types of resin

Discussion in 'Materials' started by Jas Marine, Oct 17, 2007.

  1. Jas Marine
    Joined: Apr 2007
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    Jas Marine New Member

    what is the available type if resin and there application???
    Can we have abrief and simple explaination????
     
  2. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    Epoxy and polyester resins

    Polyester Resins
    Polyester resins are the most widely used resin systems, particularly in the marine industry. By far the majority of dinghies, yachts and workboats built in composites make use of this resin system.
    Polyester resins such as these are of the 'unsaturated' type. Unsaturated polyester resin is a thermoset, capable of being cured from a liquid or solid state when subject to the right conditions. It is usual to refer to unsaturated polyester resins as 'polyester resins', or simply as 'polyesters'. There is a whole range of polyesters made from different acids, glycols and monomers, all having varying properties.
    There are two principle types of polyester resin used as standard laminating systems in the composites industry. Orthophthalic polyester resin is the standard economic resin used by many people. Isophthalic polyester resin is now becoming the preferred material in industries such as marine where its superior water resistance is desirable.


    Vinylester Resins
    Vinylester resins are similar in their molecular structure to polyesters, but differ primarily in the location of their reactive sites, these being positioned only at the ends of the molecular chains. As the whole length of the molecular chain is available to absorb shock loadings this makes vinylester resins tougher and more resilient than polyesters. The vinylester molecule also features fewer ester groups. These ester groups are susceptible to water degradation by hydrolysis which means that vinylesters exhibit better resistance to water and many other chemicals than their polyester counterparts, and are frequently found in applications such as pipelines and chemical storage tanks.

    Epoxy Resins
    The large family of epoxy resins represent some of the highest performance resins of those available at this time. Epoxies generally out-perform most other resin types in terms of mechanical properties and resistance to environmental degradation, which leads to their almost exclusive use in aircraft components. As a laminating resin their increased adhesive properties and resistance to water degradation make these resins ideal for use in applications such as boat building. Here epoxies are widely used as a primary construction material for high-performance boats or as a secondary application to sheath a hull or replace water-degraded polyester resins and gel coats.
    The term 'epoxy' refers to a chemical group consisting of an oxygen atom bonded to two carbon atoms that are already bonded in some way. The simplest epoxy is a three-member ring structure known by the term 'alpha-epoxy' or '1,2-epoxy'. The idealised chemical structure is shown in the figure below and is the most easily identified characteristic of any more complex epoxy molecule.

    Ths from the excellent SP Systems old manual.
     
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  3. rotfix
    Joined: Oct 2007
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    rotfix Junior Member

    that was informative

    any comments on vinylester vs poly? any more difficult to work with or cost significantly more? will vinyl go over poly? i assume my hull from 1987 is poly.
     
  4. TerryKing
    Joined: Feb 2007
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    TerryKing On The Water SOON

    The Smell of uncured resin??

    Landlubber, or someone... does VinylEster SMELL different than the old Polyester Resin? I walk by a boat building place here in China often, and what I smell is identical to the Good Old Days of Polyester. But might it be Vinylester?

    I don't know how to ask the question in Chinese yet!
     

  5. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    No , we use vinyl ester here (so they tell me) for the first two layers, it does not smell any different (because of the chemical makeup I guess), but it is a slightly different color.

    And yes it is entirely compatible to the polyester Ortho that we also use (I know Iso is better........)

    Vinyl has better properties as far as waterproofing go, it is a better barrier coat so that is why we use it next to the gelcoat. The cost is about twice the price, but for all we use it makes very little difference here really.
     
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