20CYT22-CHEMISTRY FOR MECHANICAL SYSTEMS�UNIT - I�

Dr.A.Geetha

Associate Professor

Department of Chemistry

Kongu Engineering College

20CYT22-CHEMISTRY FOR MECHANICAL SYSTEMS

UNIT - I

Lubricants - functions – requirements - classification with examples –properties: viscosity, viscosity index, flash and fire point, cloud and pour point, oiliness, aniline point and carbon residue – Explosives – requirements – classification – manufacture of important explosives (TNT, GTN and RDX) – Rocket propellants – properties and classification – Refractory bricks – criteria of a good refractory material – classification – properties: refractories, RUL, porosity, thermal spalling, thermal conductivity and dimension stability – general method of manufacturing of refractories – Insulators – classification with examples, thermal insulators and electrical insulators – characteristics of insulating materials.

Lubricants

Lubricants – A substance, which when applied between two moving parts reduces friction by introducing a slippery film between the two surfaces.

Lubrication - process of reducing friction and wear between two moving surfaces by applying lubricant in between the moving parts.

Characteristics of Good Lubricant

• Should possess good thermal stability
• Should have high boiling point and low freezing point
• Should have high flash and fire point than the operating temperature
• Should have high oiliness, viscosity index and aniline point
• Should show high resistance towards oxidation and corrosion
• Should have low cloud and pour points than the operating temp of the machine
• Should have higher aniline point
• Should have good detergent quality

Functions of Lubricants

Functions of Lubricants

• To keep moving parts apart - The thin layer of lubricant acts as physical barrier between the moving parts thereby reducing friction, surface fatigue and also reduces heat generation, operating noise and vibrations. This is termed as hydrodynamic lubrication.
• To reduce friction – reduced friction results in reduced heat generation and reduced formation of wear particles which in turn will results in improved efficiency. Additives known as friction modifiers are added to lubricants to reduce surface friction.
• To protect against wear - lubricants prevent wear by keeping the moving parts apart. Lubricants may have anti wear or extreme pressure additives to enhance their performance against wear and fatigue
• To transfer heat – Gaseous lubricant transfers heat, liquid lubricants transfer heat as well as reduces

thermal stress.

• To carry away contaminants and debris – lubricants have the capacity of carrying away internally

generated debris and contaminants introduced into it.

• To prevent corrosion – lubricants having additives form chemical bonds with surfaces to prevent corrosion and rust.
• To seal gases- lubricants seal the space between moving parts through capillary force. This is known as seal pistons and shafts.

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Classification of Lubricants - classified based on their physical state as

1.Gaseous Lubricants

• Have lower viscosity and higher compressibility. Ex: air, steam

2.Liquid Lubricants

• Ex: Water, mineral oil-naphthenics, PAO, lanolin (also acts as corrosion inhibitor), vegetable

oil-palm, castor, sunflower oil & whale oil.

3.Solid Lubricants

• Used at high temp, because of their lamellar structure they are effective in the form dry powder
• Graphite- in an oxidative atmosphere, graphite is effective at high temp around 450°C.

For good lubrication water vapour is necessary & not effective in vacuum.

• Molybdenum disulphide (MoS₂): has hexagonal crystal str. It works better than graphite and

effective in vacuum. It oxidizes beyond 400°C hence it can be used up to 400°C.

• Boron nitride (BN): The hexagonal form of BN has lubricating property, can be used at

high temperatures up to 1200°C and in oxidizing atm.

• Polytetrafluoroethylene (PTFE): Dispersions of PTFE in oil and water show lubricating � action. Performs up to 260°C. Unlike other solid lubricants PTFE does not have layered structure.

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• Mixture of lubricants like MoS₂, PTFE and anti-friction & anti-wear additives with polymers

and sintered ceramic powders is called Self lubricating composites.

4. Semisolid Lubricants

• Contains thickening agents like soaps of Na,Ca,Li or Al mixed with liquid lubricant.

Ex. Greases- 80% mineral oil + 10% soaps + 10% additives (inhibitors, antioxidants, antiwear)

• Lithium based greases- water, dust and coal resistant. Used in the temp range 15-130°C
• Calcium based greases (cup greases)- water resistant, can be used up to 70°C, at high temp � mineral oil and soap separates out.
• Aluminium based greases-have highest resistance to water and acids. Can be used up to 80°C.
• Sodium based greases-slightly soluble in water hence cannot be used in wet conditions. Can be

used up to 120°C.

• Non-soap greases-lubricating material dispersed in matrix of fine clay. These are also called as � high performance greases due to their broad range of temp performance.

5. Metals/Alloys Lubricants

• Used in sliding surfaces and bearings. Ex. Pb, Sn,Zn alloys are used in sliding bearings.

Properties of Lubricants

1.Viscosity

• It is the property of any liquid which is a measure of its resistance to flow. If viscosity of oil

is low, excessive wear takes place. If viscosity is too high, friction between layer increases.

• Viscosity of lubricating oil should be consistent over a wide range of temperatures.

2.Viscosity Index (VI)

• It is an arbitrary scale, used to determine the variation of viscosity of a fluid with temperature.
• Higher viscosity index - change of viscosity with temp is smaller.
• Low viscosity index - viscosity of lubricating oil changes rapidly.
• Good lubricant should have high VI.

3. Flash and Fire Point

• Flash and fire point - determine the volatility, fire resistance and uses of lubricant at high

operating conditions. Flash point is important in determining shipping, storage and safety.

• Variation in flash and fire indicates the contamination of lubricant.

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• Flash point – lowest temp at which the lubricating oil gives off enough vapours to ignite but

not burn when small flame is brought near to it.

• Fire point – lowest temp at which the vapours of oil burn continuously for at least 5s,

when flame is brought near to it. Good lubricant should have flash point above the temp at which it is to be used. Fire points are 8-10% higher than the flash point.

4.Cloud and Pour Points

• Cloud point – The temp at which lubricating oil becomes cloudy or hazy in appearance when it is slowly cooled.
• Pour point – the temp at which lubricating oil ceases to flow or pour when it is cooled slowly.
• Cloud and pour point indicate the suitability of lubricant in cold conditions as well as identifying the source of oil.
• Lubricant should possess low pour point to avoid solidification in low temp applications.

5. Oiliness

• Ability to stick on to the surface of machine parts, under pressure or load. Lubricants with

good oiliness stay on between the lubricated surfaces.

• Poor oiliness of lubricant has a tendency to squeeze out when subjected to load or pressure.
• Mineral oil possess low oiliness, can be improved by adding additives like vegetable oil.

6. Aniline Point

• Aniline point – indicates the possible deterioration of oil in contact with rubber used in packing.
• Higher aniline point means lubricant contains higher percentage of paraffinic hydrocarbons

and a lower percentage of aromatic hydrocarbons. Aromatic hydrocarbons have a tendency

to dissolve certain types of rubber hence their low level is desirable in lubricants.

7. Carbon Residue

• Lubricants are carbon rich compounds and on heating to high temp, these get deposited as

carbon residue.

• Carbon residues deposits are harmful for IC engines and air-compressors.
• Good lubricant should have low-carbon residue.

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EXPLOSIVES

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• Explosives are chemical compounds.

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• An explosive is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of  light, heat, sound and pressure.

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• Explosive may be a pure single compound or mixture of compounds.

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• They undergo decomposition rapidly under the influence of mechanical or thermal shock.

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• Explosives undergo exothermic chemical reaction.

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• During explosion, lot of energy and heat is released along with larger volume of gases.

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• Requirements of good explosives
• Should be inexpensive and stable under room temp.
• It must have at least one weak chemical bond that can be easily broken
• Its molecules should have low energy of dissociation.
• The rate of decomposition should be fast to produce large volume of gaseous products exothermally
• Explosive materials usually contains N-N,N-O,N-Cl, and O-Cl bonds.
• Normally one volume of explosive at room temp, yields about 10 to 15 volumes of hot gases.
• The bonded nitrogen in an explosive is usually liberated as nitrogen gas.
• Should have a positive oxygen balance.

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• Oxygen balance :
• A GOOD EXPLOSIVE MUST HAVE POSITIVE OXYGEN BALANCE.
• It is the amount of oxygen present in a molecule.
• This oxygen is used to convert C into CO2 and H into H2O.
• It is also expressed as a percentage surplus or deficiency of oxygen by weight.

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• The molecule is said to have a positive oxygen balance if it contains more oxygen than is needed to oxidize C and H to CO₂ and H₂O respectively then the combustion will be complete.

Classifications of Explosives

Explosives are classified on the basis of their sensitivity, velocity & physical forms

1. Classification based on sensitivity

1. Primary explosives
1. Relatively small amount of energy is required for initiation
2. Explosive is extremely sensitive to impact, friction, heat, static electricity and electromagnetic radiation.
3. They are used to initiate the explosion of large quantities of less sensitive explosives
4. Ex. Lead azide, mercury fulminate, tetracene and diazodinitro phenol.

b. Secondary explosives

• Less sensitive than primary explosive. Require substantially more energy to initiate.
• They are safe to handle and store. Ex. TNT, picric acid and RDX.

c.Tertiary explosives (blasting agents)

• Insensitive to shock and cannot be reliably detonated by primary explosives, need

secondary explosives for detonation.

• Used in mining, construction and terrorism. ex. Ammonium nitrate/ fuel oil

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High explosives are further classified into

i. Single compound explosives- contain only one chemical compound.

Ex. Ammonium nitrate- stable, non-toxic & cheap.

Picric acid- used as a booster to detonate another less sensitive explosive like TNT

ii. Binary explosives- it is a mixture of TNT with other explosive. It is heated to liquid state and poured

into the container then allowed to solidify. Ex. Pentotile- mixture of 50% TNT and 50% PETN.

iii. Plastic explosives- combination of explosives in plastic state and are hand-moulded or

press-loaded Into various shapes. Ex.PETN

iv. Dynamites- Contains nitroglycerine. It is an oily liquid, which detonates by pressure, shock,

temp above 50°C. Different types of dynamites are

• Straight dynamites - contains 15% to 60% nitroglycerine in carbonaceous fuel with sodium nitrate.

used for blasting hard rocks, coal and mineral demolitions

• Gelatin dynamites- contain nitroglycerine partly gelatinized by nitrocotton
• Gun cotton - obtained by soaking cotton for 30 min in a cooled mixture of H₂SO₄, HNO₃ then dried.

explodes rapidly when exposed to fire.

Classification based on physical form

based on physical form explosives classified as

1. Pressings, b. Castings, c. Polymer bonded explosives, d. Rubberized,

e. Extrudable, f. Binary, g. Slurries & gels, h. Blasting agents

Preparation of 2,4,6-trinitrotoluene (TNT)

TNT is synthesized in a three-step process. First toluene is nitrated using mixture of acids to mono-

nitrotoluene. Then its re-nitrated to trinitrotoluene using anhydrous mixture of nitric acid and oleum.

Preparation of Glyceryl Trinitrate (GTN) or nitro glycerin

• It is prepared by mixing pure glycerol with 50:50 mixture of conc.H₂SO₄ & HNO₃
• It is used as a major component in many explosives.
• Dynamite is a mixture of 75% GTN and 25% Kielselguhr.
• Gelatin dynamite - 8% nitrocellulose & 92% GTN

• Preparation of RDX or Cyclonite(cyclotrimethylene trinitramine)
• It is a first nitramine explosive & as powerful as PETN (pentaerythritol tetranitrate) & GTN
• Less sensitive & used in military
• Developed from hexahydro-1,3,5-trinitro-1,3,5-triazine
• War department in Woolwich,UK named it as RDX
• Prepared by treating hexamine with NH₄NO₃ & fuming nitric acid.
• Then the mixture is warmed & treated with cold water to get RDX.

Rocket Propellants

• It is a mixture of fuel and oxidizer (Fuel is a substance that burns when combined with oxygen.

an oxidizer is an agent that releases oxygen for combination with a fuel).

• Combustion takes place quickly in a controlled manner with huge emission of hot gases which exist through a small jet or nozzle at high velocities.
• Fuels used - H₂, hydrocarbon and hydrogen containing compounds like aniline, hydrazine etc..
• Oxidizer - liquid oxygen, ozone, ammonium perchlorate, etc..

Properties of a good propellant

• Should burn at a slow and steady rate.
• Should catch fire in the presence of an oxidizer in a short time.
• Should be safe to handle and store
• Should not leave any solid residue on burning, should produce products like H₂, CO₂, CO, N₂.
• Should be stable, non-corrosive and non-hydroscopic.

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Classifications propellants

Propellants are classified into solid, liquid, gaseous and hybrid

Solid rocket propellant

• Solid propellant also called as grain or stick. It’s a mixture of fuel and oxidizer.
• It is used in launching projectiles from guns, rockets and missile systems.
• Homogeneous solid propellants - mixture of propellants are thoroughly mixed in a colloidal state.
• Single-base propellant – single propellant is used. Ex. Nitrocellulose.
• Double-base propellant – solid propellant contains two materials. Ex. Ballislite has nitrocellulose

and nitroglycerine mixture.

Heterogeneous solid propellants – dispersion of oxidizing agent in a fuel mass. Ex. Gun powder

Liquid rocket propellants

• More versatile and the engine using them can be checked and calibrated easily.
• Monopropellant - homogeneous system has fuel as well as oxidizer. Ex. H₂O₂, nitromethane etc.,
• Bipropellants - liquid fuel & oxidizer injected in the combustion chamber separately.

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Gaseous rocket propellants

• In gaseous rocket propellants, the compressed gas is used in engine

Hybrid rocket propellants

• Mixture of solid and liquid fuel is used.

Few rocket propellants currently used are

• Liquid O₂ & liquid H₂- space shuttle’s main engine & in upper stage of GSLV
• Liquid O₂ & liquid CH₄- development of raptor (Space X) BE-4 engines.
• Liquid O₂ & ethanol – used in German world war II
• Inhibited red fuming nitric acid & hydrazine- Soviet Scud-C, aks SS-1.

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REFRACTORIES

Definition:

Refractories are inorganic materials which can withstand at high temperatures without getting softened or deformed in shape.

Objectives:

• The main objective of the refractory is to confine heat, i.e., to resist heat

loss during the process.

• It should resist the abrasive and corrosive action of molten metals, slags

and gases at high temperatures without getting softened or distorted in

shape.

Applications:

• It is used in the construction of lining converters, kilns, crucibles, furnaces, tanks, etc.
• It is used to manufacture cement, glass, ceramics, steel, paper, metals (both ferrous and non-ferrous), etc.

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Ceramics Refractories

Crucible

Refractories

Criteria Of a Good Refractory Material

• It should be infusible at operating temperatures.
• It should be chemically inert towards corrosive gases, metallic slags and liquids.
• It should resist the abrading action of flue gases, flames, etc.
• It should not undergo cracks and loss in size at operating temperatures.
• It should undergo uniform expansion and contraction with temperatures that both rise and fall mutually.
• It should be able to withstand overlying load of structure at operating temperatures.
• It should have high refractoriness.

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Classification of Refractories

1.Acidic refractories: These are made up of acidic materials like alumina (Al₂O₃) and silica (SiO₂). They are not attacked by acidic materials but can be easily attacked by basic material. Examples: Alumina, silica and fireclay.

2. Basic refractories: These are made up of basic materials, like CaO, Mg, etc. They are not attacked by basic materials, but can be attacked by acidic materials. Examples: Magnesite, and dolomite refractories. 

3. Neutral refractories: These are made from weakly acidic / basic materials, like carbon, chromite, zirconia, etc., are used to prepare neutral refractories.

Examples: Graphite, chromite, zirconia and carborundum refractories.

Properties of Refractories

1.Refractoriness 4. Thermal Conductivity

2.Refractoriness-under load 5. Thermal Spalling

3. Porosity 6. Dimensional Stability

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REFRACTORINESS

Definition: It is the ability of a material to withstand at very high temperatures without appreciable softening or deformation under a particular service condition. Most of the refractories are made up of a mixture of several metallic oxides. They do not have a sharp melting point.

The refractoriness of a refractory material is generally measured as the softening temperature and it is expressed in terms of Pyrometric Cone Equivalent (PCE). It is determined by using the pyrometric cone test.

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Determination of Refractoriness

• Refractoriness is determined by comparing the heat behaviour (softening temperature) of a test cone with that of a series of Seger cones of standard dimensions.
• Seger cones are also known as pyrometric cones. These cones are in pyramid shape and they are a standard refractory material with definite composition and dimensions and hence, it has a definite softening temperature.
• A test cone is prepared (with the same dimensions of Seger cones) from a refractory for which the softening temperature is to be measured and then it is placed along with Seger cones in an electric furnace.

• The furnace is heated at a standard rate of 10°C per minute during which softening of Seger cones occur along with test cone.
• The temperature at which fusion or softening of the test cone occur is measured by the apex of the cone touches the base and is taken as its softening temperature.
• The PCE numbers are found based on the softening temperature of the standard Seger cones.
• If the softening temperature lies between the two consecutive Seger cones, then the PCE number of the test refractory is approximately taken as the average of the two values.
• A good refractory should have high refractoriness.

REFRACTORINESS UNDER LOAD (RUL) (or) STRENGTH

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• The temperature at which the refractory material deforms by 10% is called refractoriness under load (RUL) or its strength.
• The refractories used in industries and metallurgical operations should invariably with- stand varying loads of the products. Hence, refractories should possess high mechanical strength under operating temperatures.
• A good refractory material must be strong enough to withstand compressive loads, tension and stress without deformation at high temperature.
• Generally, the softening temperature decreases with increasing load. The load bearing capacity of a refractory can be measured by the RUL test.

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RUL Test

• The RUL test is conducted by applying a constant load of 3.5 or 1.75 kg/cm² to the test refractory specimen of base 5 cm² and height 75 cm. The specimen with the said dimension is heated in a furnace at a standard rate of 10°C per minute.
• The record of the height of the specimen vs temperature is made by a plot. Until the test piece deforms or collapses by 10%.
• The temperature at which the refractory deforms by 10% is called RUL.
• RUL gives an indication of the temp at which the bricks will collapse.
• A good refractory should have high RUL value.

POROSITY

• It is defined as the ratio between pore volume and bulk volume. The formula for porosity is mathematically expressed as follows.

Porosity (P) = (W – D / W – A) × 100

where

W = Weight of saturated specimen (with water) in air.

D = Weight of dry specimen.

A = Weight of saturated specimen (with water) in water.

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• Porosity is an important property of refractory bricks, because it affects many other characteristics like chemical stability, strength, abrasion-resistance and thermal conductivity.

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• A good refractory should have low porosity.

THERMAL CONDUCTIVITY

• In industrial operations, refractory materials of both high thermal and low thermal conductivity are required, depending upon the type of furnace.
• A good heat conductivity of the refractory material is desirable for effective heat transmission in furnace construction.
• The least porous (no holes or pores-absence of pores) brick have the highest thermal conductivity, owing to the absence of air-voids.
• On the other hand, in porous bricks, the entrapped air in the pores, acts as a non-heat conducting material(insulators). And hence it can be used for lining in furnaces,ovens etc.,

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• For making porous refractory bricks, the refractory material is mixed with a liberal amount of carbonaceous material, then mould into bricks and burnt.

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• Highly porous refractoryreduces thermal spalling.

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• A good refractory should have low porosity.

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• The carbonaceous material burns off; leaving behind minute voids, which enhances the insulating quality.

THERMAL SPALLING

Thermal spalling of any refractory material is defined as the property of breaking, cracking, fracturing or peeling off the material under high temperature.

• The main causes of thermal spalling are

(i) Rapid change in temperature (ii) Slag penetration.

• A good refractory must show a good resistance to thermal spalling.

Spalling can be decreased by

• Using high porosity, low coefficient of expansion and good thermal conductivity refractory bricks
• Avoiding sudden temperature changes
• Oven-firing the refractories at high temperature for a sufficiently long time, to make the material less susceptible to uneven expansion or contraction, when heated.
• Proper selection of refractory material for the designed use.

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DIMENSIONAL STABILITY

It is the resistance of a refractory material to any volume changes, when exposed to high temperature over prolonged time.

The dimensional changes are of two types.

1.Reversible

2.Irreversible 

Reversible Dimensional Changes

This may result due to the uniform expansion and contraction of a refractory material. So, the dimensional changes of a good refractory must be reversible. 

Irreversible Dimensional Changes

This is due to the formation of increasing amounts of liquid from low fusible constituent of the refractory bricks, when it is subjected to long periods of soaking at high temperature.

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Example: Magnesite bricks shrink in service.

The conversion of amorphous nature of Magnesite (specific gravity is 3.05) into more dense crystalline form of Periclase (specific gravity is 3.54) on heating.

Magnesite → Periclase

(Amorphous) (Crystalline)

Spe.Gra= 3.05 Spe.Gra= 3.54

A good refractory should

have high dimensional stability.

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General method of manufacturing of refractories

Raw material processing

This consists of crushing, grinding clay and then sieving to get the raw material of correct size. The materials is further purified to remove unwanted material by processes such as (a) froth floatation (b) magnetic separation (C) Chemical Methods .The raw materials are then dried and calcined at 1200-1500⁰ C to remove volatile impurities.

  Blending and mixing

The two or more powdered raw material with equal size is thoroughly mixed with a suitable binding material and thus, it forms homogeneous mixture which makes moulding easier.

Moulding

Moulding can be done either manually or mechanically by the application of high pressure. Low strength and low density refractories are produced by hand moulding, whereas high strength and high density refractories are made by mechanical moulding.

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Drying

The drying process enables the removal of moisture from refractories and to prevent development of internal stressor cracks during use.

Firing

The refractories are fired to stabilize and strengthen their structure. This process is done at high temperatures or the temperature higher than the service temperature. Firing is carried out in chamber at the temperature ranging from 1400°C to 2000°C, depending on the composition and properties desired.

INSULATORS

Definition:

The substances which are capable of retarding or stop the flow of heat or electricity or sound through them are known as insulators.

Classification of Insulators

Thermal Insulators

Sound Insulators

Electrical Insulators

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Characteristic of Insulating Material

1. Electrical conductivity

The ability of material to conduct the electricity is called as an electrical conductivity. Resistivity is the reciprocal of electrical conductivity.

A good insulating material should possess low conductivity or high resistivity.

 2. Dielectric constant

It is a quantitative measure of the ability of the material to store electric charges. It is expressed as the ratio of the capacitance of a capacitor containing the dielectric material under study to the capacitance of the same capacitor with vacuum as the dielectric.

A good insulating material should possess low dielectric constant.

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 3. Dielectric losses

It is caused by the absorption of electrical energy and by leakage of current through the material. Dielectric losses should be minimal for an ideal insulator.

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4. Porosity

This increases the moisture-holding capacity and thus adversely affects

the electrical properties of an insulator. So dielectrics of high porosity are not used.

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  5. Thermal expansion and contraction

This should be least for a good insulator.

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  6. Resistance to external chemical effects

Insulators should be inert to chemical such as oils, solvents, acids and

alkalis.

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7. Chemical alteration in the insulating material

In some materials, chemical alteration takes place during use. However such changes should not deteriorate their properties.

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Classification of Insulators

Thermal Insulators

Sound Insulators

Electrical Insulators

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Examples for different kinds of insulating materials

• Gases (air, SF6, alternative gases),
• inorganic solid insulating materials(ceramics, porcelain, glass, mica),
• thermoplastic insulating materials (polyethylene, PVC),
• thermosetting plastics and elastomers (epoxy resin, polyurethane, silicone elastomers), nano-composites,
• insulating liquids (mineral oil, synthetic liquids, vegetable-based liquids)
• as well as impregnated fibrous materials(paper, pressboard, synthetic materials).

ELECTRICAL INSULATORS

The material which does not allow the electricity to pass through them is known as an electrical insulating material or dielectrics. A good insulating material should possess low dielectric constant.

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Thermal Insulators

The materials having extremely low thermal conductivities are known as thermal insulators.

Thermal properties of an insulator depend upon

1. Pores

2. Moisture in the pores 

Characteristic of thermal Insulating Material

1. It should have low conductivity

2. It should be fire proof

3. It should be chemically stable

4. Its cost should be low

5. It is more stable physically and mechanically.

6. It should have low density.

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Classification Of Thermal Insulating Material

1. Organic thermal Insulating Material

These materials possess very large number of fine pores scattered throughout them. These materials have low specific gravities and also naturally occurring.

Example: Wool------ 0.11 g/cm³

 2. Inorganic thermal Insulating Material

These materials are preferred as high temperature insulating material.

Example: Asbestos ---- 150⁰ C

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Sound Insulator

• Sound insulation is a kind of measure to prevent the sound waves from permeating.

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• Sound-insulating materials effectively block or stop sound waves from traveling to adjacent spaces, whereas sound absorption products absorb echoes inside a room, thereby preventing sound from bouncing around the room.

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• Heavier, more massive materials — such as gypsum board or concrete block — are used to block sound, while softer porous materials — like fiberglass or carpeting — work as sound absorbers.

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• Soundproofing Insulation

Soundproofing insulation is used in buildings and homes to reduce the amount of sound transmitted to other parts of the building. Mineral wool and fiberglass are the most common materials. It’s a relatively easy and cost-effective way to improve the soundproofing of a room.

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