hydrolysis destruction

[urisvan]

hi
there are two opinions for the same subject:
one says that hydrolysis destruction in fiberglass laminates is worse if the laminate has jelcoat on its back too. because the byproducts of hydrolysis can not leave the lamninate easily so the internal pressure rises more and this cause structural damage.
one says the opposite; the laminate that is sealed by covering gelcoat or barrier on both surfaces is more durable to hydrolysis because less water molecules penetrates into the laminate
which one is right?
cheers

[mark775]

My experience with like boats - one gel-coated inside and out and one not, is that the gel-coated one will be several percent lighter decades hence. I do not own a moisture meter.

[alex folen]

I’ll have to give it a shot for what it’s worth. I’m not a boat expert but from what I’ve seen here would love to be only a fraction of one! Polymer degeneration change properties, tensile, color, shape, ect., of a polymer under the influence of environmental factors such as heat, light, water/saltwater. It is often due to the hydrolysis of the bonds connecting the polymer chain, which in turn leads to a decrease in the molecular mass of the polymer. The degradation of polymers to form smaller molecules may proceed specifically, or in random. Other polymers undergo specific chain breakage at the ends. They also depolymerize to become monomers.….all the byproducts of hydrolysis, as you mentioned. With this I would think the less amount of water to cause the hydrolysis degradation would be optimum. A sealed compartment. In your question I would think the latter.

[bruceb]

I was a boat dealer in the 80s and early 90s when "blistering" and laminate separation really came to be recognized as major issues. I am in the southern US, where high summer water temps and high humidity have caused major damage on some boats. My non-scientific but experienced observation was that boats that were kept dry and well-ventilated had far less damage than the same brand/model that were left regularly with some water standing in the bilge. Some 24' racing sailboats that were weighed regularly could pick up 10-30lbs in a season, and that included dry sailed boats that were not kept dry on the inside. I never could tell much difference from some brands that were gel-coated inside and those that were not. Gel coat is not a very good vapor barrier, at least the way it is usually used in a production boat, and hidden areas are not usually coated anyway. In my own boat, I would prefer a bare/painted interior than gel coat, and very good ventilation. Bruce

[urisvan]

all of you thinks that, well sealed laminate is better.
still looking forward for more answers.
thanks

[urisvan]

i mean looking forward for more replies