Melt spinning and drawing of polyethylene nanocomposite fibers with organically modified hydrotalcite

Abstract

Fibers of high density polyethylene (HDPE)/organically modified hydrotalcite (LDH) were produced by melt intercalation in a two‐step process consisting of twin‐screw extrusion and hot drawing. The optimum drawing temperature was 125°C at which the draw ratios up to 20 could be achieved. XRD analysis revealed intercalation with a high degree of exfoliation for the composites with 1–2% of LDH. Higher thermal stability of nanofilled fibers was confirmed by TGA analysis. DSC data indicated that dispersed LDH particles act as a nucleating agent. Crystallization kinetics of the HDPE matrix in the composite fibers is characterized by two transition temperatures, that is, for Regimes I/II at 123°C and for Regimes II/III ranging between 114–119°C as a function of the nanocomposite composition. Fibers with 1–2% of LDH show for the drawing ratios up to 15 a higher elastic modulus, 9.0–9.3 GPa (with respect to 8.0 GPa of the neat HDPE), maintain tensile strength of 0.8 GPa and deformation at break of 20–25%. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40277.

Spinning, drawing and physical properties of polypropylene nanocomposite fibers with fumed nanosilica

“…On the other hand, the parallel increase of crystallinity and melting temperature shown in Table 2, could directly be related to the low melt flow PP, as consequence of a combined effect of both the high drawing orientation and the high drawing temperature. Analogous results were obtained for nanocomposite fibers with low melt flow HDPE (0.9 g/10 min at 190°C/2.16 kg) containing organically modified hydrotalcite [24], that showed after drawing at 125°C a relevant increase of both melting temperature (from 132-133°C up to 140-146°C) and crystallinity content (from about 50% up to 74-78%). In both cases, the effect of drawing could be interpreted as the transformation of lower perfection crystals in highly ordered structure at higher melting temperature, and it is also proportional to the orientation of non-crystalline regions.…”

Morphology and viscoelastic properties of melt‐spun HDPE/hydrotalcite nanocomposite fibers

“…Selected LDH nanocomposite fibers were previously studied by using SEM and XRD analysis . The compositions containing 1 and 2 wt% of LDH exhibited fine filler dispersion with various clusters of about 0.3 and 1.5 μm in as‐spun fibers, which evidenced intercalation and partial exfoliation in drawn fibers with draw ratio of 10 and 15.…”

“…Fibers at three different draw ratio DR = 5, 10, and 20, were selected, and compared to the as‐spun fiber (DR = 1). Other details of production have been reported in literature .…”

“…Moreover, LDH modification is usually performed to enlarge the interlayer distance of the pristine clay, to increase the hydrophobic nature and to reduce the interaction between platelets, and hence to facilitate the dispersion in polyolefins. Organically modified hydrotalcite can easily be melt‐dispersed and exfoliated forming a true nanocomposite with improved properties, e.g., a higher stiffness and thermal degradation stability . For specific applications, as rope and high performance fibers, melt spinning of high molecular weight polymer and subsequent drawing are convenient to produce high stiffness and high strength polyethylene .…”

“…Following these findings, high molecular weight HDPE was considered the most promising matrix for the high strength (high performance) fibers. Subsequently, Fambri et al obtained tenacity of drawn nanocomposite fibers in the range of 3–10 cN/dtex, corresponding to about 0.3–1.0 GPa . Studying the viscoelastic behavior, D'Amato et al specified the role of filler in the stiffening of drawn HDPE fibers containing 2% of fumed nanosilica; a higher storage modulus master curve and a lower creep compliance were observed .…”