2.4. Preparation of (composite) spheres as masterbatch for extrusion/ melt-spinning
In this work, thermally induced phase separation (TIPS) [32] was used to produce composite spheres, as detailed in our previous work [28]. The method enables the homogeneous dispersion of large quantities of dry BC, modified-BC, as well as CNCs in a polymer melt using conventional extrusion processes at later stages.
Five types of composite feedstock were made: PLLA + 2 wt.% BC; PLLA + 2 wt.% C6-BC; PLLA + 2 wt.% C12-BC; PLLA + 7 wt.% CNC; PDLLA containing 7 wt.% CNC. For the production of CNC containing composite spheres, the concentration of CNCs was adjusted to the correct amount relative to PLA in 1,4-dioxane and thesolution homogenised at 20,000 rpm to disperse them in solvent prior to subsequent freezing in liquid nitrogen and freeze-drying [28]. Neat PLLA and PDLLA spheres were also produced as feedstock
[28]. Briefly, the resulting mixtures were poured separately into individual 50 ml syringes and added drop wise into a bath of liquid nitrogen to rapidly induce phase separation. The precipitates were collected in a 500 ml round bottom flask and subsequently freeze-dried to yield porous neat polymer and composite spheres, measuring circa 2–4 mm in diameter, suitably small to enter the extruder feed port.
2.4. Preparation of (composite) spheres as masterbatch for extrusion/ melt-spinningIn this work, thermally induced phase separation (TIPS) [32] was used to produce composite spheres, as detailed in our previous work [28]. The method enables the homogeneous dispersion of large quantities of dry BC, modified-BC, as well as CNCs in a polymer melt using conventional extrusion processes at later stages.Five types of composite feedstock were made: PLLA + 2 wt.% BC; PLLA + 2 wt.% C6-BC; PLLA + 2 wt.% C12-BC; PLLA + 7 wt.% CNC; PDLLA containing 7 wt.% CNC. For the production of CNC containing composite spheres, the concentration of CNCs was adjusted to the correct amount relative to PLA in 1,4-dioxane and thesolution homogenised at 20,000 rpm to disperse them in solvent prior to subsequent freezing in liquid nitrogen and freeze-drying [28]. Neat PLLA and PDLLA spheres were also produced as feedstock[28]. Briefly, the resulting mixtures were poured separately into individual 50 ml syringes and added drop wise into a bath of liquid nitrogen to rapidly induce phase separation. The precipitates were collected in a 500 ml round bottom flask and subsequently freeze-dried to yield porous neat polymer and composite spheres, measuring circa 2–4 mm in diameter, suitably small to enter the extruder feed port.
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