PLA and PLA+, know the difference
PLA is the short name for Polylactid acid , a thermoplastic well known among 3D printing users. No wonder why is the most common 3D printing material at least when it comes to filament for FDM printers.
3D printing community has been using PLA filament since the inception of consumer-grade 3D printers but for some time now is possible to find another material similar to PLA that often creates confusion among users. We are talking about PLA+/PLA Plus.
The confusion stems from the fact that different brands use different names to refer to this material and sometimes the claimed properties and advantages may be different.
In this article, we'll try to throw some light to the question from our perspective as filament manufactures.
PLA+ is a commercial name, not a technical one.
As we mentioned in the beginning, PLA is the short name for polylactid acid a kind of thermoplastic polyester with a fixed chemical composition (C3H4O2)n. Therefore you should expect that every PLA filament in the market has basically the same composition. This affirmation comes with a caveat because even standard PLA is normally mixed with other additives to make it most suitable for 3D printing. However, in standard PLA filaments, the amount of PLA is normally more than 98% and additives represent a small part of them.
PLA filament prints great and is a well-balanced material but it has some downsides, especially its low thermal deflection temperature and relatively poor toughness.
To overcome these weaknesses, companies like ours started mixing PLA with other polymers and found that it was possible to produce filaments that retain the advantages of PLA while improving its performance. Unlike standard PLA, PLA+ can contain 80% of PLA and 20% of other additives engineered by the manufacturer in order to improve its printing, thermal or mechanical properties. The additives are typically other thermoplastics such as polyurethane, polyesters, polyamides, or sometimes even PLA different from the base one. Naturally, the exact composition is an industrial secret of each manufacturer and is rarely disclosed.
Some brands started using the name PLA+/PLA Plus to call these new formulas and the market followed behind. However, other brands use terms such PLA Pro or PLA/PHA to refer to the same kind of product. In our case, we use the name Modified PLA (MPLA) to better represent the nature of this filament but we also include the name PLA Plus in our marketing.
PLA Plus advantages (and disadvantages)
PLA Plus exists to overcome the downsides of PLA. PLA most notorious flaws are in the field of thermal performance.
Improved thermal properties
PLA has a low thermal deflection temperature, which means that it starts to get soft and bent at a temperature as low as 65 degrees. If you have ever left in a car in the hot summer a PLA printed part you may know what we are talking about. At 65 degrees PLA starts to bend even under a small force so if you printed a hook or support for your mobile phone, it might bend and fall if the temperature is high. This poor thermal performance is also critical when printing functional parts like gears that might heat up when working.
PLA+ is meant to reduce this problem by increasing the deflection temperature of the material by around 15 degrees. The difference might not seem big, but in many cases is enough to make the models functional.
Improved mechanical properties
Another common issue of PLA is its low impact resistance, at least compared to other thermoplastics. We want to remark that when we say impact resistance we are talking about toughness, not hardness. In fact, PLA hardness is superior to that of other plastics, but hardness only measures if one material is able to scratch another one, not how likely is to break and shatter. When it comes to impact resistance, PLA falls behind other common thermoplastics like PETG and ABS.
The additives in PLA+ greatly improves the toughness/impact resistance of the base formula achieving up to 5 times better performance in some tests. Is important to note that toughness tests with 3D printed specimens can be done in different ways. There are different testing methods and the testing specimens can be printed under different settings. The manufacturers normally use the higher number they got in their tests when marketing the product. So in some use cases, the extra toughness might not be so apparent.
Improvements in printability
Standard PLA is fairly printable and in this regard, there is less space for improvement, but PLA Plus also tends to outshine PLA in terms of how performs some common 3D printing mechanics.
This is the case of bridging and overhanging. PLA+ formulas are tuned to behave very well in these scenarios allowing longer and tighter bridges and steeper overhangs.
In the case of our brand though, our standard PLA is already formulated to perform excellent bridges and overhangs.
Disadvantages (if any)
Supports harder to remove
As a result of the improved toughness and layer bond, support structures printer with PLA+ may be slightly more difficult to remove, and the contact surface between the part and the supports might not be that clean and perfect.
The goods news is all modern slicers allow to configure the support settings, so if you are having a bad time removing PLA+ supports you can tune your support settings to make them sparser and reduce the contact surface.
Slightly less compatible
Standard PLA is normally more fluid than PLA+ and this can have an impact on some poorly maintained or designed 3D printers. Despite being infrequent, sometimes happens that a 3D printer that prints standard PLA just fine suffers clogging and jams when using PLA+.
If this happens normally can be solved by replacing the nozzle or the PTFE tube inside the hot-end. Sometimes a full hot-end replacement might be needed.
Price and availability
PLA+ is normally pricier than standard PLA and that is an important factor to take into count especially when printing professionally.
Also normally is easier to find standard PLA in a variety of colors and styles, such as marble PLA, Silk PLA, glitter PLA, etc...
In the case of our brand, we produce PLA+ in few and less vivid colors than standard PLA because we consider it more like a functional material aimed for industry or engineering and less for domestic or decorative purposes.
How to choose when to use PLA or PLA+
In our opinion, standard PLA is an excellent printing material very suitable for a lot of use cases so we wouldn't recommend using PLA+ for every print job.
Nowadays many domestic users use their machines to produce decorative parts such as figures, vases, lithophanes, or toy-like parts. For the majority of these use cases, PLA is perfect, and using PLA+ would kinda overkill.
However, if you are looking for functional parts like gears, hooks, or joints for assembling wood parts using PLA+ seems like a better option.
Also, if the parts you want to print are going to be exposed to temperatures near to 65 degrees using PLA+ or other high-temperature plastic is a must.