Why are Polyolefins (the world’s favourite plastics) not making an impact when it comes to 3D printing - the world’s fastest growing plastics processing technology?
To begin with I should explain, for those who’re not familiar with what polyolefins are, why I’ve referred to polyolefins as being ‘the world’s favourite plastics.’ (Thanks, British Airways )
We’re essentially talking about Polyethylene, Polypropylene and combinations of the two. In the real world, you might have seen the letters PE (or its varietals HDPE, LDPE, LLDPE and more) or PP embossed onto the bottom of an awful lot of the things you use every day from kettles to car interiors; from food and drink packaging to garden furniture. So, although you might not know ‘polyolefins’ – they’ve been a big part of our lives for decades.
[As a side note, PET (Polyethylene terephthalate) is not classed as a polyolefin due to the way it’s manufactured and doesn’t offer the same property set.]
There are good reasons why polyolefins are so popular – they’re easy to manufacture things with, can be tailored to look and feel like pretty much anything you could want, they’re resistant to water and most chemicals, and – if used in the right way – are easy to re-cycle and re-use; easier than most other plastics in fact.
But so far their benefits have yet to be exploited when it comes to 3D printing.
At Forefront, we suspect it’s down to two things, the second of which I’ll come to in a follow-on blog.
First though, the reality is that polyolefins are semi-crystalline polymers and, without getting into too much detail, the way in which they solidify and crystallise after being melted means that they might not seem like a natural fit for a technology that builds parts up on a layer-by-layer basis. Those who have tried to 3D print with either pellets or filament made from 100% Polypropylene or Polyethylene will have no doubt encountered lots of issues like warping and limited (if any) bed-plate adhesion, so the end results would have left many thinking “I’m sticking with ABS”.
So, why bother trying to make 3D printing materials from polyolefins? Well, in our opinion, PLA and ABS are not the future of 3D printing with polymers. Nor are variations of these filled with ground up metal, wood, chalk, cheese etc. It’s our opinion is that 3D printing could become (and is starting to become already) a very capable manufacturing technology on an industrial scale, and no other family of polymers has the combination of properties to compete with polyolefins.
With that in mind, how can we overcome the technical hurdles to make polyolefin pellets and filaments that print well and make fantastic parts? Not just models and prototypes, but useful products.