H2SO4 CNCs were produced following a literature method, using
cotton linter as the starting material [28]. The method for preparation
of HCl-CNCs from cotton linter follows a literature method
[27] whereas the preparation of LA-CNCs and AA-CNCs were performed
as described below. Cotton linter pieces were soaked
overnight in either concentrated acetic acid or in deionized (DI)
water. The concentration of the organic acid (acetic or lactic acid)
was about 90 wt% in water. A typical reaction mixture for the
preparation of LA-CNCs and AA-CNCs consisted of 30 g of cotton,
307 g lactic acid or acetic acid and 1.8 mL of concentrated HCl
(12 M). To prepare HCl CNCs, 30 g of cottonwas mixed with 310 g of
0.4 M HCl. The reactions were transferred to containers (Ball® 8oz
Regular Mouth Half Pint Jars) that were tightly sealed and capable
of withstanding pressures attained in reactions. The resulting suspensionwas
maintained at 150 C in a convection oven for 3 h. In all
experiments, the final solid-to-liquid ratio was 0.04 g cotton linter
per mL acid solution for both organic acid and HCl solutions. The
corresponding workup was identical for all of the aforementioned
modified and HCl-CNCs. After hydrolysis for 3 h, the suspension
was mechanically agitated in a Waring laboratory blender for
20 min. Subsequently, an equal volume of DI water was added and
CNCs were isolated by repeated centrifugation at 8600 g for 3 min
and replacement of the initially clear supernatant with DI water.
Once the pH reached about 5, the supernatant remained turbid
after centrifugation. After collection of the first turbid supernatant,
the cake was resuspended and again centrifuged to obtain additional
CNCs in the form of a turbid supernatant. The first three
turbid supernatants were recovered, combined, and analyzed. The
resulting CNC slurries were freeze-dried to produce frangible
powder suitable for use as nanofiller in polymer materials.
H2SO4 CNCs were produced following a literature method, usingcotton linter as the starting material [28]. The method for preparationof HCl-CNCs from cotton linter follows a literature method[27] whereas the preparation of LA-CNCs and AA-CNCs were performedas described below. Cotton linter pieces were soakedovernight in either concentrated acetic acid or in deionized (DI)water. The concentration of the organic acid (acetic or lactic acid)was about 90 wt% in water. A typical reaction mixture for thepreparation of LA-CNCs and AA-CNCs consisted of 30 g of cotton,307 g lactic acid or acetic acid and 1.8 mL of concentrated HCl(12 M). To prepare HCl CNCs, 30 g of cottonwas mixed with 310 g of0.4 M HCl. The reactions were transferred to containers (Ball® 8ozRegular Mouth Half Pint Jars) that were tightly sealed and capableof withstanding pressures attained in reactions. The resulting suspensionwasmaintained at 150 C in a convection oven for 3 h. In allexperiments, the final solid-to-liquid ratio was 0.04 g cotton linterper mL acid solution for both organic acid and HCl solutions. Thecorresponding workup was identical for all of the aforementionedmodified and HCl-CNCs. After hydrolysis for 3 h, the suspensionwas mechanically agitated in a Waring laboratory blender for20 min. Subsequently, an equal volume of DI water was added andCNCs were isolated by repeated centrifugation at 8600 g for 3 minand replacement of the initially clear supernatant with DI water.Once the pH reached about 5, the supernatant remained turbidafter centrifugation. After collection of the first turbid supernatant,the cake was resuspended and again centrifuged to obtain additionalCNCs in the form of a turbid supernatant. The first threeturbid supernatants were recovered, combined, and analyzed. Theresulting CNC slurries were freeze-dried to produce frangiblepowder suitable for use as nanofiller in polymer materials.
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