· n the United States, plastics are made from liquid petroleum gases (LPG), natural gas liquids (NGL), and natural gas. LPG are by-products of petroleum refining, and NGL are removed from natural gas before it enters transmission pipelines. · In 20101, about 191 million barrels of LPG and NGL were used in the United States to make plastic products in the plastic materials and equal to about 2.7% of total U.S. resins industry, petroleum consumption. Of those 191 million barrels, 190 million barrels were used as feedstock and 1 million barrels were consumed as fuel · In addition to petroleum, natural gas is used to manufacture plastic materials and about 412 billion cubic feet (Bcf) of resins. In 2010, natural gas were used to make plastic materials and resins, equal to about 1.7% of total U.S. natural gas consumption . Of
other biomass based fuels are used. All these fuels are considered as renewables and according to the international agreement the CO2 emitted by the combustion of these fuels is not listed as a greenhouse gas. Wood, in particular the shell of wood cells, consists mainly from cellulose, lignin and hemicellulose. Due to the high carbon and hydrogen content, the lignin has higher calorific value than cellulose and hemicellulose. In smaller quantities the wood contains also tar, resins and phenols that can cause fouling of heat transfer surfaces and stack interior with the deposits that are difficult to remove From the point of view of combustion technology and practical use of fuels the following properties of fuels are of most interest: chemical composition, moisture, density, fly and bottom ash content, ash melting characteristics and content of impurities (soil, dust, etc.) in the fuel. Chemical composition of wood % in dry matter
klaasistumistemperatuuri. Tulemuseks on ristseotud, välistingimustele ja lahustitele vastupidav, kõrgete mehhaaniliste omadustega jäik maatriksvaik. Siinkohal on jutt summaarsest protsessist, millel on tegelikult palju vaheastmeid. Viimaseid uuritakse soojusefektide alusel TTT diagrammide alusel (Time Temperature Transformation). Tuntumad maatriksvaigud: *Epoksüvaigud *Fenoolformaldehüüdvaigud *Polüestervaigud *Polümiidvaigud Epoksüvaigud Epoksüvaigud (epoxy resins) moodustavad üle 90 % kõikidest plastkomposiitide sideaineks kasutatavatest vaikudest. Nende eelis on head töödeldavus; neist saab valmistada eelimpregneeritud materjale prepreg'e (prepreg preliminary impregnated), millest hiljem valmistatakse plastkomposiittooteid. Epoksüvaigud molekulis epoksürühmi sisaldavad sünteetilised mono- või oligomeerid, mis kõvendiga segatult on termoreaktiivsed; vedelad või tahked läbipaistvad helekollased või
shoe-care agents, carpet cleaners, glues and adhesives, lacquers, paper, plastics, and some types of wood products. Some people are exposed to higher levels of formaldehyde if they live in a new mobile home, as formaldehyde is given off as a gas from the manufactured wood products used in these homes. Formaldehyde is used in many industries. It is used in the production of fertilizer, paper, plywood, and urea-formaldehyde resins. It is present in the air in iron foundries. It is also used in the production of cosmetics and sugar, in well-drilling fluids, in agriculture as a preservative for grains and seed dressings, in the rubber industry in the production of latex, in leather tanning, in wood preservation, and in photographic film production. Formaldehyde is combined with methanol and buffers to make embalming fluid. Formaldehyde is also used in many hospitals and laboratories to preserve tissue specimens.
143. (a) (i) amylase; 1 (ii) glycosidic; R glucosidic 1 (iii) alpha / α; 1 (b) (i) encapsulation / trapped in alginate beads; adsorption or stuck onto, collagen / clays / resins; cross linkage or covalent / chemical bonding to, cellulose (fibres); gel entrapment / trapped in silica gel; partially permeable membrane microspheres; max 2 (ii) does not mix with / does not contaminate / stays separate from, the product; ref to, no / less / easier, downstream processing; recoverable / not lost during processing;
phrase. 1. Great technological advances were made during the infancy of the United Stages' industrial growth. (A) Zenith (B) Expansion (C) Beginning (D) Recovery 2. Many cross-cultural communication difficulties can be attributed to inevitable blunders in behavior or speech. (A) Unwarranted (B) Unlikely (C) Unavoidable (D) Unpleasant 3. Teflon was inadvertently discovered by two scientists who were working with synthetic resins. (A) Unexpectedly (B) Miraculously (C) Systematically (D) Conscientiously 4. The sport of basketball highlights the athletic qualities of endurance, agility, and skill. (A) Demands (B) Encompasses (C) Emphasizes (D) Develops 5. Daniel Webster applied the oratorical skill he had mastered as a lawyer to heighten his appeal for an end to slavery. (A) Intensify (B) Convey (C) Retrieve (D) Popularize LESSON 17 agitate confidential delighted discreetly documented
partial burning of wood with a limited oxygen of the aerosol. The dispersed components supply. Generally, hardwood is used, mainly absorb and disperse light; thus their concen- oak and beech. However, for imparting spe- tration affects the optical density of the cific color or flavor to some products, wood smoke. The optical density is proportional to from other trees that are rich in resins, includ- the number of particles in a unit volume of ing coniferous, as well as heather, may be the smoke. In constant conditions, when the used. In some areas, other carbohydrate- dimensions of the particles do not change, the rich material (e.g., bagasse [sugarcane], beet optical density is correlated to the mass con- refuse from sugar making, or coconut husks) centration of the dispersed components in the is used
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