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.
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Factors affecting composite molding
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patprimmer
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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
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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
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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.
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.
Compositepro
Chemical
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.
patprimmer
New member
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
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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
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patprimmer
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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 for tips on use of eng-tips by professional engineers &
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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 for tips on use of eng-tips by professional engineers &
for site rules
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