Density Measurement for Fiber

 Equipment and Reagent:-

ð  10 ML graduated cylinder and either 100 ml graduated cylinder or six 20 ml beakers.

ð  Two liquids of known densities which are miscible in all proportions and, which will, when correctly mixed, give a range of densities from 1.0 to 1.60.

ð  Suggested liquids are

• Carbon tetrachloride (sp. gr. 1.60) and xylene (sp. gr. 0.87)
• Carbon tetrachloride (sp. gr. 1.60) and n-heptane (sp. gr. 1.10)
• Perchloroethylene (sp. gr. 1.63) and xylene (sp. gr. 0.87)

Manipulation:-

ð  Fiber density can be determined in two ways: by using density gradient tube or graduated series of liquids of known densities.

ð  Density Gradient Tube:-

·    It is prepared using 10 ml graduated cylinder, prepare the mixture of carbon tetrachloride and xylene respectively; 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, 10/90 ml/ml; add carefully 10 ml carbon tetrachloride in to 100 ml of xylene.

·     Add above nine mixtures and pour 10 ml of xylene on top.

·    The mixtures should be added in such a way that one mixture will not penetrate more than depth of 12 ml into previous mixture. 

·     The cylinder will now have a column of liquid, the density of which varies continuously down its length from 1.6 at the bottom to 0.87 at the top.

·    Now, wet out the fibers in warm xylene, dry them, and cut them into very short lengths (1mm).

·     Place them on a sheet of paper and tease them apart so that no fiber is adhering to any other.

·      Then lay them on the surface of the liquid in the cylinder. With a stirring rod, shove the fibers under the surface of the liquid and allow them to seek their level of density.

·       After 10 – 15 minutes, read off the levels at which the fibers float and identify them by referring to the below table.

Table:- Densities of Fibers

Fiber	Density (g/cc)
Cotton	1.50
Viscose	1.52
Wool	1.32
Silk	1.33
Nylon 66	1.14
Nylon 6	1.14
Polyester	1.38

Microscopic Examination for Fiber Identification

  

•  For fiber analysis, microscope is one of the most powerful tools, to see the surface characteristics and cross-sectional shape of the fibers.

 Equipment:-

•  A microscope of good quality, with magnification from 100 to 450 diameters.
• Supplemental requirements are: number of regular glass microscope slides and cover glasses, a dozen or more small glass bottles fitted with medicine droppers, pair of fine pointed tweezers, dissecting needle, a micro-tome of cross-section block, razor blades, and a light source.

Manipulation:-

• The most important step in the microscopic examination is preparation of the slide.
• Fibers to be examined should first be degreased by washing in petroleum ether or carbon tetrachloride.
• After drying the fibers on a piece of blotting paper, they are transferred to the microscope slide.

ð  For longitudinal View:-

·     Cut the fibers into short lengths, not over 1/8”, and place them in a flask containing either water to which a little wetting agent has been added or ethyl alcohol.

·     Fibers are mounted on glass plate with mounting medium and covered with cover glass.

ð  For Cross sectional View:-

·     The simplest method of preparing cross sectional view is the cross section plate. This is a stainless steel plate, the size and shape of microscope slide with two rows of five holes each drilled in it.

·     One row has holes 1/32” in diameter, the other 1/64” in diameter.

·     The projecting fibers through the plate are cut off flush with the surface of the plate with a sharp razor blade.

·      Fibers are mounted on glass plate with mounting medium and covered with cover glass.

Table:- Microscopic View of Fibers

Fiber	Longitudinal View	Cross sectional View
Cotton	A flattened, collapsed, spirally twisted tube with a rough surface, and frequent convolution that change direction	Flat, elongated or bean shaped with lumen as a line or oval parallel to the larger direction
Viscose	Uniform diameter with striations running parallel to the fiber axis	Roughly circular or irregular in cross-section with separated or scalloped edges according to the process used
Wool	Irregular and roughly cylindrical, prominent scale margins or flattened plates	Oval to circular with variation in diameter. Medulla is concentric and variables in size
Silk	Flat irregular ribbons, twisted and with longitudinal striations	Very elongated triangles normally separated, with round corners
Nylon 66	Very regular, rod like	Circular
Nylon 6	Very regular, rod like	Circular
Polyester	Very regular, rod like	Circular

Reference: 

Textile Testing and Analysis by N A Vaishnav and H D Joshi, Popular Prakashan

Burning Test for Fiber Identification

• The oldest test used to identify the fibres is burning test.
• It consist of following observations:

(a)    Odour of the gaseous products of combustion (smoke)

(b)   Rate and character of burning

(c)    Action after removal of flame

(d)   Character of ash

Equipment:- source of flame

ð  The best sources are a Bunsen burner or an alcohol lamp.

ð  Cigarette lighter can also be used as a source.

ð  Match is a poorest source, as its burning odour.

Manipulation:-

ð  Fibre should be heavy yarn; length should be 1.5 to 2” by twisting.

ð  Twist of the fibre should be tight, so burning rate will be slow.

ð  The fibre sample should be slowly introduced to the flame from the side.

ð  If the fibre burns in the flame, remove it and note whether it continue to burn. (if it burns without contact with the flame is said to support combustion)

ð  If the fibre fails to support the combustion, quickly note the odour of the gaseous products of combustion.

ð  Do not move the fibre any more than is absolutely necessary as this will cause the smoke to be dispersed in the air.

ð  Note also whether the fibre continues to glow after the flame has been extinguished.

ð  Finally examine the ash from the standpoint of amount from colour and hardness.

ð  Table shows the burning characteristics of the fibre under the conditions stated above.

Reference: 

Textile Testing and Analysis by N A Vaishnav and H D Joshi, Popular Prakashan

FULLY AUTOMATIC FLAT – BED SCREEN PRINTING MACHINE

 

In order to increase the speed of flat – screen printing, it was necessary to devise a method of printing all the colours simultaneously. Unfortunately, flat screens are not suitable coloration units for a truly continuous process, and in all the successful machines for fully automatic flat – screen printing the colour is applied through the screen while the fabric is stationary.

            The machine consists of

ð  Printing table (flat bed)

ð  An endless conveyer belt to bring the fabric on to the table under the screen periodically

ð  A number of screens

ð  A special mechanism for lowering the screen on the required parts of the fabric squeegees driven by motor

ð  A special conveyer under the table to collect extra paste

ð  An arrangement for gumming the fabric to the conveyer belt and a drier.

During printing, the fabric is brought on to the printing table through a feeding arrangement and gummed to the conveyer belt on the table. For gumming, a two shaft peddler is used in which the bottom shaft rotates in a gum box and transmits the gum on to the top shaft which transfers it to the conveyer belt. The conveyer brings the fabric periodically under the screens and stops while the screens are lowered on the required parts of the fabric by a special mechanism. The squeegee makes one or more strokes over the screen after which the screens are lifted again.

            Printing paste prepared in tanks is brought through flexible hoses and poured on the screen. It is then distributed throughout the full length of the screen. The squeegee is pressed to the screen by dynamometers placed at the both ends of the squeegee holders. One or more strokes of the squeegee ensure simultaneous printing of the patterns by the common action of all screens each of which applies the printing paste as required by the colour in the design. Extra paste is collected by a special conveyer running under the table. After printing, the fabric is dried by passing through a hot – air chamber. The conveyer returns to its original position where it is washed and dried and a new fabric is gummed on it.

            Greater production of printed cloth can be achieved by this machine as compared to ordinary hand screen printing and exact registration of prints with different repeats is possible. Printing can also be carried out with as many as 6 squeegee strokes. Since the process is mechanised, it is not laborious and yet has all the advantages of screen printing.

 

ð  FEEDING:-  Feeding device is consist of two guider (roller or plate) manufactured by metal or rubber coated, and  tension roller to maintain the fabric flow in creaseless form.

ð  GUMMING:- Gumming device consist two rubber coated roller, one is dipped in gumming tank to apply gum to another roller which is attached to the blanket.

ð  PRINTING TABLE / SYSTEM:- The cast iron bed or wooden bed duly machine cut rest on heavy duty cast iron structure to ensure vibration free operation cloth feeding is tensionless with expander or cloth guiding arrangement permanent gumming arrangement can be given with electrical heater and thermostatic temperature controller rubber printing blanket travels on bed very accurately, main drive through mechanical sector run by reduction gear box and A.C. electric motor with correction device by hydraulic cylinder, screen adjustment is very handy to set design and the setting systems is located conveniently on the machine.

ð  BLANKET WASHING UNIT:- two nos of brush rolls are driven by A.C. electric Motor and they are housed in a S.S. TANK .Special Design squeeze also attached.

ð  DRYER:- The high capacity float dryer with suitable jets, radiators, fan assembly and insulating penal gives quick and even drying for all types of print. The dryer capacity can be increased by adding extra dryer modules.

ð  ELECTRICALCONTROL PANEL:- Internally fully wired electrical penal is made from best quality contactors, relays, switches for controlling M/C Operations.

ð  INVERTOR / SERVO CONTROL PANEL:- Invertors / servo control panel that is known for its high performance and stable nature. Made from superior quality components, these panels consume less power and provide higher outputs. These compact designed highly efficient control panels which use for our fully automatic flat bed screen printing machine for quality performance.

ð  FULLEY AUTOMATIC PRINTING HEAD:- An extensive range of automatic printing head on fully automatic flat bed screen printing machine that is an auto AC inverter drive system for flat bed printing machine.

Reference:- (Book)

1.      Handbook of Textile Processing Machinery by R.S. Bhagwat

2.      Textile Printing by LWC Miles

3.      Technology of Printing by Dr. V.A. Shenai

4.      Technology of Printing by R.S. Prayag

Percentage Purity of NaOH (Sodium Hydroxide)

 

Process:

ð  Weigh 2 gm of the sample accurately in weighing bottle.

ð  Transferred the same sample in a 500 ml. volumetric flask.

ð  Made the solution up to 500 ml. with distilled water.

ð  Pipette out 10 ml. from the same solution using volumetric pipette and transferred into a conical flask.

ð  Add 2 – 3 drops of phenolphthalein indicator.

ð  Titrate it against 0.1(1/10)N HCl (Hydrochloric acid).

 Chemical Reaction:

NaOH_(aq) + HCl_(aq) à NaCl_(aq) + H₂O_(aq)

Calculation:

Answer: % Purity of NaOH is (BR) X 10