Polyester/epoxy resins and styrofoam
 

Â* Live and learn , it's expensive ! So about 14 years ago we bought a
camping trailer . One of those super lightweight units . The problem is
, nobody ever said a word about checking the caulking (roof mostly)
every year or two ... now this unit is made of bonded foam/plywood
panels with 1 1/2" thin-wall aluminum square tube framing . And there's
water damage that has caused the plywood to delaminate . I've repaired
the floor panels and laminated a layer of 3/8" plywood using a
latex-based engineered wood adhesive . Next step is regluing those
delaminated plywood panels . The interior ones I'm going to just replace
using the same/similar water-soluble(when uncured) adhesives . The
outside skin is another matter entirely . I have purchased both epoxy
and polyester resins and have formulated a plan to hold the panels
firmly against the substrate (the styrofoam) while the resin cures .
HOWEVER I have been cautioned by a local (kinda) RV repair place that
the resin MAY cause damage to the foam core - like dissolve it . I know
there are at least a couple of folks here with chemical backgrounds ,
I'm looking for an answer - is the resin going to dissolve the foam
cores of these structural panels ? A corollary question is : are all
styrofoams created equal ? I have several pieces of styrofoam insulating
board leftover/used and removed , etc that I can use for testing ,
ass/u/ming that it's all made from the same stuff . FWIW it looks like
the original bonding agent was a rubbery adhesive , I'm guessing a
latex-based contact type adhesive .Â* And I'm working to a deadline - my
wife wants to go visit her old and sickly mother later this month . I
can't leave the dog home and Max would run her mother bugnuts crazy in
under an hour ... and there ain't a motel I know of that'll let us have
a 70 pound dog in the room . I guess I could just send her off to
Kentucky alone and Max and I could stay home ... which would suit me
just fine , but y'all know how women can be about this sort of thing .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

Polyester/epoxy resins and styrofoam
 

On Tue, 9 Jul 2019 14:20:14 -0500, Terry Coombs
wrote:


* Live and learn , it's expensive ! So about 14 years ago we bought a
camping trailer . One of those super lightweight units . The problem is
, nobody ever said a word about checking the caulking (roof mostly)
every year or two ... now this unit is made of bonded foam/plywood
panels with 1 1/2" thin-wall aluminum square tube framing . And there's
water damage that has caused the plywood to delaminate . I've repaired
the floor panels and laminated a layer of 3/8" plywood using a
latex-based engineered wood adhesive . Next step is regluing those
delaminated plywood panels . The interior ones I'm going to just replace
using the same/similar water-soluble(when uncured) adhesives . The
outside skin is another matter entirely . I have purchased both epoxy
and polyester resins and have formulated a plan to hold the panels
firmly against the substrate (the styrofoam) while the resin cures .
HOWEVER I have been cautioned by a local (kinda) RV repair place that
the resin MAY cause damage to the foam core - like dissolve it . I know
there are at least a couple of folks here with chemical backgrounds ,
I'm looking for an answer - is the resin going to dissolve the foam
cores of these structural panels ?

Polyester resin will disolve styrene. Epoxy will not

A corollary question is : are all
styrofoams created equal ? I have several pieces of styrofoam insulating
board leftover/used and removed , etc that I can use for testing ,
ass/u/ming that it's all made from the same stuff . FWIW it looks like
the original bonding agent was a rubbery adhesive ,
There is ipen cell (blown) expanded styrene and closed cell expanded
styrene. Otherwise known as "bead board" and" Styrofoam SM". Both are
styrene and will be disolved by the solvents in plyester resin. There
are also IsoFoam, urethane foam, andseveral other foam board products
that will stand up to polyester - but they are not as commonly used in
things like travel trailers. Take a small chunk and put it into a jar
of gasoline. If it melts, DO NOT use polyester resin!!!
I'm guessing a
latex-based contact type adhesive .* And I'm working to a deadline - my
wife wants to go visit her old and sickly mother later this month . I
can't leave the dog home and Max would run her mother bugnuts crazy in
under an hour ... and there ain't a motel I know of that'll let us have
a 70 pound dog in the room . I guess I could just send her off to
Kentucky alone and Max and I could stay home ... which would suit me
just fine , but y'all know how women can be about this sort of thing .

Polyester/epoxy resins and styrofoam
 

On 7/9/2019 2:55 PM, Clare Snyder wrote:
On Tue, 9 Jul 2019 14:20:14 -0500, Terry Coombs
wrote:

Â* Live and learn , it's expensive ! So about 14 years ago we bought a
camping trailer . One of those super lightweight units . The problem is
, nobody ever said a word about checking the caulking (roof mostly)
every year or two ... now this unit is made of bonded foam/plywood
panels with 1 1/2" thin-wall aluminum square tube framing . And there's
water damage that has caused the plywood to delaminate . I've repaired
the floor panels and laminated a layer of 3/8" plywood using a
latex-based engineered wood adhesive . Next step is regluing those
delaminated plywood panels . The interior ones I'm going to just replace
using the same/similar water-soluble(when uncured) adhesives . The
outside skin is another matter entirely . I have purchased both epoxy
and polyester resins and have formulated a plan to hold the panels
firmly against the substrate (the styrofoam) while the resin cures .
HOWEVER I have been cautioned by a local (kinda) RV repair place that
the resin MAY cause damage to the foam core - like dissolve it . I know
there are at least a couple of folks here with chemical backgrounds ,
I'm looking for an answer - is the resin going to dissolve the foam
cores of these structural panels ?
Polyester resin will disolve styrene. Epoxy will not

Â* OK so I will use the epoxy for rebonding the outer skin . After I
test it on some of this foam board to make sure . This stuff came from
an outfit in Utah , the kit is expressly designed for rebonding
delaminated camper skins . Came with mixing cups , gloves , syringes and
tubing to inject the resin where it's needed . They recommend injecting
from an edge if possible , drilling holes in the skin and patching them
later if necessary . I'm no way going to get this thing totally repaired
in time for the upcoming trip , just gotta get it roadworthy . And fit
to stay in for a couple of days - toilet is top of the priority list ,

A corollary question is : are all
styrofoams created equal ? I have several pieces of styrofoam insulating
board leftover/used and removed , etc that I can use for testing ,
ass/u/ming that it's all made from the same stuff . FWIW it looks like
the original bonding agent was a rubbery adhesive ,
There is ipen cell (blown) expanded styrene and closed cell expanded
styrene. Otherwise known as "bead board" and" Styrofoam SM". Both are
styrene and will be disolved by the solvents in plyester resin. There
are also IsoFoam, urethane foam, andseveral other foam board products
that will stand up to polyester - but they are not as commonly used in
things like travel trailers. Take a small chunk and put it into a jar
of gasoline. If it melts, DO NOT use polyester resin!!!

Â*Â* The panel cores appear to be the same stuff they make foam cups with
.. The pour foam I used to repair the floor panels is rigid urethane ,
4lb/cu ft density . I'm not concerned about that stuff . After pouring
the foam in the cracks, gaps , etc in the sagging floor panels , I
floated it level and (reasonably) smooth with a floor patch compound
with a latex admix . I then bonded some 3/8" b/c plywood to that with
the engineered wood flooring adhesive . Also used 1" drywall screws at
6" on center into the aluminum framing , which is 16" O/C . Did I ever
mention that while I retired as a cabinet maker , I spent nearly 20
years as a floor mechanic ? I specialized in vinyl flooring with
subfloor damage . Did my own subfloor repairs because carpenters just
couldn't ****ing understand you MUST stagger joints in subflooring .
I'm guessing a
latex-based contact type adhesive .Â* And I'm working to a deadline - my
wife wants to go visit her old and sickly mother later this month . I
can't leave the dog home and Max would run her mother bugnuts crazy in
under an hour ... and there ain't a motel I know of that'll let us have
a 70 pound dog in the room . I guess I could just send her off to
Kentucky alone and Max and I could stay home ... which would suit me
just fine , but y'all know how women can be about this sort of thing .

Â* I'll be using the water-soluble adhesive for the interior panels on
the back wall , looks like I'll be saving that poly resin for another
project .
Â* Thanks Clare !

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

Polyester/epoxy resins and styrofoam
 

Upcoming trip? Cover it with a tarp.

Polyester/epoxy resins and styrofoam
 

On 7/9/2019 4:57 PM, Thomas wrote:
Upcoming trip? Cover it with a tarp.

Not an option . Some of the damage compromises the structural integrity
of the camper . Did you miss the part where I said the camper is built
of plywood clad foam panels bonded to an aluminum framework ? If them
****ers don't have a rigid material bonded to both sides they might as
well be tissue paper at 60 MPH .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

Polyester/epoxy resins and styrofoam
 

On 7/9/2019 3:55 PM, Clare Snyder wrote:
On Tue, 9 Jul 2019 14:20:14 -0500, Terry Coombs
wrote:


Â* Live and learn , it's expensive ! So about 14 years ago we bought a
camping trailer . One of those super lightweight units . The problem is
, nobody ever said a word about checking the caulking (roof mostly)
every year or two ... now this unit is made of bonded foam/plywood
panels with 1 1/2" thin-wall aluminum square tube framing . And there's
water damage that has caused the plywood to delaminate . I've repaired
the floor panels and laminated a layer of 3/8" plywood using a
latex-based engineered wood adhesive . Next step is regluing those
delaminated plywood panels . The interior ones I'm going to just replace
using the same/similar water-soluble(when uncured) adhesives . The
outside skin is another matter entirely . I have purchased both epoxy
and polyester resins and have formulated a plan to hold the panels
firmly against the substrate (the styrofoam) while the resin cures .
HOWEVER I have been cautioned by a local (kinda) RV repair place that
the resin MAY cause damage to the foam core - like dissolve it . I know
there are at least a couple of folks here with chemical backgrounds ,
I'm looking for an answer - is the resin going to dissolve the foam
cores of these structural panels ?

Polyester resin will disolve styrene. Epoxy will not

That is correct. Polyester resin is cures by cross-linking with styrene
and the monomer would attack the polystyrene