used for liquors high in sulfates. It is resistant to acidic conditions down to a pH of 3.5 and has alkali resistance similar to Portland cement [50]. 

Schneise,/. path, lane, track, course, schnell, a. fast, rapid, quick, sudden. — adv. quickly, rapidly, -abbindend, a. quick-set-ting. 

The criteria that must be satisfied for quick setting jelly desserts are as follows ... 

Table 7.4 Comparative features of gel-systems evaluated for use in quick setting jelly products. CWS = cold water soluble, LBG = locust bean gum.

Gel coat In RP processing a gel coat on the outer surface can be used to ensure a smooth surface appearance and a tough surface. It could contain a thin synthetic fiber veil to improve performance of the gel coat and/or a surfacing mat. It is a quick setting plastic and gelled prior to reinforcement layup. The gel coat becomes an integral part of the finished RP product. 

Acid-base (AB) cements have been known since the mid 19th century. They are formed by the interaction of an acid and a base, a reaction which yields a cementitious salt hydrogel (Wilson, 1978) and offers an alternative route to that of polymerization for the formation of macro-molecular materials. They are quick-setting materials, some of which have unusual properties for cements, such as adhesion and translucency. They find diverse applications, ranging from the biomedical to the industrial. 

Semler, C. E. (1976). A quick-setting wollastonite phosphate cement. American Ceramic Society Bulletin, 55, 983-8. 

Smith, D. C. (1960). A quick-setting zinc oxide/eugenol mixture. British Dental Journal, 108, 232. 

These cements are defined as materials that are formed by mixing a basic powder with an acidic liquid, and offer an alternative to polymerization as a method for forming solid substances. They are quick-setting materials, with unusual properties, which find diverse applications as biomaterials and in industry. 

I m glad you chose option four. I ve taught chemistry for over 30 years. I ve put together in this book, what I believe are the most up-to-date type of questions that you will experience on the AP Chemistry Exam. Each question is thoroughly explained, and the format of each practice exam is exactly what you will see when you take the actual exam. With other AP exams to study for and other time commitments, you need a quick set of practice exams that will cover everything you need to know. With CliffsAP Chemistry, 3rd Edition to help you cover in more detail the topics covered in the practice exams, you will be absolutely prepared. 

Zallie, J. (1988). Benefits of quick setting starches. Manufacturing Confectioner, 66,41 3. 

Zinc oxide has a wide range of uses apart from its use as an artist s pigment where it provides a more translucent white than flake white or titanium white. It is used in cosmetics, driers, quick-setting cements with syrupy phosphoric acid or zinc chloride in dental cement in the manufacture of opaque glass, enamels, car tyres, white glue, matches, white printing inks and porcelain. The photophysics of zinc oxide has been reviewed.1468 ... 

The soluble sulfate versus time curve for the cement containing the natural anhydrite is radically changed when CLS is present [130, 131]. The rate of solution of natural anhydrite, which is much slower than that of gypsum or calcium sulfate hemihydrate, is further retarded in the presence of chemical admixtures, which leads to a sulfate-starved system in the concrete, often producing rapid set and an increase in rate of concrete slump loss (Fig. 7.42). Apparently the adsorption of the lignosulfonate by the natural anhydride plus the rapid reaction between the soluble SO and the tricalcium aluminate keeps the SO level near zero concentration for the first 10-20 min causing rapid stiffening and quick set (approximately 15 min). It is also reported that chemical... 

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