The new test standards regarding thermoplastic composites pultrusion
The new test standards were released from ASTM regarding thermoplastic composites pultrusion. The new ASTM standards are below.
– Test Method for Measuring the Effect of Freeze-Thaw Cycling on a Thermoset Pultruded Composite (D7792)
– Test Method for the Evaluation of the Effects of Elevated Temperature and Moisture Conditioning of Pultruded Fiber Reinforced Polymer Composites (D7992)
Currently FRP extrusion with thermoplastic resins is one of the trends in this industries. Mass production is available if the product's cross section is the same. This is the one of the reasons why thermoplastic FRP extrusion technology is being focused.
The companies like below would be mentioned here as examples.
– Creative pultrusions
http://www.creativepultrusions.com/
– Liberty pultrusions
http://www.libertypultrusions.com/
The purpose of the released new standards is to evaluate the influence of Freeze-Thaw cycle and humidity during heating process. The molecular will be damaged by the heat-cool cycle because the polymerization of the thermoplastic resins had been already completed.
Writing more detail points, the temperature for thaw should be so high as the polymer chain could be cut if the matrix resins are the heat resistance type like super-engineering plastics. This damage by heating would lead to the material property degradation. The impact of heat cycle on the mechanical and physical properties of the composites can be evaluated by the new released ASTMs.
The humidity during heating is also critical. Especially the hydrophilic molecular like PA (Polyamide), we need to pay attention to humidity during thaw procedure. ASTM D7992 can be evaluated regarding such condition.
I have not read the contents yet but am interested in it.
ASTM presented the release in the URL below.
http://www.astmnewsroom.org/default.aspx?pageid=3831
Recently the composite pultrusions are being focused day by day. The advantage of it would be the high productivity of composites which can be applied to the structural materials.
Bending forming process seems to be attracted right now but the fiber alignment change would be unavoidable. This should lead to the mechanical and physical properties change.
Therefore, layup design change, local reinforcement and basic alignment optimization depending on the bending process would be important.
In addition, material degradation by thaw heating is not negligible. The proper degradation evaluation of materials by heating process shall be also conducted.
There is no doubt that the composite pultrusions are one of the FRP trends. But we need to design the parts and production line to achieve the stable quality, referring the new ASTM standards.
