Fused deposition modeling (FDM) is a rapidly growing additive manufacturing technology due to its ability to manufacture complex‐shaped parts in a simple process. FDM parts present inherent porosity due to the fabrication process. The mechanical performance of the built part depends on controlling several printing parameters of the specimen and the quantity of voids. PLA/PBAT [polylactic acid/poly(butylene adipate‐co‐terephthalate)] blend is a biodegradable polyester with bio‐based content that is used as a potential replacement for conventional petroleum‐based polymers. PBAT reduces the stiffness and improves the tear strength of PLA. There is a lack of research on PLA/PBAT 3D printed parts, especially the relationship between flexural mechanical properties and porosity of PLA/PBAT parts. The aim of this work is to investigate the effect of layer thickness (LT), deposition speed (DS), and printing direction (PD) on porosity and flexural properties of PLA/PBAT blend parts. Experimental design method is used to identify the set of parameters, which gives optimized results. Specimens fabricated with lower printing parameter values allowed obtaining parts with less porosity and consequently improved bending properties.
Chiral GC separation of (+/-)-2-allyl-2-carboethoxycyclopentanone (9) and the alcohols (+/-)-3-(hydroxymethyl)-5-carboethoxy-2-oxabicyclo[3.3.0]octane (7), (+/-)-2-allyl-2-carboethoxycyclopentanol (8), and their acetylated and trifluoroacetylated derivatives were investigated on three derivatized beta-cyclodextrins (CDs) diluted in SE-54 or 1701-OH: 2,3,6-tri-O-methyl-beta-CD (PMCD); 2,3-di-O-methyl-6-O-(tert-butyldimethylsilyl)-beta-CD (DIMETBCD); 2,3-di-O-acetyl-6-O-(tert-butyldimethylsilyl)-beta-CD (DIACTBCD). The understanding of these chiral separations is extremely relevant, since cyclopentanic and bicyclic cyclopentanic rings are common structural features of many important natural products and new pharmaceutical drugs. In general DIMETBCD diluted in SE-54 showed the best chiral resolution to alcohols 7 and 8 and only DIACTBCD showed enantioselectivity to 9. Hydrogen bonds prediction and dipole moments data were obtained by molecular modeling calculations for 7ab and 8ab and Ac and TFA derivatives. Comparison of these data with the chromatographic parameters for the related compounds were used to explain the differences of their elution orders and diastereo- and enantiomeric separations on the above chiral stationary phases (CSPs). The results suggest that the CSPs enantioselectivities are not affected by the carboethoxy-functionalized cyclopentanic and bicyclic cyclopentanic rings themselves but mainly by the functional group on the other stereogenic center.
This article presents the development and characterization of environmentally friendly composites comprising polypropylene (PP) reinforced with Bahia Beige (BB) marble waste. The composites were prepared using different PP/BB weight ratios and analyzed for their chemical, physical, mechanical, microstructural, and thermal properties. X-ray fluorescence (XRF) analysis revealed the composition of BB, which exhibited a significant concentration of CaO, indicating the presence of calcite and other oxides. X-ray diffraction (XRD) analysis confirmed the presence of PP and identified calcite, dolomite, and quartz phases in the composites. Due to enhanced ceramic reinforcement, the composites displayed increased crystallinity with higher BB content. Fourier-transform infrared (FTIR) analysis demonstrated the interaction between PP and BB, with the bands corresponding to PP being replaced by bands related to BB as filler content increased. The density tests indicated a slight increase in composite density without deviating significantly from pure PP, which is advantageous for low-density applications. The hardness of the composites increased with filler content, while the impact resistance decreased notably. Scanning electron microscopy (SEM) images showed the good distribution of BB within the composites and the presence of ductile characteristics on the composite surface. The heat deflection temperature (HDT) results revealed that adding BB up to 40% by weight increased HDT, whereas a significant reduction occurred at a 50% BB content. These composites demonstrated favorable properties for engineering applications, offering a sustainable solution through utilizing natural waste resources and contributing to Brazilian sustainability efforts.
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