(ask) Resin Properties

Dear People

I want to ask the resin properties effects that occur during production

1. Exoterm, as far i know this affect the shrinkage. so is it that lower exoterm resulting better properties? any effect and relationship about exoterm?

2. Promoter addition
addition like cobalt affect curing process, it is also affect hardness? any other effect? any pros cons?

3. Is that resin infusion REDUCES shrinkage?

4. Is that Resin Infusion Reduces Micro cracking during curing process? for styrened resins (PE and VE). i pressume, under vacuum, the most residual styrened get out from laminate easily, before the laminate fully cured, hence the micro hole is minimum because the styrene getting out prematurely. does it makes sense?

5. if i want to harden vinylester, i used to add alum oxide or silicon talk. what is trade off by hardening the resin ( lower elongation maybe or something)?

6. What is tensile strength of typical glass for multi axial/non woven?

7. please tell me another aspect that must be note due to resin properties?

Thanks people.

 

The answer to all the questions would take a library. You need to narrow the field and ask more specific questions.

 

I think my question is just typical question that usually face by builder, except qstn no 6, which sound very general. I just need the answer what you usually done.

I have been successfully doing resin infusion using many substitute materials like: farming plastic (used to cover soils during dry season for seeding), textile net (as mesh/flow medium), nylon fabric for peel ply, cable spiral for infusion spiral even i used generic pumps ( i have 20 m3/hour and 40 m3 per hour)

the results is just as similiar then i test the tensile, just same, resin ratio just same.

for comparison on 48 footer hull infusion (solid hull)

using pro stuff costs 1100 bucks
using subs costs 400 bucks


I want to ask those question, because PAR, You, tunnel, Mr. Spoonberg, CDK, and many other give assist on their view and explain further.

If customer ask me those question (but they seems doesnt know much about the composite sciences) i would answer positive situation, but im just not sure and i got some reference, but again, expert like you seems to be lot of talking and explain, .

 

the print through was the early trial with woven (!). the last is 48 footer, with double bias and vinylester, solid hull.

 

Know your product !!! dont guess !!! make samples !!!

General questions get a general answer !OK ?
If its something you havent used before do some small test panels till you understand what you got in your hand !!
Exotherm promotes shrinkage !! the hotter it gets the more shrinkage you will get !!
Polyester shrinks more , vinylester shrinks a little less and epoxy shringks the least amount of them all !!
You are not only cooking the product and getting shrinkage you are also heating you moldand going to make it change shape over time !!!
Cobalt needs to be left in the bottle on the shelf and unopened !!
If you are playing with colbalt you are asking for trouble !!
All it does is produce heat to make the resin gel quicker !,hence go hard quicker and the resin cures more brittle so you have a weaker part !!!
The more the heat the more britttle the resin will be !!! DONT DO IT !!
Your resin supplyer will or should have the right resin for the right job straight from the drum !!
Temprature affects the viscocity of all resins . Infusion resin as well !
At a given temprature at a given catalyst ratio you get a given gel time , there will be a upper and lower limit as to the amount of catalyst that is able to be used with the resin you are supplied with !! same with Catalysts use what is recomended ,if you deviate away from what is recomended you deserve what you get !!
Same with adding cobalt !!,you get what you deserve .
Cnange the catalyst and add coblalt and if you have a failure!!! ho ho ho who are you going to point the finger at ????

If you work outside the limitations of any of the resins you are treading on thin ice and headed for trouble

 

Let me add my 2 cents, for what it is worth:

1. Exoterm, as far i know this affect the shrinkage. so is it that lower exoterm resulting better properties? any effect and relationship about exoterm?

Lower exotherm, lower shrinkage, but also slower final cure (which is not so important when building boats, but for moulds which should produce 8 products/day or even more this is an important factor.

Exotherm is dependant on many factors, including:
-type of resin
-type and amount of cobalt and promotor added
-type and amount of curing agent added
-Vf (fiber volume ratio)
-thickness of laminate
-type of mould
-ambient temperature
-etc etc

2. Promoter addition
addition like cobalt affect curing process, it is also affect hardness? any other effect? any pros cons?

Cobalt and other promotors should not affect final barcol hardness, but they can shorten the amount of time before a given barcol is reached. They also control curing speed.

3. Is that resin infusion REDUCES shrinkage?

yes and no. yes, the Vf is higher, so less resin and more fiber, thus less shrinkage. Also usually slower curing agents are used, thus less exotherm. But with resin infusion you generally infuse a thick laminate in one go. Which can increase the amount of heat generated, thus more shrinkage.

4. Is that Resin Infusion Reduces Micro cracking during curing process? for styrened resins (PE and VE). i pressume, under vacuum, the most residual styrened get out from laminate easily, before the laminate fully cured, hence the micro hole is minimum because the styrene getting out prematurely. does it makes sense?

Infusion in general makes the resin evaporate less styrene, and the laminate is of better quality (less voids), so microcracking should be less of a problem. If microcracking is a problem though, do not use polyester.

5. if i want to harden vinylester, i used to add alum oxide or silicon talk. what is trade off by hardening the resin ( lower elongation maybe or something)?

Lower elongation, lower price, lower shrinkage, perhaps more water absorption, lower tensile strength. It all depends on the filler used.

6. What is tensile strength of typical glass for multi axial/non woven?

Check the datasheet of "Hybon 2002" from PPG. This is a roving which is used many times in multiaxial production.

7. please tell me another aspect that must be note due to resin properties?

What do you want to hear?

For starters, there are several types of resin: ortho, ortho-npg, dcpd, iso, iso-npg, vinylester (different subtypes). All with different properties.

Then you can modify resins to tailor them for your needs. Many times you can get unpromoted, neat resin and modify yourself.

-cobalt: affects geltime, potlife and final cure
-promotors: affect final cure time
-copper ocatoate: adding this lowers exotherm
-retarders: affect geltime
and there are several other modifiers, for surface quality, filler sagging, rheology, etc. But the above 4 are mostly used.

then there is the curing agent. Several types are available, with completely different behaviour. Low and short geltimes, long and short final cure, hydrogen peroxide free ones, for vinylester curing without foaming, etc.

Experimenting yourself is not a bad thing. Ask your supplier and learn.

 

Sadly we can no longer get pre promoted vinyl ester infusion resin. So we're stuck with messing about with cobalt. Its a pain!

-jim lee

 

/why? Usually there is way too much cobalt in standard resin to get decent geltimes.

 

Cobalts is what Adam used !!!
Theres better chemicals that will regulate the gel time better without the hang over of excessive extherm .
Pre promoted ?? time you changed your supplyer or gave them the message .
They are there to serve and let thee not forget that !!!.
Thats the trouble with big companies they get to big for there boots .
I like to get intermite with there chemists and even have a beer or two . scratch a back here and there .

 

Most companies we supply, buy per tanker (10ton, 20 ton or 30ton). They want their resins pre-promoted to their specifications. No time and no equipment for mixing.

The small boatbuilder however wants his resins fast at one time, and slow the next time. They usually prefer neat resin and promote themselves.

Cobalt is needed when using MEKP or AAP based curing agents. It plays part in the reaction. Other promotors can be used to futher ensure final cure, but there has to be a certain amount of cobalt.
DMA's can be used when using BPO catalyst, but not recommended in boat building.

 

Hi Herman, Selamat makan!! really thanks for reply. I just make myself satisfied by read expert opinion for what Iam believe and the expert said so. yes i know resin types and typical properties but some makes me courious.


Hi Tunnel: Thanks and actually I Never Ever add cobalt for works. all is pre promoted, Thanks actually fo straight warning.

Jim: Hi Jim, I used to work with FGI nuplex vinyester, its been pre promoted. adding cobalt has no forgiving limit.