Structural Investigation Method Of Fiber

Density 

The volumetric mass density of a  substance is its mass per unit volume. The symbol most often used for density is ρ (sometime d also). Mathematically, density is defined as mass divided by volume.

ρ = m/v

Where,

 

ρ = density

m= mass

V = volume

Density measurement by DGC (Density Gradient Column)

This method of Density measurement should be performed according to ASTM D1505.

Length Measurement Instrument

WIRA 

 It involves a rotating shaft with a spiral groove machined in it. Once end of the fiber to be measured is gripped by a pair of tweezers whose point is then placed in the moving spiral. This has the effect of moving the tweezers to the right and so steadily drawing the fiber through the pressure plate. This ensures that the fiber is extended under a standard tension. A fine wire rests on the fiber and is arranged so that when the far end of the fiber passes under the wire it allows it to drop into a small cup of mercury and thus complete an electrical circuit. This causes the shaft to stop moving, so halting the tweezers, at this point the tweezers are then raised to lift the counter immediately above where it has stopped. The counters are arranged in 0.5 cm sections and each time one is lifted it adds a unit to the appropriate length group so contributing to a cumulative total. The advantage of the apparatus is that it gives a standard tension to the fibers, it involves less operator fatigue and it gives semi-automatic recording of the results to 0.5 cm intervals. The apparatus is claimed to be able to measure up to 500 fibers per hour However, the detector wire that is used to sense the end of the fiber is very delicate and it is difficult to set up.

Fiber Sorter Method

This is done by holding the fibers in one hand and extracting the fibers by their ends with the other hand. This first step produces a bundle of fiber ends together. The fibers are then taken from this bundle by hand a few a time starting with the longest fibers and are laid down next to one another in descending order of length. This produces a fiber diagram as show in fig.

Fibre Testing

 Length measurement

    In general a longer average fibre length is to be preferred because it confers a number a advantages   Firstly, longer fibres are easier to process. Secondly, more even yarns can be produced form them because there are less fibre ends in a given length of yarn. Thirdly, a higher strength yarn can be produced from them for the same level of twist. Alternatively a yarn of the same strength can be produced but with a lower level of twist, thus giving a softer yarn.

Mean Length

When calculating the means length . There are in fact three possible ways of deriving the mean length:

1. Mean length based on number of fibers (unbaised mean length) L

2. Mean length based on fiber cross-section (cross-section biased mean length) Hauteur H.

3. Mean length based on fiber mass (mass-biased mean length) Barbe B.

Introduction To Textile Testing

 Textile testing is the term for a whole series of tests that examine the physical, mechanical and chemical properties of textile.These test are sometimes done before a textile goes into widespread use, or  they're done on textiles arriving  from other countries for sale in US markets. Countries like the United States have established standards for what should and should not be in textiles products. Tests can show whether companies making textiles are in compliance or not.

    The testing of  textile products is an expensive business. A laboratory has to be set up and furnished with a range of test equipment. Trained operatives have to be employed whose salaries have to be paid throughout the year,not just when results are required. Moreover all these costs are nonproductive and therefore add to the final cost of the product. Therefore, it is important that testing is not undertaken without adding some benefit to the final product.

Objective of Testing

• Checking the quality and suitability of raw material and selection of material .
• Monitoring of production i.e process control.
• Assessment of final product, whether the quality is acceptable or not, (how will be the yarn performance in weaving etc.)
• Investigation of faulty materials ( analysis of customer complaint, identification of fault in machine etc.)
• Product development and research.
• Specification testing : Specification are formed and the materials are tested to prove whether they fall within the limits allowed in the specification (e.g. specified by a customer)

Standardization of Testing

Application of Statistics in Textile Testing

Measurement of Central Tendency

A measure of central tendency is a single value that attempts to describe a set of data by identifying the central position within that set of data. As such, measures of central tendency are  sometime called measures of central location. They are also classed as summary statistics. The mean (often called the average) is most likely the measure of central tendency that you are most familiar with, but there are others, such as the median and the mode.

Mean

The mean (or average) is the most popular and well known measure of central tendency. It can be used with both discrete and continuous data, although its use is most often with continuous data. The mean is equal to the sum of all the values in the data set divided by the number of values in the data set. So, if we have n values in a data set and they have values X ₁,X₂,..........,Xn  the sample mean, usually denoted by  x̄ (pronounced X bar) 

Determine the micronaire value of given cotton sample by air blow method. Convert the result into S.I unit and give a suitable rating to the fiber sample

Machine Used : Micronaire tester, Weighing machine

Objective:- It is use to check the micronaire value, fiber fineness as well as maturity of cotton  fiber.

Theory:- This is indirect method of measuring fiber fineness which is based on the fact that the air flow at a given pressure difference through a uniformity distributed mass of fibers is determined by the total area of a fibers is proportional to its diameter because the air flow varies with pressure difference it is ratio of air flow to differential pressure that is determined by the fiber diameter.

Procedure :-

1. Weigh accurately 324 grams of sample tested with a weighing balance.
2. Keep the air pressure exactly as 2.5 bar before calibration.
3. Then process the calibration switch by holding and take the adjustable knob clockwise, anti-clock wise until the top of the indicating float in the glass tube rises to the calibration mark.
4. Lock the adjustable knob by pushing down and release the calibration switch now instrument is ready for testing.

Testing Room Atmosphere

The Control Of The Testing Room Atmosphere

• The THERMOSTATS and HYGROMETER CONTROL VALVES operates by compressed air.
• The air input to the conditioning plant may come from outside or be recirculated air, or a mixture of both.
• In all instance it is filtered before heating and conditioning.
• A fan blows the conditioned air in to the laboratory through special ducts with lowered outlets in the ceiling.
• All the windows are double glazed used to prevent unwanted air coming in from the corridor when people pass in and out of the laboratory.
• Automatic two "towers" are used, one for adding moisture and one for subtracting moisture from the air.

Measurement of Moisture Regain

By oven dry method (Direct)

• It contains the fiber sample in a mesh container.
• The container is suspended inside the oven from one pan of balance, the mechanism of which is outside the oven.
• This ensures that the weight of the sample can be monitored without disturbing the system.

ADVANTAGE

• All the weighing is carried out inside the oven.
• The use of the conditioning oven to dry a sample is correct standard procedure; any other method of sample drying has to be checked for accuracy against it.
• The use of the conditioning oven to dry a sample is correct standard procedure; any other method of sample drying has to be checked for accuracy against it.

Measurement of Atmospheric Moisture

Wet & Dry Bulb Hygrometer

• This is an instrument equipped with two thermometers, side by side.
• The bulb of one of the thermometers is covered with a muslin wick dipping into water.
• The water is absorbed up the muslin and evaporates, cooling.
• The difference between the wet and dry bulb temperatures is called the wet bulb depression.
• If the air is fully saturated (100% relative humidity) the water cannot evaporate, so both the wet and dry bulb temperatures are the same.

                                                            

Hair Hygrometer

• These devices use a human or animal hair under tension.
• The hair is hygroscopic (tending toward retaining moisture); its length changes with humidity, and the length change may be magnified by a mechanism and indicated on a dial or scale.

• The traditional folk art device known as a weather house works on this principle. Whale bone and other materials may be used in place of hair.
• This instrument uses strands of human or horse hair with the oils removed attached to levers that magnify a small change in hair length.

To prepare comb sorter diagram

By using comb diagram determine the following:-
1. Mean length
2. Effective length
3. Short fiber percentage
4. Dispersion percentage 

Fiber diagram

Operating Device :- Comb sorter

Material Used :- Cotton

Introduction  :- Comb sorter is the device in which we can place the fiber tuft which is selected from different or same type of fiber and also these fiber are oriented thorough comber and after this we can obtained the actual length and graph between different fiber length.

REGAIN & MOISTURE CONTENT

•  Regain is defined as the weight of water  in a material expressed as a percentage of the oven dry  weight. 
• Moisture content is the weight of water in a material expressed as percentage of the total weight. 

• let oven dry weight = d
• weight of water =W
• Regain = R
• Moisture Content = M

Mechanisms of moisture absorption

Mechanisms of moisture absorption 

• Moisture absorption in textile fibers occurs through the interaction of water molecules with polar groups within the structure (e.g. OH, -COOH). 
•  In ordered (crystalline) parts of the structure, these polar groups are not attached but in disordered (amorphous) regions there can be very free groups which can act as hooks with which the water molecules can link through hydrogen bonding. 
• Thus the absorption of moisture takes place in the amorphous regions only.

Atmospheric Condition And Relative Humidity

• Among other thing , the regain of a textile material depends upon the amount of moisture present in the surrounding air. The dampness, of the atmosphere can be described in terms of humidity either absolute humidity or relative humidity. 

Moistures in Textile

Introduction

taken form google

• The properties of textile fibers are strongly affected by the atmospheric moisture content.  
• Many fibers, particularly the natural fibers are hygroscopic in nature and they will absorb moisture if kept in a humid atmosphere. 
• Conversely, they will tend to lose moisture in a dry atmosphere (a process known as desorption.) 
• Hydrophobic fibers (e.g. Polyester) are those which do not absorb moisture if kept in a humid atmosphere.

Effluent Testing: Testing of BOD, COD, TOC and interpretation of results

Effluent testing from Nitish sharma

Textile Testing

Textile Testing

Textile Testing from Nitish sharma