Citation: Zhang, Z.; Gao, X.
Polypropylene Random Copolymer
Based Composite Used for Fused
Filament Fabrication: Printability and
Properties. Polymers 2022, 14, 1106.
https://doi.org/10.3390/
polym14061106
Academic Editors: Patrick Lee,
Ludwig Cardon and Clemens Holzer
Received: 5 February 2022
Accepted: 8 March 2022
Published: 10 March 2022
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Article
Polypropylene Random Copolymer Based Composite Used for
Fused Filament Fabrication: Printability and Properties
Zhiyao Zhang
1
and Xueqin Gao
2,
*
1
School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China;
zhangzhiyao2001@buaa.edu.cn
2
College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, China
* Correspondence: gaoxueqin@scu.edu.cn
Abstract:
Fused filament fabrication (FFF) is one of the most commonly used additive manufacturing
technologies. However, the applied material for commercial FFF is limited. Presently, though being
one of the most used polymer materials, polypropylene (PP) is rarely used in FFF because of its
serious warpage and shrinkage problems. This study investigated the impact of addition of short
glass fibers (GF) and ethylene propylene diene monomer (EPDM) on the printability of polypropylene
random copolymer (PPR) based FFF and mechanical properties of the printed samples, as well as
other properties including rheology, thermal behaviors, and morphology. The results show that the
modified PPR has excellent printability, as the printed samples are of good geometrical accuracy.
The addition of GF can significantly improve the strength and modulus of the composite, but it also
leads to serious decrease in toughness. EPDM addition can effectively improve the toughness of the
composite, showing a complementary effect with GF. This work has important meaning in expanding
the FFF applicable material and in broadening the application of PP.
Keywords:
fused filament fabrication; polypropylene random copolymer; printability; toughness;
composites
1. Introduction
Additive manufacturing (AM), also known as 3D-printing technology or rapid pro-
totyping technology, has been developing rapidly since it was first proposed in 1986 [
1
,
2
]
because of its unique advantages. AM allows for more customized characteristics and can
significantly simplify the process of prototyping, making the production more efficient [
3
].
In addition, it has little raw material waste in production [
4
] and, therefore, it is eco-friendly.
As a result, AM is nowadays widely used in different areas [
5
–
7
], such as aeronautics,
medical equipment, architecture, car industry, etc., and its application is still expanding.
After decades of advances, AM has developed into different types [
8
–
11
], including
selective laser sintering (SLS), stereolithography (SLA), Laminated Object Manufacturing
(LOM), and fused filament fabrication (FFF), etc. Among them, FFF is one of the most
widely used methods for fabricating thermoplastic parts with the advantages of low cost,
minimal wastage of raw material, and ease of material change [
3
,
12
–
14
]. The FFF process
can be described as follows [
15
,
16
]. A thermoplastic filament with uniform diameter, which
is used as the printing material, is fed into a heated extrusion head. It then melts and is
pushed out of a nozzle. The extruded melt deposits on the build platform. At the same
time, the head moves horizontally to change the position of the deposition, and the build
platform moves downwards once a layer has been finished so that the next consecutive
layer can be deposited. The printed object is modeled with the superimposition of layers.
Presently, materials such as acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA)
are commonly used for commercial FFF production [
17
,
18
]. However, FFF still has an
unignorable problem: some polymers, such as polyolefin, are barely used for commercial
FFF despite their ideal properties and broad applications.
Polymers 2022, 14, 1106. https://doi.org/10.3390/polym14061106 https://www.mdpi.com/journal/polymers
