Rubber Toughened Polyamide 6/ Polypropylene Nanocomposites: Mechanical, Thermal And Morphological Properties
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Date
2006-06
Authors
Wahit, Mat Uzir
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Rubber-toughened nanocomposites (RTNC) consisting series of
compatibilized polyamide 6 / polypropylene (PA6/PP) blends, of composition 100/0,
70/30, 50/50, 30/70 and 0/100, polyethylene-octene elastomer (POE) and organophilic
modified montmorillonite (organoclay) were produced by melt compounding followed by
injection moulding. Polypropylene grafted maleic anhyride (PPgMA) was used as
compatibilizer. Subsequently, for PA6/PP (70/30), the POE and organoclay loading was varied between 5 and 20 wt% and 2-6 wt%, respectively. For the optimum
particles dispersed in the PA6 matrix, was characterized by scanning electron
of a formulation, four different types of elastomer were incorporated into the blends i.e.
ethylene-octene elastomer (POE), ethylene-propylene elastomer (EPR), maleated POE
(POEgMAH) and maleated EPR (EPRgMAH). For the selected formulation, the
nanocomposites were also prepared through different mixing sequence of melt
intercalation i.e. direct, two times and two steps method.
The mechanical properties were studied through tensile, flexural, Izod impact
and fracture toughness testing. The morphology, essentially comprised of PP and POE
microscopy (SEM). Wide angle X-ray diffraction (XRD) was used to characterize the
formation of the nanocomposites. The thermal properties were characterized by using
differential scanning calorimeter (DSC) and thermogravimetry analysis (TGA). The
dynamic mechanical were analyzed by using dynamic mechanical thermal analyzer
(DMTA).
The results showed that, the incorporation of organoclay significantly increased
the stiffness and strength but at the expense of the toughness. Conversely, the
incorporation of the POE increased the toughness, while the strength and stiffness
decreased. The PA6/PP nanocomposites containing 4 wt % of organoclay and 10 wt%
of POE had the best balance of stiffness, strength and toughness. The results also
showed that modulus and strength of the nanocomposites was not significantly affected
by types of elastomer and their functionality and the blending sequence. However, the
toughness of the nanocomposites toughened by maleated elastomer was higher than
the unmaleated elastomer. Two steps method gave the best mechanical properties due
to its good dispersion of the organoclays and elastomer in the matrix. XRD established
that the organoclay was well dispersed (exfoliated) and preferentially embedded in the
PA6 phase. The type of elastomer and functionality and method of processing did not
significantly affect the dispersion of the organoclay in the system. Blend ratio and the
presence of organoclay were found to influence the morphology (e.g. POE particle size
and distribution) of the system. A finer particles size and better distribution of POE
elastomer has been observed in higher PP concentration system. The SEM
observation also revealed that rubber functionality and two steps method reduces the
elastomer particle size in the PA6/PP matrix.
Description
Keywords
Chemistry