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The black walnut, Junglas nigra, is indigenous to eastern North America, and abscission of its fruit occurs around October. The fruit consists of a husk, a hard shell, and kernel. The husk is commonly discarded in processing, though it contains phenolic compounds that exhibit antioxidant and antimicrobial properties. For this study, black walnut husks were extracted using supercritical carbon dioxide with an ethanol modifier. The effects of temperature, ethanol concentration, and drying of walnut husks prior to extraction upon antioxidant potential were evaluated using a factorial design of experiments. The solvent density was held constant at 0.75 g/mL. The optimal extraction conditions were found to be 68°C and 20 wt‐% ethanol in supercritical carbon dioxide. At these conditions, the antioxidant potential as measured by the ferric reducing ability of plasma (FRAP) assay was 0.027 mmol trolox equivalent/g (mmol TE/g) for dried walnut husk and 0.054 mmol TE/g for walnut husks that were not dried. Antioxidant potential was also evaluated using the total phenolic content (TPC) and 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) assays and the FRAP assay was found to linearly correlate to the TPC assay.

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Chemical surface modification of polymethylmethacrylate (PMMA) and polypropylene (PP) particles was achieved using a continuous atmospheric plasma process, resulting in increased oxidation and hydrophilicity. Contact angles of treated PMMA ranged from 79–117° (125° for untreated). Air plasma produced higher contact angles than pure nitrogen, which is attributed to primary surface degradation from oxygen. Higher energy and flow rate of water resulted in decreased contact angles. Treated PP mixed in water upon agitation, while untreated PP remained at the surface. X‐ray photoelectron spectroscopy (XPS) showed increased CO and CO for treated samples. The addition of 10% hydroxyethylmethacrylate (HEMA) to water showed a slight decrease in contact angle, but no difference from pure water in XPS results.