LACE- Ornamental openwork fabric,
made in a variety of designs by intricate manipulation of
the
fiber by machine or by hand.
LACE STITCH- In this knitting stitch
structure, loops are transferred
from
the needles on which they are made to adjacent needles to create
a
fabric with an open or a raised effect.
LAP- A continuous, considerably
compressed sheet of fibers that is rolled under pressure into a
cylindrical
package, usually weighing between 40 and 50 pounds. The lap is used to supply
the
card.
LAPPING- A term describing the movement
of yarn guides between needles, at right angles to
the
needle bar, or laterally in relation to the needle bar, or laterally in
relation to the needle bar
during
warp knitting.
LAP SPLITTING- A condition caused by a lap
that will not unwind in carding in the same
thickness
as it was wound in picking. This splitting of the sheet of fiber can result in
either a
thicker
or thinner sheet being fed into the card.
.
LASE- An acronym for load at
specified elongation- the load required to produce a given
elongation
of a yarn or cord.
LASER- A device for producing an
intense beam of coherent light. It is used for cutting,
spectroscopy,
photography, biomedical investigations, etc.
LASHED-IN FILLING- . PULLED-IN FILLING.
LASTRILE FIBER- A manufactured fiber in which
the fiber-forming substance is a copolymer
of
acrylonitrile and a diene composed of at least 10% by weight, but not more than
50% by
weight,
of acrylonitrile [-CH2-CH(CN)-]
units (FTC definition).
LATCH NEEDLE- One of the two types of
knitting machine needles. The latch
needle
has a small terminal hook with a latch that pivots automatically in knitting
to
close the hook. The fabric loop is cast off. The latch then opens, allowing a
new
loop to be formed by the hook, and loop-forming and casting-off proceed
simultaneously.
(Also . SPRING NEEDLE..)
LATENT CRIMP- Crimp in fibers that can be
developed by a specific
treatment.
Fibers are prepared specially to crimp when subjected to specific
conditions,
e.g., tumbling in a heated chamber or wet processing.
LATEX- A milky fluid found in certain
cells of some families of .d plants.
Latex
is the raw material from which rubber is made.
LAWN- A light, thin cloth made of
carded or combed yarns, this fabric is given a creaseresistant,
crisp
finish. Lawn is crisper than voile but not as crisp as organdy.
LCP- . LIQUID CRYSTAL POLYMER.
LEA- 1. One-seventh of an 840-yard
cotton hank, i.e., 120 yards. 2. A standard skein with 80
revolutions
of 1.5 yards each (total length of 120 yards). It is used for strength tests. 3. A unit of
measure,
300 yards, used to determine the yarn number of linen yarn. The number of leas
in one
pound
is the yarn number.
LEACHING- The removal of any substance or
dye from textiles by the percolating action of a
suitable
liquid.
.
LET-OFF MOTION- A device for controlling the
delivery and tension of the warp during
weaving.
LEVELING- Migration leading to uniform
distribution of dye in a dyed material. Leveling may
be a
property of the dye or it may require chemical assistance.
LEVEL LOOP- A term describing a tufted or
woven carpet with uncut, equal length loops
composing
the pile surface.
LICKERIN- A part of the feed mechanism of
the card. It consists of a hollow, metal roll with a
spirally
grooved surface containing a special saw-toothed wire. The lickerin opens up
the tufts of
the
picker lap as it is fed to the card and transfers the fibers to the main
cylinder.
LICKERIN LOADING- A condition whereby fibers are
imbedded in the lickerin wire clothing
so as
to resist transfer to the cylinder clothing.
LIGHT END- 1. The low boiling fraction in
distillation. 2. . FINE END, 1.
LIGHTFASTNESS- The degree of resistance of
dyed textile materials to the color-destroying
influence
of sunlight. Two methods of testing are in use- (1) exposure to sunlight,
either directly
or
under glass, and (2) accelerated testing in a laboratory apparatus equipped
with any of several
types
of artificial light sources.
LIGNIN- The major noncarbohydrate
portion of wood. It is an amorphous polymeric substance
that
cements the fibrous portions together.
LIMITING OXYGEN INDEX- A relative measure of
flammability that is determined as
follows.
A sample is ignited in an oxygen/nitrogen atmosphere. The oxygen content is
adjusted
until
the minimum required to sustain steady burning is found. The higher the value,
the lower
the
flammability.
LINEAR DENSITY- Mass per unit length expressed
as grams per centimeter, pounds per foot,
or
equivalent units. It is the quotient obtained by dividing the mass of a fiber
or yarn by its
length.
LINEN- Cellulosic fibers derived from
the stem of the flax plant or a fabric made from these
fibers.
Linen fibers are much stronger and more lustrous that cotton; they yield cool,
absorbent
fabrics
that wrinkle easily. Fabrics with linen-like texture and coolness but with good
wrinkle
resistance
can be produced from manufactured fibers and blends.
LINEN LEA- The number of 300-yard hanks
contained in one pound.
LINET- A French-make lining fabric of
unbleached linen.
LINING FABRIC- Fabric that is used to cover
inner surfaces, especially when the inner surface
is of a
different material than the outer. May refer to garment lining, lining for
boxes, coffins,
etc.
Generally of smooth, lustrous appearing fabrics, but also of felt and velvet.
Both
manufactured
fibers and natural fibers are used.
LINK-AND-LINK- . PURL.
.
LINKED PROCESSES- Refers to the connection of the
various steps of fiber-to-yarn
processing
via pneumatic fiber-transport systems, on-line monitoring, and process control.
Process
linking results in less labor-intensive processing. A typical linked system
might include
all
stages from bale opening through carding.
LINON A JOUR- A gauze-like linen fabric used
as dress goods.
LINT- Particles and short fibers that
fall from a textile product during the stresses of use.
LINT BALL- . BALLING UP.
LINTERS- The short cotton fibers that
are not removed from the .d during the first ginning.
The
linters are cut from the .d and used as a source for cellulose derivatives such
as
nitrocellulose
or viscose rayon.
LIQUID CRYSTAL- A liquid in which the molecules
are oriented parallel to each other
resulting
in birefringence and interference patterns visible in polarizing light.
LIQUID CRYSTAL POLYMER- Polymers such as aramids or the
thermotropic polyesters that
form
liquid crystals when in the appropriate state, (concentrated solution or melt).
Most liquid
crystal
polymers have in their structure a succession of para-ring structures. The
liquid crystal
formation
is thought to relate to the fact that there is a limiting concentration of
rod-like chains
that
can exist in a random arrangement in a solution or melt. Once this
concentration is reached,
ordering
or alignment of the chains in necessary to accommodate them. Fibers from liquid
crystal
polymers
generally have high modulus and tenacity, good chemical resistance, and
hightemperature
resistance.
They are used in a wide range of applications including protective
apparel,
tire cord, composites, ropes and cables, etc.
LIQUOR RATIO- In wet processing the ratio of
the weight of liquid used to the weight of goods
treated.
LISLE YARN- A high-quality cotton yarn made
by plying yarns spun from long combed staple.
Lisle
is singed to hive it a smooth finish.
LIVING RING- . REVOLVING SPINNING RING.
LOAD-DEFORMATION CURVE- A graphical representation of
the relationship between the
change
in dimension (in the direction of the applied force) of the specimen resulting
from the
application
of an external load, and the magnitude of that load. The load may be expressed
in
units
of weight (such as pounds or kilograms) and the deformation in either units of
length (such
as
inches or millimeters) in tension or compression tests, or degrees in shear
tests. In a tension
test, a
load-deformation curve becomes a load-elongation curve.
.
LOAD-ELONGATION CURVE- . STRESS-STRAIN CURVE.
LOFT- The properties of firmness, resilience,
and bulk of a fiber batting, yarn, fabric, or other
textile
material.
LONG STAPLE- A long fiber. In reference to
cotton, long staple indicates a fiber length of not
less
that 1-1/8 inches. In reference to wool, the term indicates fiber 3 to 4 inches
long suitable for
combing.
LOOM- A machine for weaving fabric by
interlacing a series of vertical, parallel threads (the
warp)
with a series of horizontal, parallel threads (the filling). The warp yarns
from a beam pass
through
the heddles and reed, and the filling is shot through the “shed” of warp
threads by means
of a
shuttle or other device and is settled in place by the reed and lay. The woven
fabric is then
wound
on a cloth beam. The primary distinction between different types of looms is
the manner
of
filling insertion (. WEFT INSERTION, 1). The principal elements of any type of
loom are
the
shedding, picking, and beating-up devices. In shedding, a path is formed for
the filling by
raising
some warp threads while others are left down. Picking consists essentially of
projecting
the
filling yarn from one side of the loom to the other. Beating-up forces the
pick, that has just
been
left in the shed, up to the fell of the fabric. This is accomplished by the
reed, which is
brought
forward with some force by the lay. (Also . JACQUARD.)
LOOM BARRÉ- A repeated unevenness in the
fabric, usually running from selvage to selvage,
and
caused by uneven let-off or take-up or by a loose crank arm.
LOOM-FINISHED- A term describing fabric that
is sold in the condition in which it comes
from
the loom.
LOOM FLY- Waste fibers that are
inadvertently woven into a fabric.
LOOPED FILLING- A woven-in loop caused by the
filling sloughing off the quill or by the
shuttle
rebounding in the box.
LOOPED PILE- A pile surface made of uncut
looped yarns.
LOOPED YARN- . KINK.
LOOP ELONGATION- The maximum extension of a
looped yarn at
maximum
load, expressed as a percentage of the original gauge length.
.
LOOPING- Generally, a method of uniting
knit fabrics by joining two courses of loops on a
machine
called a looper.
LOOPING BAR- A bar inserted in the bottom of
an extrusion metier around which the dried
filaments
pass as they leave the spinning cabinet.
LOOP-KNOT- . KINK.
LOOP PILE- Carpet construction in which
the tufts are formed into loops from the supply yarn.
LOOP TENACITY- The strength of a compound
strand formed when one strand of yarn is
looped
through another strand, then broken. It is the breaking load in grams divided
by twice the
measured
yarn denier or decitex. Loop tenacity, when compared with standard tenacity
measurements,
is an indication of the brittleness of a fiber.
LOOPY SELVAGE- A weaving defect at the selvage
of excessive thickness or irregular filling
loops
that extend beyond the outside selvages.
LOOSE FILLING- A fabric defect that is usually
.n as short, loose places in the filling caused
by too
little tension on the yarn in the shuttle or by the shuttle rebounding in the box.
Loose
filling
can often be felt by an examiner when passing a hand over the surface of the
fabric.
LOOSE PICK- . SLACK PICK.
LOST END- An end on a section or tricot
beam that has been broken at some stage in warping
and has
not been repaired by a knot.
LOT- A unit of production or a group
of other units or packages that is taken for sampling or
statistical
examination, having one or more common properties and being readily separable
from
other
similar units.
LOW ROWS- A carpet defect characterized
by rows of unusually low pile height across the
width
of the goods.
LUANA- A fabric characterized by a
crosswise rib effect, usually made with a filament yarn
warp
and a spun yarn filling.
LUBRICANT- An oil or emulsion finish
applied to fibers to prevent damage during textile
processing
or to knitting yarns to make them more pliable.
LUMINESCENCE- Emission of light not caused by
incandescence but rather by physiological
processes,
chemical action, friction or electrical action. (. both FLUORESCENCE and
PHOSPHORESCENCE.)
.
LUSTER- The quality of shining with
reflected light. With reference to textile materials, the
term is
frequently associated with the adjectives bright or dull to distinguish between
varieties of
manufactured
fibers.
LUSTERING- The finishing of yarn or fabric
by means of heat, pressure, steam, friction,
calendering,
etc., to produce luster.
LYOCELL FIBER- A manufacturing cellulose fiber
made by direct dissolution of wood pulp in
an
amine oxide solvent, N-methylmorpholine-N-oxide. The clear solution is extruded
into a
dilute
aqueous solution of amine oxide, which precipitates the cellulose in the form
of filaments.
The
fiber is then washed before it is dried and finished.
The
solvent spinning process for making lyocell fiber is considered to be environmentally
friendly
because the non-toxic spinning solvent is recovered, purified, and recycled as
an integral
part of
the manufacturing process. No chemical intermediates are formed, the minimal
waste in
not
hazardous, and energy consumption is low. Wood pulp is a renewable resource,
and the fiber
is
biodegradable.
CHARACHTERISTICS-
Lyocell fiber is stronger than other cellulosic fibers. It is inherently
absorbent,
having a water imbibition of 65%-75%. Lyocell retains 85% of its dry tenacity
when
wet,
making it stronger when wet than cotton. The fiber has a density of 1.15 g/cm3.
END
USES- Lyocell fiber is suitable for blending with cotton or other manufactured
fibers.
Because
of its molecular structure, lyocell has the tendency to develop surface fibrils
that can be
beneficial
in the manufacture of hydroentabled and other nonwovens, and in specialty
papers.
For
apparel uses, the fiber’s unique fibrillation characteristic has enabled the
development of
fabrics
with a soft luxurious hand. The degree of fibrillation is controlled by
cellulose enzyme
treatment.
LYOTROPIN POLYMER- Polymers that decompose before
melting but that form liquid
crystals
in solution under appropriate condition. They can be extruded from high
concentration
dopes
to give fibers of high modulus and orientation for use in advanced composites,
tire cord,
ballistic
protective devices, etc.