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
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
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
RE: Factors affecting composite molding
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
RE: Factors affecting composite molding
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