The ability of a fabric to retain dust and other contaminants. Summary of the lesson "Front and wrong sides of plain fabrics. Properties of fabrics." Contamination of fabric depending on its fibrous composition
Plan.
1. General mechanical properties of tissues
2. Drapeability
3. Physical Properties fabrics
4. Optical properties of tissues
5. Technological properties of fabrics
6. List of used literature
1. General mechanical properties of tissues.
In the process of use, the main wear of clothing occurs as a result of repeated action of tensile load, compression, bending, and friction. Therefore, the ability of the fabric to withstand various mechanical influences, i.e., its mechanical properties, is of great importance for preserving the appearance and shape of clothing and increasing the period of wear.
The mechanical properties of fabrics include: strength, elongation, wear resistance, wrinkling, stiffness, drape, etc. .
Strength tissue under tension is one of the most important indicators characterizing its quality. Tensile strength of a fabric refers to the ability of a fabric to withstand a load.
The minimum load sufficient to break a strip of fabric of a certain size is called the breaking load. The breaking load is determined by tearing strips of fabric on a tearing machine.
The tensile strength of the fabric depends on the fibrous composition of the fabrics, the thickness of the yarn or thread, density, weave, and the nature of the finish of the fabric. Synthetic fibers are the most durable. Increasing the thickness of the threads and the density of the fabric increases the strength of the fabrics. The use of weaves with short overlaps also increases the strength of the fabric. Therefore, under all equal conditions, plain weave gives the fabrics the greatest strength. Finishing operations such as rolling, sizing, decating increase the strength of the fabric. Bleaching, dyeing lead to some loss of strength.
wear resistance tissues is called their ability to withstand a number of destructive factors. In the process of using clothes, the fabric is exposed to light, sun, friction, repeated stretching, bending, compression, moisture, sweat, washing, dry cleaning, temperature, etc.
The nature of the impacts experienced by the fabric during use depends on the purpose of the product and the operating conditions. For example, linen wears out from repeated washings. ; boiling in solutions detergents under the action of atmospheric oxygen, cellulose is oxidized, the strength of the fibers is reduced; mechanical effects on the fabric during washing, as well as the effect of a heated metal surface during ironing, also lead to weakening of the fabric. Window curtains and curtains lose their strength from the action of light, the sun.
The wear of outerwear occurs predominantly from friction. In the initial stage of abrasion, pilling is observed on many textile materials.
Pilling called the process of formation on the surface of textiles of lumps of rolling fibers - pills that occur in areas that experience the most intense friction and spoil appearance products.
A great influence on wear is exerted by the action of light and repeatedly repeated bending, stretching, and compression. During the operation of products, the fabric is wiped at the bottom of the sleeves and trousers, on the elbows, knees, jacket collar.
To increase the period of wearing products at the bottom of the trousers and sleeves, it is recommended to sew on a nylon tape with a border, which prevents the fabric from abrasion.
It should be remembered that violation of the mode of wet-heat treatment of fabrics - excessive heating and duration of treatment - leads to a decrease in the wear resistance of fabrics. In areas of woolen fabric that have a barely noticeable opal, the strength and wear resistance of the fabric are reduced by 50 %.
Under the action of repeated stretching, compression, torsion, loosening of the structure of the fabric and threads occurs. Plastic deformations accumulate in the product, fabrics stretch, products lose their shape. The fibers gradually fall out, the thickness and density of the tissue decrease; tissue is destroyed.
2. Drapeability
D rapeability- the ability of the fabric to form soft, rounded folds. Drapability depends on the weight, stiffness and softness of the fabric. Rigidity is the ability of a fabric to resist shape change. The value, the inverse of stiffness, is g and b to the bone - the ability of the fabric to easily change shape.
The stiffness and flexibility of the fabric depends on the size and type of fiber, the thickness, twist and structure of the yarn, the structure and finish of the fabric.
Artificial leather and suede, fabrics from complex nylon and monokapron threads, from wool with lavsan, dense fabrics from twisted yarn and fabrics with a large number of metal threads have significant rigidity.
Fabrics made of natural silk, woolen fabrics of crepe weaves and soft overcoat woolen fabrics have good drapeability. Fabrics made from vegetable fibers - cotton and especially linen - have less drape than wool and silk.
3.Physical properties of tissues
The physical (hygienic) properties of the fabric include hygroscopicity, air permeability, vapor impermeability, water resistance, wetness, dust capacity, electrification, etc.
Hygroscopicity characterizes the ability of a fabric to absorb moisture from environment(air).
Breathability- the ability to pass air - depends on the fibrous composition, density and finish of the fabric. Low-density fabrics have good breathability.
Vapor permeability- the ability of the fabric to pass water vapor emitted by the human body. The penetration of vapors occurs through the pores of the fabric, as well as due to the hygroscopicity of the material, which absorbs moisture from the air under the clothes and transfers it to the environment. Woolen fabrics slowly evaporate water vapor and regulate air temperature better than others.
Thermal properties especially important for winter fabrics. These properties depend on the fiber composition, thickness, density and finish of the fabric. Wool fibers are the most "warm", flax fibers are "cold".
Water resistance is the ability of a fabric to resist water seepage. Water resistance is especially important for special-purpose fabrics (tarpaulins, tents, canvas), raincoat fabrics, wool coat and suit fabrics.
Dust capacity is the ability of tissues to become contaminated. Dust capacity depends on the fiber composition, density, finish and the nature of the front surface of the fabric. Loose woolen fabrics with fleece have the highest dust capacity.
electrified- this is the ability of materials to accumulate static electricity on their surface. With contact and friction, inevitable in the process of production and use textile materials, on their surface there is a continuous accumulation and dissipation of electric charges
4 Optical properties of tissues
The choice of model, development of designs, visual perception of crushing, volume, size, proportions of the product depend on optical properties tissues, i.e., from their ability to quantitatively and qualitatively change the luminous flux.
Depending on the reflection, absorption, scattering, transmission of the light flux, such properties of materials as color, gloss, transparency, whiteness appear.
If the material completely reflects or absorbs the luminous flux, then there is a sensation of an achromatic color (from white to black): with complete reflection - white, with complete absorption - black, with uniform incomplete absorption - gray in various shades.
Shine fabric depends on the degree of specular reflection of the light flux and, therefore, on the nature of the surface of the fabric, the structure of the threads, the type of weave, etc. finishes, "lacquer" increase the shine of fabrics.
Transparency is associated with the sensation of a light flux passing through the thickness of the tissue and depends on the fibrous composition and structure of the tissue. Thin, low-density fabrics made of synthetic fibers and natural silk have the highest transparency.
coloring- this is the ratio of all the colors involved in the coloring of the fabric. A combination of colors of different tonality, saturation, lightness can give fabrics a joyful or gloomy color.
plot drawings are called, which you can talk about (portraits, paintings, etc.). Plot drawings can have anniversary scarves, tapestries, tablecloths, some fabrics, etc.
Thematic drawings are called that can be characterized by some concept (peas, stripes, cells, etc.). Abstract drawings are called non-objective. In fabrics, these are various color spots or. indefinite contours.
5. Technological properties of fabrics
Technological properties fabrics are called properties that can manifest themselves at various stages of sewing production - in the process of cutting, grinding and wet-heat treatment of products.
The technological properties of fabrics include: resistance to cutting, slip, shedding, penetration, shrinkage, the ability of fabrics to be molded in the process of wet-heat treatment, the expansion of threads in the seams.
Shrinkage- this is a decrease in the size of the fabric under heat and moisture. Shrinkage occurs during washing, soaking, wet-heat treatment of products in the process of ironing and pressing. Shrinkage of fabrics can lead to a decrease in the size of the product, distortion of the shape of its parts. If the fabrics of the uppers, linings and linings shrink differently during wet dry cleaning or ironing, wrinkles and folds may appear on the product.
Some fabrics after washing shrink on the base and increase slightly in width, get the so-called draw.
draw can appear, for example, in fabrics having a cotton warp and weft made of untwisted viscose silk .
Materials Science
Lesson topic: Properties of fibers and fabrics.
The purpose of the lesson: to acquaint students with the properties of textile fibers of natural origin; give an idea of the properties of tissues; teach to determine the properties of tissues; to teach how to use knowledge about the properties of fabrics in the manufacture of garments and care for them; develop logical thinking; educate mindfulness and aesthetic taste.
Equipment: samples of cotton, linen, wool, silk fibers, samples of cotton, linen, woolen and silk fabrics, dissecting needle, magnifiers, ruler, iron, work box, textbook, notebook, scissors, water containers, matches, threads, sewing needles, multimedia projector, screen, computer.
During the classes
Class organization
Checking students' readiness for the lesson
Checking homework
A collection of fabrics made from natural fibers of animal origin, wool and silk.
Cognitive dictionary of the names of fabrics from natural fibers of animal origin - wool and silk.
Knowledge update
What do you think determines the properties of the fabric?
Student: The properties of fabrics depend on the properties of the fibers from which they are made.
What properties of fibers do you already know?
Student: Hygroscopicity - the ability of fibers to absorb moisture from the environment,
Felting - this is the ability of wool to form a felt-like covering during the felling process.
Thermal protection - the ability of a fabric to retain heat generated by a person.
Learning new material.
Everything is correct. The properties and quality of the manufactured fabric depend on the properties of the fibers. Fabric properties are affected the length and thickness (thinness) of the fibers, their strength, softness, crimp and elasticity.
From long and thin fibers produce thin, strong and even yarn, therefore, fabrics made from such yarn will be thin, durable, soft, smooth.
crimped fibers have good heat-shielding properties. Fabrics made from such fibers are often used for sewing winter clothes.
Elasticity fiber affects the wrinkling of tissues.
Practical work " Comparative characteristics natural fibers of cotton, linen, wool and silk.
I suggest you, using the textbook, your own observations, draw up a table “Comparative characteristics of natural fibers of cotton, linen, wool and silk”, which will help us to further trace the properties of fabrics.
Equipment: samples of natural fibers (wool, silk, cotton and linen), magnifiers.
Progress:
View fiber samples
Determine the properties of the fibers according to the following parameters: color, gloss, thickness, length, crimp, softness, smoothness, strength, elasticity.
Record the results of observations in the table.
|
Appearance and properties of fibers |
fiber name |
|||
|
cotton |
wool |
silk |
||
|
Color |
white |
light gray |
white, black, red and other natural colors |
white |
|
Shine |
matte |
cutting |
small |
pronounced |
|
Length |
6-52 mm |
250-1000 mm |
10-250 mm |
700-800 m |
|
Thickness |
average |
fine fiber |
thick fiber |
very fine fiber |
|
crimp |
weak |
straight fiber |
heavily twisted |
straight fiber |
|
Softness |
big |
average |
average |
big |
|
Smoothness |
fluffy fiber |
smooth fiber |
fluffy fiber |
smooth fiber |
|
Strength |
average |
high |
lower than cotton |
high |
|
Elasticity |
small |
big |
big |
average |
Comparison of the results of practical work.
Students share their observations, correcting, if any, errors in their work.
Continue reading a new topic.
According to their purpose, fabrics are divided into household, technical and special. Household fabrics are widely used in the clothing industry. These fabrics can be divided into clothing and decorative. Clothing fabrics are used for the manufacture of underwear, dresses, suits, coats, and also as a lining material. Decorative fabrics are used for furniture upholstery, making curtains, curtains, etc.
As you already know, the properties of fabrics depend on their fibrous composition, type of weave, and finishing features (bleaching, dyeing, impregnation with various substances). The main properties of fabrics are physical-mechanical, hygienic and technological. These properties are taken into account when choosing the style of the product, and the methods of its processing, as well as the mode of wet-heat treatment.
To physical and mechanical tissue properties are strength, creasing, drapeability, wear resistance.
Strength fabrics depends on the strength of the fiber, the twist of the yarn and the type of weave in the fabric. Under our conditions, the strength of the fabric can be tested by tearing the sample: the more effort we apply, the stronger the fabric.
Wrinkle fabrics depends on the elasticity and elasticity of the fibers and the degree of twist of the yarn. The crease of the fabric in the domestic environment can be checked as follows: clamp the sample in the cam, hold for a few seconds and open the cam. If the sample quickly restores its original appearance, then it is not wrinkled.
Drapeability- this is the ability of tissues to form soft folds. Let's determine the drapability of our samples: we will collect a piece of fabric, 15 cm long, on a thread, with a running line, and tighten the stitches. Rigid, poorly draped fabrics form large, protruding folds. Soft, well-draped fabrics give frequent deep folds.
wear resistance- this is the ability of a fabric to withstand the effects of friction, stretching, bending, compression, moisture, light, sun, temperature, sweat. Wear resistance depends on the strength of the fabric fibers.
Hygienic properties- these are properties aimed at maintaining human health. These include: heat-shielding, dust-holding capacity, hygroscopicity.
Hygroscopicity- this is the ability of tissues to absorb moisture from the environment (I demonstrate drops on a smooth surface, and touching the drop with the edge of the sample, I observe the absorption or not of the water drop by the prototype)
Thermal protection- is the ability of the fabric to retain the heat of the human body. The heat-shielding properties depend on the fibrous composition, the thickness of the density and the type of finish.
Dust capacity- This is the ability of the fabric to retain dust and other contaminants. Dust capacity depends on the fibrous composition, structure and nature of the fabric finish (the more villi to the fabric, the more they, electrifying, attract small particles of dust from the air).
to technological include the properties of fabrics that affect their processing in the manufacture of garments. it fabric shrinkage, thread fraying, slippage, and thread separation in the seams.
Shrinkage- this is a reduction in size during wet-heat treatment. (I am demonstrating experience: I cut out a piece of cotton fabric 10x10 cm in size and draw the same square on a sheet of paper, soak the fabric sample with water, wring it out, dry it with an iron. I compare the dimensions of the prototype by applying it to the pattern on paper. Cotton fabric, if it is new, is necessary will shrink up to 10 mm and students will see changes)
Thread fraying and thread separation in the seams lies in the fact that the threads are not held along the open sections of the material and slip out, crumble, forming a fringe or move apart at the seams. It depends on the smoothness and elasticity of the threads, the type of weave and the finish of the fabrics. (I am demonstrating an experience: I split a section of a piece of silk fabric with nails or a dissecting needle, while the threads readily fall out, forming a fringe. For comparison, I do the same experiment with a sample of cotton fabric and students see that the shedding of threads in the second case is much less than in the first ).
Slip can occur when cutting and grinding fabrics. The slip depends on the smoothness of the threads used in weaving and the type of weave. (When explaining this property to students, I fold a twill sample in two layers and shift one layer relative to the other, I do the same with a cotton fabric sample. Students have the opportunity to compare and draw conclusions regarding this property)
Technological properties of fabrics must be taken into account when sewing products. For example, from fabrics with a large thread separation, it is not recommended to sew tight-fitting products.
Fixing the material. Practical work"Comparative characteristics of tissue properties"
I suggest you, using the textbook, your own observations, draw up a table "Comparative characteristics of the properties of the fabric."
Equipment: samples of fabrics made from natural fibers (wool, silk, cotton and linen), magnifiers, dissecting needle, iron, needle, spool of thread.
Progress:
Conduct experiments with tissue samples, write down the results of observations in the table.
|
Fabric properties |
fabrics |
|||
|
cotton |
woolen |
silk |
||
|
Physical and mechanical |
||||
|
Strength |
average |
high |
less than at cotton- paper |
high |
|
Wrinkle |
average |
big |
very small |
very small |
|
Drapeability |
small |
small |
average |
high |
|
Hygienic |
||||
|
Hygroscopic |
significant |
big |
significant |
significant |
|
Dust capacity |
average |
small |
big |
small |
|
Thermal protection |
average |
weak |
high |
Somewhat higher than at cotton- paper |
|
Technological |
||||
|
significant |
signifi- body |
significant |
significant |
|
|
Thread shedding |
weak |
average |
average |
significant |
|
Sewing threads in the seams |
small |
average |
average |
significant |
|
Slip |
insignificant |
average |
insignificant |
high |
Summing up the practical work
Tell us about the properties of cotton fabrics?
Tell us about the properties of linen fabrics?
Tell us about the properties of woolen fabrics?
Tell us about the properties of silk fabrics?
Summing up the lesson.
When is it necessary to take into account the physical and mechanical properties of tissues?
Student: The physical and mechanical properties of fabrics are taken into account when choosing the style of the product, and the methods of its processing, as well as the mode of wet-heat treatment.
How are the technological properties of fabrics taken into account?
Student: The technological properties of fabrics must be taken into account when sewing products. For example, from fabrics with a large thread separation, it is not recommended to sew tight-fitting products.
How are the hygienic properties of fabrics taken into account?
Student: The hygienic properties of fabrics must be taken into account when choosing the purpose of clothing.
Homework.
Make up a vocabulary for today's lesson.
Fabric properties
1. Mechanical properties of tissues
2. Physical properties of tissues
3. Optical properties of fabrics, coloring, pattern and coloring of fabrics
4. Technological properties of fabrics
1. Mechanical properties of tissues
In the process of use, the main wear of clothing occurs as a result of repeated action of tensile load, compression, bending, and friction. Therefore, the ability of the fabric to withstand various mechanical influences, i.e., its mechanical properties, is of great importance for preserving the appearance and shape of clothing and increasing the period of wear.
The mechanical properties of fabrics include: strength, elongation, wear resistance, wrinkling, stiffness, drape, etc.
Tensile strength of the fabric is one of the most important indicators characterizing its quality. .
Tensile strength of a fabric refers to the ability of a fabric to withstand a load.
The minimum load sufficient to break a strip of fabric of a certain size is called the breaking load. The breaking load is determined when the fabric strips are torn on a tensile machine (Fig. 31). Sample 7 is fixed in clamps 8 and 6. The lower
Fig.31. Universal tensile machine
press 8 moves up and down from the electric motor,the upper clamp 6 is connected to the load lever 5.
When lowering the lower clamp, the sample, stretching, moves down the upper clamp, which rotates the load lever 5, which causes the pendulum force meter 4 with the load 9 to deflect. load scale 2 the magnitude of the load acting on the sample.
Under the influence of a tensile force, the specimen elongates and the distance between the clamps increases. The elongation value is fixed on the elongation scale 3 with an arrow 10.
For the test, three strips of fabric are cut out along the warp and four strips along the weft so that one is not a continuation of the other. It is important that the width of the strip exactly matches the established dimensions, and that the longitudinal threads are intact. The width of the strips is 50 mm. The distance between the clamps of the machine is taken for woolen fabrics equal to 100 mm, and for fabrics from all other fibers - 200 mm. The strips are cut 100 - 150 mm more than the clamping length. In order to save fabric, the small strip method has been developed, in which a strip 25 mm wide is tested with a clamping length of 50 mm.
The breaking load is calculated separately for warp and weft. The tensile strength of the sample on the warp or weft is the arithmetic mean of the test results of all warp strips or all weft strips.
When evaluating fabric in laboratories, the breaking load is determined and compared with the norms of the standards. For example, the strength of cotton dress fabrics is 313 - 343 N on the warp, 186 - 235 N on the weft, 687 - 803 N on the warp, 322 - 680 N on the weft, 322 - 588 N on the warp, weft 294 - 490 N. Despite the fact that cotton suit fabrics have greater tensile strength than wool, they wear out faster during use. This is due to the fact that woolen fabrics have higher extensibility and elasticity.
The tensile strength of the fabric depends on the fibrous composition of the fabrics, the thickness of the thread (yarn), density, weave, and the nature of the finish of the fabric. Synthetic fibers are the most durable. Increasing the thickness of the threads and the density of the fabric increases the strength of the fabric. The use of weaves with short overlaps also contributes to increasing the strength of the fabric, therefore, all things being equal, the plain weave gives the fabrics the greatest strength. Finishing operations such as rolling, sizing, decating increase the strength of the fabric. Bleaching, dyeing lead to some loss of strength.
Simultaneously with the strength of the fabric on a tearing machine, the elongation of the fabric is determined. The increase in the length of the sample at the moment of rupture - elongation at break - can be determined in millimeters (absolute elongation) or expressed as a percentage of the original length of the sample (relative elongation in).
where /1 - the initial length of the sample; /2 - the length of the sample at the moment of rupture. For example, the breaking elongation of chintz on the warp is 8-10%, on the weft 10-15%; bumazeya on the basis of 4-5%, on the duck 12 - 15%; linen on the basis of 4 - 5%, on the duck 6 - 7%; canvases made of natural silk on the warp 11%, on the weft 14%; staple fabric on the basis of 10%, on the duck 15%.
Modern tensile testing machines are equipped with chart instruments that record load-elongation curves.
The breaking load is plotted vertically, and the breaking elongation in millimeters or percentages is plotted horizontally. Elongation curves give an idea of how a material deforms under increasing load. This allows, for example, to judge how the fabric will behave in the processes of sewing production at loads that are much less than breaking.
Linen fabric, for example, has greater strength than woolen, but due to its low extensibility, less energy is spent on breaking it than on breaking woolen fabric, which has less strength but greater elongation.
The quality of the fabric is largely determined by the ratio of the proportion of elastic, elastic and plastic elongation of the fabric. If the fabric has a large proportion of elastic elongation, it wrinkles little, and the creases that occur on the fabric during operation quickly disappear. Elastic fabrics are more difficult to wet-heat treatment, but retain the shape of the product well during wear. If a larger percentage of the total elongation of the fabric is elastic elongation, then the wrinkles that occur when wearing clothes gradually disappear - the clothes have the ability to "sag". If, however, a large proportion of the total elongation is plastic elongation, then the tissues are strongly wrinkled, the clothes quickly lose their shape, and elbows and knees appear "bubbles". Such products need to be ironed frequently.
The value of the total elongation of the fabric and the proportion of elastic, elastic and plastic elongation in the composition of the total elongation depend on the fibrous composition, structure and finish of the fabric.
Synthetic and pure wool fabrics made of twisted yarn, fabrics made of textured threads, dense fabrics made of wool with lavsan have the greatest elasticity. Fabrics made from natural fibers of animal origin (wool, silk) have a significant elastic elongation, so they wrinkle little and gradually restore their original shape. Linen, cotton, viscose fabrics, i.e., fabrics made from plant fibers, have a large plastic elongation, so they are strongly wrinkled and do not restore their original shape on their own (without wet-heat treatment). Flax has the largest share of plastic deformation, so linen fabrics are wrinkled more than others.
The composition of mixtures and the percentage of fibers of different origin in them affect the elasticity of the fabric. For example, the addition of staple viscose fiber to wool reduces the elasticity of the fabric, the addition of staple lavsan or nylon, on the contrary, increases elasticity. To increase elasticity, up to 67% of lavsan is introduced into the composition of linen fabrics in the form of staple fibers or complex threads. The use of elastic fabric or spandex threads in the main and weft systems makes it possible to obtain materials of a three-dimensional structure with high extensibility. For example, for sports trousers, a fabric with an elastic base is produced, which ensures good stretchability of the fabric during exercise and maintains the appearance and shape of the product after repeated workouts. The use of elastic as a weft in swimwear fabrics makes it possible to obtain products that fit the figure tightly and do not restrict movement when swimming. High quality corsets are made from spandex threads.
With a homogeneous fibrous composition, the elasticity of the fabric will depend on its structure, that is, on the thickness and twist of the threads (yarn) and the density of the fabric. An increase in these indicators increases the elasticity of the tissue.
The ratio of disappearing and remaining elongations depends on the magnitude and duration of the tensile force. With an increase in the load and its duration, the proportion of remaining elongations increases. With prolonged wear, repeated loads lead to the accumulation of irreversible deformation, as a result of which the product loses its shape more and more.
Fabric elongation affects all stages of sewing production. When creating a model and developing a product design, it is necessary to take into account the percentage of elongation and the ratio of vanishing and remaining elongations. In models made of fabrics that do not have elasticity, tapered sleeves, tight skirts and trousers, etc. should be avoided.
When laying elastic fabrics, the sheets should be laid without tension. The stretching of the fabric in the deck results in a reduction in the size of the pieces. The fabrics are especially strongly stretched along the oblique thread, i.e. at an angle of 45 ° and close to 45 °. Therefore, when laying, it is necessary to ensure that there is no distortion of the fabric, displacement and sliding of the sheets in the flooring. When the fabric is warped and the canvases are displaced, the shape of the cut details is distorted. When sewing oblique cuts, the fabric is greatly stretched, the direction of the stitch is distorted, which spoils the appearance of the product. Stretching of the upper and lower webs and displacement of parts can occur. During wet-heat treatment, by forced stretching of the fabric (pulling), the product is given a certain shape. At the same time, undesirable stretching of parts can occur, which leads to damage to the product.
To reduce the stretching of the fabric along the edges of the sides of the outerwear, a low-stretch linen tape (edge) or a low-stretch fabric with an adhesive coating (adhesive edge) is laid. The edge is laid in the armholes of the sleeves, along the waist line and in other details of men's and women's suits. To preserve the shape of the pockets, strips of cotton fabric (doleviks) are laid.
Wrinkle - this is the ability of a fabric to form wrinkles and folds under kinks and pressure, which are eliminated only with wet heat treatment. The cause of wrinkling are plastic deformations that occur in the tissue under the action of bending and compression. Fibers, which have a significant proportion of elastic and elastic elongation, after bending and compression deformation, straighten more or less quickly and take their original position, so the creases disappear.
Crease depends on the fiber composition of the fabric, the thickness and twist of the threads, the weave, density and finish of the fabric. Fabrics made from elastic fibers are slightly wrinkled: wool, natural silk, and many synthetic fibers. Fabrics made from cotton, rayon, and especially linen tend to wrinkle. Increasing the thickness and twist of the threads reduces the wrinkling of fabrics. The gradual disappearance of folds in woolen, natural silk and synthetic fabrics is explained by the manifestation of the elastic properties of the fibers, due to which, after bending, the fibers take their original position. An increase in density prevents the threads from shifting in the fabric when it is bent, so dense fabrics are less wrinkled.
Big influence finishing has an effect on fabric wrinkling. To reduce the crease of cotton, staple, viscose fabrics, anti-crease finishes are used. In the clothing industry, to impart wrinkle resistance and ensure the shape of the product, they produce forenail processing.
Wrinkle reduction can be achieved by changing the structure of the fabric and using different types of twisted threads. The creation of fabrics of three-dimensional structures with the wide use of textured threads makes it possible to produce a wide variety of low-crease and elastic silk fabrics.
The sheen, coloring, and pattern of the fabric can emphasize or visually reduce wrinkling. Wrinkles and folds are most noticeable on light, shiny, thin fabrics in satin and twill weaves, such as lining fabrics. It seems that light-colored plain-dyed fabrics wrinkle more than the same multicolored or printed fabrics. The pattern does not reduce the wrinkling of the fabric, but makes it less noticeable.
Wrinkling of fabrics spoils the appearance of clothes and complicates the sewing process. Easily wrinkled fabrics wear out faster, as they experience more friction in places of bends and folds, and also lose strength during frequently repeated wet-heat treatments.
The wrinkling of tissues can be determined organoleptically by wrinkling the tissues in the hands and in the laboratory using special instruments. There are devices for determining oriented and non-oriented crushing (the "artificial arm" device IR-1, which is used to study the deformability of textile materials in the elbow area of the sleeves under repeated tension and compression; a device for determining the bending resistance of fabrics, designed to establish the bending angle of the fabric in degrees after load equal to 124 bends per minute).
When testing a tissue sample for wrinkling, depending on the degree of wrinkling, it is given the following assessment: strongly wrinkled, wrinkled, weakly wrinkled, non-wrinkled.
Drapeability - the ability of the fabric to form soft rounded folds. Drapability depends on the weight, stiffness and flexibility of the fabric. Rigidity is the ability of a fabric to resist shape change. The reciprocal of stiffness is flexibility - the ability of a fabric to easily change shape.
The stiffness and flexibility of the fabric depend on the size and type of fiber, the thickness, twist and structure of the thread, the structure and finish of the fabric. Low-density fabrics made from thin flexible fibers and low-twisted yarns are characterized by significant softness and flexibility. Flexible fabrics have good drapeability, but require attention when laying and sewing, as they warp easily.
The bending stiffness of household fabrics is determined on the PT-2 device by measuring the amount of deflection of a strip of fabric under the action of its own mass. There are special devices for determining stiffness and elasticity faux leather and film materials.
Artificial leather and suede, fabrics from complex nylon and monokapron threads, from wool with lavsan, dense fabrics from twisted yarn and fabrics with a large number of metal threads have significant stiffness. Interlacing with short. Overlapping and finishing increase the rigidity of the fabric. Rigid fabrics do not drape well - they form gentle folds with sharp corners. Rigid fabrics are well laid, do not warp during grinding, but at the same time they have high cutting resistance and are difficult to wet heat treatment.
The requirements that apply to the drape of a fabric depend on its purpose and model of the product. To create models of dresses and blouses of a free silhouette with soft lines, gathers, frills, soft folds, fabrics with good drape ability are required. Models of a strictly straight silhouette and extended downwards should be made of stiffer fabrics with less drape. Fabrics for men's suits and coats may have less drape than dresses, as they are used for products with a straight silhouette.
Fabrics made of natural silk, woolen fabrics of crepe weaves and soft coat woolen fabrics have good drapeability. Fabrics made from plant fibers have less drape than wool and silk fabrics.
D \u003d (200 - A) 1 00/200.
The disk method is used to determine the drapeability of the fabric in all directions (Fig. 32). From the fabric you
cut the sample in the form of a circle and impose it on a disk of smaller diameter. The drapeability of the fabric is determined depending on the number and shape of the formed folds and on the projection area that the fabric gives when the disk is illuminated from above.
The drape factor is the ratio of the difference
Rice. 32. Determination of fabric drape by disk method: / - fabric; 2 - projection
sample area and its projection to the sample area.Drapery coefficient Kd, %, is calculated by the formula
Kd \u003d (So - SQ) 100 / So,
where So is the sample area, mm2; SQ - projection area
sample, mm2.
The drapeability of artificial fur is determined by the loop method on the DM-1 device.
According to TsNIIShP, the drapability of a fabric is considered good if the following values of the coefficients are obtained as a result of tests. For wool suits, coats and cotton fabrics, the drapability is more than 65%. And for woolen dress fabrics - more than 80%, for silk dresses - more than 85%.
wear resistance tissues is called their ability to withstand a number of destructive factors. clothing fabric is exposed to light, sun, friction, bending, compression, moisture, sweat, washing, etc.
A complex set of mechanical, physicochemical and bacteriological effects leads to a gradual weakening, then to the destruction of the tissue.
The nature of the impacts experienced by the fabric during use depends on the purpose of the product and the operating conditions. For example, linen wears out from repeated washings, window curtains and curtains lose their strength from the action of light, the sun; wear of outerwear occurs mainly from friction. In the initial stage of abrasion, pilling is observed on many textile materials.
Pilling is the process of formation on the surface of textiles of lumps of rolling fibers - pills that occur in areas that experience the most intense friction and spoil the appearance of the product.
Textile materials can be pilled during the manufacture of garments, their use, washing, dry cleaning. The scheme of the appearance and disappearance of pills is as follows: the exit of the tips of the fibers to the surface of the materials, the formation of moss; pill formation; detachment of pills from the surface of materials.
Fabrics, knitwear, non-woven materials containing short fibers, especially synthetic ones, have the greatest pilling ability. Of the staple fibers, polyester fibers give the greatest pilling. Cotton weft fabrics give more pilling than viscose weft fabrics.
Pilling resistance is especially important for lining materials. The determination of pilling in textile materials is carried out using devices of various designs, called pilling testers. Depending on the number of pills on an area of 10 cm2, materials are divided into non-pilling, low-pilling (1-2 pills), medium-pilling (3-4 pills) and strong-pilling (5-6 pills).
Under the action of friction, the destruction of the fabric begins with abrasion of the bends of the threads protruding to the surface of the fabric, forming the so-called supporting surface of the fabric. Therefore, the abrasion resistance of a fabric can be improved by increasing the support surface of the fabric. This is achieved by using weaves with elongated overlaps. Other things being equal, satin and satin weave fabrics have the highest resistance to abrasion. Therefore, most lining fabrics are produced with satin and satin weaves.
When cutting, it must be taken into account that the destruction of the fabric occurs more slowly if the abrasion is directed along the threads that form the front covering.
During the operation of products, the fabric is wiped along the bottom of the sleeves and trousers, on the elbows, knees, collar. To increase the period of wearing products at the bottom of the trousers, it is recommended to sew on a nylon tape with a side, which prevents the fabric from abrasion. Along the line of the side, the fly-off of the collar and the bottom of the sleeves in women's products, a braid can be sewn, which serves as an ornament and at the same time prevents wear. In products sports style and in work clothes they make elbow and knee pads, which increase the durability of products.
Capron fabrics and fabrics with synthetic fibers have the highest resistance to abrasion. Therefore, to increase the resistance to abrasion, staple synthetic fibers are added to woolen fabrics. Thus, investing 10% of staple nylon fibers in a woolen fabric increases its abrasion resistance three times.
It should be remembered that violation of the mode of wet-heat treatment of fabrics - excessive heating and duration of treatment - leads to a decrease in the wear resistance of fabrics. In areas of woolen fabric that have a barely noticeable opal, the strength and wear resistance of the fabric are reduced by 50%.
Under the action of repeated stretching, compression, torsion, loosening of the structure of the fabric and threads occurs. Plastic deformations accumulate in the product, fabrics stretch, products lose their shape. The fibers gradually fall out, the thickness and density of the tissue decrease; tissue is destroyed.
The resistance of a fabric to repeatedly repeated mechanical stress is called endurance. Each tissue has an endurance limit, after which irreversible changes occur and accumulate in the tissue.
Durability the product increases if, during the operation of the fabric, the loads on it do not exceed its endurance limit.
Due to the fact that clothing wear occurs as a result of a complex set of environmental influences and depends on operating conditions, a unified method for determining wear resistance has not yet been established. The wear resistance of new sewing materials can be determined by experimental wear. From the tested materials, a batch of products is sewn, which are transferred for experimental wear to a certain group of people. After a set period of time, the products are examined in organizations conducting experimental wear, analyze the causes leading to wear, and decide on the advisability of "introducing new materials into mass production.
In laboratory conditions, individual factors or complexes of factors leading to fabric wear are determined: resistance to abrasion, washing and dry cleaning, resistance to repeated stretching and bending, resistance to light weather.
For a comprehensive study of materials in tension, relaxation (recovery of dimensions) in various environments and at various temperatures, an electronic device is used - a strograph.
The resistance of fabrics and knitted fabrics to abrasion can be determined on devices of various designs. But the principle of operation of the devices is the same - the material is subjected to friction on metal surfaces with a notch, on emery bars, on fabric, etc. The device counts the number of revolutions of the abrasive surface when the material under test is abraded to holes or after a certain number of strokes of the device, a decrease in the strength of the material is determined. An acoustic method has been developed for testing materials without their destruction, based on the dependence of the attenuation of ultrasound on the wear of the material.
Different fibrous materials resist and retain dirt differently. When judged visually, wool is more resistant to soiling, but at the same time, it is able to hold the most dust. In other words, wool retains dirt and at the same time does not look soiled.
Data on the contamination of fabrics depending on their structure and type of fibers are given in the table.
FABRIC CONTAMINATION DEPENDING ON ITS FIBROUS COMPOSITION |
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| Textile | Fabric weight g/m2 | Weave type | Difference in light reflection from the surface before and after contamination, in % |
The amount of dirt retained by the fabric, in % |
| Woolen gabardine | 186 | twill | 28,8 | 1,25 |
| Flannel wool | 207 | twill | 29,3 | 1,60 |
| fine wool | 109 | linen | 21,7 | 0,85 |
| Nylon | 95 | linen | 27,0 | 0,86 |
| Acetate | 190 | linen | 33,9 | 1,04 |
| Viscose | 125 | linen | 37,2 | 1,36 |
| Cotton | 132 | linen | 34,8 | 0,96 |
As can be seen from the data in the table, in terms of reflectance, woolen and nylon fabrics are less polluted than fabrics made of cotton, acetate and viscose fibers. In terms of the amount of dust retained, the data is completely different. This is apparently due to the fact that the structure of the fabric is the main factor influencing contamination.
One of the causes of tissue contamination is the formation of charges static electricity on them and the attraction of dust particles. Static electricity is generated when fibrous materials rub against each other or against other objects.
The surface of various fabrics is contaminated in different ways: the finer the fibers, the more they hold dust. This is also facilitated by the presence on the surface of the fibers of various channels and other irregularities, electrification of the fibers. According to the ability to electrify the fibers can be arranged in the following row: fiberglass, nylon, wool, natural silk, viscose fiber, cotton, acetate fiber, orlon (nitron).
Humidity helps dissipate static electricity., therefore, a greater electrostatic charge is formed on hydrophobic fibers than on hydrophilic ones.
Hydrophobic fabrics almost do not absorb water, so dirt remains on the surface of the fibers and can be easily removed from it with the appropriate cleaning method. If we take the reflection of light from the surface of the fabric as an indicator of the effectiveness of cleaning a fabric from pollution, then during aqua treatment in a soap solution, woolen and cotton fabrics are cleaned in the same way. When aqua-treated in synthetic detergents, wool is cleaned better than cotton.
In softened water without the addition of detergents, more contaminants are removed from wool than from cotton. When cleaning, the structure of the fabric also plays a role. How denser fabric, the more difficult the process of removing contaminants from it.
Street dust and dirt - the most common type of pollution. Street dirt contains oils, sewage, unburned particles emitted with smoke. Prolonged interaction of street dirt with the fabric can cause the dye to break. The particle size of street dirt is in the range of 1-20 microns.
Particles of dust and dirt with a size of up to 10 microns have the greatest ability to be deposited on the fabric and be retained by it.
1. Properties of fabrics: mechanical, technological, hygienic. A brief description of.
In order not to make a mistake in choosing a fabric for manufacturing for the manufacture of any product, it is necessary to be able to correctly determine the properties that it possesses. The properties of fabrics depend on their composition, type of weave and finishing features. The properties of fabrics affect the choice of model and the processing of the product.
All properties of fabrics are divided into mechanical, physical and technological.
Mechanical properties determine the ratio of the material to the impact on it of various external forces. Under the influence of these forces, the material is deformed: its dimensions and shape change.
To mechanical properties fabrics include: strength, wear resistance, wrinkling, drape.
Strength is the ability of a fabric to resist tearing. The strength of the fabric depends on the strength of the fibers, the structure of the yarn, the weave and the nature of the finish of the fabric. This is one of the important properties that affect the quality of the fabric.
Creasing is the ability of a fabric to form small wrinkles and folds during compression and pressure on it. Crease depends on the properties of the fibers, the type of yarn, the density of the yarn, the density of the fabric and the nature of its finish.
Drapeability is the ability of a fabric to form soft, rounded folds when suspended.
Natural silk fabrics and some woolen fabrics have good drapeability. Rigid, dense cotton and linen fabrics drape worse.
Wear resistance is the ability of a fabric to withstand the effects of friction, stretching, bending, compression, sun, temperature, washing. The wear of the fabric depends on the strength of the fibers in the fabric. Violation of the mode of wet-heat treatment of fabrics also reduces the wear resistance of the fabric.
Physical Properties- These are the properties of tissues aimed at maintaining human health. These include: heat-shielding properties, dust holding capacity and hygroscopicity.
Heat-shielding properties are the ability of a fabric to retain the heat of the human body. These properties depend on the fiber composition, thickness, density and finish of the fabric.
Dust holding capacity is the ability of a fabric to retain dust and other contaminants. Dust capacity depends on the fiber composition, structure and finish of the fabric.
Technological properties- these are the properties that the fabric exhibits during the manufacturing process of the product, from cutting to the final wet-heat treatment. Technological properties of fabrics include: sliding, crumbling, shrinkage.
Sliding is the movement of one layer of tissue relative to another. Sliding can occur when cutting, basting and grinding fabrics. This property depends on the smoothness of the surface of the fabric and the type of weave.
Shedding is the loss of threads along open sections of fabric. The friability of the fabric depends on the type of yarn and weave, as well as on the density and finish of the fabric.
Shrinkage is a decrease in the size of the fabric under the influence of heat and moisture, for example, during wet-heat treatment and washing. The shrinkage of fabrics depends on their fibrous composition, structure and finish.
2. Personal professional plan.
Millions of young men and women, graduating from school, vocational schools, are trying to find their way in life, but not everyone manages to achieve the desired success. One of the reasons is that a person's personal professional and life plans are not always well thought out, drawn up without taking into account their abilities and possible obstacles.
A life plan is a person's idea of the desired lifestyle (social, professional, family status) and ways to achieve them. Professional plan - a reasonable idea of the chosen field labor activity, about ways of mastering the future profession and prospects for professional growth.
Professional Plan Scheme:
1. The main goal: who I will be, what I will be, what I will achieve, etc.
2. Immediate tasks and more distant prospects: field of activity, specialty, labor test of strength, what and where to study, prospects for professional growth.
3. Ways and means to achieve the goal: the study of reference literature, conversations with specialists, admission to an educational institution (vocational school, college, university).
4. External obstacles to achieving the goal: difficulties, opposition from one of the people.
5. Internal conditions for achieving the goal: one's own capabilities (health, will, propensity for practical or theoretical work).
6. Fallback options and ways to achieve them: if you do not pass the competition in the university, try to enter the same specialty in college.
A personal professional plan is a mental representation of the future, everything in it depends on a person: his character, experience, mindset. Plans should be comprehensively analyzed, several options should be considered. This is an opportunity to avoid the stress of failure. A successfully drawn up professional plan is the foundation of a person's future professional activity, his career (rapid achievement of success, material gain, well-being).