Resin Chemistry

General Discussion
1

Ok, so I’ve been under discussion with my lecturer (for polymers and composites) at uni and seems that my 4th year project is probably all go for next year. That is research into resins and construction techniques for surfboards. My problem is I have to give him some basics on how its conventionally done and the materials used. I’ve written out a basic shaping guide for him and list of equipment/tools/materials used and also the different types. EPS, PU, XPS, Epoxy, PE etc.

My problem is he wants to know a bit bout the basics (the chemistry of resins) of these as according to him polyester resin should be fine to use on polystyrene blanks. I’ve always been told that polyester would melt polystyrene.

Could anyone give a quick run down on whether this is fact or myth as I cant be bothered going and testing it myself as he needs a quick answer (by early next week)

Also if anyone knows the basic mix ratios of the resins used in surfboard manufacturing. Not the hardener:resin ratio.

I’m more talking about polyester resin being 60% PE, 35% styrene and the last 5% being UV protectors, plastic sizers, etc. So the full chemistry of the resins used or just whats added, don’t need to know %.

Thanks

Phil

2

yes ,polyester resin will definetly melt polystyrene foam

doesnt your school have books?

3

Really? schools have books, wow.

Maybe I should go talk to my lecturer again, but according to what I gathered yesterday, pure polyester doesn’t react with polystyrene. I thought it would be the solvent that is used to thin it, but styrene is used to thin it.

The other option would be that it was confused with polyethylene not polyester.

4

There are heaps of good links in the archives for the chemistry of polyester and epoxy resin.

Put on the kettle and start reading.

Polyester resin will eat big holes in polystyrene foam, ask anyone who’s tried to fix an EPS board with PE resin. That styrene is bad gear.

Good Luck

5

Simple.

Always do a patch test first if you’re in doubt.

Why…?

Because after many hours of conceptual designing ,materials sourcing and creative construction, my

" one of a kind " carbon fibre surf rocket is rooted beyond repair.

I sat and grieved over it for days before I had the strength to stick it in the trash.

Its not a truly traumatic life experience but it sure does PISS you off when youve done your best but missed a basic error in materials compatability…

6

Here a little snippet of history from the Handbook of Compsites about why styrene monomer is used in polyester resin:

"Organic polymers are divided into two types,

reinforced-thermoplastic and thermoset. With

thermoset polymers such as unsaturated polyesters

and vinyl esters, a chemical reaction

cross links the material so that it cannot be

returned to liquid form. Other common thermosetting

polymers include epoxy and

phenolic resins. Thermoset plastics made with

polyester and vinyl ester resins represent the

major portion of the reinforced plastic composites

industry today.

Early workers on unsaturated polyesters

soon learned that despite the possession of

reactive double bonds, these resins were sluggish

in reacting with themselves. Even with

effective catalysts, they still required high temperatures

and lengthy cure times to complete

the cross linking reaction. The key to modern

day application of unsaturated polyesters was

the discovery by Carlton Ellis in 1937, that the

addition of reactive monomers, such as styrene,

gave mixtures that would copolymerize many

times faster than homopolymerization. The

styrene addition produced the added benefit of

an easily handled liquid material that could be

pumped, transported and fabricated into a finished

plastic by a myriad of molding processes.

Developments during the 1940s accelerated

the commercial applicability of unsaturated

polyesters to the position they hold today.

Styrene became readily available and lower in

cost as a result of the US Government’s sponsored

production of styrene-butadiene rubber.

At the same time, scientists found that styrenated

polyesters could yield high strength,

light weight structures when reinforced with

glass fibers. They also learned that fiberglass reinforced

polyesters had excellent electrical

properties and that large structures could be

molded at low pressures with low cost tooling.

As a result, commercial development proceeded

rapidly after World War II with

materials and molding research moving in

many directions. In the 20 years that followed,

polyester and vinyl ester resins matured

rapidly and by the mid-l970s, the composites

fabricator and end user had numerous options

with these matrix systems to achieve the

desired properties in the finished part."

7

Hi

I’m in my fourth year at a Uni and I’ve decided to do a term paper on surfboard construction.

The only thing is, my teacher actualy wants me to putforth effort by explaining what the chemical

composition of resins and epoxies and how the different materials react with each other.

Do you think you guys could tell me all I need to know so I can just cut and paste onto my term paper.

As I’m not inclined to actualy do the research myself. It would be so much easier if you just tell me what I need to know.

piripi

you are not impressing your instructor by asking other people for the answers

YOU need to do the reserch!

read a book!

do the work for the grade!

8

Thanks heaps for that atomized thats wicked.

As for you Ken I wish I was doing a term paper on this but unfortunately Im not, and we don’t get to do fun studies on this in 3rd year instead we get taught what blends, copolymers, monomers, atatic, isotatic, syndotatic systems, moulding techniques and how to calculate mass, atom and composition of polymers. and our labs are crappy as, uni doesn’t teach how to apply things to the real world but rather the fundamentals of it. well thats how it works in NZ.

As I’ve only shaped a couple of boards and they have all been out of EPS and epoxy I haven’t experienced the so called melt with polyester.

Thanks for everyones feed back. I’d say in the discussion with my lecturer polyethylene and polyester was mixed up.

Cheers

9

piripi

please accept my appologies

I missjudged your post’s

we do get a few vultures around here on occasion

what I know and for what its worth is poly resin attacks polystyrene like acid

I’ve been told its the thinning agent (styrene) and maybe the kobalt additive

But “I” think its just the resin itself

And yes I learned the hard way, fried a board when I was a kid.

once again my appologies and good luck with your search

10

Heres a really informative link

At first it looks like a high school “learning is fun!” website, but as you get deeper into it, there is really good info about polymers, including their application in composites.

I refer to this suprisingly often

http://pslc.ws/macrog/maindir.htm

Kit

11

Check out “Level 4 - making polymers”

Theres some good stuff about poly in there

12

Thanks heaps for that Kit. The website is epic. I see that you’re a student, what are you studying if I may ask. Love the compsands boards too, how long you been making them?? If I have enought time maybe I could make a sample up of the compsands and put them under the machines next year see how they stack up on a computer to the rest of the boards. :slight_smile: Hopefully all going to plan and I get to do this project.

Thanks for the apologies Ken, I’m sorry if I sounded a bit off hand too. Just to let you know I do take my studies very seriously and hopefully it’ll come in handy when I finish. I also take my surfing seriously which is why this project would be wicked to do, and any information I can get from more experienced shapers comes in handy. I know a few peeople would think this is a waste of time, but I think that the scientific research would be an epic way to take surfing to greater levels, just look what it did for yachting and formula one. Hopefully what I look into will also be able to be used for all board sports. Thats the plan anyway. I might as well make use of the millions of dollars in testing equipment while I can.

So any contributions is welcomed.

13

Your professor is right. Polyester will work just fine with eps, that is if you can find it suspended in something other than styrene monomer. It does exist but it is not common.