Polymer nanocomposites were produced using a commercial HDPE, Alathon 5618 from LyondellBasell, and a surface modified montmorillonite (MMT), Nanomer I.31PS nanoclay, which contains 15–35 wt% octadecylamine and 0.5–5 wt% aminopropyltriethoxysilane, supplied by Nanocor. A maleic anhydride grafted linear low-density polyethylene (MA-g-PE), OREVAC 18341 from Arkema, was used as a coupling agent.
Initially, a matrix blend consisting of HDPE/MA-g-PE at a 10:1 weight ratio was prepared in a Beutelspacher SB-19 single screw extruder at 140 °C. The extruded material strand was cooled in a water bath and pelletized. HDPE–nanoclay composites were then prepared by incorporating 1, 3, and 5 wt% of I.31PS nanoclay into the HDPE/MA-g-PE matrix blend, designated as HDPE-1, HDPE-3, and HDPE-5, respectively. Prior to mixing, the nanoclays were sieved using a 20 m mesh to remove large agglomerates and dried in a fan oven at 60 °C for 24 h. Nanocomposites were prepared in the same extruder at 140 °C, water cooled, and pelletized. The obtained HDPE–nanoclay composite pellets were extruded two more times to promote the shear-induced exfoliation of the nanoclays and a good dispersion in the HDPE/MA-g-PE matrix. To keep an equal thermal history, the same was done with the remaining HDPE/MA-g-PE (HDPE-0) pellets used as a control.
For the HSDT tests, rectangular plates of 108 × 214 × 6 mm3 with a 1 mm depth 90 °V axial groove for guiding the crack path (Figure 1 b) were molded in a Battenfeld HM 100/525 injection molding machine at an injection temperature of 190–220 °C, an injection pressure of 60 MPa, and a packing pressure of 50 MPa. The mold was kept at room temperature. A 40 mm pre-crack was introduced at one end of the plate (at the end opposite to the injection gate), while an axial razor blade slit was scored on the opposite surface of the V groove to inhibit ligament tearing [20 (link)].
Initially, a matrix blend consisting of HDPE/MA-g-PE at a 10:1 weight ratio was prepared in a Beutelspacher SB-19 single screw extruder at 140 °C. The extruded material strand was cooled in a water bath and pelletized. HDPE–nanoclay composites were then prepared by incorporating 1, 3, and 5 wt% of I.31PS nanoclay into the HDPE/MA-g-PE matrix blend, designated as HDPE-1, HDPE-3, and HDPE-5, respectively. Prior to mixing, the nanoclays were sieved using a 20 m mesh to remove large agglomerates and dried in a fan oven at 60 °C for 24 h. Nanocomposites were prepared in the same extruder at 140 °C, water cooled, and pelletized. The obtained HDPE–nanoclay composite pellets were extruded two more times to promote the shear-induced exfoliation of the nanoclays and a good dispersion in the HDPE/MA-g-PE matrix. To keep an equal thermal history, the same was done with the remaining HDPE/MA-g-PE (HDPE-0) pellets used as a control.
For the HSDT tests, rectangular plates of 108 × 214 × 6 mm3 with a 1 mm depth 90 °V axial groove for guiding the crack path (
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