Like PETG? You'll love PCTG!
PCTG, like PETG, is an amorphous co-polyester, but PCTG is more impact, chemical, and weather resistant than PETG. PCTG has a similar strength and stiffness to PETG, but is preferred for dynamic environments and applications! PCTG without fibers was the only co-polyester we tested that made a 2 layer, 0.40 mm living hinge that didn't break! PCTG is also relatively low moisture absorbing and easy to print with generic PETG or PCTG settings. Big plus!!!
Compared to Protopasta HTPLA, co-polyesters "feel" stronger because they bend without breaking, but they are actually lower in ultimate strength and stiffness than Protopasta HTPLA. Similarly, filaments like PLA+, Pro PLA, and Polymaker HTPLA have additives that make PLA "feel" stronger by bending at a lower load but without breaking abruptly.
Protopasta HTPLA remains the ideal choice for ease of printing, rigidity, strength, temperature resistance (when heat treated), and availability of color/finish variety.
Still, PCTG has it's place! Here's a look at the properties of PCTG (without fibers):
Making PCTG better
What if we could boost stiffness and strength of PCTG? PCTG is about half as stiff as Protopasta HTPLA, but adding fibers can increase the stiffness to HTPLA levels without making PCTG brittle. We did something similar by adding CF to PETG years ago, but we're going further with PCTG because the superior mechanical properties are alluring.
We added glass fibers to make PGGF at an intentional loading level to double stiffness without sacrificing strength or durability. Glass fiber also elevates the surface finish for a premium low gloss, layer-hiding textured in any color. Think professional quality, durable prints that don't even look 3D printed. Which colors would you choose? Contact us with custom color needs to feed your print farm.
We took a new approach with carbon fiber PCTG (PGCF) as well. PCTG's ductility allowed us to create two PGCF loading levels: one optimized to retain ductility and impact durability (HIG) in gray and a second formulation with higher loading (HSB) that sacrifices some ductility for even higher strength and stiffness without feeling too brittle in black. Below are all 4 new PCTGs from left to right: Clear (without fibers), White Glass Fiber, Gray High Impact CF, and Black High Strength CF.
After formulating, we couldn't help but sample some other brands to see how they compare. While all co-polyesters without fibers had similar strength and stiffness, fiber-filled versions have more variation in properties. Bambu Carbon Fiber PETG was the weakest and least stiff, likely because there's only enough CF for the aesthetic. I understand Atomic Filament's Carbon Fiber PETG is formulated in a similar way though I haven't tested it yet because it's lost in transit (which can happen with USPS and is not Atomic's fault).
Most of the other carbon fiber filled amorphous co-polyesters we tested (like from Push Plastics, 3DXTech, and Polymaker Fiberon) are on the brittle side with what is probably too much carbon fiber or a different type of carbon fiber. More is not always better...
All amorphous co-polyesters had similar temperature limitations. Still, the durability is desirable compared to HTPLA for dynamic applications <80 C. In applications >80 C, heat treated HTPLA still has the edge over PCTG and PETG. Consider the table below with select values generated from tensile testing filaments in-house at Protoplant with our specialized filament testing fixture shown in this blog. New Protopasta PCTGs highlighted green. Please us to compare materials in this chart, but not as absolute values. Printed part performance will vary.
Which of the above materials do you find most intriguing? Which are most useful? Do you have an application in mind? I look forward to learning how you use these materials. Tag Protopasta to show us what you make!!!
Missed out on January's Endless Exploration? Get PCTG at Protopasta.com starting in February and/or subscribe to our next Endless Exploration by February 28th for our March shipment where we'll be premiering world's first filament made with quantum dots!
Take care and enjoy the pasta,
Alex and the Protopasta Team
More about how to print PCTG
As you've seen in previous blogs, I like to sweep a range of volume rates from 2-24 cu mm/s from bottom to top at one or more temperatures for a given material. Typically a clear material is transparent and glossy at low rates but becomes more opaque as the rate increases, indicating that the material is less melted. Below is a look at what I found when screening PCTG at 255 C (left) and 275 C (right):
Printing should be quite straight-forward starting with a generic PETG or PCTG profile. Both run quite similarly with the main difference being that PCTG likes to run a bit hotter and will jam at a lower rate than PETG. Still, 255 C is a great starting point for volume rates up to 6 cu mm/s for a full melt, though be aware that PCTG stopped extruding at 24 cu mm/s (see how the above left print is a little shorter?).
At 275 C, you do have to be careful not to print at too low of a volume rate (see the haze at the bottom left when printing at 2 cu mm/s?), but you can also reach a full melt to a higher volume rate, 12 cu mm/s, and rates up to 24 cu mm/s were possible without jamming. Keep in mind that as you increase from 12 to 24 cu mm/s at 275 C, you will see clarity and thus interlayer bonding decrease for lower strength. Still, if you don't require maximum strength or consistent finish, you can print at a rate up to 24 cu mm/s at 275 C.
Want a full melt above 12 cu mm/s or to print faster? Consider a high flow nozzle with larger heat affected zone. Increasing the nozzle beyond 275 C shows diminishing returns.
We experienced some warping at 70 C without fibers, so we recommend an 80 C plate temp. A lower temperature is possible with fiber filled PCTG, but why risk it? We also ran without fans or slowdowns.
More about Protopasta
Protopasta is 100% made in the USA by Protoplant Inc. Founded in 2013 by engineers, Dustin and Aaron Cram, we control every step of the process with in-house made machinery and materials. We’re a small team with a passion for making things, just like you! We’re here because of you. We’re here for you. Thank you for choosing Protopasta!