User:Yammy cock/sandbox

Moisture in textiles
All textile materials are less or more hygroscopic and have moisture relations in textiles. Also, they contain a certain amount of moisture which depends upon the relative humidity of the surrounding air atmosphere. They will absorb moisture, in a damp condition and they will give up moisture in a dry atmosphere. Therefore it follows that weight will vary with the R.H. of the surrounding atmosphere. Hence properties of the material will be affected. The following properties vary with the amount of moisture
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Mechanical properties of fibres Electrical behaviour Elasticity and strength Yarn rigidity and hairiness etc

Hence moisture present in textiles is very important, especially from the following point of the view

Moisture in textiles at purchasing
At purchasing time, money is paid accordingly to the weight of the material which highly depends on the moisture present in the material. So the buyer must know the moisture weight in the material otherwise he may face a loss of money. Standard regain of different materials is given blow material

Fibre type	Moisture content % Cotton	8.5 Wool	17 Viscose	11~13 Silk	11 Jute	14 Polyester	0.3~0.4 Nylon	4.2

Moisture relation for textiles processing point of view
With respect to processing, moisture plays a very important role. It must be nearly standard as given blow

Department	Moisture % Mixing	7 ± 0.5 Lap/ chute feed	5.5 ± 0.5 Silver	5.5 ± 0.5 Roving	5.5 ± 0.5 Ring	5.0 ± 0.5 Winding	6 ± 0.5 Packing	8.5 ± 0.5

More moisture results in poor opening, nepinss, overlapping of rollers and also the rusting of metallic surfaces may occur. At roving and ring end breakage rate increases and straightening and parallelization decrease

Less moisture in the material results in fibre breakage and damage.

Effect on yarn quality
The strength of fibres increases in the case of cotton and decreases for other fibres when moisture is increased. Also, low moisture results in lint loss and unnecessary wastage increases.

Some definitions of moisture in fibres

Original weight
"Weight of material in its original condition containing any moisture level". It is denoted by O.W

Dry weight
"The weight of the material without any moisture is called dry weight". It is denoted by D.

Oven dry weight
"Weight of material dried at oven state i.e. at 1050C". It is also called oven dry weight.

Moisture regain
"Weight of moisture based on the dry weight". It is denoted by R

Moisture content
"Weight of moisture based on original weight". It is denoted by M.

M.R = W/D

M.C = W/(W+D)

or

R = W/D x 100

M = W/(W+D) x 100

Where R and M are M.R and M.C, expressed in percentage. Also,

M = W/(W+D) x 100

= (W/D)/(W/D + D/D) x 100 = (R/100)/(1+R/100) x 100

or M = (R/(100+R)) x 100

Similarly

R = (M/(100-M)) x 100

From the above relations, it is quite clear that R is always greater than M.

Correct condition weight ( correct invoice weight)

weight of material at an 8.5% moisture level ( for cotton fibre) is called invoice weight. Setting and purchasing are done on the basis of this weight. Corrected condition weight is equal to oven dry weight plus standard regain.

i.e. corrected condition weight (C.C.W) = dry weight + dry weight x 8.5/100

= D(100+R)/100

Absolute humidity
"The weight of water in a unit volume of air,   " i.e. gram/m3 etc.

Relative humidity
The ratio between actual vapour pressure to vapour pressure at saturation is expressed in percentage.

R.H% = actual water vapour pressure/vapour pressure at saturation

From the hygrometer we measure R.H

i.e.

R.H = 98.6-(dry temperature-wet temperature weight)/dry temperature x 100

Moisture hysteresis
In the desorption process, at any given relative humidity, a wet fibre material retains more moisture compared to this can adsorb. This moisture absorption difference at the same relative humidity in the desorption and adsorption curves is called moisture hysteresis.

Hysteresis of moisture regain
The sorption hysteresis phenomenon is well-known for wood to understand. Also, hysteresis means the equilibrium moisture content (EMC) is due to differences in the adsorption and desorption processes.

The hysteresis process is further caused by friction and structural changes in the fabric. With the decrease of fabric density the hysteresis increases, which determines the contact points number of fabric within a given length.