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  • ADHESIVES
    • Poly-vinyl acetate (PVA)
      • commonly known as school glue
      • Synthetic polymer
      • vinyl acetate is suspended in an emulsion of water, which makes it an excellent adhesive for porous materials such as wood and paper
      • will dry to a solid transparent material in around 30 minutes.
      • Advantages: -Strong,permanent, hard wearing, non-toxic, good for adhering to porous materials, readily avaliable
      • Cannot easily be removed when set.
    • Epoxy resin
      • Thermosetting plastic
      • •When the polymer and catalyst are mixed they heat and harden (the molecules cross link and so form a rigid grid). 
      • Epoxy resins are extremely strong and much more resistant than other adhesives.
      • They are commonly used for wood, metal and plastics
      • may be used directly to adhere a wide range of materials or impregnated between the weave of glass or carbon fibres to create rigid materials.
      • used in the constructions of boats, body armor, fishing rods, tennis rackets, hockey sticks, racing cars, road cars, helicopter rota blades, aeroplane engine and space shuttles
      • Epoxy resin is: •Very strong •Hard-wearing •Resistant to heat •Resistant to solvent attack •Excellent at adhering a range of materials Readily avaliable in hardware and art suppliers
      • Epoxy resin: •Requires preparation for use •Can be messy if not used carefully •Cannot easily be removed when set •Is relatively expensive Must be used in a well ventilated environment
    • Spray glue
      • know as spray mount, is an adhesive used for joining lightweight materials such as, paper, cardboard, acetate and metal foil
      • stored in a pressurized can with a chemical expellant
      • can is shaken and the nozzle is pressed a mist of glue is released
      • advantages of spray glues is that an even surface can be applied quickly to a range of sheet materials avoiding the possibilty of smearing or tearing the surface.
      • There are 2 types of spray glue.
        • Strength is determined by the weight of the materials; paper will require a low strength, fabric a higher strength and wooden laminates the highest.
        • :Tack is the length of time the glue takes to set or become hard.  •A short tack dries instantly and a long tack allows for a period of adjustment and correction before setting.
      • can only be used for lightweight materials can be messy if not used carefully is not permanent must be used in a well ventilated environment
    • Hot Gllue
      • Hot melt glue is a thermo or thermosoftening plastic 
      • When the hot melt glue is heated it softens and its viscosity increases and becomes molten
      • Upon cooling it returns to a solid state and is ideal as an expensive, quick to apply and versatile temporary adhesive for certain materials
      • The glue gun uses a heating element, similar to the one used in kettles, electric fires or electronic curling tongs
      • The molten plastic is then pushed through the application nozzle by a mechanism attached to the hand trigger
      • Hot glue has a major safety issue which must be considered
      • The hot melt gun becomes molten at around 250ºF/120ºC. If the glue or the heating element come into contact with skin they can create serious burns
      • in thickly applied areas the core of the glue may remain molten and dangerously hot for a considerable time
      • Hot glue is:: •Easily applied •joins a variety of materials •requires limited preparation •joins uneven surfaces •avalaible in a range of colours •relatively inexpensive.
      • Hot melt glue: •can only be used for lightweight materials •can be messy if not used carefully •is not permanent •can cause injury if misused must be used in a well ventilated environment
    • Tensol Cement
      • Tensol cement is a solvent and is ideal for joining thermoplastics but cannot be used for thermosetting plastic or other materials
      • The bonds produced are very strong, non-porous and are resistant to weathering, which makes them ideal for outdoor signage.
      • The solvent melts the upper layer of the plastics, which mix together and reharden, effectively becoming one piece
      • Tensol cement fumes can be harmful and it must only be used in a well ventilated environment
      • Tensol cement is: •permanent •equivalent to welding metals •extremely strong •able to produce invisible finishes •weatherproof •non-porous.
      • Tensol cement: •can only be used for thermoplastics •can be messy if not used carefully •must be used in a well ventilated environment.
    • Adhesive tape
      • •Adhesive tape is, as the name implies, a tape with an adhesive applied.  •These are used as inexpensive non-toxic temporary joining methods. 
      • •The most common is self-adhesive or pressure sensitive tape. •Unlike other glues the adhesive does not need a catalyst and is constantly in active form, needing only an application of pressure to adhere to a surface.  Other adhesive tapes require a catalyst such as water or heat
      • •Adhesive tapes are used widely in the packaging industry but are often hidden from use. 
      • •One interesting use of transparent self-adhesive tape is as a hinge on transparent containers on beauty product counters in department and beauty stores.
      • Adhesive tape is: •easy to apply •available in a range of colours and sizes •available with a variety of catalysts •easily removable •readily available.
      • Adhesive tape: •is not permanent •degrades in time •is relatively weak •can be removed accidentally •can fail after repeated use •is visible.

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