Development of Thermoplastic Composites for Fdm-Type 3d Printers

Kunal Patel

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International journal of mechanical engineering

(ISSN: 2693-3713)

Volume 05, Issue 02, 2025, pages 24-43

Published Date: - 22-08-2025

Doi: -

https://doi.org/10.55640/ijme-05-01-05

Development of Thermoplastic Composites for Fdm-Type 3d

Printers

Kunal Patel

Mechanical Engineer, Mega Circuit Inc., USA

Abstract

FDM

–

type 3D printing has greatly increased in recent years but there is still a demand for stronger and stiffer

materials. The objective of this work is to extrude and test various types of thermoplastic composite filament to be
used for 3D printing. ABS thermoplastics was combined with various lengths of fiberglass. Using these thermoplastic
composites several specimens were prepared per ASTM D638 by compression molding and tested. The fiberglass
was introduced to increase mechanical strength and stiffness of the thermoplastic filament. Three types of fiber
sizing were evaluated, the original epoxy-based sizing, an alkoxysilane Gelest sizing, and a water-based Michelman
sizing. One hundred specimens were fabricated from composite material. Specimens varied by sizing, by fiberglass
lengths, and by fiberglass volume fraction. Out of all the specimens tested, those with Michelman sizing produced
the most consistent and overall best bonding. The Gelest sizing produced the highest and lowest values. Epoxy
sizing produced almost as good results, and no sizing was worst. FDM thermoplastic filament of 1.75 mm diameter
was extruded, and was used on a ROBO 3D FDM printer to 3D print objects. Mechanical strength and stiffness were
not improved as expected because fiber lengths were much shorter than advertised. Other possible reasons include
incomplete mixing of materials, processing errors, voids in specimens, and improper treatment of fibers with sizing.

Key words

:

FDM 3D Printer

–

Fused Deposition Modeling type 3D printer, 3D printer Filament, Thermoplastic

Material, ABS Fiberglass, Extrusion, Sizing.

1.

Introduction

Extruders are used to produce plastic products such as flexible pipes and plastic sheets. They can also be used to
mix materials. Basically, extrusion is a process of applying heat and pressure to melt a polymer and force it through
an orifice in a continuous process. It is used to produce polymer products of uniform shape and density. Extruder
used to mix different polymers with additional materials like pigment, fillers, reinforcers etc. Melting is
accomplished by frictional heating within barrel as material undergo shearing between screw barrel set up. Because
the barrel is generally heated with heaters mounted around it. The barrel section temperature is optimized so that
the viscosity of the melt is low enough to allow conveying down the barrel and proper mixing. Figure 1 shows a
general extruder setup with single screw. Most extruders are electrically heated with either band-type resistance
heaters, cast-in block heaters or tubular resistance heaters wrapped around the barrel. An efficient barrel cooling
system is important to control the tendency for mechanical shear heat developed in the melt to override the
electrical heater controls. The optimal extruder barrel length for extruder is 30-32 times its internal diameter (30:1
L/D, 32:1 L/D). Although shorter barrels can be used, mixing efficiency and melt uniformity are not optimal. Cooling
to the extruder feed throat is critical to prevent surging or bridging. Internal cooling to the screw is not needed [1].
The objective of this paper is to study mechanical properties of thermoplastic material used in 3D printer and

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enhanced its Mechanical properties by adding various filling material as well as sizing materials to make it much
more stronger and cost effective.

2.

Discussion And Comparison

Figure 1. Components and features of an extruder for plastics and elastomers [2].

Material flow in single screw extruders is driven by the properties of the material. Depending on the material being
fed, a different screw can be used to handle the new material. Single screw extruders are popular and can handle
some of the toughest materials. The single screw extruder pictured as shown in Figure 1 comes with a flame-
hardened screw for handling abrasion and corrosion. In single screw extruders, a screw mixer melts the entering
plastic materials, pushes the material through the extruder, and forms the plastic into the desired shape [3].

Extruders have three key components [3],

(a)

The hopper, where material is fed to the extruder.

(b)

The screw, which runs along the length of the machine.

(c)

The optional static mixers at the end.

Figure 2. Single screw extruder [3].

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Figure 2 shows single screw extruder set up. Single screw extruders rely on the friction between the material and
the barrel for flow: the greater the friction, the slower the flow. One way to increase friction is to increase the length
of the barrel, but this could result in a change in viscosity with position. The extruder temperature can be adjusted
to control the viscosity [3].

Figure 3. Twin screw extruder [3].

Figure 3 shows the setup of twin screw extruder. Not all extruders with two screws are twin screw extruders. Screw
placement and type are also important determinants. Twin screw extruders have two intermeshing screws and
operate in the same manner as a single screw extruder. The picture shows the barrels of the extruder exposed.
Twin screw extruders depend minimally on the friction of the material against the barrel to move forward. They
rely instead on the properties of the extruder and the screws. Meshing characteristics and type of rotation are the
two most key features of twin screw extruders. Intermeshing screws can engage each other fully, partially, or not
at all. Non-intermeshing twin screws would operate as parallel single screw extruders, and the flow would be
governed by material properties. Nonconjugate screws are those in which there is ample clearance between the
two screws. Conjugated screws result in minimum clearance and narrow flights. In counterrotating screws, a travel
between screws rotating in opposite directions. In corotating screws, two streams of material travel in parallel along
two screws rotating in the same direction. In additive manufacturing process such as FDM 3D printing, the building
material is 3D printer filament. This 3D printer filament is produced using extruders. Apart from using large
commercial extruder for making filaments, some private individuals have developed desktop extruders to produce
filaments which terme

d as “Filament Extruder” as shown in Figure 4 [3].

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Figure 4. Filament extruder layout [3].

The main part of the extruder is a barrel containing a screw (auger), which is encased by a heater towards its far
end. On the other end, the screw is connected to an electric motor which will, via mechanical action, transport
thermoplastic pellets through the barrel towards the heater. Pellets are gravity-fed continuously from a hopper. As
the motor is continuously driving the auger, the resin pellets are pushed into the heater. The thermoplastic pellets
will soften and melt because of the heat and are then pushed mechanically through a die. Pushing the soft
thermoplastics through the die will cause it to form a continuous filament strand with the diameter of the die. The
filament is passed through a water bath and cooling fan which cool the filament and is pulled by a puller at constant
speed. After that a filament winder is used to make a spool. This process is called extrusion. In most filament
extruder, two diameters of filaments are produced, either 0.069 inch (1.75 mm) or 0.112 inch (2.85 mm) [3].

The most common FDM 3D printing filament materials are ABS and PLA. Reinforced thermoplastic materials also
used to make 3D printing filaments. ABS and Fiberglass can be combined to making reinforced thermoplastic
filament. Carbon fibers or CNT can also be used as reinforcement. W. Zhong shows a method.

The most common FDM 3D printing filament materials are ABS and PLA. Reinforced thermoplastic materials are
also used to make 3D printing filaments. ABS and Fiberglass can be combined to make reinforced thermoplastic
filament. Carbon fibers or CNT can also be used as reinforcement. W. Zhong shows a method to make reinforced
FDM 3D printing filaments [4]. For example, ABS were selected as raw material due to its ready availability in the
market and good balance of processing and performance properties. Its softening point is approximately 212 F
(100°C), which could meet the heat-resistance requirement of the FDM parts. ABS begin to flow at about 392 F
(200°C). So, the part-building temperature cannot be too high. ABS begin to decompose at approximately 482 F
(250°C). Thus, there is a difference of 122 F (50°C) between the flowing and decomposing temperature. This makes
the heating temperature range wide enough to allow for a wide processing window in which the material can be
heated to flow properly without decomposing. Pure ABS exhibits excessively large shrinkage, resulting in less-than-
satisfactory part accuracy. To improve the mechanical properties of ABS, glass fiber was added as a reinforcement.
Compared with pure ABS, the strength and stiffness of glass fiber reinforced ABS composite were increased, and
both the softening temperature and the heat distortion temperature were increased as well. Also, shrinkage was
decreased and the surface rigidity was improved, but the surface toughness was reduced. These are issues to
consider in polymer composite extrusion, whether for FDM or injection molding, such as force required for
extrusion/injection and tool wear caused by glass fibers. An increased fiber content in a thermoplastic composite
will increase the forces required for extrusion/injection and will increase the tool wear rate, so the determination

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of an appropriate fiber content in the filament for FDM must strike a compromise between processing difficulty
and performance characteristics of the resulting composites [4].

Figure 5. Extrusion based AM process [7].

A.

General Overview of the FDM 3D Printing Process

Fused deposition modeling (FDM) is an additive manufacturing technology commonly used for modeling,
prototyping, and production applications. It used in variety of applications like aerospace, automotive, marine and
construction industries.

Additive manufacturing (AM) is defined as “a process of joining materials to make objects

from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies” [5].

For

FDM,

several

types

of

thermoplastic

filaments

are

used.

3D

printing

filament

is

a very fine thread or threadlike structure. ABS is widely used filament for 3D printing. It melts consistently at
around 437 F (225°C),

relatively strong, a little flexible and has a relatively high “glass transition temperature” of

around 212 F (100°C). That is the temperature above which a plastic goes from its solid state to a pliable state where
it can lose its shape. These characteristics mean ABS is very suitable to 3D Print functional parts, like spare parts for
machines or objects that are exposed to elevated temperatures like sunlight or hot water. To increase strength and
stiffness of filament several types of fibers like fiber glass, carbon fiber and carbon nanotubes used to make

reinforced thermoplastics [5]. “Composite material refers to bonding between two or more homogeneous materials

with different material properties to derive a final product with certain desired material a

nd mechanical properties”

[6].

Key elements of a FDM type 3D printing extrusion system include a material feed mechanism, liquefier and print
head, gantry, build surface and build environment. Components of a generic system as illustrated in Figure 5. For
3D printing, generally 0.0689-inch (1.75 mm) or 0.1181-inch (3.00 mm) diameter filaments are used. The filament
is pushed through the system using a pinch roller mechanism. One or both rollers may have a grooved or toothed

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surface like a gear to create sufficient friction for the roller to grab the filament and feed it to the liquefier without
slippage. The basic process of 3D printers has several steps such as first CAD geometry is prepared and converted
into a STL file format & the STL file is imported in a 3D printer software, which will generate G-codes and runs the
3D printer. A Larger nozzle diameter creates faster parts and a smaller nozzle creates finer details [7].

Figure 6. Set up of fabrication test procedure for carbon fiber/ABS [8].

Ning F. and Cong W. explain the entire fabricating process of thermoplastic matrix CFRP composites as shown in
Figure 6 [8]. The raw materials used in this paper were virgin ABS thermoplastic pellets and carbon fiber powder.
The carbon fiber powder had two different average carbon fiber lengths, 0.006 inch (0.15 mm) and 0.004 inch (0.10
mm), with a common fiber diameter of 0.00028 inch (0.007 mm). The pellets and carbon fiber powders were mixed
in a blender with varying carbon fiber contents (3 wt%, 5 wt%, 7.5 wt%, 10 wt%, and 15 wt%) [8].

A plastic extruder was used to fabricate the carbon fiber filled filaments. During the extrusion processes, extrusion
temperature, filament yield speed, and nozzle diameter were set at 428 F (220°C), 79 in/min (2006 mm/min), and
0.1122 inch (2.85 mm), respectively. The filaments could be cut into small pieces and re-fed in the extruder for a
second extrusion to increase bulk density, which led to more consistent flow rates and fusion on each layer. During
such process, filaments with more homogeneous distribution of carbon fibers could be obtained, thereby improving
the FDM fabrication process and parts performance. The ASTM D638-10 and ASTM D790-10 standards were
followed for tensile test and flexural tests, respectively. Five thermoplastic matrix CFRP composite specimens of
each sample were prepared by FDM for both tests. Typical tensile strain stress curves with varying carbon fiber
contents are illustrated in Figure 7. With the increase of carbon fiber content from 0 wt% to 5 wt%, tensile strength

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firstly increased, and then decreased with the levels of carbon fiber content increasing from 5 wt% to 10 wt%
(especially when the carbon fiber content increased from 7.5 wt% to 10 wt%, a sharp reduction of tensile strength
occurred) as shown in Figure 8 [8].

Figure 7. Ning-Cong tensile strengths of carbon fiber/ABS as function of %wt of CF [8].

Figure 8. Ning-Cong tensile strengths of carbon fiber/ABS as function of %wt of CF [8].

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After an increase of Young's Modulus with an increase of carbon fiber content from 0 wt% to 7.5 wt%, there was
also a sudden decrease in Young's Modulus when the carbon fiber content increased from 7.5 wt% to 10 wt%, as
shown in Figure 9. Continuing increase in carbon fiber content to 15 wt% resulted in Young's Modulus increasing
again [8].

Figure 9. Young’s Modulus result of CF/ABS specimen as function of % wt CF [8].

CFRP composite filaments were firstly prepared from carbon fiber and ABS by extrusion processes. Experimental
investigations on if adding carbon fiber (different content and length) into ABS plastic can improve the mechanical
properties of FDM fabricated parts have been conducted. After testing specimens, their conclusions were as follow
[8].

1.

Compared with pure plastic specimen, adding carbon fiber into plastic materials could increase tensile
strength and Young's Modulus, but may decrease toughness, yield strength, and ductility.

2.

Specimen with 5 wt% carbon fiber content had the largest mean value of tensile strength and specimen

with 7.5 wt% carbon fiber content had the largest mean value of Young’ Modulus. The tensile strength and

Young's Modulus of fabricated specimen with 5 wt% or 7.5 wt% carbon fiber content could increase 22.5%
and 30.5%, respectively [8].

Strength of fiberglass is almost as high as carbon fiber, so for strength intensive applications fiberglass is a good and
cheaper choice. Fiberglass has 1/10

th

price of carbon fiber. Also, fiberglass is 30 times stiffer than ABS. Figure 10

and Figure 11 represents the comparison of tensile strength and tensile modulus for neat ABS, CF-AS 4 and GF-E
type respectively.

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Figure 10. Tensile strength comparison for neat ABS, CF-AS 4 and GF-E type [9].

Figure 11. Tensile modulus comparison for neat ABS, CF-AS 4 and GF-E type [9].

Research Objectives

The primary objective of this work is to create reinforced thermoplastic composite filaments for 3D printing. Varying
the amount of fibers such as glass fiber with ABS material. Specifically, the tasks to complete these objectives are:

1.

Apply several types of sizing to chopped fibers, mix with ABS and determine which sizing is best for our use.

a.

Mix sized and un-sized fibers with ABS.

b.

Fabricate and test dog bone specimen. All material should have same volume fraction. The various
configurations of the test specimens are listed in Table 1.

0

200

400

600

NEAT ABS

CF - AS 4

GF - E type

T

en

sil

e

S

tr

en

gth

(ksi

)

0

10000

20000

30000

40000

NEAT ABS

CF - AS 4

GF - E type

T

en

sil

e

m

od

u

lu

s (ksi

)

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Table 1. Test specimens configuration for ABS/FG.

ABS

%V

f

FG

Fiber Length

Without Fiber

10%,15%,20%

Unsized Fiber

–

Acetone

Treated

10%,15%,20%

FG 1-16, FG 1-32

Sized Fiber

–

Michelman

10%,15%,20%

FG 1-16, FG 1-32

Sized Fiber

–

Gelest

10%,15%,20%

FG 1-16, FG 1-32

Sized Fiber - Epoxy

10%,15%,20%

FG 1-16, FG 1-32

c.

Using best sizing, extrude filament with fiber and thermoplastic at various volume fraction.

d.

3D Print dog bone specimens from filament and test.

3.

Fabrication Of Specimens & Testing

A.

Fabrication Process

The importance of various extrusion parameters such as die swell, extrusion speed, puller speed, type of material,
temperature, and viscosity were discussed. So before making 3D printer filaments, we need to evaluate the
mechanical properties of our filled composites. Various thermoplastic composite specimens were made from ABS
and chopped fiberglass. It includes the application of sizing on fiberglass, proper mixing of ABS matrix with
fiberglass, and the fabrication of tensile dog bone specimens. It also includes the determination of chopped
fiberglass dimensions, and actual fiber volume fractions.

Two different lengths of E-type chopped fiberglass were used. They are identified as FG 1-16 and FG 1-32. Initially,
we used chopped fiberglass which had an advertised length of 1/32 inch but we determined after microscopic
examination that it was actually not 1/32 inch but was much shorter. It was then termed FG 1-32. We ordered
another set of chopped fiberglass. It had an advertised length of 1/16 inch, but after measurement of its length we
concluded that the average length of it was also shorter than advertised length. Thus, it was termed FG 1-16.
Fiberglass with 1/8 inch length was termed FG 1-8. We should have used actual 1/16-inch and 1/32-inch fiberglass
for this work, but due to time constraints we were unable to do so.

The fabrication process includes mixing of an ABS polymer matrix and fiberglass that has the proper sizing. It is then
pressed in an ASTM D638 aluminum mold to make tensile dog bone specimens. The specimens varied by sizing,
fiberglass volume fraction, and fiberglass length. Four specimens were fabricated for each material configuration.
Table 2 shows the various specimen configurations for ABS with fiberglass to make thermoplastic tensile dog bone
specimens. To summarize there are 4 neat ABS specimens, 24 specimens total of ABS with two unsized fiberglass
lengths and three fiberglass volume fractions,24 specimens total of ABS with two Michelman- sized fiberglass length
and three fiberglass volume fractions, 24 specimens total of ABS with two Gelest-sized fiberglass lengths and three
fiberglass volume fractions, and 24 specimens total of ABS with two epoxy-sized fiberglass length and three
fiberglass volume fractions. The total number of specimens were 100.

Table 2. Test specimen configurations for ABS/FG.

Material

V

F

of

FG (%)

Fiberglas

s length

#Speci
mens

ABS
Without
Fiber

0%

4

ABS/Unsiz
ed Fiber

10%,
15%,
20%

FG 1-16,
FG 1-32

24

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ABS/Sized
Fiber

–

Michelma
n
ABS/Sized
Fiber

–

Gelest
ABS/Sized
Fiber

–

Epoxy
Sizing

10%,
15%,
20%
10%,
15%,
20%
10%,
15%,
20%

FG 1-16,
FG 1-32
FG 1-16,
FG 1-32
FG 1-16,
FG 1-32

24
24
24

The standard procedure to apply sizing on fiberglass is summarized in the following section. First, the current sizing
is removed using acetone. A water-based HP3-02 sizing from Michelman or an alkoxysilane based SIM 6487.5 sizing
from Gelest were then applied. The solution is applied on the chopped fiberglass surface by immersing the fiberglass
in the solution for 15 hours. The ratio of water or isopropyl alcohol and sizing was critical to make proper solution,
so take care to add the right fraction of each part. To avoid fiberglass clumping, use a shallow pan to soak chopped

fiberglass in solution and make a thin layer as shown in Figure 12 ensuring that as the fibers dry, that they don’t
clump. The fibers were heavier than the solution thus they didn’t f

loat in the solutions. Sizing must be diluted in

required quantity as recommended by the company because too much or too little sizing may create fiberglass
clumping.

Figure 12. Loose FG 1-32 with Michelman Sizing in a shallow pan.

Other methods to apply sizing on fiberglass include vapor phase deposition, spin on, and spray application. For a
vapor phase deposition, sizing can be applied to substrates under dry aprotic conditions by chemical vapor
deposition methods. These methods favor monolayer deposition. In the spin on method, these applications can be
made under hydrolytic conditions which favor maximum functionalization and poly layer deposition or dry condition

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which favor monolayer deposition. The most widely used application method is the spray method. This method
widely used for continuous fiberglass. They involve alcohol solutions and continuously hydrolyzed aqueous
solutions employed in architectural and mas

onry applications” [10].

ABS and chopped fiberglass must be mixed together to make a homogeneous mixture such is essential to provide
consistent mechanical properties, and to eliminate the clogging. For a better mixture of fiberglass and ABS matrix,
make a thin ABS layer on heated press plate and scatter fiberglass uniformly onto it. Now, fold and press it in heat
press for 8-10 times to mix it evenly. Then shred it in the heavy-duty shredder.

Figure 13. Heavy Duty shredder used to make small granules.

Thermoplastic specimens were fabricated to determine tensile stress, tensile Modulus, and strain at break. For
plastics, the ASTM D638 test method should be used. It helps in making better 3D printing filaments with optimum
mechanical properties. An ASTM D638 mold was designed and fabricated by Panchal [11], who fabricated
thermoplastic composite tensile test specimens for his project work. For fabrication of specimens, the mold must
be cleaned with acetone and paper towel. Frekote WOLO mold release is applied to the aluminum mold and it is
dried for 10-12 minutes in an oven at 320°F (160°C). A weighted amount of ABS/FG pellets is placed into the lower
part of the mold as shown in Figure 21. Insert upper half of the mold properly and place it in heat press as shown
in Figure 22 at 380°F (181°C) temperature and 10,000 to 11,000 lbs. force for 15-18 minutes. The mixture will have
filled the cavity and produce dog-bone specimen.

After the dog-bone specimen is removed from an aluminum mold, it is place in front of a fan to cool down for 10-
15 minutes. Figure 16 shows some thermoplastic specimens from the mold.

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Figure 14. ASTM D638 Aluminum mold

Figure 15. Heated press for compression molding.

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Figure 16. Thermoplastic specimens from an ASTM D638 mold using compression molding.

The quality of specimens should be better to tensile test it. Specimens should have similar thickness to get
consistent tensile test result. Feed enough material in mold to get perfect specimen without voids. Some post
processing steps include remove flashing of specimens using utility knife.

B.

Testing Of Specimens

The fabricated specimens were tested under tension with a MTS Universal Testing Machine. All the tensile tests
were conducted according to ASTM D638, which is the standard test method for tensile testing of plastics. For
testing, an MTS 632.26E-43 model extensometer, which has a gauge length of 0.5 inches, was used to measure
actual strain in the specimens. An MTS load cell with a 5 kN load capacity was used in tensile testing, as it was more
accurate, compared to a larger load cell with 100 kN load capacity. MTS wedge grips were used to hold the specimen
during testing. The grips and extensometer used in the tensile tests are shown in Figure 17. Figure 18 show some
of the tested specimens. Width and thickness of each specimen was measured using a digital caliper to determine
cross-sectional area of specimen. The tests were carried out with a grip separation of 4.5 inches, at a test rate of
0.2 in/min. The load frame used in the current work is a MTS model C45 universal testing machine. The load and
displacement were converted into stress and strain respectively.

A shortened notation used for the specimen configuration is as follows:

ABS

–

XX

–

YY

–

FG

–

ZZ

–

n

Where: ABS = ABS thermoplastic,

XX = sizing type; US = Unsized,

ES = Epoxy Sizing,

MS = Michelman Sizing,

GS = Gelest Sizing.

YY = Fiber volume fraction; 10%, 15%, and 20% by volume,

FG = Fiberglass,

ZZ = Advertised fiberglass length; 16 = 1/16 inch,

32 = 1/32 inch,

08 = 1/8 inch.

and

n = the specimen number. For example, ABS-ES-10-FG-32-1 means ABS thermoplastic, epoxy sizing with

10% fiber volume fraction, has an advertised fiber length of 1/32 inch and is specimen number 1.

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Figure 17. MTS Grips and Extensometer setup.

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Figure 18. Tested Composite Specimens.

Table 3 shows data from neat ABS specimens which gives tensile strength, stiffness, failure strain and standard

deviation for each specimen. S defined as tensile stress, E defined as Young’s Modulus and Ɛ

f

defined as failure

strain.

Table 3. Test summary of neat ABS specimens.

Specimen

Configuration

Specimen #

S (psi)

E (psi)

Ɛ

f

(in/in)

Published ABS

-

6670

355,000

0.180

ABS Only

1

6155

451,826

0.018

2

5254

345,093

0.048

3

3917

279,261

0.013

4

4085

391,371

0.011

Average, Std. Dev.

5165±1038

396,096±55,018

0.027

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Table 4. Test summary of ABS/FG 1-32 without sizing

Specimen

Configuration

Specimen #

Actual

(V

f

)

S (psi)

E (psi)

Ɛ

f

(in/in)

10% Fiberglass

1

2735

257,284

0.017

2

3103

270,434

0.023

3

2552

341,923

0.008

4

2221

297,647

0.009

Average, Std.

Dev.

0.097

2652±367

291,822±37,391

0.014

15% Fiberglass

1

2140

351,752

0.026

2

3500

309,445

0.019

3

3215

387,038

0.012

4

3771

371,877

0.015

Average, Std.

Dev.

0.146

3156±714

355,028±33,650

0.015

20% Fiberglass,

1

2639

453,548

0.012

2

2987

462,273

0.011

3

2208

305,515

0.010

4

2424

438,433

0.006

Average, Std.

Dev.

0.193

2564±332

451,418±12,061

0.010

Table 4 shows test data of ABS and FG 1-32 without any sizing for various fiber volume fractions that is 10%, 15%
and 20%. Also, average V

f

, S, E, and

Ɛ

f

are given.

Table 5. Test summary of ABS/FG 1-32 epoxy sizing specimens.

Specimen

configuration

Specimen #

Actual

(V

f

)

S (psi)

E (psi)

Ɛ

f

(in/in)

10% Fiberglass

1

3274

271,582

0.024

2

3540

366,699

0.014

3

4252

299,518

0.015

4

4139

447,557

0.010

Average, Std.

Dev.

0.097

3801±470

346,339±78,401

0.016

15% Fiberglass

1

4365

681,246

0.009

2

4157

502,482

0.024

3

3372

563,780

0.030

4

3300

361,228

0.009

Average, Std.

Dev.

0.146

3798±541

582,502±90,840

0.018

20% Fiberglass

1

3247

421,604

0.025

2

3214

568,796

0.008

3

3337

509,469

0.027

4

3153

472,377

0.028

Average, Std. Dev.

0.197

3237±76

516,880±48,634

0.022

Table 5 shows summary data of ABS and FG 1-32 with epoxy sizing for various fiber volume fractions that is 10%,
15% and 20%. Also, average V

f

, S, E, and

Ɛ

f

are given.

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Table 6 shows data of ABS and FG 1-32 with Michelman sizing for various fiber volume fraction that is 10%, 15%
and 20%. Also, average V

f

, S, E, and

Ɛ

f

are given.

Table 6. Test summary of ABS and FG 1-32/Michelman sizing (HP3-02) specimens.

Specimen configuration Specimen #

Actual (V

f

)

S (psi)

E (psi)

Ɛ

f

(in/in)

10% Fiberglass

1

4243

491,564

0.016

2

4139

368,970

0.011

3

3490

441,907

0.013

4

3503

478,667

0.010

Average, Std. Dev.

0.097

3843±403

445,277±55,050

0.012

15% Fiberglass

1

4312

520,123

0.009

2

4020

501,908

0.025

3

3350

487,786

0.030

4

3480

485,887

0.009

Average, Std. Dev.

0.150

3790±446

498,926±15,836

0.018

20% Fiberglass

1

2630

450,565

0.012

2

2960

460,765

0.011

3

2208

310,345

0.010

4

2418

424,165

0.006

Average, Std. Dev.

0.197

2554±172

411,460±69,152

0.010

Table 7 shows data of ABS and FG 1-16 with Michelman sizing for various fiber volume fractions that is 10%, 15%
and 20%. Also, average V

f

, S, E, and

Ɛ

f

are given.

Table 7. Test summary of ABS and FG 1-16 with Michelman sizing (HP3-02) specimens.

Specimen

configuration

Specimen #

Actual

(V

f

)

S (psi)

E (psi)

Ɛ

f

(in/in)

10% Fiberglass

1

3835

473,354

0.009

2

4704

435,558

0.013

3

2537

426,578

0.006

4

4475

360,621

0.016

Average, Std. Dev.

0.097

4338±450

424,027±46,879

0.011

15% Fiberglass

1

4243

454,887

0.015

2

4244

480,406

0.011

3

3430

311,379

0.013

4

3420

385,336

0.010

Average, Std. Dev.

0.146

3834±473

408,002±75,917

0.012

20% Fiberglass

1

3621

467,522

0.008

2

4271

476,244

0.011

3

2993

412,738

0.008

4

2522

446,046

0.007

Average, Std. Dev.

0.193

3351±760

450,637±28,274

0.008

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Table 8 shows the data with ABS matrix and FG 1-32 with Gelest sizing for various fiber volume fraction that is 10%,
15% and 20%. Also, average V

f

, S, E, and

Ɛ

f

are given.

Table 8. Summary of ABS and FG 1-32/Gelest Sizing (SIM 6487.5) Specimens.

Specimen

configuration

Specimen #

Actual

(V

f

)

S (psi)

E (psi)

Ɛ

f

(in/in)

10% Fiberglass

1

2309

271,957

0.011

2

1710

216,351

0.015

3

2711

371,758

0.015

4

2767

369,833

0.012

Average, Std. Dev.

0.097

2595±249

337,849±57,072

0.013

15% Fiberglass

1

2271

263,694

0.011

2

2093

313,969

0.009

3

2207

281,554

0.010

4

2576

417,081

0.007

Average, Std. Dev.

0.146

2286±206

319,074±68,571

0.009

20% Fiberglass

1

2414

339,778

0.007

2

2221

323,861

0.009

3

2343

402,001

0.006

4

2734

253,962

0.016

Average, Std. Dev.

0.197

2428±213

355,213±41,293

0.010

Table 9 shows the data with ABS matrix and FG 1-16 with Gelest sizing for various fiber volume fraction that is 10%,
15% and 20%. Also, average V

f

, S, E, and

Ɛ

f

are given.

Table 9. Test summary of ABS and FG 1-16/Gelest sizing (SIM 6487.5) specimens.

Specimen configuration Specimen #

Actual (V

f

)

S (psi)

E (psi)

Ɛ

f

(in/in)

10% Fiberglass

1

4427

518,091

0.016

2

3991

367,437

0.020

3

4037

432,638

0.014

4

5365

407,838

0.039

Average, Std. Dev.

0.010

4455±637

431,501±63,674

0.022

15% Fiberglass

1

4715

317,964

0.019

2

3270

373,481

0.010

3

3850

3771.90743

334,521

0.025

4

5106

247,133

0.038

Average, Std. Dev.

0.146

4557±642

341,988±52,829

0.023

20% Fiberglass

1

3345

347,003

0.020

2

1968

290,963

0.008

3

3199

488,556

0.015

4

3109

596,130

0.009

Average, Std. Dev.

0.193

3217±119

542,343±76,066

0.013

4.

Conclusion

Composite specimens were fabricated using ABS and various lengths of chopped fiberglass. Various specimens were
tested under tension on an MTS, per ASTM D638. Tensile test results were grouped according to sizing used, fiber
volume fraction, and fiber length. Overall, mechanical properties of the thermoplastic composite specimens were

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not improved compared to neat ABS. This is probably because fiber lengths were much shorter than minimum
critical lengths. Other reasons for poor results, include poor bonding between matrix and fiberglass, fabrication
errors, processing errors, and poor mixing of ABS and chopped fiberglass.

No one sizing completely dominated. ABS/FG specimens with Epoxy sizing and Gelest sizing had better strength
than other types of sizing. ABS/FG with Michelman sizing and epoxy sizing had better stiffness than other types of
sizing. After comparing current

test results with previous work of Panchal’s results, mechanical properties of current

composites were not improved. Unsized specimens had the lowest strength and stiffness. Overall, Gelest sizing
specimens had the highest and lowest individual strengths and stiffnesses, Michelman sizing specimens had the
most consistent strength and stiffness and Epoxy sized specimens were almost as good as the others. Specimens
with longer fibers had better strength and stiffness than those with shorter fibers, as expected.

References

[1]

The Lubrizol Corporation 2016

Extrusion Process Guide

[Online]. Available: (

https://www.lubrizol.com/

)

[Accessed: July 2016].

[2]

Petervaldivia 2017

Fabrication of Plastics

[Online]. Available: (