Halloysite Containing Thermoset Nanocomposites via Free Radical Photocrosslinking Polymerization

Abstract

Naturally occurring halloysite nanotubes (HNTs) are first functionalized by 3‐(trimethoxysilyl) propyl methacrylate and then used as nanofillers in a mixture of difunctional methacrylates (triethylene glycol dimethacrylate and bisphenol A glycerolate dimethacrylate). Upon free radical photocrosslinking of this mixture enables the in situ preparation of HNT/thermoset nanocomposites. The covalent bonding of HNT in the thermoset matrix is proven by following characteristic bands of the mixture using Fourier transformed infrared spectroscopy. Furthermore, the presence and distribution of HNT in the nanocomposites are confirmed by scanning electron microscopy with energy dispersive X‐ray spectroscopy, and transmission electron microscopy observations. In addition, a mixed morphology containing agglomerated/nonagglomerated HNTs in the thermoset matrix is also determined. Both tensile strength and elasticity modulus of nanocomposites are dramatically increased with increase in HNT loading up to 4% ratio. On the other hand, these nanocomposites exhibit higher thermal properties compared to the neat thermoset.

Thermoset nanocomposites reinforced by vinyl‐functionalized halloysite

“…These mechanical properties were different from those obtained in the recently published study by our team in which the HNT was modified by 3-(trimethoxysilyl) propyl methacrylate (silane agent) and the same multifunctional methacrylate monomers were used as Bis-GMA and TEGDMA. [16] This indicated that the type of silane agents directly affected the interaction mechanisms between HNT nanofiller and polymer matrices. Similar results were also reported by Xie et al [19] and Abdelmouleh et al [20] on the effects of silane coupling agent on the mechanical and outdoor performance of the natural fiber/composites.…”

“…Due to the promising features of HNT such as large surface area and high-aspect ratio, it has been used to provide strong interfacial interactions and homogeneous dispersion in the polymer matrix. [16,18] In this work, exterior/interior hydroxyl groups of HNTs were functionalized with VTES as silylation agent to form vinyl-functional halloysite nanotubes (HNT-Vinyl). Chemical structure of obtained HNT-Vinyl was verified by both FT-IR spectroscopy and thermogravimetric analysis (Figures 1 and 2).…”

“…Bubble effect was also noticed on the walls of the nanotubes because of the prolonged exposure to electron bombardment and irradiation of interlayer water molecules during TEM observations. [16,25] As noted in the literature, the effect of heating and electron bombardment could damage the specimen foil during TEM imaging. [26] This may be disrupting the HNT microstructure.…”

“…Remarkable improvements in both tensile strength and elastic modulus values were noted with up to 4% HNT loadings. [16] The vinylmodified HNT was used to enhance the properties of unsaturated polyester resin in another study. [17] The resulting nanocomposite containing 1 wt% vinyl-modified HNT exhibited enhanced glass transition and degradation temperatures compared to the neat unsaturated polyester resin.…”

HNT-Tiyol İçeren Termoset Nanokompozitlerin Serbest Radikal Fotopolimerizasyon Yöntemi ile Hazırlanması

“…GİRİŞ HNT (1:1 katmanlı Al2Si2O5(OH)4.nH2O), geniş en boy oranı, doğal kullanılabilirliği, iyi biyouyumluluğu ve yüksek mekanik mukavemet özelliklerini içeren tek boyutlu yeni nesil doğal bir nanodolgudur [1]. Ayrıca HNT/polimer nanokompozitleri düşük maliyetle ve yüksek mekanik, termal ve biyolojik özelliklere sahip olarak hazırlanabilmektedir [2]. HNT aynı zamanda aktif maddelerin kontrollü salım uygulamalarında kullanım potansiyeline sahiptir.…”