Combination of the foam and FRPs
Polyphenylsulfone ( PPSU ) foam materials are going to apply to the interior products for Airbus 350 XWB. The press release is below.
http://www.prw.com/article/20160308/PRW/160309870/airbus-agrees-take-off-for-solvay-ppsu-foam
PPSU is presented as one of the new thermoplastic resins. This chemical structure is below.
（ The image above is referred from http://www.anc-chem.com/products-detail.php?product_id=10 ）
The function groups of sulfone, ether and phenyl indicate that this molecular is pretty stiffened.
It has also the character like easy to paint in addition to the relatively highest performance in the sulfone group resin systems.
PPSU showed the higher impact and chemical resistance compared to polyetherimide ( PEI ).
The structure of PEI is shown below.
（ The image above is referred fromhttp://www.sigmaaldrich.com/catalog/product/aldrich/700193?lang=ja®ion=JP ）
PPSU has the enough heat resistance against steam water for sterilization, so one of the representative applications are the medical materials.
The important points to understand PPSU are below.
High HDT of 207°C (405°F)
The deflection temperature under load is over 200 degree C, and it's almost as same as its glass transition temperature. The glass transition temperature of BASF PPSU ( P3010 ) is 220 degree C as an example. It should be the very high value, compared to the representative thermoplastic resins.
Superior toughness and impact strength
P3010 is one of the examples to understand the mechanical properties.
The summary of the properties are below.
– E11 ( Tensile modulus ) @ R.T.: 2.3GPa
– Izod impact resistance : 50KJ/m2 ( 10 times higher than epoxy resins)
– CTE ( coefficient of thermal expansion) 4 – 6 [10-5/K]
Exceptional long-term hydrolytic stability
Withstands over 1,000 cycles of steam sterilization without any significant loss of properties
You can imagine that PPSU has the high hydrolytic stability by phenyl groups in the structure.
Better chemical resistance than PSU and PEI
The group material of Polysulfone ( PSU ) is shown below.
As you can see, the small difference of the chemical structure would have a big impact on the properties. This is the reason why I insist that FRP engineers should have the basic skills of organic chemistry.
（ The image above is referred from https://en.wikipedia.org/wiki/Polysulfone ）
Inherently flame retardant
This should be the biggest advantage, compared with epoxy resins.
The market needs to add the flame retardant to epoxy but PPSU has the much higher priority of the properties.
Transparent
Colorable
This properties would be important if you would use it as interior products because the customer can design and make the color very easily.
Why do I write about PPSU here?
Because Solvay supplies PPSU as Radel® in the production lineup.
http://www.solvay.com/en/markets-and-products/featured-products/radel.html
And Solvay acquired Cytec which is the prepreger of thermoplastic resin system composites.
I suppose that Solvay would expand their Radel® application, combination with the CFRP and/or GFRP.
CFRTP is the expensive.
But if CFRTP can be used as the combination with PPSU form materials which lead to the high cubic volume, CFRTP application should be also increased.
The basic concept of their combination may be the balance among the light weight, high strength and reasonable cost.
You may have seen the some products of the PPSU foam with CFRTP in JEC Europe 2016, but the displayed products are not the latest one.
It should be reasonable to think that Solvay has progressed far away already.
The big chemical companies may be trying to grasp the aeronautical industries recently. They are developing the new type of the combination of thermoplastic resin systems and FRPs.
If below of the middle size chemical companies choose the similar business strategy, it should not work because the severe cost race would start soon.
More reasonable strategy for them shall be the niche area where the big companies can't make their business.
In order to make this strategy work, the high and wide view points to understand the market needs should be necessary. This should be the actual "FRP design view point" as I explained before.
The information gained from internet or exhibition is not always true. So the consistent strategy based on the FRP design view point should be the key to make the breakthrough.
