HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Apr 13, 2013, 04:00 PM
Entropy is happening!
Jim.Thompson's Avatar
Bellingen NSW Australia
Joined Aug 2008
6,717 Posts
Fillers?

[QUOTE=tom43004;24709216]Fillers.................QUOTE]

What are these Tom? "Q" cells/ Flocked Cotton/ Colloidal silica etc??
Jim.Thompson is online now Find More Posts by Jim.Thompson
RCG Plus Member
Latest blog entry: Yet another light plank!
Reply With Quote
Sign up now
to remove ads between posts
Old Apr 13, 2013, 04:50 PM
Father of Fr3aK, DLG Pilot
tom43004's Avatar
USA, OH, Worthington
Joined May 2002
6,709 Posts
I use all of them. Cabosil (colloidal silica) and Q cells are the two that I bake moisture out of.
tom43004 is offline Find More Posts by tom43004
Reply With Quote
Old Apr 13, 2013, 05:05 PM
Entropy is happening!
Jim.Thompson's Avatar
Bellingen NSW Australia
Joined Aug 2008
6,717 Posts
I thought that was what you were referring to by your term "fillers".
Good point, I have never even thought about drying them before use.
Thanks.
Jim.Thompson is online now Find More Posts by Jim.Thompson
RCG Plus Member
Latest blog entry: Yet another light plank!
Reply With Quote
Old Apr 24, 2013, 12:13 PM
Composites guy
North OC, Ca.
Joined Jun 2005
1,180 Posts
just an fyi-

water boils at room temp with enough vacuum.

The partial pressure of the water vapor within the lay-up can lead to bubbles in the right circumstance.

High performance resins typically absorb up to 4% moisture in the cured composite.

In a high humidity environment, if I had a concern, I would degass the base resin before and after adding the curing agent. Dry the fabric as well if concerned.

Another problem is that moisture can inhibit a cure or act as a plasticizer- both bad.

Scott
sarmoby is offline Find More Posts by sarmoby
Reply With Quote
Old Apr 26, 2013, 01:45 PM
Graham Kirkland
graham1234's Avatar
Port Alfred South Africa
Joined Jun 2009
359 Posts
I have found the source of my skin adhesion problem and it had nothing to do with humidity.

I cut all my cores with a hot wire CNC machine. This is non contact cutting and the hot wire leaves a thin skin on the surface of the foam. The cores are coming out so good now that I have to do very little sanding of the surface before bagging. The minor skin adhesion problems started recently and I realised that it may have something to do with the way that I am preparing the cores.

We recently had a period of fairly high humidity and I fully sanded some cores and bagged them with a very dry layup. The skin adhesion was excellent and all subsequent efforts have produced good results.

So I think that puts that issue to bed. Thanks for the input from the guys working in really humid climates. It had me questioning whether I was on the right track and it turns out that I was wrong.

Graham
graham1234 is online now Find More Posts by graham1234
RCG Plus Member
Reply With Quote
Old Apr 26, 2013, 03:19 PM
ETS....Energy retention system
timbuck's Avatar
gold coast australia
Joined Aug 2008
5,421 Posts
Cool Graham.. Always good to put a finger on the cause.

Tim
timbuck is offline Find More Posts by timbuck
RCG Plus Member
Latest blog entry: Gizmo 36 pics
Reply With Quote
Old Apr 26, 2013, 08:59 PM
Entropy is happening!
Jim.Thompson's Avatar
Bellingen NSW Australia
Joined Aug 2008
6,717 Posts
Good outcome.

That's a good outcome Graham.

What do you mean by "non contact cutting"?

Did you post cure at all?
Jim.Thompson is online now Find More Posts by Jim.Thompson
RCG Plus Member
Last edited by Jim.Thompson; Apr 26, 2013 at 09:00 PM. Reason: additional question.
Reply With Quote
Old Apr 27, 2013, 07:05 AM
Registered User
Memphis3's Avatar
Joined Apr 2013
26 Posts
Composite Engineer

Don't heat cloth
Glass cloth
Has was is call sizing
It is only good for about 1 year at best.
With out sizing you can not wet out the fibers. There is nothing you can do to fix this.
Delamination is the result.
but
You have to get a 10x and look at the type of delam.
If the epoxies cracks at the fiber it is wetting (sizing) fault.
If the epoxies cracks at the cloth to cloth interface it is a processing problem.
Humidity has no or little effect on composite processing
Humidity
Effect layup of prepregs (cloth with epoxies frozen) only by handling or stick of the prepreg but age of prepreg is more important..
Curing of epoxies is a condensation reaction
Meaning
The harding (cure) of the epoxies is buy chemical linking of short polymers into longer polymers.
This chemical linking releases water (condensation reaction).
Water must be removed that is why you use breathers and a vaccum to remove the condensation water as the epoxied cures.
Memphis3 is offline Find More Posts by Memphis3
Reply With Quote
Old Apr 27, 2013, 07:34 AM
ETS....Energy retention system
timbuck's Avatar
gold coast australia
Joined Aug 2008
5,421 Posts
Thanks M3 interesting read.

Epoxy releases water ??? When curing ??
So on a 50 foot resin infused boat...once infusion Is stopped where does the water go as it cures.


Curing link.

http://pslc.ws/macrog/lab/epoxy.htm

Tim
timbuck is offline Find More Posts by timbuck
RCG Plus Member
Latest blog entry: Gizmo 36 pics
Reply With Quote
Old Apr 30, 2013, 07:10 AM
Registered User
United States, OH, Cleveland
Joined Aug 2002
304 Posts
Out the Vacuum pump? I run mine double the Thin Set cure time.
JIM CALDWELLA is offline Find More Posts by JIM CALDWELLA
Reply With Quote
Old May 01, 2013, 02:37 PM
Graham Kirkland
graham1234's Avatar
Port Alfred South Africa
Joined Jun 2009
359 Posts
Quote:
Originally Posted by Jim.Thompson View Post
That's a good outcome Graham.

What do you mean by "non contact cutting"?

Did you post cure at all?
CNC hot wire cutters cut through the foam without touching it. The hot wire melts the foam in front of it and forms a slit in the foam called the kerf which is wider than the wire. This seems to create a slightly different surface on the foam to cutting with templates and a bow.

I dont post cure but I cure all my parts at about 45 Deg C for 8 to 10 hours.

Graham
graham1234 is online now Find More Posts by graham1234
RCG Plus Member
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Question Helium envelope fabrics for a hot environment and high humidity(120 Celsius degrees) carlitosrusia Blimps 21 Apr 08, 2013 10:33 PM
Question Just how sensitive is 5.8GHz? Casey_S FPV Talk 2 Jan 23, 2013 10:51 PM
Discussion Sensitivity problem with Syma s109g Apache scarymike23 Coaxial Helicopters 1 Jan 21, 2013 11:29 AM
Alert Is the key chain camera more sensitive to vibration? avt Aerial Photography 4 Jan 11, 2013 05:54 PM
Question WHOAH high humidity makes my KK board not funtcion!!! Waffleman Multirotor Electronics 4 Jan 04, 2013 12:28 PM