10.1002/spepro.004091
An excellent compatibilizer for
PA66/ABS blends
Huahao Yang, Xinyu Cao, Yongmei Ma, Jingjing An, Yucai Ke,
Xiaoming Liu, and Fosong Wang
Maleic anhydride-grafted polybutadiene increases the molecular interaction between polyamide 66 and acrylonitrile-butadiene-styrene
copolymer, helping the two plastics blend.
Polyamide (PA) is one of the most important thermoplastics, with
good strength, stiffness, and resistance to non-polar solvents. Within
the PA series, PA66 is mechanically strong and is widely used in automobile parts and apparatus casings. Nevertheless, PA66 has relatively
low notched impact strength and dimensional stability, which limits
its applications. Blending PA66 with acrylonitrile-butadiene-styrene
copolymer (ABS), which can provide toughness and better dimensional
stability, would be expected to produce a useful material for circumstances that demand higher strength and stiffness. But despite the
extensive literature about PA66/ABS blends, there are only limited reports on the compatibility of the components.1–6 In order to effectively
blend PA66 and ABS, it is necessary to find a compatibilizer that will
allow the two polymers to interact and diffuse through each other when
mixed.
Here we confirm that maleic anhydride-grafted polybutadiene
(PB-g-MAH) is an efficient compatibilizer for PA66/ABS blends.7, 8
It is different from commonly used polymer compatibilizers for these
blends because PB-g-MAH is compatible with the core part of ABS,
which is a polybutadiene phase. PB-g-MAH also has a low molecular weight, which could help improve the toughness and processing
properties of the blend. Our work suggests a new strategy in choosing
polymer compatibilizers.
The Molau test (see Figure 1) is a convenient way to assess the
compatibility of blends. We dissolved the uncompatibilized and compatibilized blends in formic acid, which is a good solvent for PA66 but a
poor one for ABS. The results indicate that the addition of PB-g-MAH
increases the interaction between PA66 and ABS.
We observed the morphology of uncompatibilized and compatibilized blends with a scanning electron microscope. The results
(see Figure 2) show that the addition of PB-g-MAH reduced interfacial tension and suppressed the coalescence of ABS particles.
Figure 1. Molau tests of (a) polyamide (PA66), (b) acrylonitrilebutadiene-styrene copolymer (ABS), (c) uncompatibilized blend, and
(d) compatibilized blend.
Figure 2. Scanning electron microscope (SEM) photos of the fracture
sections of samples as prepared: (a, b) uncompatibilized blend and
(c, d) compatibilized blend.
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10.1002/spepro.004091 Page 2/3
Figure 3. SEM photos of the fracture sections after strain-stress testing
the samples: (a, b) uncompatibilized blend and (c, d) compatibilized
blend.
Figure 5. Temperature dependence of the mechanical loss (tanı) at 1Hz
for (a) pure PA66, (b) ABS, and (c) uncompatibilized and compatibilized blends.
Figure 4. (a) Fourier transform IR spectra in the full range: (1) PA66,
(2) ABS, (3) maleic anhydride-grafted polybutadiene, and (4 and 5)
melt blend samples. (b) The enlarged spectra in the wave-number range
from 2000 to 1500cm 1 .
We demonstrated the effect of the compatibilizer on interfacial adhesion by observing the fracture section of the blends after a tensile test
(see Figure 3). ABS particles in the uncompatibilized blend debonded
and showed little plastic deformation. In comparison, the ABS particles in the compatibilized blend did not debond from the matrix after
the tensile test, and the originally spherical particles were elongated
into elliptical ones with distortion ratios of 68, which confirmed the
enhanced interfacial adhesion.9
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10.1002/spepro.004091 Page 3/3
Based on the analysis of Fourier transform IR (FTIR) spectra
(see Figure 4) and the plots of temperature dependence of mechanical loss (tanı) for uncompatibilized and compatibilized blends (see
Figure 5), we propose that PB-g-MAH locates at the interface of
PA66/ABS. The FTIR spectra showed the anhydride carbonyl (MAH)
peak disappear and new peaks appear. This suggests that the PB-gMAH forms maleimide with the amino end groups of PA66 and chain
entanglements via the interactions with the polybutadiene phase of
ABS.
In summary, PB-g-MAH promotes the compatibility of PA66/ABS
blends and enhances interfacial adhesion by tangling with the polybutadiene chain in ABS and grafting with PA66 through its amino
end groups. We propose that PB-g-PA66 copolymer formed in situ
more firmly anchors the interface between the two polymers, not only
effectively reducing interfacial tension but also increasing interfacial
adhesion. Consequently, the mechanical properties of the blend increase with the rise in PB-g-MAH content. In the future we plan to
extend the applications of PA66/ABS/PB-g-MAH, especially in the
field of engineering and automobile parts. And the successful use
of PB-g-MAH as the compatibilizer in PA66/ABS blend, which can
interact with the core phase (polybutadiene phase) rather than the
shell phase (SAN phase) of ABS, provides an alternative strategy for
choosing polymer compatibilizers.
Author Information
Huahao Yang, Xinyu Cao, Yongmei Ma, Jingjing An, Yucai Ke,
Xiaoming Liu, and Fosong Wang
Institute of Chemistry
Chinese Academy of Sciences
Beijing, China
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