; hydrophilic
Documents
Resources
Learning Center
Upload
Plans & pricing Sign in
Sign Out

hydrophilic

VIEWS: 1 PAGES: 19

  • pg 1
									Introduction to Fibers II
Measuring Properties – Moisture Terms
• hydrophilic (Gr.: hydros = water + philos = love)-fibers with
  an affinity to water
• hydrophobic (Gr.: hydros = water +phobos = loathe)-fibers
  with no affinity to water
• The moisture properties of a fiber is determined, in large
  measure, by its chemical composition; does it have an
  affinity for water.
• Also hydrophilic fibers may either absorb or adsorb water.
    •   Absorb – moisture penetrates into the fiber
    •   Adsorb – moisture bound on the fiber’s surface
Regain & Moisture Content

              r c
          Supe S           pa
                    ale Com ny

                                 W   grams
                                                                                100




                                             Hot & Ready Oven Co.




Regain = (W – w)/w x 100%
                                              Super Scale Company

                                                                    W
Moisture Content = (W – w)/W x 100%                                     grams
Mechanical Properties - Tenacity

      A fiber that is made from
      a less strong material
      may be able to carry
      more load than one
      made from a stronger
                                                        strong material
      material if the former is        weak mat erial

      greater in size.


                    tenacity = strength/λ
Mechanical Properties - Elongation
                                                        Similarly, a long fiber
                                                        will extend further
                             ext en s ion               when stretched than a
                                                        short fiber, even if
                                                        they are of the same
                                                        material.

           elongation = “stretched length” – original length

                  strain = elongation/original length


  Often these are multiplied by 100% to give percent elongation and percent strain
Measurement of Mechanical Properties
              Electronic Lo ad                Video Mo nitor
                    Ce ll
                                 Co mputer
                                 Inte rface




         Gauge          Fibe r
         Le ngth                                       



                                               Pe n Reco rder
 Pull Apart Co ., Inc
Measurement of Mechanical Properties

Tenacity
                                     1. Initial modulus
           u           2
                                       (stiffness) –
                                        resistance to
                                        deformation
                                     2. Ultimate tenacity and
                1   
                    3                   strain
                
                                     3. Specific work of
                        
                        u
                            Strain      rupture – energy
                                        (stored or released)
                                        at time of rupture
Natural Fibers
Cellulosic

         H     CH OH
                   2

                         H O                   OH
     O                             H       H                  OH
                                                       H
         HO
                              OH       O                             H
                   H
              H                                H            O
                                           H
         glycoside linkages
                                               CH OH
                                                   2
                                                           D-glucose unit
Cotton
                                            • Seed hair fiber
                                            • Hydrophilic – affinity
             cuticle (out er wax y layer)     between the
                    primary wall              hydroxyl groups
                                              (OH-) and water
     lumen
               seco ndary wall
                                              (H—OH)
                                            • Adsorbs
                       co nvo lution
Wool
•   18 different amino
    acids all with the               R
                                               O
    structure shown to the
    right                    H2 N    C     C
                                                   OH
                                     H

                              General amino acid
Polypeptide chain


         R1       O           R2          O

     N   C    C   N           C       C

     H   H        H           H

                      amide linkage
Crosslinking-cystine



     O=C                          C=O

            CH•CH •S•S•CH •HC
                  2           2
                 cystine link
      H—N                         N—H
Wool

 •   Depending upon the             Cortex
     source, wool fibers range
     in length from 38-375 mm
 •   round, and have a
     diameter of about 25 µm.
 •   The fibers can be identified            Scale s
     by the scales on the
     surface
 •   Felting
Wool
                • 2 types of cortical cells
       ortho
                • Natural waviness
                • Because each amino
                  acid has different
                  properties
                    •   Hydrophilic
                         •   absorbs
         para
                    •   Amphoteric – behaves
                        like both acid and base
Silk
       •   Protein fiber
       •   The secretion of the larva
           of the Bombyx mori moth,
           used to form its cocoon
       •   The major fiber protein is
           fibroin, which is composed
           of 15 amino acids in a
           polypeptide chain
       •   Very few cystine cross-
           links
       •   Not amphoteric.
Silk
• The larva secretes two 'D'     sericin
  shaped filaments (called
  brins) simultaneously, held
  together by the protein
  gum sericin.
• The fibers are highly
  regular and very lustrous.
• The cocoon of the
  silkworm contains about
  800-1200 meters of fiber
  (two strands); each fiber is
  about 10 µm thick              fibroin
Asbestos
•   Asbestos is the only naturally
    occurring mineral fiber
•   There are 6 forms of asbestos:
    Six minerals are defined as
    "asbestos" including, chrysotile,
    amosite, crocidolite, tremolite,
    anthophyllite and actinolite
•   Vast majority of textile fibers are
    chrysotile asbestos, hydrated
    magnesium silicate,
    [Mg3Si2O5(OH)4]
•   Flame resistant

                                          chrysotile
Next

•   Monday: Short reports
•   Tuesday: Manufactured Fibers

								
To top
;