Chemical Forums

Specialty Chemistry Forums => Materials and Nanochemistry forum => Topic started by: miker on October 07, 2010, 03:28:17 AM

Title: How to re-melt silicone???
Post by: miker on October 07, 2010, 03:28:17 AM
Hello to everyone!
New to this forum and here is my first question!
I want to know if there is any chemical substance to use on solid silicone and make it possible to reshape again!
Title: Re: How to re-melt silicone???
Post by: Borek on October 07, 2010, 04:02:13 AM
Reshape? Melt? Please elaborate. I guess the only way is to heat it high enough.

Unless you can use mechanical methods.
Title: Re: How to re-melt silicone???
Post by: miker on October 07, 2010, 05:00:27 AM
to make it easier!
I want to change the shape of a diving mask made from silicone!
I have all ready use heat but nothing!
Somebody told me there are chemical the make the silicone somehow malleable!
Thank you!
Title: Re: How to re-melt silicone???
Post by: Borek on October 07, 2010, 08:41:34 AM
My mistake, I was thinking about silicon. Sometimes my English fails me.

Perhaps some solvent will modify silicone properties, but somehow I think that will be a nasty stuff to work with.
Title: Re: How to re-melt silicone???
Post by: miker on October 07, 2010, 11:50:29 AM
and what kind of solvent is this???
Title: Re: How to re-melt silicone???
Post by: oneat on October 07, 2010, 01:29:41 PM
maybe HCOOH? Silicon often smell of this.
Title: Re: How to re-melt silicone???
Post by: DrCMS on October 07, 2010, 02:16:18 PM
maybe HCOOH? Silicon often smell of this.

NO and NO.

Silicon is an element and does not smell of formic acid.

Silicone sealants are often formulated with Methyltriacetoxysilane as a cross-linker which releases acetic acid, CH3COOH, during curing.

The mask started off as a liquid that reacted to give a cross-linked solid.  Now you have a solid you can not modify the shape.
Title: Re: How to re-melt silicone???
Post by: typhoon2028 on October 07, 2010, 02:16:40 PM
The silicone rubber is probably a thermoset.  It will not melt.  You could heat it up and reform it
Title: Re: How to re-melt silicone???
Post by: typhoon2028 on October 07, 2010, 02:19:04 PM
Quote
NO and NO.

Silicon is an element and does not smell of formic acid.

Silicone sealants are often formulated with Methyltriacetoxysilane as a cross-linker which releases acetic acid, CH3COOH, during curing.

The mask started off as a liquid that reacted to give a cross-linked solid.  Now you have a solid you can not modify the shape.

This is not always true.  The silicone rubber could be partially cross-linked.  With heat and pressure it may retain a different shape.  It should no melt to a liquid.
Title: Re: How to re-melt silicone???
Post by: miker on October 07, 2010, 02:28:47 PM
don't want to make it again liquid!
I only want to stretch a part o the mask!
I tried heat (even bare flame from gas stove) but nothing work!!!
Title: Re: How to re-melt silicone???
Post by: typhoon2028 on October 07, 2010, 03:43:01 PM
I wouldn't expose it to an open flame.

Maybe you could post a picture and describe more on what you want to do.
Title: Re: How to re-melt silicone???
Post by: miker on October 08, 2010, 06:33:30 AM
simply stretch a part of the mask to make it more comfortable for my nose!
Title: Re: How to re-melt silicone???
Post by: miker on October 11, 2010, 04:13:53 AM
maybe HCOOH? Silicon often smell of this.
Where can i find these substance?
Title: Re: How to re-melt silicone???
Post by: typhoon2028 on October 11, 2010, 09:41:10 AM
maybe HCOOH? Silicon often smell of this.
Where can i find these substance?
It is commonly known as vinegar in low concentrations.
Title: Re: How to re-melt silicone???
Post by: DrCMS on October 11, 2010, 10:21:17 AM
maybe HCOOH? Silicon often smell of this.
Where can i find these substance?
It is commonly known as vinegar in low concentrations.


No it is not; HCOOH is formic acid

CH3COOH is acetic acid or vinegar.

Neither of them will have much effect on silicone.
Title: Re: How to re-melt silicone???
Post by: typhoon2028 on October 11, 2010, 06:12:54 PM
bad mistake, definitely misread that one

wow, feeling mighty dumb
Title: Re: How to re-melt silicone???
Post by: miker on October 12, 2010, 02:53:48 AM
bad mistake, definitely misread that one

wow, feeling mighty dumb

I can't understand what you mean
It's bad to try this acid?
Title: Re: How to re-melt silicone???
Post by: vmelkon on October 16, 2010, 02:38:18 PM
Heat doesn't soften silicone. It decomposes and burns of you heat it enough and you end up with a white powder (probably SiO2).
I once put it in contact with gasoline. Doesn't do anything but it came off the glass. (Silicone sticks very well to glass).
Title: Re: How to re-melt silicone???
Post by: cil-baha on December 03, 2010, 10:38:52 AM
Silicone is a thermosetting plastic made by a chemical reaction, the acetic acid mentioned above is part of the 'curing' process and will not redissolve silicone; silicone will not melt with heat, it will decompose usually with charring.
You need to buy a new mask, or if you  think you're onto something you can try dissolving with acetone, Tetrahydrofuran THF, benzene, petroleum ether, toluene, dichloromethane, acetonitrile or any organic solvent you think will work -  try inorganic caustic soda and muriatic acid as well (separately, of course). 
Let us know how far your achievements proceed with results - we want to know.