Mechanical and Morphological Properties of Polypropylene and High Density Polyethylene Matrix Composites Reinforced with Surface Modified Nano Sized TiO2 Particles

Plastics occupy wide place in the applications of automotive, electronics and house goods. Especially reinforced plastics become popular because of their high strength besides their advantages of low weight and easy manufacturability. In this study, mechanical and morphological properties of polypropylene (PP) and high density polyethylene (HDPE) matrix composites reinforced with surface modified nano titan dioxide (TiO2) particles were investigated. Surface modification was made by coating the nano powders with maleic anhydride grafted styrene ethylene butylene styrene (SEBS-g-MA) and silane, respectively. After surface modification, PP/TiO2 and HDPE/TiO2 composites were obtained by using twin screw extruder at titan dioxide loading of 1 wt.%, 3 wt.% and 5 wt.%. Effects of surface modification were determined by thermal and morphological analysis. SEBS-g-MA provided bridging effect between TiO2 particles and polymer matrix while silane was effective as a dispersant. Depending on that, homogenous structures without agglomeration were obtained. Mechanical tests were performed on the injection moldings of the composites for obtaining the impact strength, tensile strength, stress at break, elongation and elastic modulus. Reinforced HDPE and PP moldings gave higher tensile strength and elastic modulus due to the rigid structure of TiO2. Slight increment was seen in stress at break. Elongation and impact strength decreased due to the stiffness of the nano titan dioxide.

Authors:

• Mirigul Altan
• Huseyin Yildirim

Keywords:

• High density polyethylene
• mechanical properties
• nano TiO2
• polypropylene.

References:

[1] Yang H., Zhang Q., Guo M., Wang C., Du N.R., Fu Q., "Study on the
phase structures and toughening mechanism in PP/EPDM/SiO2 ternary
composites" Polymer, vol. 47(6), pp.2106-2115, 2006.
[2] Kruenate, J.;Tongpool R.; Panyathanmaporn T. "Optical and mechanical
properties of polypropylene modified by metal oxides", Surface and
Interface Analysis, vol. 36, pp. 1044-1047, 2004.
[3] Bao, S.P., Tjong, S.C. "Impact essential work of fracture of
polypropylene/montmorillonite nano composites toughened with SEBSg-
MA elastomer", Composites: Part A vol. 38, 3pp. 78-387, 2007.
[4] Garakani, M.M.;Arefazar, A.; Nazockdast, H., "Study on
Morphological, Rheological and Mechanical Properties of PP/SEBSMA/
SGF Hybrid Composites", Journal of Applied Polymer Science,
vol.104, pp.2704-2710, 2007.
[5] Ishak Mohd, Z.A.; Chow, W.S.;Rochmadi, T.T. , " Compatibilizing
Effect of SEBS-g-MA on the mechanical properties of different types of
OMMT filled polyamide 6 / polypropylene composites", Composites:
Part A, vol.39, pp.1802-1814, 2008.
[6] Setz, S;Stricker, F.; Kressler ,J., Duscher, T.;Mulhaupt, P, "Morphology
and Mechanical Properties of Blends of Isotactic or Syndioatactic
Polyropylene with SEBS Block
Copolymers",J.Appl.Polym.Sci.,1996,59, 1117-1128.
[7] Scheirs, J. "Compositional and Failure Analysis of Polymers", John
Wiley&Sons, England, 2000i ch.5.
[8] Zebarjad, S.M., Sajjadi S.A., Tahani, M., Lazzeri A., "A study on
thermal behaviour of HDPE/CaCO3 nano composites", Journal of
Achievements in Materials and Manufacturing Engineering, vol.17(1-2),
pp. 173-176, 2006.
[9] Wang, Z., Wang X., Zhang Z., "Nucleating Activation and Spherical
Crystals Morphology of LLDPE/LDPE/TiO2 Nano Composites
Prepared by Non-Isothermal Crystallization", Journal of Dispersion
Science and Technology, vol.30, pp.1231-1236, 2009.
[10] Olmos, D., Dominguez C., Castrillo P.D., Gonzales-Benito, J.,
"Crystallization and final morphology of HDPE: Effect of high energy
ball milling and the presence of TiO2 nano particles", Polymer vol. 50,
pp.1732-1742, 2009.
[11] Garcia, M, Vliet G.V., Jain, S., Schrauwen B.A.G., Sarkissov A.,
Boukamp B., " Polypropylene/SiO2 nano composites with improved
mechanical properties", Reviews on Advanced Materials Science vol. 6
pp. 169-175, 2004.
[12] Tjong, S.C., Bao S.P, "Fracture toughness of high density
polyethylene/SEBS-g-MA/montnorillonite nano composites",
Composite Science and Technology vol. 67, pp. 317-323, 2007.
[13] Long Y, Shanks, R.A., "PP-elastomer filler hbrids I. Processing structure
and mechanical properties", Journal of Applied Polymer Science, vol.
61, pp.1877-85, 1996.