5-7 OCTOBER

ISFR

2011

169

TOLEDO (SPAIN)STUDY OF THE MECHANICAL PROPERTIES OF ABS-HIPS BLENDS WITH SEBS.
F. Parres1, A. Nadal1, R. Navarro1, S. Sánchez-Caballero1 and M. A. Selles1
1Department of Mechanical and Materials Engineering, Universitat Politècnica de Valencia, Plz Ferrandiz y Carbonell, s/n;03801; Alcoy – Alicante (Spain)
e-mail: fraparga@dimm.upv.esAbstract
The recovery process configuration produces a significant quantity of mixed material that has no commercial value. Duringstyrene waste recovery processes, a mixture of ABS - HIPS is often produced which cannot be sold or used as either HIPSor ABS, but which must be commercialized as a blend with particular characteristics. A binary blend (ABS-HIPS 50% wt) was
prepared on a twin-screw extruder at 190-210 ºC. The different properties were then analyzed using tensile strength andimpact tests, melt flow index (MFI). The analysis of mechanical properties showed a decrease in elongation at break andimpact strength. Moreover, the addition of SEBS to the binary system (ABS-HIPS) allowed us to increase the ductileproperties (elongation at break and impact strength), as well as reducing the viscosity.

Keywords: Polymer, Blend, Recycling, compatibility, interaction

1. Introduction
The economic viability of polymer waste recovery
processes rests on recovery of a large quantity of wastematerial, and given the great variety of polymers inexistence it is not possible to have separate productionlines for each type of material, so each line must be used
for a range of polymers. This recovery process
configuration produces a significant quantity of mixedmaterial that has no commercial value. During styrene
waste recovery processes, a mixture of ABS - HIPS isoften produced which cannot be sold or used as either
HIPS or ABS, but which must be commercialized as ablend with particular characteristics.
Following on from this, the objective of this study is tocharacterize ABS – HIPS blends and then to use SEBS
to add value to these blends. Optimization of theproduction process requires that the recycling production
line does not stop for a moment, and for this reason,
when there is a change of material (from HIPS to ABS orvice versa) a certain quantity of each is lost. This changein material in fact means a change from 100% ABS to100% HIPS, but in reality, the sum of the wasted material
is made up of 50% of each.

2. Materials and Methods
Materials
The HIPS, ABS, and SEBS used in the experiment arecommercial products HIPS (PS Impact 6541; Total
petrochemical, Belgium), ABS (Terluran® GP22, BASF,Germany), and SEBS (Megol® TA, Applicazioni
Plastiche Industriali, Italy)interiores libro.indd 169

Sample preparation
A binary blend (50%ABS – 50%HIPS wt) wasconducted on a conventional extrusion machine, at 190 –195 – 200 – 210 ºC extrusion temperatures. Finally,
ternary blends were prepared by varying the SEBS
content, from 0% to 30 % (wt %)3. Results and Discussion
ABS – HIPS – SystemThe mechanical properties of any material are
fundamental for its use in any particular application.
Traction and impact tests are extremely importantbecause they allow us to understand properties such as
tensile strength, elongation at break and impact strength.
Table 1. Mechanical properties of ABS, Blend 50%, andHIPS.

ABSBlend 50%HIPS

TensileStrength,
MPa
41.47
27.05
18.51

Elongation
at break,%10.888.65
16.6

ImpactStrength,kJ m-2
20.74
5.25
8.76

In the study carried out on the ABS-HIPS system, thegraph showing tensile strength for the virgin (ABS andHIPS) and the 50% blend show a linear evolution of thevalues, where the 50% by weight blend has values thatfall between those of virgin ABS and HIPS.
This result indicates the compatibility between theelements that form the blend. However, the values forelongation at break and impact strength of the 50% blend
are very low; even lower than those of virgin material.
While the elongation at break values, indicate a clear

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6th International Symposium on Feedstock Recycling of Polymeric Materials

compatibility of the compounds, the properties related toductility show they are not completely compatible (Table1).
This behaviour has been observed by other authors
when analyzing the properties of the blend obtained fromrecovery of waste materials from the electrical andelectronic sectors [1]. The superficial characteristics after
the breaking process allow us to more easily understandthe mechanical behaviour of the material under test. This
breaking process includes both the beginning of thecrack and its evolution.
When we observe the break sections of virgin material(ABS and HIPS) and the 50% blend, we can see somedifferences in the way the break occurs and develops.
Firstly, both virgin materials show a break section that iscompletely perpendicular to the stresses applied, whileon the other hand, the break section of the ABS - HIPS
blend occurs initially as a fan shaped crack before
developing perpendicular to the stresses applied (Fig. 1).
The reason for the loss of ductile mechanical properties
could be due to a heterogeneous distribution of the twomaterials in the blend in the injected piece.

On analyzing the results from the addition of SEBS tothe ABS – HIPS blend, we conclude that the ideal
percentage of SEBS is 10%, which causes a 10%
decrease in tensile strength but a 50% increase in both
elongation at break and impact strength values.
We found the reason for this recovery of ductile
properties in the break sections of the samples, where
the incorporation of SEBS to the ABS – HIPS blend
causes a radical change in the break surface. Where
previously we saw a fairly rough area, the addition ofSEBS causes a peak which increases in size with theaddition of more SEBS. The presence of this peakindicates the capacity of plastic deformation which isrecovered with the presence of SEBS in the blend (Fig.
2).

Fig. 2. Micrographs of the break surfaces after thetraction tests of blend with 30% SEBS content.

4. Conclusions

Fig. 1. Micrographs of the break sections obtained fromthe tensile strength test on the various samples.
ABS – HIPS – SEBS System
The elastic character of SEBS must bring improved
ductile properties to the ABS – HIPS system. One of thefirst effects that can be observed in Table 2 is a decreasein tensile strength as the percentage of SEBS increases.
Table 2. Mechanical properties of Blends in function ofSEBS content.
TensileElongation
ImpactStrength,
at break,Strength,MPa%kJ m-2Blend 50%
27.05
8.65
5.25
10% SEBS
24.04
12.41
8.51
20% SEBS
18.10
22.98
11.37
30% SEBS
11.13
27.71
13.18
This decrease is lighter for a SEBS content of 10%,and after this the tensile strength declines more rapidly
reaching a loss of 60% for a 30% SEBS content.
Although there is a loss in tensile strength, the recoveryof high elongation at break and impact strength values
more than compensate for this loss (Table 2).

interiores libro.indd 170

Our results suggest that the compatibility between
ABS and HIPS is only partial and that a significant loss ofductile properties is produced in the 50% by weight blendof the two materials. The addition of SEBS allows us torecover the ductile properties of the ABS – HIPS blend,with some loss of tensile strength. Analyzing the breaksurfaces allowed us to understand more easily theresults obtained in the mechanical characterization as wesaw an increase in plastic deformation when thepercentage of SEBS is higher.

References[1] LB Brennan, DH Isaac, JC Arnold. Recycling ofAcrylonitrile–Butadiene–Styrene and High-Impact
Polystyrene from Waste Computer Equipment. Journal
Of Applied Polymer Science, 86, (2002) 572 - 578

Acknowledgements
To the VIDI of the Universitat Politecnica de Valencia
for the help granted to the project: “Ternary systems
research applied to polymeric materials for the upgradingof waste styrene”, Ref: 20091056 within the program ofFirst Projects of Research (PAID 06-09) where this work
is framed.

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