Search Results (8)

In the current environmental scenario, the proposal of alternatives for petroleum-based products has considerably increased, with the aim of looking for bioproducts with interesting properties such as biodegradability, sustainability and efficiency, among others. In this sense, the role of biolubricants is promising, offering a wide range of possibilities through different methods and operating conditions. Specifically, double transesterification could be a suitable process in a biorefinery context. The aim of this work was to produce a biolubricant through double transesterification with methanol and neopentyl glycol (NPG) under different reaction conditions by using homogeneous catalysis (sodium methoxide). Different catalyst concentrations, among other changes in reaction conditions (temperature ranging between 100 and 140 °C and NPG/FAME ratios between 0.5 and 2), were used, obtaining high conversion values (96%) and a final product with a high viscosity (20.7 cSt), which allows for its use as engine oil (SAE 5W). In conclusion, biodiesel and biolubricant production was feasible through homogeneous catalysis, proving the feasibility of this process at the laboratory scale. Further studies, including the use of different heterogeneous catalysts, as well as the implementation of this process at a semi-industrial scale, are recommended. Full article

Elastomer composites for dynamic mechanical applications with a low dissipation of energy are of great importance in view of their application in tire compounds. In this work, furnace carbon black functionalized with 2-2,5-dimethyl-1H-pyrrol-1-yl-1,3-propanediol (SP) was used in place of silica in an elastomer composite based on poly(styrene-co-butadiene) from solution anionic polymerization and poly(1,4-cis-isoprene) from Hevea Brasiliensis. The traditional coupling agent used for silica was also used for the CB/SP adduct: 3,3′-bis(triethoxysilylpropyl)tetrasulfide (TESPT). The composite with the CB/SP + TESPT system revealed a lower Payne effect, higher dynamic rigidity, and lower hysteresis, compared to the composite with CB + TESPT, although the latter composite had a higher crosslinking density. The properties of the silica and the CB/SP + TESPT-based composites appear similar, though in the presence of slightly higher hysteresis and lower ultimate properties for the CB/SP-based composite. The use of CB in place of silica allows us to prepare lighter compounds and paves the way for the preparation of tire compounds with lower environmental impacts. Full article

Elastomer composites with low hysteresis are of great importance for sustainable development, as they find application in billions of tires. For these composites, a filler such as silica, able to establish a chemical bond with the elastomer chains, is used, in spite of its technical drawbacks. In this work, a furnace carbon black (CB) functionalized with polar groups was used in replacement of silica, obtaining lower hysteresis. CBN326 was functionalized with 2-(2,5-dimethyl-1H-pyrrol-1-yl)-1,3-propanediol (serinol pyrrole, SP), and samples of CB/SP adducts were prepared with different SP content, ranging from four to seven parts per hundred carbon (phc). The entire process, from the synthesis of SP to the preparation of the CB/SP adduct, was characterized by a yield close to 80%. The functionalization did not alter the bulk structure of CB. Composites were prepared, based on diene rubbers—poly(1,4-cis-isoprene) from Hevea Brasiliensis and poly(1,4-cis-butadiene) in a first study and synthetic poly(1,4-cis-isoprene) in a second study—and were crosslinked with a sulfur-based system. A CB/silica hybrid filler system (30/35 parts) was used and the partial replacement (66% by volume) of silica with CB/SP was performed. The composites with CB/SP exhibited more efficient crosslinking, a lower Payne effect and higher dynamic rigidity, for all the SP content, with the effect of the functionalized CB consistently increasing the amount of SP. Lower hysteresis was obtained for the composites with CB/SP. A CB/SP adduct with approximately 6 phc of SP, used in place of silica, resulted in a reduction in ?G?/G? of more than 10% and an increase in E’ at 70 °C and in ?₃₀₀ in tensile measurements of about 35% and 30%, respectively. The results of this work increase the degrees of freedom for preparing elastomer composites with low hysteresis, allowing for the use of either silica or CB as filler, with a potentially great impact on an industrial scale. Full article

In the first part of this review, secondary carbon-carbon bond formation by using allylic coupling reactions with aryl and alkenyl borates is presented. Early investigations have revealed the suitability of a nickel catalyst and [R^TB(OMe)₃]Li (R^T: transferable group). Due to their low reactivity, the borates were converted to more reactive congeners possessing an alkanediol ligand, such as 2,3-butanediol and 2,2-dimethyl-1,3-propanediol. Borates with such diol ligands were used to install aryl and alkenyl groups on the monoacetate of 4-cyclopentenyl-1,3-diol. Furthermore, alkenyl borates showed sufficient reactivity toward less reactive allylic alcohol derivatives with bromine atoms at the cis position, producing dieneyl alcohols. In the second part, copper-based and/or copper-catalyzed substitutions of secondary allylic picolinates, propargylic phosphonates, and alkyl (2-pyridine)sulfonates with RMgX are briefly summarized. The application of these reactions to the synthesis of biologically active compounds is also discussed. Full article

A series of poly(ester amide)s based on dimethyl furan 2,5-dicarboxylate (DMFDC), 1,3-propanediol (PDO), 1,6-hexylene glycol (HDO), and 1,3-diaminopropane (DAP) were synthesized via two-step melt polycondensation. The phase transition temperatures and structure of the polymers were studied by differential scanning calorimetry (DSC). The positron annihilation lifetime spectroscopy (PALS) measurement was carried out to investigate the free volume. In addition, the mechanical properties of two series of poly(ester amide)s were analyzed. The increase in the number of methylene groups in the polymer backbone resulted in a decrease in the values of the transition temperatures. Depending on the number of methylene groups and the content of the poly(propylene furanamide) (PPAF), both semi-crystalline and amorphous copolymers were obtained. The free volume value increased with a greater number of methylene groups in the polymer backbone. Moreover, with a lower number of methylene groups, the value of the Young modulus and stress at break increased. Full article

The production of sustainable and biodegradable products, for energy or material use, is becoming important for local economies. Thus, biorefineries can play an important role in sustainable development at regional levels and therefore the search for feedstocks with multiple uses is vital. The goal of this research was to assess the implementation of Cynara Cardunculus L. oil as the basis of a biorefinery for biodiesel and biolubricant production, proposing the main steps for this purpose. The chemical reaction selected for biodiesel and biolubricant production was transesterification, using methanol and other more complex alcohols. The optimization of each step was carried out, assessing the yield by gas chromatography. Once the optimum conditions were selected, the main characteristics of the biofuel or biolubricant were measured, paying attention to viscosity and oxidative stability. As a result, Cynara Cardunculus L. oil could be a suitable feedstock for a biorefinery, as long as some antioxidants are added in final products, especially to increase its oxidative stability in biodiesel (whose value was 1.35 h). Concerning biolubricant production, the yields were acceptable (exceeding 92%) and the products showed variable viscosity values (from 8.6 to 18.85 cSt), implying a desirable diversification of production depending on demand. Full article

The hydrophilic copolyester polyethylene terephthalate (PET) (ENCDP-X) was successfully synthesized by chemical modification consisting of copolymerization and blending and the comonomers, including sodium isophthalate-5-sulfonate (SIPE), polyethylene glycol (PEG), 2,2-dimethyl-1,3-propanediol (NPG) and matting agent TiO₂ with different content. Moreover, the structural characterization of sequential structure, crystallization and thermal properties were studied. The results showed that the comonomers were successfully embedded in the copolyester, the actual molar ratio in the copolyester was consistent with the relative feed ratio and the degree of randomness was calculated to be 0.99, showing that the random copolymers synthesized during the melt polycondensation process and the chemical structure was roughly consistent with the expected molecular chain sequence structure. The thermal parameters of the modified copolyester, containing the glass transition temperature (T_g), melting point (T_m), crystallinity (X_c) and thermal degradation temperature, were decreased, and the cold crystallization temperature (T_c) was increased. In addition, with the increasing of the TiO₂ content, it improves the thermal performance of the copolyester and it is beneficial to processing and application. The above conclusion is further verified by non-isothermal kinetic analysis. In addition, the copolyester exhibited the better hydrophilicity than pure PET. Full article

The aim of this work is to prepare flame-retardant biobased poly(lactic acid) materials through incorporating a novel flame retardant dihydroxy-containing ammonium phosphate (DAP) derived from 2-chloro-5,5-dimethyl-1,3,2-dioxaphosphinane-2-oxide (DOP) and 2-amino-2-methyl-1,3-propanediol (AMPD). Interestingly, PLA modified with only 0.5% DAP passed UL-94 V-0 rating, and possessed a limiting oxygen index (LOI) value of 24.6%, which would further increase with the increasing loading of DAP. PLA/DAP did not exhibit obviously improved results in terms of heat release rate (HRR), as the loading of DAP was relatively low. It was found that DAP showed little effect on the thermal stability of PLA and the onset decomposition temperatures of PLA and PLA/DAP blends were very close. Besides, the degree of crystallization increased because of the plasticized effect of DAP. Based on the analyses of flame-retardant mechanism of DAP, it disclosed that DAP decomposed to generate incombustible compounds, such as water and ammonia, to dilute the concentration of oxygen and fuels, and then release some phosphorus-containing fragments that could produce phosphorus-containing free radicals to interrupt free-radical reactions, and finally noncombustible melt dripping was produced so as to bring away large amount of heat and stop the feedback of heat to the matrix. Full article