东华大学：《纺织材料学》课程教学资源（PPT课件讲稿，英文版）Chapter 11 Silk Fibers

米 Chapter1 Silk Fibers Yiping Qiu

Chapter 11 Silk Fibers Yiping Qiu

Introduction The larva of certain insects for use in their building webs, climbing ropes and cocoons riders Commercial silk industry: use larva of silkworm Application Mostly apparel, was also used for parachutes

Introduction The larva of certain insects for use in their building webs, climbing ropes and cocoons Spiders Commercial silk industry: use larva of silkworm Application: Mostly apparel, was also used for parachutes

米 Structure Macrostructure Length: 1000-1300 yds(915-1190 m)/cocoon Max 3000yds(2750m)/cocoon, 1 fiber/cocoon Thickness 9-11 um or 1.2-1.5 denier Varies: thickest in the middle thinnest inside(maybe running out of raw material, or maybe just make itself comfortable)

Structure Macrostructure: Length: 1000-1300 yds (915-1190 m)/cocoon Max 3000yds (2750m)/cocoon, 1 fiber/cocoon. Thickness: 9-11 mm or 1.2-1.5 denier. Varies: thickest in the middle thinnest inside (maybe running out of raw material, or maybe just make itself comfortable)

米 Structure Microstructure cross-Section: 2 triangular filaments co extruded by a worm The two are called brins held together by sericin(gum or silk glue Wild silk worms produce ribbon-like silk fibers

Structure Microstructure cross-section: 2 triangular filaments co￾extruded by a worm. The two are called brins held together by sericin (gum or silk glue). Wild silk worms produce ribbon-like silk fibers

米 Structure Submicrostructure Silk from cultivated worm: no identifiable submicrostructure Wild silk or tussah silk has internal fibrillar structure

Structure Submicrostructure Silk from cultivated worm: no identifiable submicrostructure. Wild silk or Tussah silk has internal fibrillar structure

米 Structure Fibroin protein polymer a chain of amino acids forming a protein called fibroin composed of 15-18 different amino acids Glycine, alanine and serine occupy 86% of the polymer The side groups of the above 3 amino acids are small compared with those in wool glycine:R=H alanine: R=-CH3 Serine: r=-ChbOH Crystallize readily: 70-75%/

Structure Fibroin protein polymer A chain of amino acids forming a protein called fibroin composed of 15-18 different amino acids. Glycine, alanine and serine occupy 86% of the polymer The side groups of the above 3 amino acids are small compared with those in wool: glycine: R = H alanine: R = -CH3 Serine: R = -CH2OH Crystallize readily: 70-75%

米 Structure Fibroin protein polymer Pack well: lots of h-bonds small number of ionic bonds No cystine: no S-s bonds Configuration: pleated B-sheet Degree of polymerization of silk DP Silk >Dp wool

Structure Fibroin protein polymer Pack well: lots of H-bonds, small number of ionic bonds No cystine: no S-S bonds Configuration: pleated b-sheet Degree of polymerization of silk DPsilk > DPwool

P roperties For silk producers. 1. e. silk worm. spider etc. silk fibers are for protection transport and food capture Me echanical properties Medium tenacity but higher than wool resulted from molecular structure zigzag B-sheet of silk vs a-helix of wool higher crystallinity than wool

Properties For silk producers, i.e. silk worm, spider etc., silk fibers are for protection, transport and food capture Mechanical properties Medium tenacity but higher than wool resulted from molecular structure: zigzag b-sheet of silk vs a-helix of wool higher crystallinity than wool

P roperties Mechanical properties Medium elongation at break High elastic recovery at low elongation When elongated 2%, 90% elastic recovery Medium modulus Medium abrasion resistance Medium resilience: (cotton silk wool) oleated sheets can slide over one-another

Properties Mechanical properties Medium elongation at break High elastic recovery at low elongation When elongated 2%, 90% elastic recovery Medium modulus Medium abrasion resistance Medium resilience: (cotton < silk < wool) pleated sheets can slide over one-another

P roperties Comfort High heat of wetting: lots of polar groups available High water absorption: up to 1/3 of its weight Smooth and soft High luster: high crystallinity and triangular croSs-sectional shape Scroop: rustling sound due to an acid treatment that hardens fiber surface

Properties Comfort High heat of wetting: lots of polar groups available High water absorption: up to 1/3 of its weight Smooth and soft High luster: high crystallinity and triangular cross-sectional shape. Scroop: rustling sound due to an acid treatment that hardens fiber surface