exam 1 Flashcards
calculation for tenacity
grams/denier
or
measure of force/
unit of weight
calculation for stress
breakpoint force (g)/
denier
calculation for strain
elongation (cm)/
original length
x100
=%
calculation for Initial Modulus
a Stress/
a Strain
calculation for Modulus of Elasticity (MOE)
y2-y1/
x2-x1
side by side bicomponent fiber
like split ice cream
helical crimp
adds bulk
which adds stretch
cover core biocomponent fiber
caramel apple
changes surface characteristics
Matrix-fibril type biocomponent fiber
multiple cores
-changes optic qualities (luster, reflectance, dye uptake)
-increases molecular weight which increases strength
cysteine linkages
-in protein
-amino/acid
-basic/acidic reactions
-positive/negative charge reactions
-polarity attracts water
protein molecule
-cystine linkages
-bottle shape chain
-open space allows area for reactions, water absorption, and collapse
- ability to shrink
-poor stability
cellulose molecule
-chicken wire chain structure
-6 OH groups (6n) for absorption
-poor resiliency
-can’t bounce back well
c
II
o
amide linkage
-effects absorbency and
heat stability
-ideal is 4 carbon per amide for optimal absorbency.
COOH3
acetate
-crystalline structure
-substitutes OH for LOWER absorption
-heavier molecule=higher heat stability
crystallinity
compact structure
-higher heat stability
-strong but brittle
amorphous
openly spaced
-low absorbency
-less heat resistant
aromatic ring
-stronger
-heat/flame resistant
n
degree of polymerization
-number of molecules per repeat structure
-higher n=more absorbent and heat resistant
dimensional stability
physical changes when heat or moister are applied
specific gravity/density
weight of material in denier
denier
weight of fiber per 9000 meters
fiber theory
fibers are made up of polymers via a process of linking molecules (monomers) together called polymerization
types of fiber identification
-burn test
-staining test
-chemical solubility
-density gradient
-light microscopy
-polarizing microscopy
-electron microscopy
-infrared microscopy
modification ratio
outer diameter (x)/
Inner diameter(y)
-larger ratio = soiling, crushing, matting
melt spinning
polymer is heated and solidified into any shape through the spinneret
wet spinning
a polymer and a solvent are mixed into a solution and spinneret extrudes into a bath that neutralizes the solvent
dry spinning
a polymer and a solvent are mixed into a solution and spinneret extrudes into the air where the solvent evaporates from the core.
E/V
ratio of solvent evaporation in dry spinning
E= evaporation rate from surface
V= diffusion rate of solvent from center of filament
E<V= round crossection
E>V=irregular
E«<V= collapse center
acrylic vs modacrylic
acrylic has :
-Higher tenacity
-lower density
-higher regain
acetate vs. triacetate
acetate has:
-double the regain (absorbency)
-lower softening temp
-more intense care (dry clean)
-5% more elongation
-worse resiliency
-worse elastic recovery
DS
degree of substitution
absorbency
moistier regain
effects:
-comfort (good for hydrophilic)
-static build up (good for hydrophilic)
-dimensional stability in water (good for hydrophilic)
-wrinkle recovery (poor for hydrophilic)
abrasion resistance
ability to resist wear from abrasion
-nylon has great abrasion resistance
-lyocell and acetate have poor
elasticity
ability to elongate and recover
-spandex has high elasticity as an elastomeric
flexibility
capability of a fiber to bend without breaking.
-flexible fibers have good drape (ie. acetate)
-generally thinner
-rigid fabric holds shape
Hand
the way fabric feels
-effected by fiber surface
-either crimped or straight
pilling
broken ends of a fiber tangling together on the surface
- common for hydrophobic fibers with static
-strong fibers hold on to pill
-rough fiber surface snags (wool)
