Preparation and characterization of polydopamine-modified halloysite nanotubes and their effect on a natural rubber, chloroprene rubber and chloro-isobutylene-isoprene rubber blend

AbstractThe superior physical and mechanical performances of halloysite nanotubes (HNTs) make them ideal fillers for rubber reinforcement. However, due to the abundant hydroxyl groups on their surface, they are highly polar and have poor compatibility with polymers, making it difficult for them to disperse uniformly in polymers, thus limiting their application in rubber composites to a certain extent. In this paper, noncovalently modified HNTs filled with a natural rubber/chloroprene rubber/chloro-isobutylene-isoprene rubber (NR/CR/CIIR) blend system, using polydopamine（PDA） as a surface modifier, was investigated. and a green and high-performance PDA/HNTs/NR/CR/CIIR composite was prepared by mechanical blending. Transmission electron microscopy (TEM) showed that the original HNTs had a hollow, multi-walled nanotube structure, and the outer surface of the PDA-modified halloysite nanotubes（PDA/HNTs）showed an obvious cladding layer. X-ray diffraction indicated that the modification experiments did not damage the halloysite crystal structure; the modifier only interacted on the outer surface of the HNTs. Zeta potential and thermogravimetric analysis (TGA) further indicated the presence of interfacial interactions between PDA and HNTs, suggesting that PDA was successfully grafted to the surface of HNTs. In addition, the effects of PDA/HNTs on the mechanical properties, vulcanization properties and Rubber Process Analyzer (RPA analysis) of the NR/CR/CIIR blend were also investigated. The dispersion of HNTs in the NR/CR/CIIR blend was enhanced by the adsorption of PDA on the HNTs surface by non-covalent bonds, and the comprehensive properties of the composites were improved.Keywords: halloysite nanotubesdopaminecomposite materialsDisclaimerAs a service to authors and researchers we are providing this version of an accepted manuscript (AM). Copyediting, typesetting, and review of the resulting proofs will be undertaken on this manuscript before final publication of the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal relate to these versions also. Declaration of conflicting interestsThe authors declare no potential conflicts of interest.Data Availability StatementsThe data sets generated and/or analysed during the current study are available from the corresponding author on reasonable request.Additional informationFundingThis research was funded by the research fund of Qingdao University of Science and Technology（9210-1203043003023）