×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Factors affecting composite molding

Factors affecting composite molding

Factors affecting composite molding

(OP)
i did a study of different factors (Temperature ,pressure ,time) affecting hot molding process of a composite based on polyester fiber material. what i observed the pressure has no significant effect as the temperature. did someone get the same conclusion , and according to your experience , how factors (T,pressure and time) influence the hot molding process.

RE: Factors affecting composite molding

Your question is a bit confusing so I am going to guess you actually mean composites using thermosetting polyester resins and reinforcing fibres such as glass or carbon as these are the typical composites industry materials.

I am also going to presume you will use an autoclave for the pressure and temperature control rather than a hydraulic press and a hot metal mould although both methods are used extensively.

The thermoset polyester resin cure times are determined by catalyst type and concentration and temperature. Pressure has nothing to do with it other than if the pressure in itself increases temperature which is possible.

For the fastest cure, you need to kick it off as fast or hot as possible without the exotherm getting the temperatures so high, you either boil the resin and generate bubbles or you start a fire.

An indirect benefit of higher pressure is that it raises the boiling point of the resin. The boiling point also increases as the polymerisation progresses. ie monomer has the lowest boiling point of about 160 deg C from memory, maybe. It's an old memory.once it polymerises to some degree, like maybe the resin in a prepreg, the boiling point increases with degree of polymerisation. DP is roughly indicated by viscosity.

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules

RE: Factors affecting composite molding

(OP)
Thanks Pat,

i will calarify . i do not use any resine . the product initally is a non woven (fibrous material) part made by airlay process, and after i mold it to get a finished part. the part is 100% polyester.and i am looking for a good set up for my hot press (plaques molding).you can consider the part as a thermoplastic composite. sorry for confusion.

RE: Factors affecting composite molding

Pat responded to the only reasonable interpretation of your question. If your material is only polyester fiber, then it is not a composite. Now it sounds like you are heat-setting a polyester fiber mat. But I don't feel like playing guessing games.

RE: Factors affecting composite molding

This sounds like a process used to make some automotive head linings and disposable fabrics like overalls and surgeons gowns.

Mostly this is done by air entanglement then a resin like PVA is used as a binder like the starch in paper making.

Akzo Nobel had a process where the polyester was co extruded with a lower melting point resin when the fibre was made. This gave a lower melting point surface so heat welding could occur without noticeably weakening the core fibre.

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules

RE: Factors affecting composite molding

(OP)
100% polyester is an industrial term , it is a blen of poly and bicopolymer fiber used as a binder.

RE: Factors affecting composite molding

One more tooth extracted. How many more. I'm not a dentist and don't intend to continue to extract information from you in a manner as similar to pulling teeth.

Give a proper description of what you are really doing or I will red flag this thread as a stupid waste of time.

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules

RE: Factors affecting composite molding

(OP)
sorry abusing your time.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources