Modern Fibres

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Modern Fibres

  1. 1. MODERN FIBRES WOOL RESEARCH ASSOCIATION By , SUDEEP SHAW
  2. 2. Man made fibers • Nylon Polyester Olefin PAN • Rayon Elastomeric (Spandex)
  3. 3. Properties & Features
  4. 4. The step change in strength and stiffness from first generation to second generation manufactured fibres.
  5. 5. A fibre that is specially designed and manufactured to give some specific performance characteristics under some specific ambient conditions. Such as : HM-HT Fibres - Kevlar, PBO, UHMWPE, Carbon. Thermally Resistant Fibres. - Nomex, Kevlar, PBO, Carbon. Definition of High-Performance Fibre
  6. 6.  Linear Polymers - Kevlar, PBO, UHMWPE, etc.  Two Dimensional Networks - Carbon Fibres  Three Dimensional Networks - Glass & Ceramic Fibres HM-HT Fibres fall into three groups :
  7. 7. • Sufficiently high polymer chain lengths. • High degree of orientation among the polymer chains. • High degree of crystallinity. A diagram drawn by Staudinger, which is the ideal form of a linear- polymer fibre with high strength & stiffness Requirements of a linear polymer to act as a HM-HT Fibre :
  8. 8. Very high chain flexibility in polymer melt / solution Leads to high degree of entanglements of the polymeric chains Extremely difficult to remove / open-up these entanglements during drawing process Thus such a structure with high strength & high modulus can not be achieved. The main constraint towards achieving such a structure
  9. 9. • Using polymeric chains of rigid in nature, so that their flexibility will be low and it will be easy to orient them and chances of formation of entanglements will be low. • Using flexible polymeric chains, but by some means preventing the formation of entanglements right at the polymeric-melt / solution state. Two ways to solve the problem
  10. 10. Classification of Linear HM-HT Fibres
  11. 11. Rigid rod-like polymers shows a particular state, which is known as liquid crystalline polymer state , and therefore sometimes called LCP. Liquid crystals are of two types –  Lyotropic liquid crystal ( KEVLAR, VECTRAN ).  Thermotropic liquid crystal ( PBO ). Liquid Crystalline Polymer ( LCP )
  12. 12. Polymer Solvent Increase in polymer concentration ( Viscosity increases ) Isotropic solution Increase in polymer concentration ( Viscosity increases ) Lyotropic Liquid Crystalline Solution(Viscosity starts decreasing and reaches a lowest value) Increase in polymer concentration ( Viscosity increases ) Solid Lyotropic liquid crystal
  13. 13. Polymer ( Chip-form / Δ T Direct from polymerisation Reactor ) Viscosity decreases Isotropic polymer melt Δ T Viscosity decreases Thermotropic Liquid Crystalline Melt ( Vicosity reaches lowest value and then starts increasing ) Δ T Viscosity increases Isotropic polymer melt Thermotropic liquid crystal
  14. 14.  A manufactured fiber in which the fiber-forming substance is a long-chain synthetic polyamide in which at least 85% of the amide (-CO-NH-) linkages are attached directly between two aromatic rings . • Invention • DuPont – Morgan, Kwolek et. al. Aromatic Polyamides “Aramids”
  15. 15. • Diamine and diacid chloride – DuPont • Low temperature • Monomer purity and concentration • Amide solvent (NMP, HMPA, DMA)  A lot of structural diversity can be introduced into these polymers by changing the identity of the aromatic groups in the monomers. Solution Polycondensation
  16. 16. Dry-jet Wet Spinning • Spinning Solution – 10-20 wt% polymer – 100% H2SO4(H2O free) • Elongation aligns crystalline domains • Precipitates out of coagulation bath • Crystallinity of solution is translated to fiber • paraaramids show LC due to the rigidity of their chains which comes from the para linkages between all the aromatic groups Aramid Fiber Spinning (p-Aramids)
  17. 17. • Poly(m-phenylene isophthalamide) Nomex® • First commercial aromatic polyamide. • spun from isotropic solutions (not liquid crystalline like Kevlar) so it has greater flexibility than Kevlar fibers. NOMEX
  18. 18. • Poly(p-phenylene terephthalamide) (PPTA) Kevlar® • DuPont – Bair, Blades, Morgan, Kwolek • AKZO – Leo Vollbracht, Twaron® KEVLAR
  19. 19.  Positive Attributes : • High tensile strength (five times stronger per weight unit than steel); • High modulus of elasticity; • Very low elongation at breaking; • Low weight; • High chemical inertness; • Very low coefficient of thermal expansion; • High Fracture Toughness (impact resistance); • High cut resistance; • Flame resistance Properties of Kevlar Fibre
  20. 20.  Negative Attributes : • very low resistance to axial compression typically around 20% of the corresponding tensile strength • fibres break into small fibrils (fibres within the fibre) • fibres are hygroscopic (they absorb water) • fibre surfaces are susceptible to degradation by ultraviolet light. Properties of Kevlar Fibre ( contd. )
  21. 21. KEVLAR NOMEX Applications of Aramids
  22. 22. • Thermoset polurethane synthetic material.(aromatic hetrocylic polymer). • Trade name: Zylon, produced by Toyobo Corpn, japan since 1998. • Condensation polymerisation of 4,6-diamino-1,3- benzenediol dihydrochloride (DABDO) or Diamino resorcinol with terephthalic acid (TA). • Dry-jet Wet Spinning • 15-18 wt% polymer • Spinning Solution • 77% PPA at 60-80°C High degree of polymerisation (between 82–84%) PBO Poly(p-phenylene benzobisoxazole)
  23. 23. Characteristics •The poor compressive strength of these fibres restricts their use in composites. • Characterised by high rigidity and form highly ordered structures. • PBO fibres exhibit very high flame resistance and have exceptionally high thermal stability. •Extremely high tensile strength, an extremely high modulus. •Uses: •Fire fighting , bullet proof vest , race yacht sail , aero space etc. •Ideal for heat and flame resistant work-wear such as for fire fighters, Motorcycle suits, gloves, hot gas filtration media etc. •General applications for reinforcement include those for tyres, belts, cords, etc.
  24. 24. The backbone of polyethylene is highly flexible, because of the possibility of rotation around “C – C’’ bonds and because the only other element present is light hydrogen. - Thus a high degree of entanglement is present in normal industrial grade PE. UHMWPE
  25. 25. • In ‘ C ’- axis direction, diamond is composed of fully aligned zig-zag chains of carbon just like those in polyethylene. • Young modulus of diamond is 1160 GPa and the cross-sectional area per chain is 0.0488 nm2 • While for polyethylene it is 0.182 nm2 , i.e.- four times higher. • From this analogy we can expect a modulus of 285 GPa for fully aligned polyethylene, well above that of steel. - But, the normal industrial grade HDPE has a modulus of only 5 GPa. Frank has offered an elegant explanation of the physical basis for this high modulus offered by UHMWPE
  26. 26. 1) Theoretical modulus of this polymer is very high. 2) Availability of high molecular weight material. 3) It has high crystallinity and fast crystallizing property. 4) The structure of the polymer chain is zig-zag linear, without any bulky side-groups. 5) Low intermolecular interactions. Then, why PE was chosen for preparing HM-HT Fibre ?
  27. 27. UHMWPE HDPE Macromolecular Orientation - Therefore we are required to prevent the formation of entanglements at the polymer- melt / solution state. Macromolecular structure of UHMWPE & HDPE
  28. 28. • First , in the well-known melt-spinning and hot drawing route ( followed for PET, Nylon ); by which a maximum modulus of 60 GPa and tenacity of 1.3 GPa was achieved. • Second, through Gel-Spinning and subsequent drawing. This process was first invented and patented by Smith & Lemstra ( DSM High-Performance Fibres ). The fibre they had produced had a modulus of 200 GPa and tenacity of 7 GPa . The earlier research work was carried out in two different directions
  29. 29. GEL SPINNING Thus the prevention of the formation of entanglements at the solution state is possible through -----
  30. 30. a ) Dissolution, b) Spinning, c) Drawing Steps involved in GEL Spinning
  31. 31. Solution of UHMWPE of Mol. Wt.- 30 to 60 Lacs, for polymer concentration of 0.65 to 0.40 g/100 ml. , using Decalin / Paraffin oil as solvent Heated to 100 – 130 °C, with continuous stirring for proper dissolution Cooled down to room temerature which forms spherulites, and gets precipitated Steps involved in GEL Spinning ( contd. )
  32. 32. spherulites are separated and mixed with proper amount of decalin / paraffin with rigorous stirring to obtain 10 % wt solution At the point , where spinning stress is applied, the temerature is increased to 130 – 140 ° C, so that the spherulites are destroyed Water is used as the non-solvent in the extraction bath and a draw-ratio of upto 100 – 200 is applied during subsequent drying, to achieve high orientation. Steps involved in GEL Spinning ( contd. )
  33. 33.  Positive Attributes :  Density - ≈ 0.90-0.93 g/cc  Moisture Regain - ≈ 0 %  Tenacity - ≈ 3 GPa or 22-24 g/den  Modulus - ≈ 120-180 GPa or 900-1400 g/den  Elongation - ≈ 2.5-3.5 %  High Abrasion Resistance ( Inspite of having high modulus )  Chemically inert to most acids & alkalis upto 100 ° C.  Impact resistance very high. Properties of UHMWPE
  34. 34.  Negative Attributes :  Creep High  Thermal properties not good. Melting Temp - ≈ 160-165 °C Has to be used in an atmosphere where the temperature does not increase above 120 °C  Poor adhesion properties Properties of UHMWPE ( contd. )
  35. 35. Specific strength vs Specific modulus of various fibres Comparison of some of the properties :
  36. 36. Abrasion & Flex life of various fibres Comparison of some of the properties :
  37. 37.  Ballistic Protection : Dyneema UD & Spectra Shield are used for ballistic protection. These are made of unidirectional layers, in which yarns are not woven but lie parallel to each other and are bonded by various thermoplastic matrices. Construction of Dyneema UD & Spectra shield Applications of UHMWPE
  38. 38.  Why UHMWPE is most suitable for ballistic protection ? 1) Very high strain wave propagation rate ( 12300 m/sec; for KEVLAR it is 7000 m/sec ), due to low fibre density. R = K.W.C = K.W. √ ( Ef / ρf ) [ R = Energy applied by the bullet/ Energy that can absorbed by the substrate. K = Constant depending on various parameters. W = Energy required to break per unit fibre length. C = Starin wave propagation velocity. Ef = Modulus of the fibre. ρf = Density of the fibre. ] Applications of UHMWPE ( contd )
  39. 39. 2 ) Very high impact resistance - It’s glass transition temp ( - 10 ° C ) is below the room temperature, therefore in room temperature the material is in rubbery state and thereby giving a high impact resistance. 3 ) UHMWPE has the highest rate of increase in modulus , with increase in rate of loading. - Thereby showing very high modulus at the moment of impact. Applications of UHMWPE ( contd )
  40. 40.  Damage Tolerent Radar Domes : UHMWPE has very low dielectric constant ( 2.25 at 22 °C and 10 6 Hz ), thereby being more or less transparent to the waves. Thus loss due to reflection is low. Moreover, high degree of structural intigrity, high impact tolerence are the essential properties of radar domes. Applications of UHMWPE ( contd )
  41. 41.  Ropemaking : Where the number of contact points are very high, there the rope that is being used, should have high strength & modulus; as well as very high abrasion resistance. Moreover light-weight, floatability, flexibility, low moisture absorption and outstanding flex fatigue performance makes UHMWPE most suitable for this purpose. Applications of UHMWPE ( contd )
  42. 42.  Composites : UHMWPE fibres in non-ballistic composites are mainly used to improve the impact resistance and the energy absorption of glass or carbon fibre reinforced products. Hybrid fabrics with glass or carbon can be used and the fibre or the fabric can be plasma treated to improve the adhesion of the matrix to the fibre. The matrix material is normally an epoxy or polyester resin. The basic limitation here is that the curing temperature should not exceed 140°C. Applications of UHMWPE ( contd )
  43. 43.  Medical Application : Sutures, artificial ligaments, medical transplants . Applications of UHMWPE ( contd )
  44. 44. Schematic structure of graphite CARBON FIBRE
  45. 45. In late 1950s & early 1960s three groups were involved in serious efforts to produce high strength carbon fibre.  Research group at Wright Patterson Air Force Base in Dayton, Ohio, USA ;using viscose rayon as the precursor.  Shindo in the Industrial research Institute in Osaka, Japan, using PAN as the precursor.  Watt, Johnson and Phillips in the Royal Air crafts Establishment in Farnborough, England, using PAN as the precursor. Early Research-Works
  46. 46. 1) During pyrolysis the precursor material should not melt, and maintain it’s filament form. 2) Precursor material should give high amount of carbon yield. 3) A stabilization step is required to make the material thermally stable and infusible. 4) A step involving preferential orientation of the graphitic layers , i.e- carbonization step is required to be carried out. 5) The hexagonal structure formation that starts at carbonization step , must be completed perfectly & properly; for which graphitization process need to be carried out. Important requirements for the Production of carbon fibre :
  47. 47.  PAN-Based Precursor Process  Rayon-Based Precursor Process  Pitch-Based Precursor Process Commercially used Precursor Processes :
  48. 48.  Most widely used ( 90 % market share).  Comparatively higher carbon yield than the rayon process.  PAN in filament form is used for this purpose.  Most cost effective process. PAN-Based Precursor Process :
  49. 49. 1) Stabilization : First two steps that are involved in stabilization of PAN are cyclization and dehydrogenation which is carried out at a temperature of 200 - 220°C. Steps involved in PAN-Based Precursor Process :
  50. 50. The third step involved in stabilization is oxidation, which is carried out at a temperature of 220 – 300°C in the presence of air and thereby forming hydroxyl, carbonyl and carboxyl groups on the ladder polymer. In this process the material gets fully stabilized and becomes infusible. Steps involved in PAN-Based Precursor Process : ( contd. )
  51. 51. 2 ) Carbonization ( under tension ) : The black oxidized fibre is heated slowly to a temperature of 1000 – 1500°C in an inert atmosphere ( N2 ) under tension resulting in elimination of low molecular wt. gaseous products ( HCN, NH3 , H2 , CO, CO2 ). Steps involved in PAN-Based Precursor Process : ( contd. )
  52. 52. 3 ) Graphitization ( under stretch ) : The carbonized filaments are heat treated at 1500 – 2700°C in an inert atmosphere ( Ar ) under 30 % stretch, when the structure becomes more ordered and turns towards a true graphitic form, with the elimination of nitrogen ( N2 ). Steps involved in PAN-Based Precursor Process : ( contd. )
  53. 53.  Almost an obsolete process (2 % market share ).  Rayon in filament form is used for this purpose.  Carbon yield is very low ( ≈ 20 % ).  Resultant product has many defects & imperfections.  During graphitization almost 300 % stretch is required, which makes the process costlier & difficult. Rayon-Based Precursor Process :
  54. 54. Pitch-Based Precursor Process :  Comparatively newly developed process ( 8 % market share).  No tension is required to be applied in this process.  The final material has very high degree of purity ( upto 99.9 %).  The resultant carbon fibre ( Ultra High Modulus ) has very high modulus .  Meso-Phase pitch is converted into filament form for further processing.  Costlier process.
  55. 55. Comparison of carbon fibres produced from different precursors :
  56. 56. Comparison of different types of carbon fibres Carbon-fibre type Tensile Strength ( GPa ) Tensile Modulus ( GPa ) Breaking Elongation ( % ) Density ( g/cm3 ) Carbon Content ( wt % ) Electrical Resistivity (x 10– 4 Ω cm) Low Strength 2.5 – 3 240 – 270 1.2 – 1.4 1.7 – 1.8 92 – 93 15 – 16 High Strength 3.8 – 4.3 240 – 270 1.2 – 1.4 1.7 – 1.8 92 – 93 15 – 16 Ultra-High Strength 4.7 – 4.9 250 – 270 1.2 – 1.4 1.7 – 1.8 93 – 94 15 – 16 Intermediate Modulus 5.7 – 6.0 ≈ 300 1.2 – 1.4 1.7- 1.8 95 – 96 17 – 18 High Modulus 2.5 – 3.0 380 – 400 0.6 – 0.7 1.8 – 1.9 > 99.0 9 – 10 Ultra-High Modulus 3.8 – 4.0 530 - 540 0.3 – 0.4 1.9 – 2.1 > 99.9 6 – 7
  57. 57.  Positive Attributes :  High strength & high modulus.  High temperature resistance ( upto 2400 – 2500°C )  Not subjected to creep or fatigue failure.  Good electrical conductivity.  Chemical & biological inertness. Properties of carbon fibre :
  58. 58.  Negative Attributes :  Low impact strength / compressive strength.  Carbon fibres are expensive. Properties of carbon fibre : ( contd. )
  59. 59.  Carbon fibre rarely used alone.  Major use is reinforcement in composites.  Crabon fibre surface is very smooth, due to graphitization and relative chemical inertness of carbon atoms.  Thus resin bonding in case of carbon fibre composite production becomes difficult; resulting in low Interlaminar Shear Strength ( ILSS ).  Plasma treatment and different chemical treatments are applied to modify the fibre surface. Surface treatment of carbon fibres :
  60. 60. Surface treatmet of carbon fibres : ( contd. )
  61. 61.  Aerospace & Aviation :  Booster rocket casing of US Space Shuttles  Satellite antennas  Rocket nosel cone  Air-craft main-wings & tail-units  Helicopter blades Applications of Carbon fibre :
  62. 62.  Industrial :  Shuttles in textile machinery  Machinery items such as turbine, compressor, bearings, gears, etc.  Windmill blades  Industrial high pressure gas cylinder  Concrete reinforcement composites Applications of Carbon fibre : ( contd. )
  63. 63.  Sports & Leisure :  Tennis & badminton racquet handles  Pole vaulting pole  Golf-club shafts  Skis  Fishing rods  Bi-cycle frames, wheels  Racing car & bike components Applications of Carbon fibre : ( contd. )
  64. 64.  What is Glass? Glass is an amorphous solid, with isotropic three – dimensional network. “ American Society for Testing and Materials ’’ ( ASTM ) defines glass - as an inorganic product of fusion which has been cooled to a rigid condition without crystallizing . Glass Fibre
  65. 65. • A: high alkali grade ( Soda-lime glass ) – originally made for window glass • C: chemical resistance or corrosion grade – for acid environments • D: low dielectric – good transparency to radar: Quartz glass • E: electrical insulation grade - the most common reinforcement grade (E ~70 GPa) • M: high modulus grade • R: reinforcement grade – European equivalent of S-glass • S: high strength grade (a common variant is S2-glass) – fibre with higher Young’s modulus and temperature resistance – significantly more expensive than E-glass Different classes of Glass Fibre
  66. 66. Glass forming Oxides Oxide % in E- glass % in S- glass Effect on Fibre Properties SiO2 54 65 very low thermal expansion Na2 O trace trace high thermal expansion, moisture sensitivity K2 O - - high thermal expansion, moisture sensitivity Li2 O - - high thermal expansion, moisture sensitivity CaO 17.5 trace resistance to water, acids and alkalis MgO 4.5 10 resistance to water, acids and alkalis B2 O3 8.0 trace low thermal expansion Al2 O3 14 25 improved chemical durability Fe2 O3 trace trace green colouration ZnO - - chemical durability PbO - - increased density and brilliance (light transmission) and high thermal expansion BaO - - high density and improved chemical durability TiO2 improved chemical durability especially for alkali
  67. 67. Steps involved in Glass-Fibre manufacturing :
  68. 68.  Density : ( 2.48 – 2.55 ) g/cm3  Tenacity : ( 11 – 21 ) gpd  Modulus : ( 320 – 390 ) gpd  Elongation : ( 3 – 5.3 ) %  Maximum usable temperature : ( 300 – 350 )°C  Low thermal & electrical conductivity.  Being a three-dimensional isotropic structure, the mechanical properties along the fibre axis are the same as transverse to the axis, resulting in good compressive strength; which is ideal for use in composites. Properties of Glass Fibre
  69. 69.  Composites : Glass fibre reinforced plastics for industrial & automotive applications, in various components of lightweight aircrafts, in sports & leisure activities.  Thermal & Electrical Insulation  Optical Fibres Applications of Glass Fibre
  70. 70.  Advantages of Optical fibre compared to conventional copper-wire for telecommunication : 1) High information carrying capacity. 2) Low electromagnetic interference. 3) Higher chemical & thermal stability. 4) Light weight.  Applications : Telecommunication, Medical application ( Laser ballon angioplasty ), etc. Optical Fibre
  71. 71.  The working principle of optical fibre is based upon Total Internal Reflection of light. Optical Fibre ( contd. )
  72. 72. Optical Fibre ( contd. ) Commercially Silica-Glass Ge- doped optical fibres are used.[ Normal SiO2 in the cladding and Ge-doped SiO2 in the core ]  Different doping agents are used to increase or decrease refractive index. Ge, P, Cl Increases R.I. F, B Decreases R.I.
  73. 73. Types of Optical Fibre
  74. 74. Types of Optical Fibre ( contd. )
  75. 75. Types of Optical Fibre ( contd. )
  76. 76. Fibre type Density (g/cm3 ) Strength (gpd) Elongation ( % ) Modulus (gpd) Maximum Use temp. ( °C ) Kevlar 1.43-1.47 20-26 1.5-3.6 430-1100 200 Nomex 1.38 5 22 140 200 Vectran 1.47 25 2-2.25 700 150 PBO 1.54-1.56 42 2.5-3.5 1300 300 Spectra 0.97 32 3.5 1800 120 Carbon 1.7-2.1 16-40 1.2-1.4 1510-3200 2400-2500 Glass 2.48-2.55 11-21 3-5.3 320-390 300-350 steel 7.8 11 4.8 220 500 Summary
  77. 77. THANK YOU
  78. 78. ? ANY QUESTION ?

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