What is PLA+? How is it different than PLA? I'm looking for science, composition, formula, safety concerns (or lack thereof), etc.
I picked up a roll of PLA+ at Microcenter (their in-house Inland brand) because it was on clearance. I didn't even notice the "+" until I decided to try that color, and then I noticed it on the sticker. It prints well, feels like ABS, smells like PLA when printing, and I can use PLA temps on my printer. It sands better than PLA, and if I I hadn't noticed the PLA+ sticker, and the smell, I would think it was ABS. It will break its line into my printer like PLA does; ABS doesn't break if left alone. However, PLA+ lasts longer than regular PLA before breaking.
Getting info from the Internet
Aside from a few discussions on reddit (review, commercial introduction), I can't find anything about it.
Getting info from the Manufacturer
I went back to Microcenter and the guy that was there working the 3d printing section did not know what I was talking about.
I went to Microcenter another time and the guy in the filament area said that all of their PLA filament was now PLA+, and that the + meant it was to be used at a higher temperature. The boxes are labeled with 205 - 225°C. It seems that all the inland brand PLA I have is PLA+, save for the first roll I bought. It does not have any kind of temperature markings on it.
Flash forward 1.5+ years from the original question
This question got some recent attention, so I looked to find the answer again. I found this article, which is a hot pile of !usefulness, giving no data, lots of opinion, and probably some direct insights from someone's marketing department.
These guys say it's good stuff, but nothing about the chemical or compositional difference between the two. When I find people talking about the difference (like on reddit), those are the details usually mentioned, which are vague, anecdotal, and opinionated, and could be clever marketing (could be, not guaranteed to be). One man's shiny is another man's matte for example.
Monoprice confirmed what I already did by reading the label and printing with it, but does mention TPU, which might be Thermoplastic polyurethane. No quantity or proportion or anything, and since they're the only manufacturer/reseller to officially say this, I consider it unconfirmed. One of the answers below says that PLA+ probably includes TPU or something like it, but that's conjecture or opinion by their own admission.
PLA+ is a variation of PLA that has added material in order to make the filament less brittle, have a smoother surface finish, and less likely to absorb moisture. Typically, TPU is added into the filament in order to achieve this property. PLA+ will have the feel and functionality of ABS without the smell. If you didn’t know better, you would think it was ABS. We suggest printing with PLA+ at 205 to 210 degrees Celsius and with a bed temperature of 45 degrees Celsius. PLA+ responds very well to blue painter’s tape and a glue stick to hold properly and not peel up when printing.
These people also ask what it is, but they're doing science about it circa 2014 to try to figure it out.
I'm not sure what to think of this manufacturer/seller's description. It sounds like they are implying that PLA has a branding problem, so they added a plus to it for a new formula to fix their branding.
PLA Plus is an enhanced version of our PLA that's less brittle and more durable. ‘Enhanced’ PLAs have a bad reputation, some are no better than PLA, some perform worse in some conditions. We’ve taken a different approach: our ‘regular’ PLA is regarded as the strongest pure PLA in the industry, it’s hard to improve on the best. But sometimes you need something a little more durable. Enter our specially formulated PLA Plus. Prints like PLA, but with better durability. Its available with their brighter color options!
I find a lot of articles/posts talking about "eSun PLA+" specifically. I'm starting to think that this might be the OEM and that other companies are selling it with their own branding, but that all PLA+ comes from the same place. I found their product page, and it says this, which mentions nothing about the formula:
- extracted and purified from corn grain;
- high rigidity, good glossiness and transparency;
- suitable for printing larger models;
- toughness is 2 times more than the PLA on the market;
- no wiredrawing problems, the surface of the printouts will be smoother and more delicate;
- no cracking problem.