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Published in Antonio Paesano, Handbook of Sustainable Polymers for Additive Manufacturing, 2022
Braskem (Brazil) produces a biobased, sustainable version of PE called BioPE™ derived from sugar contained in sugarcane and sugar beet. Filgueira et al. (2018) selected BioPE™ to develop for the first time a fully sustainable fiber-filled PE filament for FFF that met requirements related to surface finish, void content, warping, bending, interlayer adhesion, and water uptake, and overcame the incompatibility between natural hydrophilic fibers and hydrophobic matrix. The authors selected two BioPE™ grades: one with MFI 20 g/10 min (labeled BioPE1) and the other with MFI 4.5 g/10 min (labeled BioPE2), and thermomechanical pulp (TMP) fiber from Norway spruce chips with initial length and diameter of 1.5 mm and 33 μm, respectively. Since PE is hydrophobic whereas TMP fibers are hydrophilic, fiber surface was modified, by grafting one of two hydrophobic compounds and antioxidant food additives, octyl gallate (OG) or lauryl gallate (LG), with the aid of laccase, an environmentally friendly enzyme. The maleic anhydride PE Licocene MA 4351 by Clariant was also added to improve the compatibility between TMP fiber and PE. Blends of 14 different compositions of the above ingredients (TMP fiber content was 10 and 20 wt%) were extruded into 2 mm diameter filaments for FFF at 150−160°C and 155−165°C using higher and lower MFI, respectively. Some filaments were extruded twice to improve the filament’s quality. Under SEM, the filaments extruded twice showed fibers uniformly distributed and absence of large voids, and fibers modified with LG and OG were more uniformly distributed than fibers unmodified. Compared to filaments made of BioPE1, those made of BioPE2 were smoother, featured lower thickness variation, and showed better fiber blending. Importantly, fiber-matrix interfacial adhesion might have depended on the degree of hydrophobicity acquired by the TMP fibers, and chemical structure of PE. Porosity was very large (Figure 11.2), and likely to markedly penalize the mechanical properties (not measured). Namely, in filaments made of unfilled BioPE1 and BioPE2 void content was 0.1%, but in fiber-BioPE1 and fiber-BioPE2 it jumped to 8‒47% and 11‒27% respectively: porosity at 10 wt% fiber content was lower than at 20 wt%, and lower at smaller MFI than at greater MFI. Higher MFI and fiber content were associated to higher water uptake than lower MFI and fiber content. BioPE2 outperformed BioPE1 in printability that was assessed in terms of swelling, shrinkage, geometrical fidelity, and interlayer adhesion. Surface finish was evaluated visually not instrumentally on printed samples of BioPE2, and appeared not significantly different between unmodified and modified fibers. Samples printed with LG-TMP fibers showed a similar smoothness without warping or curling for both 10 wt% and 20 wt% fiber content, while items with OG-TMP fibers where smoother at 20 wt% than at 10 wt%.
Combined application of gallate ester and α-tocopherol in oil-in-water emulsion: Their distribution and antioxidant efficiency
Published in Journal of Dispersion Science and Technology, 2020
YangLing Wang, Chen Wu, XiaoYa Zhou, MoRan Zhang, Yi Chen, ShaoPing Nie, MingYong Xie
Stripped corn oil was bought from MERYER chemical technique (Shanghai, China). Ethylenediaminetetraacetic acid (EDTA) disodium salt, FeSO4, Tween 20, BaCl2, phosphoric acid, sodium phosphate mono- and dibasic were purchased from Aladdin (Shanghai, China). Gallic acid, propyl gallate (R3), octyl gallate (R8), and dodecyl gallate (R12) were purchased from jkchemical (Shanghai, China). Methanol was obtained from Fisher Scientific (Pittsburgh, PA). Trolox, α-Tocopherol quinone and N-(1-naphthyl) ethylenediamine dihydrochloride (NED) were purchased from Sigma-Aldrich (St. Louis, MO). Double-distilled and deionized water was used for the preparation of all solutions.