Wood and its properties = Древесина и ее свойства. Учебное пособие

UNIT 4

EXPOSURE TO CHEMICALS

1. Read the following words and state what Russian words help to guess their meaning.

Strength, alkaline, resistance, oxidation, exposure, hardwoods, cypress, redwood, lumber, cedar, plywood, hardware, fastener, waterborne, weakening.

2. Check up if you remember the following verbs.

To reduce, to penetrate, to decay, to promote, to occur, to tend, to loose, to avoid.

3. Match the following word combinations.

4. Read and translate the text into Russian.

CHEMICAL DETERIORATION

The strength of wood may be reduced by exposure to severe acidic or alkaline environments; yet wood is more resistant than steel to acidic

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conditions. Chemical fertilizer and highway salt storage buildings are often built from wood because of its ability to resist corrosion and deterioration when in contact with these chemicals. Chemical deterioration of the cell wall can result in loss of strength from hydrolysis of cellulose, oxidation, or delignification by alkalis. The strength of wood may be reduced by exposure to severe acidic or alkaline environments Softwoods tend to be more resistant to chemical deterioration than hardwoods. Woods that are less permeable to moisture movement tend to be more resistant because the chemicals penetrate more slowly. For this reason, under conditions where chemical deterioration might occur, white oak is preferable to red oak, Douglas fir heartwood to sapwood, and old - growth cypress to second - growth. Cypress, Douglas fir, southern pine, and redwood are often used where contact with acidic materials or conditions are expected. A type of chemical deterioration can also occur around iron or steel fasteners such as nails or bolts. When moisture is present in acidic woods or those that contain high extractive levels, particularly tannins, a chemical reaction occurs that produces iron salts. With high moisture, these salts can act as galvanic cells and promote localized weakening of the wood around the fastener and reduce the natural resistance of the wood to decay. This action may continue until the nail or other connector is corroded and becomes loose in the wood. This effect is sometimes seen in old unpainted buildings where it is easy to pull nails from the lumber. It is also a nontrivial issue with some types of metallic salt - type preservatives. When using nails in an exterior application with redwood, cedar, oak, or cypress, or when fabricating structures with waterborne salt - based treated (such as ammoniacal copper quaternary [ACQ] compound) lumber or plywood, it is always advisable to use specially coated or stainless steel fasteners and hardware to avoid such problems.

[From: Shmulsky R., Jones P. D. Forest Products and wood science / R. Shmulsky, P. D. Jones. – US : Willey-Blackwell, 2011. – P. 221]

5. Read the following statements and define whether they are true or false according to the text.

1.Chemical fertilizer and highway salt storage buildings are often built from wood.

2.Long - term exposure can`t ultimately reduce wood to pulp.

3.Woods that are less permeable to moisture movement tend to be more resistant because the chemicals penetrate faster.

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4.Hardwoods tend to be more resistant to chemical deterioration than softwoods.

5.A type of chemical deterioration can also occur around iron or steel fasteners such as nails or bolts.

6.When moisture is present in acidic woods or those that contain high extractive levels, particularly tannins, a chemical reaction occurs that produces iron salts.

7.Where chemical deterioration might occur, white oak is preferable to red oak.

8.It is always advisable to use specially coated or stain steel fasteners and hardware to avoid problems.

9.Cypress, Douglas fir, southern pine, and redwood are often used where contact with acidic materials or conditions are expected.

10.When moisture is present in acidic woods or those that contain high extractive levels a chemical reaction occurs that produces iron salts.

6. Give the English equivalents for the words and word combinations given below and memorize them.

Кислая и щелочная среда, делигнификация щелочами, твердая древесина, южная сосна, локализованное ослабление, кедр, дуб, кипарис, крепежные детали из нержавеющей стали, пиломатериалы, фанера, экстрактивные уровни.

7. Give the Russian equivalents for the words and word combinations given below.

Acidic conditions, steel fasteners, waterborne salt, moisture movement, salt storage, acidic woods, nails, oxidation, coated or stain steel, softwoods, galvanic cells, hydrolysis of cellulose, strength of wood.

8. Translate the following sentences from Russian into English.

1.Склады с химическими удобрениями и солями часто строятся из дерева.

2.Ухудшение химических свойств клеточной стенки может привести к потере прочности в результате гидролиза целлюлозы, окисления или делигнификации щелочами.

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3.Длительное воздействие химических соединений может, в конечном счете, изменить древесину до древесной массы.

4.Любой тип химического разрушения может происходить под воздействием железного или стального крепежа, а именно гвоздей или болтов.

5.При высокой влажности соли металлов могут выступать в качестве гальванических элементов и способствовать локализованному ослаблению дерева и уменьшать сопротивление древесины к гниению.

6.Проблема может возникать с некоторыми типами солей металлов.

7.Желательно использовать нержавеющую сталь или крепеж (оборудование) из нержавеющей стали, чтобы избежать проблем.

8.В условия, когда может произойти ухудшение химических свойств, белый дуб предпочтительнее красного дуба.

9.Прочность древесины может быть уменьшена под воздействием тяжелых кислот и щелочной среды.

10.Хвойные, как правило, более устойчивы к химическому износу, чем лиственные породы.

9. Fill in the gaps.

1.Chemical deterioration of the cell wall can result in loss of strength from

………of cellulose, oxidation, or delignification by……….

2.The strength of wood may be reduced by …………acidic or alkaline environments.

3.Softwoods tend to be more resistant to chemical ……….than hardwoods.

4.Douglas fir heartwood to sapwood, and old - growth cypress to second - growth. Cypress, Douglas fir, southern pine, and redwood are often used where …………….or conditions are expected.

5.When moisture is present in acidic woods or those that contain high…………, particularly tannins, a chemical reaction occurs that produces …….salts.

6.This action may continue until the …….or other connector is corroded and becomes ………in the wood.

7.This effect is sometimes seen in old …………where it is easy to pull nails from the lumber.

8.When using nails in an ……………..with redwood, cedar, oak, or cypress, or when fabricating structures with waterborne salt - based treated (such as ammoniacal copper quaternary [ACQ] compound) lumber or…………, it is always advisable to use specially coated or stainless steel

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fasteners and ………..to avoid such problems.

9.Сhemicals penetrate more………..

10.Yet wood is more resistant than steel to…………….

10. Translate the following phrases.

Steel fasteners, кислотные условия, unpainted buildings, высокая влажность, acidic materials,южная сосна, hardwood to sapwood,

гидролиз целлюлозы, lumber or plywood, локализованное ослабление, delignification by alkalis, уменьшать сопротивление древесины, extractive levels, прочность в результате гидролиза, waterborne salt.

11. Check yourself with the following questions.

1.Why are chemical fertilizer and highway salt storage buildings often built from wood?

2.What can chemical deterioration of the cell wall result in?

3.What may the strength of wood be reduced by?

4.What kind of wood tend to be more resistant?

5.Why do woods that are less permeable to moisture movement tend to be more resistant?

6.When can chemical reaction that produces iron salts occur?

7.How can salts act in high moisture?

8.What is always advisable to use to avoid chemical deterioration?

9.What kind of steel is preferable to use while wood treating?

10.Why do softwoods tend to be more resistant then hardwoods?

12. Make a summary of the text.

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UNIT 5

IMPACT ON SPECIFIC GRAVITY

1. Read the following words and state what Russian words help to guess their meaning.

Quantities, extractives, infiltrates, terpenes, resins, tannins, silicates, carbonates, maturation, sapwood, cavity, fluctuations.

2. Check up if you remember the following verbs.

To contain, to include, to remain, to vary, to remove, to determine, to tend.

3. Match the following word combinations.

4. Read and translate the text into Russian.

EXTRACTIVES AND INORGANIC MATIRIALS

Wood often contains measurable quantities of extractives and infiltrates including terpenes, resins, polyphenols such as tannins, sugars, and oils as well as inorganic compounds such as silicates, carbonates, and phosphates. These materials are located within the cell wall, where they are deposited during the maturation of the secondary wall and as remnants in

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the cell cavity after heartwood formation. Thus, heartwood has higher concentrations of these materials than sapwood; therefore, the density of heartwood is often slightly higher than that of sapwood.

The amount of extractives in wood varies from less than 3 to over 30 percent of the OD weight. Obviously, the presence of these materials can

to observed specific gravity variation. The specific gravity of wood from which extractives have been removed tends to be more uniform than if the weight of extractives is included. In research work, it is often desirable to determine the density of the wood without extractives. Both water and organic solvents are used for extraction when determining extractive - free density. Some of the bulking effect is lost when extractives are removed, so in addition to weight loss, samples tend to show greater dimensional change with moisture fluctuations.

[From: Shmulsky R., Jones P. D. Forest Products and wood science / R. Shmulsky, P. D. Jones. – US : Willey-Blackwell, 2011. – P. 181]

5. Read the following statements and define whether they are true or false according to the text.

1.Wood often contains measurable quantities of extractives.

2.The density of sapwood is often slightly higher than that of heartwood sapwood.

3.The amount of extractives in wood varies.

4.The specific gravity of wood from which extractives have been removed tends to be more uniform.

5.In research work, it is often desirable to determine the density of the wood.

6.Some of the bulking effect is lost when extractives are removed.

6. Give the English equivalents for the words and word combinations given below.

Изменение размера, органические растворители, существенное влияние на плотность, быть более однородным, масса эктрактивных веществ, измеряемые величины, свободная плотность, колебания

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влажности, высокая концентрация, потеря веса, исследовательская работа, полость клетки, присутствие материалов, период созревания.

7. Give the Russian equivalents for the words and word combinations given below.

Sapwood, a major effect, water and organic solvents, determining extractive, heartwood, heartwood formation, weight loss, desirable to determine, remnants in the cell cavity, higher concentrations.

8. Translate the following sentences from Russian into English.

1.Древесина часто содержит количество экстрактивных веществ, которые можно измерить.

2.Материалы могут быть расположены в клеточной стенке.

3.Количество экстрактивных веществ в древесине изменяется.

4.Наличие этих материалов может оказать существенное влияние на плотность.

5.У некоторых видов, в том числе сосны, было показано, что наличие экстрактивных веществ помогает наблюдать специфическую гравитационную вариативность.

6.В научно-исследовательской работе желательно определять плотность древесины без экстрактивных веществ.

9. Fill in the gaps.

1.These materials …………within the cell wall.

2.Heartwood has higher concentrations of these materials than ……….

3.In research work, it is often desirable to determine …….of the wood without extractives.

4.In some species, including pine, ………….that the presence of extractives contributes significantly.

5.Both water and organic solvents …………………….when determining extractive - free density.

6.Some of the bulking effect is lost when ………….are removed.

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10. Translate the following phrases.

Measurable quantities, количество экстрактивных, determining extractive,

клеточная стенка, presence of extractives, гравитационную вариативность, bulking effect, существенное влияние, major effect, влажность, tend to show, включение экстрактивных веществ, desirable to determine.

11. Check yourself with the following questions.

1.What do extractives and infiltrates include?

2.Where are the materials located?

3.Does heartwood have higher concentrations of these materials than sapwood?

4.What is the range of the amount of extractives in wood?

5.What can we observe with the presence of extractives?

6.What is used for extraction when determining extractive - free density?

12. Make a summary of the text.

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UNIT 6

FIRE RETARDANT

1. Read the following words and state what Russian words help to guess their meaning.

Heat, carbon, timber, humidity, gypsum, ammonium, beam, insulator, combustion, ceiling, lumber, resistance, breakdown.

2. Check up if you remember the following adjectives.

Flammable, volatile, retardant, incorporate, heavy, thermal, combustible, hygroscopic, proper, commercial, common.

3. Match the following word combinations.

4. Read and translate the text into Russian.

HEAT AND FIRE

When wood is heated above about 100 ° C (212 ° F), molecular decomposition occurs. If the temperature is between 100 and 200 ° C (212 and 392 ° F), decomposition occurs slowly. Water vapor is driven off along with carbon dioxide and carbon monoxide. Flammable gases volatilize at

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