Ques.: What are silicones ?
Ans.: Silicones are organo - metallic compounds of silica.
Ques.: What is surfactant ? Give examples.
Ans.: Surfactants are the those chemical species which reduce the interfacial tension & is active only at interfaces.
1. To from micelle
2. To adsorbed on the surface
Alcohol ethoxylate, nonyl phenol ethoxylate, Lauryl alcohol ethoxylate
Ques.: Classify the different type of emulsions made at Acorn ?
Ans.: Micro, Macro, Semi micro
Ques.: What are different types of surfactant ?
Ans.: a. Anionic
c. Non ionic
Quest.: Differentiate between macro and micro emulsions?
Ans.: Macro emulsions are milky in appearance. Micro emulsions are clear and transparent. This difference is due to the difference in particle size. It ranges between 0.01 to 0.1 microns for micro and 0.1 to 10 microns for macro emulsions.
Ques.: What is an emulsion ?
Ans.: Emulsion is a mixture of two immiscible liquids one dispersed in another stabilized by a third surfactant system.
Ques.: What are enzymes ?
Ans.: Enzymes are biocatalysts which will enhance the chemical reaction without being consumed in the reaction.
Ques.: Advantages of silicone emulsion over cationic emulsions ?
Ans.: 1. It give permanent finished.
2. Non toxic in nature
3. Penetrate in side the fabric
4. Increase the tear strength of fabric
5. Reduced the friction between the thread and needle
Ques.: Why micro emulsions are preferred for textile applications ?
Ans.: Micro emulsions owing to their minute particle size are capable of penetrating in to the fabrics giving inner softness where as macro emulsions remain on the fabric surface giving only surface smoothness.
Ques.: General machineries used for finishing ?
Ans.: Garment industry: Belly washer, Winch, Tumble drier, Centrifugal m/c.
Mill sector: Padding with a stenter., Softflow m/c, Godet, P/A,
winding, Cheese winding.
Ques.: What is the property of silicone that aids in mould release ?
Ans.: 1. Hydrophobicity [water-disliking]
2. Incompatibility with organic surfaces.
3. Brushing action of – CH3 groups.
4. Low Surface tension
Ques.: How is viscocity of a emulsion checked ?
Ans.: Viscosity is checked by viscometer.
Ques.: What are different types of Auxiliaries ?
1. DESIZING :- Desizing is done to facilitate weaving & to prevent the breaking due to the friction. The yarn is coated with size in fats/waxes or other substances vinyl co-polymer size is used. To remove the size we have to apply some solution by the method of boiling in soap/live seed oil for viscous yarns (soda ash) and for highly oxidized sized it is treated with trichloroethylene (dilute acid for resin removing)
2. SCOURING :- The natural impurities must be removed from the fibres, with the soap or synthetic detergent. This process is done to remove the impurities/fats.
3. BLEACHING:- Bleaching is done by employing Hypochlorides like hydrogen peroxide/potassium permagnet/hydro sulphites and sulphites and peroxide. Peroxide is economically successful.
4. STOVING. :- Blankets, knitted woolens and white flannels are bleached by stoving. This is done by the application of sulphurous acid.
5. MERCERISING:- The fibre is applied with the caustic soda on natural fibres to make them permanent lustrous and to remove the alkali. This also helps in absorbing the dye and cotton and rayon are treated by this process.
6. RAISING :- Raising is done to impart heavy surface on the cloth. The fibre is lifted usually out of the yarn by raising.
7. NAP FINISHING:- This is done for fibrous surface. Fibre is raised and with rubbing small curls and mobs appear on the surface of the fibres (roughly hair surface).
8. DRESS FACE FINISH:- This process is called FELTING. The texture is dense & fibrous and the luster is imparted to the surface by boiling the fabric.
9. CROPING/SHERING:- This process is undertaken to cut the pipes of the fibre and it gives well defined weaves.
10. BRUSHING AND STEAMING:- It is used for woolen materials in a double process. Both before and after cutting BRUSHING is done to remove all loose fibres. STEAMING is done to soften the fibre and this helps to give brightness to the surface of fabric.
This process is applied on smooth and lustrous fabric and is used to remove all loose fabre or fluffy the cloth. In this process, constant heat has to be applied through plates or it will not be uniform and the patches will appear.
Through this process the space between the cloth is closed up to flatten them and to impart lustre.
This is to ensure that warp and weft don’t slip on to each other and remain permanent in position. (worsted fabrics)
Tweed cloth or other fabrics with dense texture require to pass through this process. This is to ensure that the fabric don’t shrink and so on the cloth soap and sodium carbonate or acid is used.
This is done to stretch the fabric to the certain width and also in dying of textile.
16. WATER PROOFING:-
Nylon fabrics are treated with Silicone Resin. Cotton linen and rayon fabric are treated with aluminium acetate, wax, and rubber. Amonialal Copper Oxide gives heat to form a durable film appear.
This process is undertaken for anti crease and water repellent finish.
18. CREASE RESISTANT:-
This process is carried out after bleaching, dyeing or printing. A melamine dehyde resin is prepared.
19. MOTH PROOFING:-
This treatment is carried out during dyeing or scouring. The substance used is chlorinated phenols and used in woolen fabrics.
20. ROT PROOFING:-
All natural fibres are subject to attack by mildew or bacteria, so to avoid rotting some chemical or mineral dyes are used.
21. FLAME RESISTANT:-
Cloth is treated with mineral salts and it helps to provide efficient flame resistant.
The machine shrinks and stretch the material to the required degree.
This is done to impart lustre, smooth and glossy appearance to the cotton fabric.
24. MOIR FABRIC:-
These fabric resemble a water reflection.
This done to fix the resin in higher temperature using synthetic resin like area, formal dehyde, melamine formal dehyde.
26. VELVET FINISH VELVETTEN:-
These are brushed to remove all surplus fibres and the pile is sheered.
27. PILLING:- This is done because the yarn should be spun with
sufficient twist to prevent
Ques.: What is the classification of siloxanes in Chemistry ?
Ques.: Why Silicones are not used in metal to metal lubrication ?
Ans.: Silicones have high coefficient of friction
Ques.: A customer complains of low release using a release agent for
moulding rubber. What could be the probable causes ?
Ans.: Mould not cleaned
Usage, dosage etc
New mould – not conditioned
Ques.: What are the types of surfactants? What is the role of surfactent
in emulsification ?
Ques.: Distinguish between micro and macro emulsion ?
| || || || |
||Transluscent to transparent
| || || || |
||Highly stable, thermodynamically stable
| || || || |
| || || || |
|| Particle size
||0.5 – 5
| || || || |
||Stays on interface
||Penetrates fiber network
Ques.: Define a. Antifoam b. Defoamer:
Ans.: Antifoam – Prevents foam formation
Defoamer – Kills foam
Ques.: Antifoams should have an HLB less than 12. True / False – Why ?:
Ans.: True. Because it should be insoluble in foaming medium. Also
antifoams should not foam
Ques.: List down three non textile applications of amino fluids ?:
Ans.: Personal care, as coupling agent, in lubrication of cutting edges, metal finishing, Auto polish, leather.
Ques.: Why does a micro emulsion turn macro ?:
Ans.: While preparing – With change in HLB or emulsifier quantity, micro emulsion turns macro and viscosity of emulsion also gets effected.
On storage – over a period of time the micelle come together to form clusters which tend to agglomerate, due to this the particle size changes and micro emulsion turns hazy or macro.
Ques.: Write appearance for the following particle size of the emulsion and the application?:
Ans.: greater than 200 micron – Milky white dispersion
50-100 micron – milky white dispersion
~ 1 micron – milky white dispersion
0.2-5 micron – Translucent
0.1-.05 micron – Transparent
Less than 0.05 micron – Transparent
Ques.: How do you check whether a piece of rubber is silicone or not ?:
Ans.: By burning it
Ques.: What are the three main components in paper coating?:
Ans.: Reactive Siloxane, Crosslinker, Catalyst
Ques.: Can silicone coatings be used in any other substrate. If yes give three examples?:
Ans.: Yes. Conformal coatings, Textiles, Mould release, glass.