POLYMER TESTING Polymer Testing 27 (2008) 566–580 Material Properties Influences of blend compatibilizers on dynamic, mechanical, and morphological properties of dynamically cured maleated natural rubber and high-density polyethylene blends Skulrat Pichaiyut a , Charoen Nakason a,Ã , Azizon Kaesaman a , Suda Kiatkamjornwong b a Faculty of Science and Technology, Department of Rubber Technology and Polymer Science, Center of Excellence in Natural Rubber Technology, Prince of Songkla University, 181 Charoen Pradit Road Rusamilae, Pattani 94000, Thailand b Faculty of Science, Department of Imaging and Printing Technology, Multidisciplinary Program of Petrochemistry and Polymer Science, Chulalongkorn University, Bangkok 10330, Thailand Received 23 January 2008; accepted 5 March 2008 Abstract Influences of various types and loading amounts of blend compatibilizers on properties of maleated natural rubber/high- density polyethylene thermoplastic vulcanizates (MNR/HDPE TPVs) were investigated. It was found that TPV with any of the three types of compatibilizer exhibited superior mechanical and dynamic properties to those of the TPV without compatibilizers. Furthermore, the phenolic modified polyethylene compatibilizers (i.e., PhSP-PE and PhHRJ-PE) showed a better compatibilizing effect than HDPE-g-MA. Comparing the three types of compatibilizer, the TPVs with PhHRJ-PE exhibited the best mechanical and dynamic properties and the smallest dispersed vulcanized rubber domains in the HDPE matrix. Five loading amounts of PhHRJ-PE were then studied. The PhHRJ-PE at a loading amount of 5 wt% of HDPE exhibited the best overall properties. The TPVs with lower and higher loading amounts of PhHRJ-PE exhibited inferior mechanical, dynamic and morphological properties. r 2008 Elsevier Ltd. All rights reserved. Keywords: Maleated natural rubber (MNR); Thermoplastic vulcanizate (TPV); High-density polyethylene; Phenolic modified polyethylene; Graft copolymer; Maleic anhydride 1. Introduction Thermoplastic vulcanizates (TPVs) are blends in which the elastomer component is dynamically vulcanized in situ during melt mixing with the thermoplastic components at high shear and ele- vated temperature. The dynamic vulcanization process enables the crosslinked elastomer to become the dispersed phase, even in cases where the elastomer is the majority component or its volume fraction is greater than 0.5 [1]. Therefore, TPVs are two-phase materials in which cured elastomer particles having a diameter of a few micrometers are dispersed in the thermoplastic matrix. They can be fabricated into end-use parts by conventional ARTICLE IN PRESS www.elsevier.com/locate/polytest 0142-9418/$ - see front matter r 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymertesting.2008.03.004 Ã Corresponding author. Tel.: +66 73 31 393 050. E-mail address: ncharoen@bunga.pn.psu.ac.th (C. Nakason).