SEM725 Materials for Additive Manufacturing: Polymer Composite Report

This report explores the use of recycled polymer composites for structural applications, focusing on the enhancement of mechanical properties through the addition of various fillers. The study investigates the properties of a proprietary mix of post-mechanical plastic waste, examining the impact of calcium carbonate, mica, and glass fiber on the resulting composites. The methodology involves compounding, injection molding, and mechanical testing to assess tensile, flexural, and CTE properties. Results indicate that the addition of fillers like calcium carbonate and mica increases modulus, while glass fiber significantly enhances strength. The report also discusses the effects of a fire retardant and analyzes the microstructural features using scanning electron microscopy. The findings highlight the potential of recycled polymer composites, offering insights into their application in various industries.

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COMPOSITES OF RECYCLED POLYMER FOR STRUCTURAL APPLICATIONS
Introduction
Recovered plastics are conventionally separated into types of polymers as then used in the
production of second grade pallets. Nevertheless, the range of applications of such pallets is
limited as a result of minimal properties as well as the possibility of contamination that prevents
them from being used ion food contact application. An alternative way that is explored in the
study is composed of upgrade of plastic recyclates through the addition of rigid fillers to enhance
their structural performance features as well as render them ideal for long term or even semi long
term applications.
Literature review
Polymers come with numerous advantages in comparison with the conventional materials that
are used for structural applications especially in cases where there are opportunities of improving
the stiffness as well as strength. The use of recycle materials result in a significant reduction in
the cost even though the formulation as well as production of polymers may be challenging to
address the natural variability in feedstock. Semi crystalline polyefins have numerous desirable
properties that may be used for structural applications including high electricity resistivity,
chemical resistance, good toughness, high resistance to fatigue, low absorption of water,
excellent resistance to corrosion as well as UV stability [2]. Conventional building products are
of higher stiffness, better creep resistance as well as lower coefficient of thermal expansion
(CTE). The study is investigative of use of fillers in enhancing the features of a propriety mix of
plastics.
The polymer mix inspected in this work comprises essentially of post-mechanical plastic waste.
Post-modern squander is the piece from modern procedures, for example yarn bobbins, jerry jars,

and end of runs, misprinted pots, and so forth. It is typically spotless and isolated by sort, which
presents impressively less bunch to clump property changes contrasted with residential polymer
squander. The mix is an exclusive polymer detailing containing both semis crystalline
furthermore, undefined thermoplastics so as to accomplish a decent harmony among strength and
firmness [3]. The impact of filler on the mechanical properties will rely on its substance piece,
molecule shape and size, measure appropriation, explicit surface territory, surface science,
intraparticle separating and degree of agglomeration. Higher viewpoint proportion fillers give
more noteworthy fortification and produce higher firmness, heat contortion temperature and
creep opposition.
The normal round fillers are calcium carbonate, mud, glass dabs, carbon dark and alumina
trihydrate. Among these, calcium carbonate is the most generally utilized filler as it is promptly
accessible and of low cost. It diminishes warpage expands modulus and, in virgin materials,
lessens the expense of material. In such applications, quality is regularly decreased marginally.
Effect strength is likewise decreased, except for fine added substance grades, which can go about
as effect modifiers. Stearate coatings are frequently used to improve surface holding and
scattering. The sort of polymer is likewise significant where filler/grid interfaces are considered.
For instance, the covered filler expanded the effect sturdiness in polypropylene (PP)
homopolymer; be that as it may, it diminished the sturdiness in high thickness polyethylene and
PP [4]
Despite the fact that subtleties on mix creation can't be revealed, every one of parts were item
polymers ordinarily plenteous in landfills, and outcomes displayed in this investigation are
commonly applicable for the reusing of mixed together polymer squander streams. Past
investigations from Rutgers University have appeared that it is conceivable to accomplish

polymer mix morphologies with high mechanical properties without the addition of
compatibiliser through right mix detailing and preparing.
Mica has a perspective proportion just matched by stringy materials. For good clinging to non-
polar plastics, it should be silane treated or blended with maleic anhydride changed polymers.
Most business applications try not to legitimize addition of costly silane treatment. Mica has low
CTE and great enduring performance. A cooperative energy was found by some authors while
adding low amounts of mica to glass fiber strengthened polyolefin to build modulus, improve
dimensional security and lessen cost. The addition in properties was credited to a constructive
outcome of mica on the fibre– lattice bond.
Methodology & Methods
Materials
The polymer utilized was an exclusive mix of normal undefined and semi crystalline reused
polymers. The plastics were destroyed and granulated to 10 mm measured drops and afterward
tumble blended. The mix had a liquefy stream file of 11.1 g/10 min at 230uC. Four distinct
added substances were exacerbated with the mix.
(I) Omyalene 102M calcium carbonate from Omya UK: An 86 wt.-% stearic corrosive covered
chalk whiting in a polyolefin bearer. The particles have an angle proportion of 1 and a normal
molecule distance across of 2 mm. The particular surface territory is 2.5 m2 g21 as per BET ISO
4652
(ii) Micro Mica W160 from Norwegian Talc AS what's more, disseminated by Omya: a
muscovite with angle proportion 20 : 1 and a middle molecule size of 13.5 mm (wet examination

Malvern Mastersizer X) or on the other hand 4.2 mm (X-beam investigation Sedigraph 5001).
The explicit surface zone is 6.8 m2 g21 as indicated by Wager ISO 4652 [5]
(iii) 3299 EC13 cleaved strand glass fiber from PPG Industries: a silane treated fiber of 14 mm
measurement and greater than 5 mm length. For extra coupling, 2% Bondyram 1001 maleic
anhydride changed homo-polypropylene from Polyram was included 58578-M1-300 Superex
POV0-HF fire resistant masterbatch from Americhem, an exclusive halogen free intumescent fire
resistant in low thickness polyethylene transporter.
The fire resistant was added at an appropriate dimension to give UL 94 V0 rating.14
Preparation of Sample
The materials were intensified utilizing a Berstorff ZE25 co-turning twin screw extruder with a
temperature profile of 180– 210uC and a speed of 430 revolutions per min. The intensified
material was palletised into 5 mm long pellets. Standard test examples were infusion shaped
utilizing a NegriBossi V55-200 with a 62 ton greatest clip power. The temperature profile was
200– 230uC. The shape was not cooled [6].
Mechanical testing
Examples were tried utilizing a Hounsfield HK100-S.
Type 2 ISO 1367 canine bone examples were elastic tried at a speed of 5 mm min21. ASTM D
970 flexural examples (1276127632 mm) were tried to flexural three-point twist test with a range
of 51.2 mm at a speed of 2 mm min. The help noses had a distance across of 5.95 mm. The
stacking nose had a distance across of 6.3 mm.

Direct CTE
Two unique techniques were utilized to quantify the straight CTE. A Perkin Elmer Diamond
thermomechanical analyser was utilized over the scope of 220– 60uC and at an incline rate of
2uC min. Estimation of change long of flexural test bars in the wake of molding at 218 and 55uC
was completed utilizing a standard research facility stove and cooler. Vernier callipers were
utilized to gauge the adjustment in measurements.
Scanning electron microscopy
Flexural test bars were dunked in fluid nitrogen, clasped in a bad habit and cracked by a mallet
blow. The examples were carbon covered amid the example arrangement strategy. The crack
surfaces were inspected utilizing a Philips XL 40 in optional electron what's more, backscattered
electron modes.
Results
CaCO3 alongside mica were added to the reused polymer mix to assess the potential property
upgrades that can be accomplished utilizing minimal effort fillers. The properties coming about
because of addition of a flame retardant are likewise revealed for correlation. Along these lines,
the impact of glass fiber fortification was assessed to evaluate whether the higher upgrade in
properties legitimizes their extra expense and preparing intricacy. A further step was the
examination of half breed frameworks containing glass fiber and a lower perspective proportion
filler so as to acquire a more extensive scope of property upgrade and further improvement of
specific properties through synergistic impacts.

Mechanical features
The impact of every filler is reliant on the technique for stacking. The particulate fillers
increment tractable and flexural moduli fundamentally (Fig. 1). The higher improvement of
pliable modulus for mica filled frameworks is in line with literature. Mica has a far higher
perspective proportion than calcium carbonate, which builds the contact zone between the mica
and framework and leads to an increasingly critical impact on properties. The expanded surface
territory empowers improved pressure exchange to the filler. Still, mica has a higher malleable
modulus (more than 100 GPa) contrasted with CaCO3 (35 GPa). Rigidity diminishes, and
flexural quality increments somewhat (Figure 2) [6].
The decrease of malleable quality for the CaCO3 filled frameworks showed poor interfacial grip
for this framework. The stearic corrosive covering on CaCO3 for the most part improves
scattering, yet has no or constrained coupling effect. For the mica filled framework, the elasticity
was basically unaltered, as mica has preferred strengthening capacity over calcium carbonate and
ordinarily does not discourage quality considerably. In flexure, the pressure is most extreme at
surfaces. The power is compressive on the stacked surface with an equivalent and inverse pliable
weight on the inverse surface. The addition in flexural quality for both particulate filled
frameworks was thus credited to the compressive part of mechanical reaction.
The compressive quality of filled frameworks will in general increment notwithstanding for
uncoupled frameworks past examinations on filled thermoplastics, which detailed the
compressive solidarity to be straightforwardly corresponding to Young's modulus. The addition
of an intumescent fire resistant increments pliable modulus however is inconvenient to quality
and causes a surprising lessening in flexural modulus [7]. The exclusive masterbatch (40 wt.-%)
was required to give the required enhancement for combustibility properties. This abnormal state

would be required to significantly affect mechanical properties. Intumescent fire resistant
frameworks are not revealed to have a fortifying impact, in addition to their hydrophilic nature
makes a poor interfacial bond with hydrophobic polymers.
Studies have revealed an addition in modulus also, heat diversion temperature, yet a lessening in
sway quality and different mechanicals. Coupling specialists have been considered, appearing in
mechanical properties without a hindering impact on combustibility. Lengthening in pressure
was decreased for all fillers, in specific for glass strands. Be that as it may, lengthening at break
for all frameworks was above 3.5%. Such estimations of lengthening at break are adequate to
ensure an attractive execution in semi structural applications, which are commonly intended for
solidness with high safety factors [8].
Glass fiber fundamentally expanded the quality and modulus of reused polymer mix (Figures 3
& 4). Attributable to the expense and handling confinements for the reused composite, the most
extreme measure of glass fiber consolidated in the item was 30 wt.-%. Optional filler was added
to the glass fiber strengthened frameworks to further improve the basic properties without
expanding the expense. Calcium carbonate had a comparable impact in the glass filled mix
similarly as with the unadulterated polymer mix. In the two cases, addition of calcium carbonate
caused a slight increment in the mechanical properties, with the exception of elasticity.
Scanning electron microscopy
Scanning electron microscopy demonstrated a very much scattered mix of various polymers. The
introduction of filaments toward procedure stream (opposite to the break surface) can be seen at
broke surface (Figure 6). The calcium carbonate addition demonstrated great circulation with a

little agglomeration (Figure 7). The most extreme agglomerate size watched was underneath 10
mm (Figure 7b).
Discussion
Stearate covered calcium carbonate carried on as anticipated from the prior revealed literature.
The modulus was expanded by 24%, and quality was diminished marginally. In flexural mode,
the modulus was expanded by 40%, and quality was likewise expanded somewhat. The higher
improvement in flexural properties was expected to the blend of elastic and compressive modes.
The uncoated mica brought about an expanded fortification impact true to form with the addition
in angle proportion. The malleable modulus was expanded by 86%, and quality diminished
imperceptibly [9]. This improvement is in line with different examinations that revealed 50–
100% higher properties contrasted with powder or calcium carbonate, with practically no
decrease in effect strength.
In flexural mode, the modulus expanded by 114% and quality expanded somewhat. The silane
treated glass fiber with maleic anhydride polypropylene compatibiliser essentially improved the
quality and modulus of mix, as anticipated. The 15 wt.-% glass fiber expanded the rigidity by
70% also, the flexible modulus by 63%. The flexural quality was again expanded by 60% and
flexural modulus by 210%. The 20 wt.-% mica expanded the pliable modulus to a similar degree
as 15 wt.-% glass fiber, in any case without addition in quality. Mica could be utilized as a
choice to glass fiber for specific applications. The 30 wt.-% glass fiber expanded the rigidity by
85% still, the modulus by 240%. The flexural quality was expanded by 115% for this situation,
and flexural modulus by 445%, true to form in an all-around arranged and united glass fiber
composite [10].

The addition of 5 wt.-% calcium carbonate to 15 wt.-% glass fiber in the reused polymer mix
expanded the elastic and flexural moduli by further 20%, while the quality was diminished in
strain. The 15 wt.-% glass fiber fortified PP (GRPP) tests strengthened with 5 wt.-% mica
displayed comparative property improvements; with the distinction that mica improved the
elastic quality. Nonetheless, a substantially more articulated synergistic impact was watched for
addition of mica to 30 wt.-% filled glass fiber mix. For this framework, mica improved the
elastic modulus by as much as 35% and flexural modulus by 7%, with a minor increment in
quality [11].
An as well amazing impact has been watched for mica filled glass fiber fortified PP by Zhao and
co-workers. The creators found that addition of moderate loadings of mica to glass fiber tangle
fortified thermoplastic PP drove to a considerable increment in ductile and flexural modulus (in
the request of 100%), joined with a moderate improvement of solidarity. This collaboration was
clarified by the increment in outspread compressive remaining weights on the glass filaments
(and in this manner an upgraded fibre– network attachment) achieved by the addition of mica.
Amid hardening, the distinction in CTE between polymer framework and glass filaments created
a compressive outspread worry at interface, which is relative to the distinction in warm
development coefficient and to the versatile modulus of matrix. The fundamental impact of
adding mica to the polymer framework is addition in flexible modulus, though the variety in
CTE is just moderate. This can prompt a more grounded interfacial collaboration between the
glass strands also, the polymer grid, prompting a huge increment in solidness. The present work
appears to demonstrate that to get this impact, mica shouldn't be surface treated. The untreated
mica utilized in this investigation would in general increment the CTE of polymer mix, which

could prompt a further increment in compressive worry at interface and a more noteworthy
improvement in the versatile modulus.
Conclusion
The impact of addition of different monetarily accessible fillers to a mix of reused polymers was
explored to assess the synchronous improvement of key basic properties (solidness, quality and
CTE) of mix. Differing results were gotten by the consolidation of a solitary filler (CaCO3, mica
or glass fiber), contingent upon the angle proportion of filler and strategy for stacking. Half and
half frameworks containing glass fiber and lower angle proportion filler accomplished a more
extensive scope of property improvement also, further improvement of specific properties
through synergistic impacts. Round calcium carbonate gave an unassuming increment in pliable
and flexural modulus to the disservice of tractable quality, while plate-like mica expanded the
moduli fundamentally with minor upgrades in quality. Glass fiber fortification contributed a
critical increment in quality and moduli, especially in flexural mode. The 20 wt.-% mica
expanded the modulus to a similar degree as the 15 wt.-% glass fiber without causing an addition
in quality. Mica could be utilized as a substitution for glass fiber in specific applications. The
addition of mica to glass fiber brought about a further improvement of mechanical properties,
especially in pliable mode.

References
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dissertation, University of Sheffield)
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