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Polymers, Polymers to focus on, Polymer degradation mechanisms, Power law …

- - - - therefore crystallinity is more (chains can be packed closer)
- - - - example : Carbon black in rubber(Tyres)
  - - - Aligned
      - Randomly oriented
    - - length should be more than critical length to achieve max fiber efficiency
        
        (sigma(f)*d)/2tao(c)
        d=fiber diameter
        sigma(f) = fiber ultimate tensile strength.
        tao(c) = shear strength of fiber-matrix interface
        
        Stress transfers more efficiently from matrix to fiber
- - - - 75% of composites using polymer use this kind
      - examples: Epoxy, Polyurethane, vinyl ester etc.
      - 2Part formulation
        
        uncured liquid
        
        curing agent
        
        Curing environment to be provided for good laminates
        
        temperature
        
        It keeps a check on viscosity w.r.t degree of curing
        
        pressure
        
        radiation
        
        viscosity and elasticity both increase during the curing process
      - Pros
        
        Ease of manufacturing
        
        lower viscosity
        
        Lower processing temperatures
        
        economical forming for large components
        
        high service temperature for moderate costs
        
        good stiffness and fatigue resistance
      - Cons
        
        curing process is irreversible - reuse/recycle impossible!!
        
        The temperature point doesn't really becomes a pro because certain thermoplastics can do the same.
      - Epoxy
        
        Superior mechanical properties
        
        water resistance
        
        less shrinkage than other thermosets
    - - examples: PP, PA, ABS, PVC, PC
      - Pros
        
        improved recyclability
        
        injection molding and extrusion process can be used for mass production
        
        higher dimensional stability (shrinking is less than thermosets)
      - Cons
        
        Stiffness is low
        
        Stiffness at higher temp is really bad
- - - - very large parts ;)
    - - High manual labour
      - high fiber volume fraction not possible ( thick matrix)
      - difficulty in obtaining reproducible parts
  - - - High performance
      - reproducible products
- - - - imparts stiffness and strength
      - can be made into small dia 7-20micrometer
        
        therefore low defects
      - flexible
      - highly aligned
  - - - non-crystalline
        
        sillicon tetrahedron with 4 oxygen
        
        covalent bonding
    - - sticks to the oxy
    - - E-glass
        
        high strength, low stiffness, cheap af
      - S-glass
        
        high performance
      - C-glass
        
        Chemically enhanced
    - - transparent to visible light
      - isotropy
      - resistant to high temp, softens at 850C
    - - very susceptible to surface damage cause glass dude
  - - - for high stiffness grades
    - - Covalent bonding in graphene sheets which take the load from longitudenal direction
      - Van der waals forces between the basal planes
    - - High modulus
      - High strength
      - Chemical inertness
      - dimensional stability
      - relatively, higher thermal and electrical conductivity
    - - Black color
      - Highly anisotropic
- - - - nano particles
    - - nano-wires
        nano rods
    - - 2D nano-fillers
- - - - last region = high slope ( chain reaches it's extremum and the covalent bond's stress increases)
- - - - provide tensile loading to a sheet, the surface starts to tear, forming bands of cracks
      - PS, PMMA elongation
      - T<40C
      - surface phenomenon
        
        dust scrathes and crack initiation points of high stress
      - band is in transverse direction of applied load.
- - - - slip tilting of the lamellae is induced
        
        lamellae fragments(crstal packs) get aligned in the direction of load, forming fibrils of alternating crystal blocks
- - - - can coalesce into phases
    - - can control thee molecular weight of the branches
      - can seprately polymerize , backbone nad side chains
- - - - 3.Stress whitening
        
        3.Necking
        localized reduction in cross-sectional area
        
        4.can or cannot have stress hardening in the end
      - micro-cracking between spherulites
      - changes the optical parameters
        where these cracks generate
  - - - lamellae fragments align in the direction of stress forming fibrils of alternating crystal and amorphous regions