A

A B S O R P T I O N

The process by which a gas or liquid is taken up within a material. An absorbent nonwoven holds the gas or liquid within the fibers themselves.

A D S O R P T I O N

The process by which a gas or liquid is taken up by the surface of a material.  An adsorbent nonwoven wicks and holds the gas or liquid between the fibers. 

A E R O S O L

Small particles, solid, semi-solid or liquid, suspended in the air. The diameter of the particles may vary from 100 microns down to 0.02 microns Examples are dust, smoke and fog. 

A I R L A Y I N G, A I R L A I D P R O C E S S

A nonwoven web forming process that disperses fibers into a fast-moving air stream and condenses them onto a moving screen by means of pressure or vacuum.

A I R P E R M E A B I L I T Y (A I R P E R M)

The rate at which air flows through a fabric. Also referred to as BREATHABILITY. Often measured in cfm (cubic feet per minute per square foot) or cm3/sec/cm2.

A M O R P H O U S

Not crystalline. A random rather than a regular arrangement of chains of molecules within regions of a polymer or fiber.

A N T I O X I D A N T

An additive that retards the deterioration of a material’s functional and aesthetic properties by reaction with the oxygen in the air.

A N T I S T A T

An additive that reduces the accumulation or assists the dissipation of electrical charges that arise during the processing of fibers, fabrics and films and during the use of such materials.

A R A M I D F I B E R

A synthetic fiber that is part of the NYLON (POLYAMIDE) family.  Aramid is short for Aromatic Polyamide.  META-ARAMIDS (NOMEX) exhibit very high heat resistance and PARA-ARAMIDS (KEVLAR) exhibit very high strength as well as high heat resistance.  Other brand names include TWARON, TECHNORA, and HERACRON. 

A S H R A E 

The acronym for American Society of Heating, Refrigeration and Air Conditioning Engineers. Most air and liquid filter manufacturers in the United States use the ASHRAE test methods. 

A S T M

The acronym for American Society for Testing and Materials International.  ASTM standards are used for a variety of nonwoven testing and specifications.  

A T T E N U A T I O N

Drawing or pulling of molten polymer into a much-reduced diameter filament or fiber.  This can add strength to the filament or fiber by making it less amorphous and more crystalline in structure.

B

B A C K I N G

A web, nonwoven or other material that supports and reinforces the back of a product such as carpeting or wallpaper.  Backings provide dimensional stability and enhance the performance of the face fabric.

B A C K C O A T I N G

An adhesive type substance applied to the back side of a fabric for the purpose of locking pile yarn into a carpet backing, or bonding a secondary backing to the primary backing, increasing fabric body or stiffness, or imparting flame retardancy to the fabric.

B A L E 

A compressed and bound package of fibers – a common shipping package for fibers. 

B A T C H 

A number or an amount of items forming a group i.e. a batch (amount) of fibers.

B A S I S W E I G H T (M A S S P E R U N I T A R E A)

The mass of a unit area of fabric.  Examples: grams per square meter – ounces per square yard.  Basis Weight is mass per square area and is not the same a DENSITY, which is mass per cubic volume.

B A T T, B A T T I N G

A soft bulky assembly of fibers, usually carded. A carded web is sometimes referred to as a batt. 

B I C O M P O N E N T F I B E R S

Fibers consisting of two polymeric compounds arranged in a core-sheath (concentric or eccentric) or a side by side or a matrix or ‘islands in the sea’ configuration, chosen to ensure one component softens at a sufficiently lower temperature than the other in order to maintain the structural integrity or to create specific characteristics.

B I N D E R

An adhesive substance, generally a high polymer in a solid form (powder, film, fiber) or as a foam, or in a liquid form (emulsion, dispersion, solution) used for bonding the constituent elements of a web or enhancing their adhesion, in order to provide the nonwoven fabric cohesion, integrity and/or strength and additional properties.

B I N D E R F I B E R

Generally, thermoplastic fibers used as thermal bonding fibers in conjunction with other fibers with a higher softening point or non-melting fibers. Some binder fibers that may not be thermoplastic can be activated by solvent (e.g. water).

B I O D E G R A D A B L E

The ability of a substance to be broken down by bacteria so that it can be consumed by the environment.

B L E N D

A combination of two or more fiber types in making fabrics.

B O N D I N G

Conversion of a fibrous web into a nonwoven by chemical (adhesive/solvent) means or by physical (mechanical or thermal) means. The bonding may be distributed all over (through or area bonding) or restricted to predetermined, discrete sites (point or print bonding).

B R E A T H A B I L I T Y

See AIR PERMEABILITY. 

C

C A L E N D E R

A machine used to bond fibers of a web or sheets of fabric or film to each other or to create surface features on these sheets. It consists of two or more heavy cylinders that impart heat and pressure to the sheets that are drawn between them. The rollers can be mirror smooth, embossed with a pattern, or porous.

C A L E N D E R B O N D I N G

A process for thermally bonding webs by passing them through the nip of a pair of rolls, one or both of which are heated. Plain or patterned rolls may be employed (see POINT BONDING). Alternatively, a blanket calendar may be used.

C A L E N D E R I N G

A mechanical finishing process used to laminate or to produce special surface features such as high luster, glazing and embossed patterns.

C A R D

A machine designed to separate fibers and remove impurities; align and deliver them to be laid down as a web or to be further separated and fed to an airlaid process. The fibers in the web are aligned with each other predominantly in the same direction. The machine consists of a series of rolls or a drum that are covered with many projecting wires or metal teeth. These wire-clothed rolls or drums are called cards.

C A R D I N G 

A process for making fibrous webs in which the fibers are aligned essentially parallel to each other in the direction in which the machine produces the web (machine direction).

C A R D E D N O N W O V E N

A carded web, bonded by one or more techniques to provide fabric integrity.

C A R T R I D G E F I L T E R

A disposable filter media which is generally long and cylindrical which is placed in a sealed filtration receptacle. The contaminated fluid flows from the outer edge of the filter to the inner hollow core on exiting but leaves its particles in the cartridge media.

C E L L U L O S I C F I B E R S

Made from plants that produce fibrous products based on polymers of the cellulose molecule. Cotton plants produce separate cellulose fibers, whereas wood pulp is made by mechanically and/or chemically separating wood fibers. Other sources of cellulose are fibers such as flax manila, ramie and jute.
Rayon is made by dissolving wood pulp in a solution and extruding that solution through spinnerets into a chemical bath that regenerates the fibers. 

C F M

Cubic Feet per Minute.  Technically, Cubic Feet per Minute per Square Foot.  Unit of measure for quantifying airflow through a filter media. 

C H E M I C A L B O N D I N G

A method of bonding webs of fibers by chemical agents that may include adhesives and solvents. The process may entail one or more of the following methods: impregnation, spraying, printing and foam application.
NOTE: chemical bonding using chemical agents occurs only in a reactive system, e.g. a crosslinkable dispersion. Normal polymer bonding as it happens with non-reactive polymer binders (e.g. fibers, adhesives or lattices) is a physical process. 

C L O U D Y W E B

An uneven or irregular web that gives a cloud-like appearance.  Also referred to as WINDOWS. 

C O F O R M

The formation of a nonwoven web through the concurrent use of elements from at least two different web formation technologies.

C O A T I N G

Application of a liquid material to one or both surfaces of a fabric, which is followed by drying or curing.

C O H E S I O N

The resistance of like materials to be separated from one another. Examples are: The tendency of fibers to adhere to each other during processing, the resistance of a web to being pulled apart, and the resistance of a component of a laminate to being torn apart when the adhesive interface in the laminate is being stressed.

C O M B I N G

In carding, the part of the process that removes neps and straightens the fibers.

C O M P O S I T E M A T E R I A L

Combination of two or more distinct materials having a recognizable interface between them.

C O M P O S I T E N O N W O V E N

Term used when the essential part of the composite can be identified as a nonwoven material.  If the essential part can not be identified, the term composite nonwoven is used when the mass of the nonwoven content is greater than the mass of any other component material.

C O N T I N U O U S F I L A M E N T

A fiber of unending length, usually made by extruding a plastic or polymer solution through a hole in a die called a spinneret.

C O N V E R T E R

An organization that manufactures finished products from fabrics supplied in rolls; or provides intermediate processing steps such as slitting, dyeing and printing.

C O P O L Y M E R

A polymer chain made up of monomeric units from more than one monomer, e.g. vinyl acetate / ethylene polymers.

C O R O N A C H A R G E

An electrostatic charge applied to some filter media to increase the initial filtration properties of the filter.

C O T T O N F I B E R

A unicellular, natural fiber composed of an almost pure cellulose. As taken from plants, the fiber is found in lengths of 8 mm – 50 mm. For marketing, the fibers are graded and classified for length, strength and color.

C O V E R, C O V E R A G E

The degree to which a fabric hides an underlying structure.

C O V E R S T O C K

A lightweight nonwoven material used to contain and conceal an underlying core material. Examples are the facing materials that cover the absorbent cores of diapers, sanitary napkins and adult incontinence products.

C R E P E

A quality in a fabric imparted by wrinkling or embossing to give a crimped surface and greater fabric bulk.

C R I M P

The waviness of a fiber. Crimp amplitude is the height of the wave with reference to the straight uncrimped fiber.

C R I M P F R E Q U E N C Y O R L E V E L

The number of crimps per unit of length.

C R O S S D I R E C T I O N, C R O S S M A C H I N E D I R E C T I O N (CD, CMD, XMD)

The width direction, within the plane of the fabric, that is perpendicular to the direction in which the fabric is being produced by the machine.

C R O S S-L A P P I N G, C R O S S-L A Y I N G

Forming a multilayer web on to a conveyor belt by laying thereon a web back and forth at right angles to the direction in which the conveyor belt travels. The orientation of the fibers is dependent on the speed of the web delivery, the speed of the conveyor belt, and the width of the final web. Cross-lapping balances the MD (machine-direction) and CD (cross-direction) properties of the nonwoven.  The WEB coming directly from a card has fibers and strength mostly oriented in the MD.  A balanced cross-lapped web will have equal strength and elongation on both the MD and CD.  Depending on the relative speed of the conveyors, cross-lapped webs may also be stronger in the MD or CD, by design. 

C R O S S-L A I D, C R O S S L A P P E D

A web of fibers, formed by cross-laying or cross-lapping.  A variable percentage of the fibers are oriented in both the MD and CD directions, providing more ISOTROPIC physical properties than a PARALLEL-LAID web.  

C R O S S L A P P E R

A machine used to fold or layer fiber webs across their widths. The crosslapper provides webs with both machine direction and cross direction fiber orientation, can change web width, or web weight.

C R O S S S E C T I O N

The outline profile of a cut end of a fiber when it is cut perpendicular to its long axis. These profiles can be round, oval, irregular or complex shapes depending on the shape of the die used to extrude the synthetic fiber; or for a natural fiber, depending on its growth pattern.

C R Y S T A L L I N E

Orderly arrangement of molecules and polymer chains in a fiber or plastic.

C U R I N G

A process by which resins, binders or plastics are set into or onto fabrics, usually by heating, to cause them to stay in place. The setting may occur by removing solvent or by crosslinking so as to make them insoluble.

D

D A C R O N ®

A brand name for POLYESTER.

D E C I T E X (D t e x)

Weight in grams of 10,000 meters of a fiber. It is one-tenth of a tex (see Te x).

D E L A M I N A T I O N

Tendency of a fabric to be pulled apart (layer separation) by normal surface forces or shear tensions.

D E N I E R

The measure of a mass per unit length of a fiber. Denier is numerically equal to the mass in grams of 9000 meters of material. Low numbers indicate fine fiber sizes and high numbers indicate coarse fibers.

D E N S I T Y

Mass per unit volume, i.e. grams/cubic centimeter.  Density is different that BASIS WEIGHT, which is mass per square area, not cubic volume.  

D E P T H F I L T E R

A filter medium which is thick and captures particles within the media.  See also, SURFACE FILTER.

D I A T O M A C E O U S E A R T H

A filter media made from diatoms, which are fossils that collect at the bottom of sea beds in prehistoric seas. Also known as “kieselguhr,” the material is characterized by pores and cavities capable of capturing and retaining contaminants.

D I E

A system to produce a thin filament of molten polymer in spunlaid and melt blown technology. A small annular orifice for spinning man-made fibers.

D I F F U S I O N

The movement of molecules or ions through a solution or material in response to differential concentrations or repulsive or attractive forces.

D I M E N S I O N A L S T A B I L I T Y

The ability of a fabric to maintain or resume its original geometric configuration.

D I P P I N G

Immersion of a textile in a finishing liquid (dip) such as dye or binder softener to improve its adhesion or water repellent properties.

D O F F

1. (verb) The term used for removing a finished fabric from the machine: Doff the roll, or doffing the roll.                                                            2. (noun) In some regions, the term also refers to the roll of finished material removed from the machine.

D O F F E R

The last cylinder of a card from which the sheet of fibers that has been formed is removed by a comb (doffer comb or roll).

D O P

Dioctylphthalate (diethyhexyphospate) is a viscous liquid that is heated into an aerosol in the critical particle range to challenge a filter. The aerosol’s presence upstream of the filter and downstream are measured to determine the media’s efficiency. DOP is used to measure HEPA and ULPA media performance.

D R A P E

The ability of a fabric to fold on itself and to conform to the shape of the article it covers.

 

D R A W I N G

A process of stretching a filament after it has been formed so as to reduce its diameter. At the same time, the molecules of the filament are oriented, thereby making it stronger. The ratio of the final length to the initial length is called the draw ratio. 

D R Y F O R M I N G (D R Y L A Y I N G)

A process for making a nonwoven web from dry fiber. These terms apply to the formation of carded webs, as well as to the air laying formation of random webs.

D R Y L A I D

A web of fibers produced by dry-laying.

D R Y L A I D N O N W O V E N

A drylaid web bonded by one or more techniques to provide fabric integrity.

E

E F F I C I E N C Y

The ability of a filter device or media to remove particulate of a certain size from a liquid or gaseous fluid by measuring the concentration of the particles upstream and downstream of the device or media.

E L A S T I C I T Y

The ability of a strained material to recover its original size and shape immediately after removal of the stress that causes deformation.

E L A S T O M E R S

Polymers having the rubbery qualities of stretch and recovery.

E L E C T R O S T A T I C W E B

A web produced by an electrostatic process. Forming a web of fibers, especially BONDING microfibers, by means of an electrostatic field from a polymer solution or emulsion, or from a polymer melt.

E L O N G A T I O N

 Measured by determining the percentage a material will stretch in the machine and cross directions of the fabric while under specific weight loads depending on the testing method used.

E L O N G A T I O N A T B R E A K

The point at which the last component of the stretched material breaks.

E M B O S S I N G

A process whereby a pattern is pressed into a film or fabric, usually by passing the material between rolls with little clearance and where one or both rolls have a raised design. At least one of the rolls is usually heated.

E M U L S I O N

A suspension of finely divided liquid droplets within another liquid (see DISPERSION).

E N T A N G L E M E N T

A method of forming a fabric by wrapping or knotting fibers in a web about each other by mechanical means, or by use of jets of pressurized air or water, so as to bond the fibers (see MECHANICAL BONDING).

E X T R U S I O N

A process by which a heated polymer is forced through an orifice to form a molten stream that is cooled to form a fiber. Examples of this process are Polypropylene and Polyester.
Alternatively, a solution of polymer can be forced through an orifice into a solvent that causes the fiber to solidify. Examples are Kevlar and rayon.

A

A B S O R P T I O N

The process by which a gas or liquid is taken up within a material. An absorbent nonwoven holds the gas or liquid within the fibers themselves.

A D S O R P T I O N

The process by which a gas or liquid is taken up by the surface of a material.  An adsorbent nonwoven wicks and holds the gas or liquid between the fibers. 

A E R O S O L

Small particles, solid, semi-solid or liquid, suspended in the air. The diameter of the particles may vary from 100 microns down to 0.02 microns Examples are dust, smoke and fog. 

A I R L A Y I N G, A I R L A I D P R O C E S S

A nonwoven web forming process that disperses fibers into a fast-moving air stream and condenses them onto a moving screen by means of pressure or vacuum.

A I R P E R M E A B I L I T Y (A I R P E R M)

The rate at which air flows through a fabric. Also referred to as BREATHABILITY. Often measured in cfm (cubic feet per minute per square foot) or cm3/sec/cm2.

A M O R P H O U S

Not crystalline. A random rather than a regular arrangement of chains of molecules within regions of a polymer or fiber.

A N T I O X I D A N T

An additive that retards the deterioration of a material’s functional and aesthetic properties by reaction with the oxygen in the air.

A N T I S T A T

An additive that reduces the accumulation or assists the dissipation of electrical charges that arise during the processing of fibers, fabrics and films and during the use of such materials.

A R A M I D F I B E R

A synthetic fiber that is part of the NYLON (POLYAMIDE) family.  Aramid is short for Aromatic Polyamide.  META-ARAMIDS (NOMEX) exhibit very high heat resistance and PARA-ARAMIDS (KEVLAR) exhibit very high strength as well as high heat resistance.  Other brand names include TWARON, TECHNORA, and HERACRON. 

A S H R A E 

The acronym for American Society of Heating, Refrigeration and Air Conditioning Engineers. Most air and liquid filter manufacturers in the United States use the ASHRAE test methods. 

A S T M

The acronym for American Society for Testing and Materials International.  ASTM standards are used for a variety of nonwoven testing and specifications.  

A T T E N U A T I O N

Drawing or pulling of molten polymer into a much-reduced diameter filament or fiber.  This can add strength to the filament or fiber by making it less amorphous and more crystalline in structure.

B

B A C K I N G

A web, nonwoven or other material that supports and reinforces the back of a product such as carpeting or wallpaper.  Backings provide dimensional stability and enhance the performance of the face fabric.

B A C K C O A T I N G

An adhesive type substance applied to the back side of a fabric for the purpose of locking pile yarn into a carpet backing, or bonding a secondary backing to the primary backing, increasing fabric body or stiffness, or imparting flame retardancy to the fabric.

B A L E 

A compressed and bound package of fibers – a common shipping package for fibers. 

B A T C H 

A number or an amount of items forming a group i.e. a batch (amount) of fibers.

B A S I S W E I G H T (M A S S P E R U N I T A R E A)

The mass of a unit area of fabric.  Examples: grams per square meter – ounces per square yard.  Basis Weight is mass per square area and is not the same a DENSITY, which is mass per cubic volume.

B A T T, B A T T I N G

A soft bulky assembly of fibers, usually carded. A carded web is sometimes referred to as a batt. 

B I C O M P O N E N T F I B E R S

Fibers consisting of two polymeric compounds arranged in a core-sheath (concentric or eccentric) or a side by side or a matrix or ‘islands in the sea’ configuration, chosen to ensure one component softens at a sufficiently lower temperature than the other in order to maintain the structural integrity or to create specific characteristics.

B I N D E R

An adhesive substance, generally a high polymer in a solid form (powder, film, fiber) or as a foam, or in a liquid form (emulsion, dispersion, solution) used for bonding the constituent elements of a web or enhancing their adhesion, in order to provide the nonwoven fabric cohesion, integrity and/or strength and additional properties.

B I N D E R F I B E R

Generally, thermoplastic fibers used as thermal bonding fibers in conjunction with other fibers with a higher softening point or non-melting fibers. Some binder fibers that may not be thermoplastic can be activated by solvent (e.g. water).

B I O D E G R A D A B L E

The ability of a substance to be broken down by bacteria so that it can be consumed by the environment.

B L E N D

A combination of two or more fiber types in making fabrics.

B O N D I N G

Conversion of a fibrous web into a nonwoven by chemical (adhesive/solvent) means or by physical (mechanical or thermal) means. The bonding may be distributed all over (through or area bonding) or restricted to predetermined, discrete sites (point or print bonding).

B R E A T H A B I L I T Y

See AIR PERMEABILITY. 

C

C A L E N D E R

A machine used to bond fibers of a web or sheets of fabric or film to each other or to create surface features on these sheets. It consists of two or more heavy cylinders that impart heat and pressure to the sheets that are drawn between them. The rollers can be mirror smooth, embossed with a pattern, or porous.

C A L E N D E R B O N D I N G

A process for thermally bonding webs by passing them through the nip of a pair of rolls, one or both of which are heated. Plain or patterned rolls may be employed (see POINT BONDING). Alternatively, a blanket calendar may be used.

C A L E N D E R I N G

A mechanical finishing process used to laminate or to produce special surface features such as high luster, glazing and embossed patterns.

C A R D

A machine designed to separate fibers and remove impurities; align and deliver them to be laid down as a web or to be further separated and fed to an airlaid process. The fibers in the web are aligned with each other predominantly in the same direction. The machine consists of a series of rolls or a drum that are covered with many projecting wires or metal teeth. These wire-clothed rolls or drums are called cards.

C A R D I N G 

A process for making fibrous webs in which the fibers are aligned essentially parallel to each other in the direction in which the machine produces the web (machine direction).

C A R D E D N O N W O V E N

A carded web, bonded by one or more techniques to provide fabric integrity.

C A R T R I D G E F I L T E R

A disposable filter media which is generally long and cylindrical which is placed in a sealed filtration receptacle. The contaminated fluid flows from the outer edge of the filter to the inner hollow core on exiting but leaves its particles in the cartridge media.

C E L L U L O S I C F I B E R S

Made from plants that produce fibrous products based on polymers of the cellulose molecule. Cotton plants produce separate cellulose fibers, whereas wood pulp is made by mechanically and/or chemically separating wood fibers. Other sources of cellulose are fibers such as flax manila, ramie and jute.
Rayon is made by dissolving wood pulp in a solution and extruding that solution through spinnerets into a chemical bath that regenerates the fibers. 

C F M

Cubic Feet per Minute.  Technically, Cubic Feet per Minute per Square Foot.  Unit of measure for quantifying airflow through a filter media. 

C H E M I C A L B O N D I N G

A method of bonding webs of fibers by chemical agents that may include adhesives and solvents. The process may entail one or more of the following methods: impregnation, spraying, printing and foam application.
NOTE: chemical bonding using chemical agents occurs only in a reactive system, e.g. a crosslinkable dispersion. Normal polymer bonding as it happens with non-reactive polymer binders (e.g. fibers, adhesives or lattices) is a physical process. 

C L O U D Y W E B

An uneven or irregular web that gives a cloud-like appearance.  Also referred to as WINDOWS. 

C O F O R M

The formation of a nonwoven web through the concurrent use of elements from at least two different web formation technologies.

C O A T I N G

Application of a liquid material to one or both surfaces of a fabric, which is followed by drying or curing.

C O H E S I O N

The resistance of like materials to be separated from one another. Examples are: The tendency of fibers to adhere to each other during processing, the resistance of a web to being pulled apart, and the resistance of a component of a laminate to being torn apart when the adhesive interface in the laminate is being stressed.

C O M B I N G

In carding, the part of the process that removes neps and straightens the fibers.

C O M P O S I T E M A T E R I A L

Combination of two or more distinct materials having a recognizable interface between them.

C O M P O S I T E N O N W O V E N

Term used when the essential part of the composite can be identified as a nonwoven material.  If the essential part can not be identified, the term composite nonwoven is used when the mass of the nonwoven content is greater than the mass of any other component material.

C O N T I N U O U S F I L A M E N T

A fiber of unending length, usually made by extruding a plastic or polymer solution through a hole in a die called a spinneret.

C O N V E R T E R

An organization that manufactures finished products from fabrics supplied in rolls; or provides intermediate processing steps such as slitting, dyeing and printing.

C O P O L Y M E R

A polymer chain made up of monomeric units from more than one monomer, e.g. vinyl acetate / ethylene polymers.

C O R O N A C H A R G E

An electrostatic charge applied to some filter media to increase the initial filtration properties of the filter.

C O T T O N F I B E R

A unicellular, natural fiber composed of an almost pure cellulose. As taken from plants, the fiber is found in lengths of 8 mm – 50 mm. For marketing, the fibers are graded and classified for length, strength and color.

C O V E R, C O V E R A G E

The degree to which a fabric hides an underlying structure.

C O V E R S T O C K

A lightweight nonwoven material used to contain and conceal an underlying core material. Examples are the facing materials that cover the absorbent cores of diapers, sanitary napkins and adult incontinence products.

C R E P E

A quality in a fabric imparted by wrinkling or embossing to give a crimped surface and greater fabric bulk.

C R I M P

The waviness of a fiber. Crimp amplitude is the height of the wave with reference to the straight uncrimped fiber.

C R I M P F R E Q U E N C Y O R L E V E L

The number of crimps per unit of length.

C R O S S D I R E C T I O N, C R O S S M A C H I N E D I R E C T I O N (CD, CMD, XMD)

The width direction, within the plane of the fabric, that is perpendicular to the direction in which the fabric is being produced by the machine.

C R O S S-L A P P I N G, C R O S S-L A Y I N G

Forming a multilayer web on to a conveyor belt by laying thereon a web back and forth at right angles to the direction in which the conveyor belt travels. The orientation of the fibers is dependent on the speed of the web delivery, the speed of the conveyor belt, and the width of the final web. Cross-lapping balances the MD (machine-direction) and CD (cross-direction) properties of the nonwoven.  The WEB coming directly from a card has fibers and strength mostly oriented in the MD.  A balanced cross-lapped web will have equal strength and elongation on both the MD and CD.  Depending on the relative speed of the conveyors, cross-lapped webs may also be stronger in the MD or CD, by design. 

C R O S S-L A I D, C R O S S L A P P E D

A web of fibers, formed by cross-laying or cross-lapping.  A variable percentage of the fibers are oriented in both the MD and CD directions, providing more ISOTROPIC physical properties than a PARALLEL-LAID web.  

C R O S S L A P P E R

A machine used to fold or layer fiber webs across their widths. The crosslapper provides webs with both machine direction and cross direction fiber orientation, can change web width, or web weight.

C R O S S S E C T I O N

The outline profile of a cut end of a fiber when it is cut perpendicular to its long axis. These profiles can be round, oval, irregular or complex shapes depending on the shape of the die used to extrude the synthetic fiber; or for a natural fiber, depending on its growth pattern.

C R Y S T A L L I N E

Orderly arrangement of molecules and polymer chains in a fiber or plastic.

C U R I N G

A process by which resins, binders or plastics are set into or onto fabrics, usually by heating, to cause them to stay in place. The setting may occur by removing solvent or by crosslinking so as to make them insoluble.

D

D A C R O N ®

A brand name for POLYESTER.

D E C I T E X (D t e x)

Weight in grams of 10,000 meters of a fiber. It is one-tenth of a tex (see Te x).

D E L A M I N A T I O N

Tendency of a fabric to be pulled apart (layer separation) by normal surface forces or shear tensions.

D E N I E R

The measure of a mass per unit length of a fiber. Denier is numerically equal to the mass in grams of 9000 meters of material. Low numbers indicate fine fiber sizes and high numbers indicate coarse fibers.

D E N S I T Y

Mass per unit volume, i.e. grams/cubic centimeter.  Density is different that BASIS WEIGHT, which is mass per square area, not cubic volume.  

D E P T H F I L T E R

A filter medium which is thick and captures particles within the media.  See also, SURFACE FILTER.

D I A T O M A C E O U S E A R T H

A filter media made from diatoms, which are fossils that collect at the bottom of sea beds in prehistoric seas. Also known as “kieselguhr,” the material is characterized by pores and cavities capable of capturing and retaining contaminants.

D I E

A system to produce a thin filament of molten polymer in spunlaid and melt blown technology. A small annular orifice for spinning man-made fibers.

D I F F U S I O N

The movement of molecules or ions through a solution or material in response to differential concentrations or repulsive or attractive forces.

D I M E N S I O N A L S T A B I L I T Y

The ability of a fabric to maintain or resume its original geometric configuration.

D I P P I N G

Immersion of a textile in a finishing liquid (dip) such as dye or binder softener to improve its adhesion or water repellent properties.

D O F F

1. (verb) The term used for removing a finished fabric from the machine: Doff the roll, or doffing the roll.                                                            2. (noun) In some regions, the term also refers to the roll of finished material removed from the machine.

D O F F E R

The last cylinder of a card from which the sheet of fibers that has been formed is removed by a comb (doffer comb or roll).

D O P

Dioctylphthalate (diethyhexyphospate) is a viscous liquid that is heated into an aerosol in the critical particle range to challenge a filter. The aerosol’s presence upstream of the filter and downstream are measured to determine the media’s efficiency. DOP is used to measure HEPA and ULPA media performance.

D R A P E

The ability of a fabric to fold on itself and to conform to the shape of the article it covers.

 

D R A W I N G

A process of stretching a filament after it has been formed so as to reduce its diameter. At the same time, the molecules of the filament are oriented, thereby making it stronger. The ratio of the final length to the initial length is called the draw ratio. 

D R Y F O R M I N G (D R Y L A Y I N G)

A process for making a nonwoven web from dry fiber. These terms apply to the formation of carded webs, as well as to the air laying formation of random webs.

D R Y L A I D

A web of fibers produced by dry-laying.

D R Y L A I D N O N W O V E N

A drylaid web bonded by one or more techniques to provide fabric integrity.

E

E F F I C I E N C Y

The ability of a filter device or media to remove particulate of a certain size from a liquid or gaseous fluid by measuring the concentration of the particles upstream and downstream of the device or media.

E L A S T I C I T Y

The ability of a strained material to recover its original size and shape immediately after removal of the stress that causes deformation.

E L A S T O M E R S

Polymers having the rubbery qualities of stretch and recovery.

E L E C T R O S T A T I C W E B

A web produced by an electrostatic process. Forming a web of fibers, especially BONDING microfibers, by means of an electrostatic field from a polymer solution or emulsion, or from a polymer melt.

E L O N G A T I O N

 Measured by determining the percentage a material will stretch in the machine and cross directions of the fabric while under specific weight loads depending on the testing method used.

E L O N G A T I O N A T B R E A K

The point at which the last component of the stretched material breaks.

E M B O S S I N G

A process whereby a pattern is pressed into a film or fabric, usually by passing the material between rolls with little clearance and where one or both rolls have a raised design. At least one of the rolls is usually heated.

E M U L S I O N

A suspension of finely divided liquid droplets within another liquid (see DISPERSION).

E N T A N G L E M E N T

A method of forming a fabric by wrapping or knotting fibers in a web about each other by mechanical means, or by use of jets of pressurized air or water, so as to bond the fibers (see MECHANICAL BONDING).

E X T R U S I O N

A process by which a heated polymer is forced through an orifice to form a molten stream that is cooled to form a fiber. Examples of this process are Polypropylene and Polyester.
Alternatively, a solution of polymer can be forced through an orifice into a solvent that causes the fiber to solidify. Examples are Kevlar and rayon.