Reality Check

One thing I’ve learned on my year on placement is that, sometimes, not everything works. It could be perfect on paper and in theory but in reality, sometimes it just can’t be done.

Film selfie with a fellow student, Fiona!  Taken during some (unfortunately unsuccessful) flame tests!

Film selfie with a fellow student, Fiona!
Taken during some (unfortunately unsuccessful) flame tests!

This isn’t a total shock when you think about it, but previous experiences in the undergraduate teaching labs lead you into almost a false sense of security. In the teaching labs, the experiments you do are designed to be full proof and you get a good yield and then writing the report on it is easy. This isn’t the case most of time in the real world – my real world being the design and manufacture of various polyester films – and it does sting when things don’t work out like you’d hope they would.

My main project at DuPont Teijin Films is making flame retardant films and for this we use a variety of techniques and additives. The general rule goes, up to a point, that increasing the flame retardant additive level will cause the flame retardant properties of the film to also increase. There are a lot of factors to take into account (cost of the final product is a big one) but generally we assume that we can physically make our samples for testing. However, increasing the amount of additives in a film can cause it to be brittle; sometimes the film can be so brittle that as we try to make it, it can split right down the middle. Splitting of the film during the process results in shards of film having to be manually pulled out of the line and causes quite a mess!

Film coming out of the stenter looking as it should

Film coming out of the stenter looking as it should

It’s not just making the film which can be a problem – I’ve done some work on coatings for films this year too. One problem I’ve seen with coatings is that they don’t always “wet” onto the film very well, basically the film can be too hydrophobic for the coating to evenly spread across it and you end up with the same sort of situation as when you pour water onto a greasy pan. This is usually fixed by adding a surfactant which acts to lower the surface tension between the film and the coating, but sometimes it can be more desirable to find a coating which will wet onto the film without the aid of a surfactant. Once a coating which behaves well is produced it still needs to look good overall, because no one is going to buy a film which looks bad – and that’s the next issue to be addressed.

Once we have our film, we’ve got to test it all for all our desired properties; in the case of flame retardant films this basically means trying to set it on fire (lots of fun). At the beginning of my placement year a lot of our films did burn but through a lot of hard work by the flame retardant dream team (my boss and I), they got a lot better!
I hope I don’t put you off, but the harsh reality is that not everything works, but you have to keep trying because all the problems you might encounter (for me: processing issues, splits in the film, problematic coatings and film that just looks plain bad) will only work to increase the appreciation and happiness you feel when you get a product that works and looks great! I am really not exaggerating here – we have literally jumped up and down in excitement over a good film before.

Until next time, and always trying,

Claire

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