Fabrication and characterization of ABS nano composite reinforced by nano sized alumina particulates

Int J Plast Technol 13(2):133–149 133

RESEARCH ARTICLE

Received: 10 August 2009 / Accepted: 3 December 2009© LARPM, Central Institute of Plastics Engineering and Technology, 2009

Fabrication and characterization of ABS nano composite reinforced by nano sized

alumina particulates

Vivek Kumar1, J. RamKumar1 , S. Aravindan2, S. K. Malhotra3,K. Vijai4, Mukul Shukla5

1Department of Mechanical Engineering, Indian Institute of Technology, Kanpur – 208016, India2Department of Mechanical Engineering, Indian Institute of Technology Delhi,

Hauz Khas, New Delhi – 110 016 India3Department of Mechanical Engineering, RMK Engineering College, RSM Nagar,

Kavaraipettai - 601206 (TN), India4Central Institute of Plastics Engineering and Technology, Lucknow - 226008, India

5Department of Mechanical Engineering, MNNIT, Allahabad - 211004 (UP), IndiaE-mail: [email protected]

AbstractTo study the effect of addition of alumina nano sized particles in ABS thermoplastic composites, ABS was reinforced by nano sized alumina particles through melt compounding. The microstructure, thermal stability, dynamic mechanical, static mechanical properties and tribological analysis of the developed nano composite were investigated in detail. The dispersion morphology of alumina particles in the ABS polymer matrix was investigated through SEM. Addition of the alumina into the ABS matrix increased the thermal stability of new developed composite. Dynamic Mechanical Analysis (DMA) tests are carried out to investigate the viscoelastic deformation of ABS/Al2O3 nano composites with different (1–5 %) loading of alumina nano particles. It has been observed

content and and change in Tg was obtained. The resulting nano composites with 1–3 vol %, alumina nano particles exhibit the maximum improvement of young’s modulus, tensile strength

of elongation at break. The tribological properties were investigated by a pin-on-disc apparatus against the abrasive counter face. The addition of nano alumina nanoparticles was found to be able

and wear rate of ABS/alumina nano composites.

Keywords: ABS Nano composites Morphology Thermal stability Dynamicmechanical Static mechanical properties Tribological analysis

Introduction

application is primarily aimed at the cost reduction and mechanical

134 Int J Plast Technol 13(2):133–149

improvement. ABS (Acrylonitrile – butadiene - styrene terpolymer) is a member of the styrene family of polymers and shares many properties with this group materials. The properties of a particular grade of ABS depend on the blend ratio of the three major constituents (Acrylonitrile, butadiene and styrene). The acrylonitrile component gives chemical resistance and heat stability, the butadiene gives toughness and impact strength and the styrene gives rigidity and processability.The main application of ABS polymer are automobile parts, household items and electrical housing ect. The main advantages of ABS polymer are good stain resistance, impact resistance even at low temperatures, good abrasion resistance, tough and stiff. But besides these properties there are some limitations with ABS polymer such as poor weathering resistance, poor heat resistance, poor transparency and scratches easily. Polymer nanocomposites

particles produces ultra-large interfacial area per unit volume between the

nanoscopic dimensions fundamentally differentiate polymer nanocomposites

nanocomposites over conventional composites are; dramatic improvements in mechanical properties, greater thermal stability, very good transparency and good scratch resistance. There are several nano particles to prepare a polymer nanocomposite.Limited work has been done on different nano particles like; clay, MMT, mica, talc and alumina etc. in ABS polymeric systems. There are still only a few reports about the preparation of ABS nano composites and limited work has been done on alumina nano particles in ABS polymeric systems. Lee and

discussed the dispersion of clay particles in an ABS matrix comparing this system with a Styrene-Acrylonitrile (SAN) polymer based nanocomposite where it was observed that the ABS/MMT composite clay resides in the Styrene acrylonitrile phase of ABS and accumulates preferential at the rubber particles surface.

solvent/non-solvent method and working with different kinds of mixers while

the clay surfactant on to the morphology and performance of ABS/clay nano

the effect of the particle size on mechanical properties and microstructure, they observed better in nano scale composites, the fracture mode in nano composite

effect of nano sized alumina on mechanical and thermal stability of PEEK nano composites and they found improvement in both the properties as increased of


alumina reinforced polyamide composite and they found that nano alumina improved the wear resistance compared with micron alumina composite. Nano structural interfacial bonding between the polymer and alumina improve the

highly desired. With this concern the newly developed nano composites would come in to competitive candidates. The aim of the present work is to investigate the morphological study of Al2O3 particles in the ABS matrix. The effect of varying nano particles content inclusion on the enhancement of thermal Stability and viscoelastic properties of ABS/Al2O3 nano composites are also under investigation. The mechanical

particles and the ABS matrix are under examination. The effect of nano alumina particles on the tribological performance of ABS nano composites are also under investigation.

Experimental

Material

The matrix material chosen for this study was ABS polymer (Absolac-920 Bayer),

particles obtained from Allied High Tech. Products (USA). The alumina particles are in spherical shape with an average particle size of ~50 nm. Nano alumina

50 nm; melting Point 2323K. It was designed to be a reinforcing additive to improve the various properties of plastic materials. Note that the alumina particles are added in lower amount in volume as compared with conventional polymeric composites. This means that the current nano composites would not alter much the process ability or density of the ABS matrix.

Compounding and sampling

graduals and Nano alumina powder at different volume % (1, 3, 5,). Manually, followed by melt mixing in single screw Extruder (Hakke Rheomix 9000) 18 mm

12 hours to remove moisture & volatiles. The nano alumina was also dried at


manner and the extrudates were cooled by water at the exit of the die, and then air-cooled, after cooling the composite rods cutted in to graduals form in uniform size through the Pelletizer machine. The nano composite samples for mechanical characterization were prepared by Injection Molding process.

Testing and characterization

Morphological analysis

Scanning electron microscopy (SEM)SEM was used to determine dispersion morphology of alumina particles in the ABS polymer matrix. Through the SEM micrographs analyze the morphology of developed nano composite. Scanning Electron Microscope (SEM) at 20 KV.

study the morphology of ABS/alumina nano composites.

Thermal testing

Thermogravimetry analysis (TGA) In the current study, the degradation pattern and thermal stability of the various nanocomposites were determined by Pyris TGA-1 (Perkin Elemer) thermal analyzer. The percentage weight loss of the samples was analyzed as a function of temperature through TGA. The quantity of the sample for each test was

min under nitrogen atmosphere. Onset of degradation, maximum degradation temperature and the weight loss at the maximum degradation temperature were the parameters determined from the TGA curves.

Dynamic mechanical analysis (DMA) DMA is simply a dynamic method of characterizing the viscoelasticity of a material. This is done by applying a sinusoidal force (or displacement) and measuring the response to that input. In the present study, viscoelastic behavior of neat ABS resin and ABS composites reinforced by nano alumina particulates were measured using SII EXSTAR6000 model series DMS 6100 (SIINanotechnology, Japan). Rectangular bar specimens of 50 x 13 x 2 mm3 size were

rate of 10 deg C/min.

Mechanical tests

The mechanical tests were conducted on Universal Testing Machine (LLOYD,LR-100 K) with the max. load capacity 100 KN. Tensile tests were performed at room temperature following ASTM D-638 type 1 method with 50 mm sample gauge length. The crosshead speed was 50 mm/min. Flexural test according to

x 6.4 mm3. The span length was 100 mm and the crosshead speed was 2.5 mm/

strength and modulus were calculated. Notched Izod impact test was carried out according to the ASTM D-256. The sample size for Izod impact test was 63.5

3

Tribological analysis

Friction and wear behavior In order to study the tribological properties of ABS /alumina nano composites, the abrasive wear tests were conducted on a pin-on- disc machine. Silicone

the specimen contact surface area (10 mm x 10 mm) glued to a bottom of the pin (dia. 10 mm x length 100 mm). Before testing, the test samples were shaped and polished by same emery paper for better contact between the abrasive counter surface and the test sample. In the current study, the test was conducted on a

which resulted in a sliding speed of 2.49 m/s in the wear track. The sliding was performed at applied load of 400 gm for 150 sec.

Fig. 1 (A) Experimental set-up: pin-on-disc machine. (a) balance weight, (b)load weight (c ) pin with sample, (d ) wear track on abrasive disc (B) Pin assembly showing location of the test sample on the rotating disc.

(A) (B)


(a) (b)

Fig. 2 SEM images of ABS nano composites (a) 3 % alumina +ABS, (b) 5% alumina +ABS

Ws = m

FN S ……… (1)

= ΔVFN S

……… (2)

μ = FfFN

……… (3)

Ff is the frictional force obtained from the machine output.

Results and discussion

Microstructure characterization

Scanning electron microscopy (SEM) In Fig. 2 (a) and 2 (b), the SEM micrographs of the nano composites containing 3 and 5 vol % of the alumina nanoparticles are shown as an example. From

3% loading is good and only a few nano powder agglomeration phenomena have been noted in the case of low concentration of nanoparticles content. Asthe alumina concentration increases the agglomeration starts and properties decreased due to weak interfacial bonding. This result allows to assume that the used preparation methodology permits to obtain a good dispersion of the nanoparticles into the polymeric matrix also at a relatively high content of


Table 1. Degradation temperature of the samples from TGA.Samples Td 10% weight loss ( C) Td 50% weight loss ( C)Neat ABS 438.48ABS + 1 % alumina 395.41 439.61ABS + 3 % aluminaABS + 5 % alumina 454.46

in the polymer matrix, and in turn decrease the reinforcing effects. It is seen that the dispersion condition of alumina nano particles in the ABS matrix are reasonably uniform in 3 % vol. It is conceivable that, with further improvement

expensive, the mechanical properties can be further upgraded.

Thermal properties measurements

Thermogravimetry analysis (TGA) The thermal stability and degradation characteristics of the nano composites samples can be revealed from TGA thermo grams. Temperature of decomposition at 10 % weight loss (Td 10%) and Td 50% weight loss were obtained from those curves and are listed in Table 1. Generally, the incorporation of alumina nano particles in to the polymer matrix is found to enhance the thermal stability with the alumina acting as a good insulator and mass transport barrier to the volatile products generated during decomposition. The ABS/alumina nanocomposites

stability of the nano composites is substantially higher than the pure ABS. There is also a linear increase in the temperature of 50% weight loss temperature from

as shown in Fig. 3. The enhancement of the thermal stability can be attributed to the strong interaction between ABS chain and nano alumina particles. The overall thermal stability is seen to increase with the increase in the alumina loading levels.

Dynamic mechanical analysis (DMA)The viscoelastic behavior of neat ABS resin and ABS composites reinforced by nano alumina particulates were characterized by DMA.The storage modulus of the nano composites shown in Fig. 4 (A) are lower than that of pure ABS up to 3% loading of nano alumina particles in to ABS matrix and with 5% content

that the incorporation of alumina reduce the material stiffness during sinusoidal


(A)

Fig. 3 Normalized weight loss for different alumina content

stress on the ABS composites. It has been observed that above Tg the storage modulus decrease with temperature and the magnitude is lower than neat ABSmatrix. Fig. 4 (B) shows the loss modulus data of ABS/alumina nano composite. As shown in Fig. 4 (B) the E” curves of nano composite at loading of 1 to 3% is lower than that of neat ABS, it is due to because the alumina particles restricted the motion of chains segments of ABS matrix, hence less amount of energy lost due to hindrance of the chains, but at higher loading about 5% of alumina there is some dissipation of heat due to friction between the polymer chains and nano alumina particles, therefore increase in loss modulus at 5% content of alumina but not higher than pure ABS matrix. Glassy transition temperature Tg of ABS/

shown in Fig.4 (C). It is seen in Fig.4 (C) that Tg value of ABS nano composites increase with the increase of nano alumina content from 1 to 3% but at 5% loading it shows a little reduction in the Tg value.


Mechanical properties analysis

Tensile StrengthAs shown in Fig. 5. The tensile strength increases about 24% with the loading of alumina nanoparticles of 1–3 vol % and at 5% alumina content the strength slowly decreased. We can attribute this strength weakening to the result of poor dispersion of the nanoparticles in the 5% nanocomposite. The trend is very similar to the other nano alumina composites like vinyl ester/alumina composite

of nano alumina the tensile strength of ABS nanocomposites increased and it reduced with high content. This was probably that at low content of alumina, bonding between alumina particles and ABS matrix was strong enough and

(B)

(C)Fig. 4 DMA plots for neat ABS and its nanocomposites as a function of temperature


tensile strength is increased. But with high loading the dispersion of alumina

agglomerate. The agglomerates were easy to debond from the matrix, and the debonded nanoparticles did not bear any fraction of the external load, so the tensile strength decreased as shown in Fig. 5.

Tensile (Young’s) modulus Fig. 6 shows the effect of alumina nano particles on Young’s modulus by tensile loading. As the nano alumina content increases from 1 to 5 vol % in ABSmatrix, it has been observed that the modulus is increased by near about 9% as compared to neat ABS. The trend is same as follows by vinyl ester/alumina

content as shown in Fig. 6. It seems that the concentration of nano particles

segments would in turn deform themselves in a less mobile manner, accounting for the higher Young’s modulus.

Elongation at break The percentage elongation in the composite material has been found to decrease

composites show a sharp decrease at 3% vol. fraction of nano particles, after that a steady decrease in elongation at break with increasing alumina content as shown

Fig. 5 Effect on tensile strength of ABS by loading of alumina nano particles


The addition of alumina reduces the extensibility of the butadiene rubber chains in ABS, thus reduced the elongation of the matrix composite. Introduction of a very small amount of alumina change the mode of failure from a ductile to

agglomerates may act as stress concentrators and reduce the elongation at break. This fact has also been supported by SEM micrographs which also reveal that agglomeration takes with increasing of nano particles.

Fig. 6 Effect on tensile modulus of ABS by loading of alumina nano particles

Fig. 7 Effect on % elongation of ABS by loading of alumina nano particles


Flexural properties

reinforced ABS composite as shown in Fig.8. This is an increase of 36 % in

alumina particles is the contribution of strong interaction between matrix

Fig. 8

increased with increasing alumina content, and a low increment occurred when high contents were incorporated as shown in Fig. 9. The increment has

3 nano

also depend on the interaction of the ABS and alumina nano particles. Hence

alumina content increased as shown in Fig. 9.

Impact strengthThe impact strength of the ABS composite with varying of nano alumina particles has been characterized by performing the Izod impact on the test specimens. It has been observed that Izod impact strength of neat ABS decrease continuously


generally decrease the impact strength of polymer. The impact strength decreases

the nanoparticles. Yilmazer and Ozden observed this type of behavior for PS-

surface to surface inter-particle (ligament- thickness) and it must be smaller than a critical value. As we increase the nano particle content in the ABS matrix the number density of nano particle in the composite was much higher, therefore

Fig. 9

Fig. 10 Effect on Izod impact of ABS by loading of alumina nano particles


Tribological analysis

Friction and wear measurements The effect of nano alumina addition to ABS on the friction and wear behavior under abrasive conditions is shown in Fig. 11 (A), (B), ( C ) in terms of wear

Pure ABS exhibits the highest wear volume loss while the ABS nanocomposite

Fig. 11 (B). An improvement of the wear rate performance of about 23.64% can be observed by 5% loading of nano alumina particles. The tribological behavior of polymeric material against abrasive conditions is related to the contact between

Fig. 11 Effect on Tribological properties of ABS by loading of nano alumina particles (A)Wear volume loss (mm3 3

Fig. 11(C). It was observed that friction and wear of neat ABS was higher due to the soft nature of the ABS matrix and high wear debris adheres on the abrasive sheet during sliding motion. As nano alumina content is increased in ABS matrix wear and friction is reduced, the reason is that alumina particles are hard and good enough wear resistance, they restrict the ABS particles to come into direct contact with the SiC abrasive particles, hence during sliding there is a contact between alumina and SiC abrasive particles in case of ABS/aluminanano composites. Friction and wear is decreased with increased of nano alumina content in ABS matrix.

Conclusion

1. SEM micrographs of the developed nanocomposites showed a better dispersion of nano particles into the polymeric matrix at lower loading

content in the ABS polymer matrix.2. The ABS/alumina nanocomposites show an increase of the 10% weight loss

nanocomposite. There is also a linear increase in the temperature of 50 %

the case of the 5 vol % nanocomposites The enhancement of the thermal stability can be attributed to the strong interaction between ABS chain and nano alumina particles.


3. DMA shows that the storage modulus dramatically decrease by about 42% when alumina content is up to 3 vol % in comparison to neat ABS, while the

function of alumina loading about 3vol % probably due to the reinforcing effect of nano alumina particles in to the ABS polymer matrix.

at 3% loading of alumina particles and with a greater amount to 5vol % , the clustering problem would start to lower the tensile strength, but still continuously upgrade the elastic modulus. A reduction in % elongation and Izod impact of the composite material observed suggesting that ductile to brittle transition is taking place upon the incorporation of nano alumina particles.

5. Flexural modulus increases near about 23% at 3vol % of alumina content, the

at 3% of alumina loading. The modulus of the developed nanocomposites is

also depends on the dispersion of alumina particles in the ABS matrix.

reduces from 6.6 x 10–2 to 5.0 x 10–2 with addition of 1 to 5% loading of

follows the same trend. It was found that the strong interaction between

the nanocomposite.

Acknowledgements

Authors would like to express their sincere thanks to, the Indian Institute of

interactions with the staff members of Central Institute of Plastic Engineeringand Technology (CIPET) Lucknow, Miss Sirisha Kongala and Mr. Devesh Shukla who provided advice, including the TGA, UTM and Haake Rheomex Compounder performed by Mrs. Rashmi Singh , Mr. B.K.Singh and Mr. Gopal Benerji. A special thanks to all friends who gave their full Support.

References

Fabrication and characterization of ABS nano composite reinforced by nano sized alumina particulates

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