HECOL170 Lecture Notes - Lecture 5: Candle Wick, Paper Towel, Static Cling
13 Jul 2018
School
Department
Course
Professor
Chemical Proper!es
Chemical Properties
moisture related properties
electrical conductivity
effect of heat
chemical reactivity and resistance
resistance to biological attack
resistance to light
Moisture Related Properties
Absorbency
the ability of a fibre to take water into its internal structure from the body or form the
environment
measured as moisture regain
absorbency of the fibre
relates to its crystallinity - a more absorbent fibre will have low levels of crystallinity
related to how many polar sites - —OH hydroxyl groups.
ex/ non polar polyester and high crystallinity is not absorbent
fibres with a high absorbency also tend to have a high dyeability
fibres with food absorbency tend to be good electrical conductors
-do not build up static charge readily and do not attract lint or create problems with static
cling
Moisture Regain
ratio of mass of moisture in a material to oven-dry mass
standard textile testing conditions - 20 C , 65% relative humidity (RH)
reason we do the testing at certain levels - textiles act really different with different levels of
moisture in the atmosphere, and how dry they are
ex/ moisture regain of:
cotton 6%-8%
wool - 11%-13%
polyester - 0.4%
use a 5cm x 5cm piece of fabric, need to be very accurate in taking the weight of the object,
weigh it about 5 times, putting it back into the oven each time
(wet weight — dry weight)
dry weight x 100 = % moisture regain
Adsorbency
the ability of a fibre to hold water on its surface
microfibres have low deniers - have a better absorbency - travel towels, cleaning cloths
greater surface area makes it have a higher adsorbency
Imbibed water - water contained within the yarn and fabric interstices
Wicking
the spread of water through a fabric (vertically or horizontally) by capillary action
capillary action - very small narrow channel that draws liquid in, candle wick able to draw up the
candle fluid to the top in order for the flame to catch
needs to be a lot of liquid to occur
polyester used for sportswear, paper towel, sponges. most fabrics will have some
degree of wicking:
vertical wicking - wicking coming up vertically
horizontal wicking - ex/ drawing moisture from the skin and taking it to the front of the fabric in
sportswear apparel
Water Repellent
the relative degree of resistance of a fabric to surface wetting, water penetration, water
absorption, or any combination of these properties
-ex/ spill something that was liquid, have the time to clean up the spill before stains
only a certain amount of resistance to water, not waterproof
Waterproof and Water Resistant
ability of fabrics to be fully resistant to penetration by water
want to have some degree of water vapour permeability
-ex/ rain gear
Water Vapour Permeability
rate of diffusion of water vapour through a fabric.
usually called ‘breathability’ by marketers, but not in textile science
clothing that will make sure you are not hot and sweaty
Drying Rate
how quickly a fabric may dry
important in physical comfort - don’t want it to be heavy, or make body cold
Hydrophilic
have a strong affinity for water
tends to mix with or dissolve or be wetted by water
is ‘water loving’
-ex/ cotton, polyester, rayon, not completely crystalline, and polar
possible to put a hydrophilic finish - help water be attracted more so to the fabric
usually used for casual work apparel and children’s wear because it absorbs moisture readily
Hydrophobic
lacks affinity for water
tending to repel and not absorb water
tending not to dissolve in or mix with or be wetted by water
a repelling treatment would be a hydrophobic finish
tend to be oleophilic - have a strong affinity for oil
-tend to bond quickly and tightly with oil, cleaning becomes an issue
nylon and polyester often used in outer shell of rain coats
Hygroscopic
readily absorbs water (usually from the atmosphere)
Document Summary
Chemical properties moisture related properties electrical conductivity effect of heat chemical reactivity and resistance resistance to biological attack resistance to light. Bres with a high absorbency also tend to have a high dyeability. Bres with food absorbency tend to be good electrical conductors. Do not build up static charge readily and do not attract lint or create problems with static cling. Adsorbency the ability of a bre to hold water on its surface micro bres have low deniers - have a better absorbency - travel towels, cleaning cloths greater surface area makes it have a higher adsorbency. Imbibed water - water contained within the yarn and fabric interstices. Water repellent the relative degree of resistance of a fabric to surface wetting, water penetration, water absorption, or any combination of these properties. Ex/ spill something that was liquid, have the time to clean up the spill before stains only a certain amount of resistance to water, not waterproof.
