Influence of the silane grafting of polyethylene on the morphology, barrier, thermal, and rheological properties of high‐density polyethylene/organoclay nanocomposites

Abstract

In this work, silane-grafted high-density polyethylene was prepared by reactive extrusion. This product and neat high-density polyethylene were then melt-compounded with organically modified montmorillonite to form nanocomposites. A series of tests, including Fourier transform infrared spectroscopy, small-angle X-ray diffraction, and transmission electron microscopy, were done on the specimens to investigate the grafting efficiency and its compatibilizing effect and the microstructure of the samples. In addition, the thermal, rheological, and barrier properties were examined to study of the grafting effects and nanocomposite characteristics. The results indicate that an intercalated structure could be easily obtained in the nanocomposites with a grafted matrix. A significant reduction in the degree of crystallinity and an increased crystallization temperature with grafting and the incorporation of nanoclay were proven by thermal analysis (differential scanning calorimetry), whereas the melting temperature did not change noticeably. Dynamic rheological testing indicated the disappearance of the Newtonian plateau and solidlike behavior of the nanocomposites based on grafted polyethylene in lower frequencies. Furthermore, the oxygen transfer rate of the samples decreased significantly with the incorporation of nanoclay in the grafted matrix and the moisture crosslinking of the samples. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 125: E305-E313, 2012

Effect of organoclay and silane grafting of polyethylene on morphology, barrierity, and rheological properties of HDPE/PA6 blends

“…The pristine clay (curve a) showed the characteristic peak at As it could be seen obviously, the position of characteristic peak of nanocomposites based on neat HDPE (curve b and c) did not change significantly, and thus, nongrafted PE chains did not intercalate efficiently into the clay galleries. 22 Finally, absence of any characteristic peak of the organoclay in the PAn nanocomposite (curve e) at examined 2H values indicated that the Org-MMT plates were completely delaminated by PA6 chains because of their hydrophilic nature, consistent with previous results. On the other hand, the basal reflection for the clay was shifted to lower angle in the curve d (nanocomposite with HDPE-g-Si as matrix) which implied a higher d-spacing (d ¼ 38.4 A ), indicating the intercalation of polymer chains inside the clay galleries.…”

“…From our previous researches, 22,27 and also try and error we set optimum amount of VTMS equal to 4 phr (weight part per hundred part of PE) and DCP equal to 0.1 phr for which best melt rheology and silane grafting efficiency was accessible. This solution was absorbed in PE granules during mixing in turbo mixer for about an hour in ambient temperature.…”

“…22 Another works 23,24 also explained that the alkoxy groups of silane used in manufacture of cross-linkable PE, which are mainly vinyl silane such as vinyltrimethoxysilane (VTMS), cause noticeable improvement of interfacial adhesion between PE and clay layers. 22 Another works 23,24 also explained that the alkoxy groups of silane used in manufacture of cross-linkable PE, which are mainly vinyl silane such as vinyltrimethoxysilane (VTMS), cause noticeable improvement of interfacial adhesion between PE and clay layers.…”

Dispersing hydrophilic nanoparticles in hydrophobic polymers: HDPE/ZnO nanocomposites by a novel template-based approach

“…The moduli get flat at low frequency, with a prominent effect on G$ which increases of more than two order of magnitude with respect to the unfilled matrix despite the low amounts of filler considered. It is worth noting that similar alterations in the viscoelastic behavior cannot be found in the literature for HDPE-based nanocomposites unless performing modifications of the particle surface and/or adding suitable compatibilizers to reduce the chemical incompatibility between the polymer and the filler [23][24][25]. The viscoelastic behavior has been investigated also in the solid state by means of DMA ( Figure 10).…”

Investigation of crosslinking behaviour of silane grafted polyethylene through rheology

“…Moreover, there is a difficulty of uniform distribution of silane and thus there exists the probability of localized grafting and consequent formation of small gels [4]. Even if significant progress has been made in understanding of crosslinking reactions for silane-grafted polyethylenes [1][2][3][4][5][6][7][8][9][10][11], there is still free space for the research in this field to obtain knowledge, which could help to optimize the silane grafting process and processing conditions.…”