Plasti corder

PBSA blended with PHEF were produced in a Brabender Plasti Corder equipment, processing 55 g of material in each trial at 140 °C, at a roller speed of 60 rpm, and a mixing time of 2.5 min. Sheets of the material were prepared by compression molding at 170 °C and controlled cooling in a pressing machine. 0.8 mm thickness sheets were used to shape the tensile bars and perform the aging test. One physical blend of PBSA and PHEF was prepared with 5 wt% of the ferulic acid-based oligomer (PBSA_BLEND) while two additional blends were reactively mixed in presence of 0.25 and 0.5 wt% of a radical source such as Luperox^® 101XL45 obtaining PBSA_REX0.25 and PBSA_REX0.5 respectively. A reference formulation was also prepared based on neat PBSA with 0.5 wt% of commercial Irganox^®1010 as a common industrial stabilizer for long-term protection of polyolefins (PBSA_0.5IRG). A maximum of 0.5 wt% of Irganox^® was used in the reference formulation following the recommendations of the technical datasheets of the product.

In the two-step preparation procedure, the solution casted TPS (step 1) was homogenized with PCL by melt-mixing (MM; step 2) at elevated temperature in the W50EH chamber of the twin-screw laboratory mixer (Brabender Plasti-Corder; Duisburg, Germany). The samples were mixed in the chamber preheated to 120 °C, using rotation speed 60 rpm for 8 min. The blend was compression molded to 2 mm thick plaques in a laboratory hot press (Fontijne Grotnes; Vlaardingen, Netherlands) at 130 °C for 2 min under 50 kN to deaerate, plus another 1 min under 100 kN followed by water cooling for ca 15 min under 100 kN to obtain the final plaques.

HDPE, polyester from RS-polyol, polyester from WPET, and their hybrid (50:50) were blended using weight ratios 100/0, 95/5, and 90/10 in an internal mixer (Brabender plasticorder) at 30 rpm and temperatures 170 °C. First, HDPE was added to the mixer, and the polyester was added after the polymers had reached their melt flow temperature, followed by silica in a fixed weight ratio (5%). The mixing process took 5 min on average. Next, the resultant composite was removed from the mixer, pressed into fixed dimensions (152 × 125 × 2.85 mm), using a laboratory hydraulic hot press at 170 °C for 5 min, and then cooled down to room temperature.
The mechanical measurements of polyesters and their composites, such as tensile strength, elongation at break, and modulus of toughness from stress–strain curves, were investigated using Zwick tensile testing machine (model Z010, Germany) according to ASTM D 638-03.
The morphology study was examined, after coating the samples with gold, by scanning electron microscopy using the Quanta instrument (model FEG250, FEI, Hillsboro, Oregon, USA), running the electron beam at 20 kV accelerating voltage.

All compositions were prepared using a Brabender mixer Type W50 driven by a Brabender Plasticorder. Initially the polypropylene was added and allowed to melt at 210 °C at 20 rpm for 15 min, followed by addition of graphene. The combined composite was then mixed at 210 °C at 50 rpm for another 15 min. Following compounding the composites were cut into small pellet-like pieces for easier use.

Grafting of MA onto NR was done by mixing the NR with 4 phr of MA in a Brabender Plasticorder at 145 °C at a rotor speed of 60 rpm under a normal atmosphere. The mixing lasted for 10 min. The resulting rubber was purified by reprecipitation. This was done just for the purpose of characterization by FTIR. The resulting MNR was then purified to confirm the grafting of MA onto NR. This was carried out by dissolving the rubber sample in toluene at room temperature for 24 h and then at 60 °C for 2 h. The soluble part was collected and precipitated in acetone. The sample was dried in a vacuum oven at 40 °C for 24 h. The purified MNR was finally characterized by the FTIR spectrum.

PLA and PCL pellets were previously dried under a vacuum at 80 and 45 °C, respectively, for 12 h before the melt blending. The blending was carried out using a Brabender Plasticorder with a chamber volume of 55 cm³ and roller blades at 200 °C for 9 min with a rotation speed of 60 rpm. The blend ratio was controlled at 90:10 wt %, and EMA-GMA was added at 0, 2, 4, 6, 8, and 10 phr. Furthermore, the pure PLA was subjected to the same mixing treatment to create the same thermal history as that of the blends. The abbreviation for each formulation is assigned as follows: PLA, PLA/PCL, PLA/PCL/2, PLA/PCL/4, PLA/PCL/6, PLA/PCL/8, PLA/PCL/10, respectively. Then, all of the samples were hot-compression-molded into 1- or 4-mm-thick sheets at 200 °C and 12 MPa for 6 min. All the samples were conditioned at 50% relative humidity and 25 °C for at least 48 h before the testing.