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Abstract:In this study, polymer composites using low-density polyethylene (LDPE) and layered hydroxide salts (LHS) were synthesized. The following compositions of LHS were obtained Zn 5 (OH) 8 (A n-) 2/n .yH 2 O, where A was varied in order to obtain hydrophilic (A = NO 3 -) or hydrophobic (A = DDS --dodecyl sulfate or DBS --dodecyl benzene sulfonate). Synthesis was carried out by co-precipitation in alkaline medium and drying, being followed by characterization via Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy. A variable amount of filler was then incorporated into the LDPE via extrusion, which was then injection molded to obtain specimens for evaluating tensile properties (Young's modulus, tensile strength, strain at break and toughness). For comparison, the sodium salts of the surfactants (NaDDS and NaDBS) were also used as fillers in LDPE. The X-ray diffraction results indicated that the hydrophobic LHS were exfoliated in the polymer matrix, whereas the hydrophilic LHS was only delaminated. In the LDPE composites, melting and crystallization temperatures were nearly constant, along with the crystallinity indexes. The mechanical properties were mainly varied when the organophilic LHS was used. Overall, fillers based on LHS, especially those containing hydrophobic anions, may be interesting alternatives in the production of reinforced thermoplastics.

Resumo: O presente trabalho descreve a síntese e caracterização de hidróxidos duplos lamelares (HDL) de Zn/Al na razão molar 2:1, os quais foram intercalados com íons cloreto hidratados e ânions derivados dos corantes azo alaranjado de metila (AM) e alaranjado II (AII). Após caracterização, os materiais foram utilizados como cargas em polietileno de alta densidade (PEAD) e nanocompósitos foram preparados por extrusão e injeção, seguindo a norma ASTM D638-10. Os teores de cargas variaram de 0,1 até 2% (incluindo-se os sais de sódio dos corantes) e os nanocompósitos homogêneos foram avaliados em relação as suas propriedades estruturais, térmicas e mecânicas. De modo geral, após a adição das cargas existe somente uma pequena influência na temperatura de fusão e cristalização do PEAD. Para os HDLs contendo o pigmento intercalado com o ânion do corante AM e sais de sódio de ambos os corantes, as propriedades mecânicas apresentaram leve aumento do módulo e tensão de ruptura e diminuição do alongamento em relação ao polímero puro e um comportamento inverso foi observado para o ânion AII, além do HDL contendo ânions cloreto hidratados. Palavras-chave: Polietileno de alta densidade, nanocompósitos, hidróxidos duplos lamelares, corantes azo, intercalação. High-Density Polyethylene Nanocomposites Containing Layered Double Hydroxides, Intercalated with Anions Derived from Azo Dyes.Abstract: The present work describes the synthesis and characterization of Zn/Al layered double hydroxides (HDL) in the molar ratio 2:1, which were intercalated with hydrated chlorine ions and anions derived from the azo dyes methylorange (AM) and orange II (AII). After characterization, the materials were used as fillers into high density polyethylene (HDPE) and the nanocomposites were prepared by extrusion and injection, following the norm ASTM D638-10. The filler contents varied from 0.1 to 2% (including the sodium dye salts) and the homogeneous nanocomposites were evaluated in relation to their structural, thermal and mechanical properties. In general, after the fillers' addition there is only a small influence in the melting and crystallization temperature of HDPE. For HDLs intercalated with the anionic dye AM and both sodium dyes, the mechanical properties presented a small influence on Young's modulus and tensile strength and an increase in elongation compared to pure HDPE and an inverse behavior was observed for the anion AII, in addition to the HDL containing hydrated chlorine anions. Keywords: High density polyethylene, nanocomposites, layered double hydroxides, azo dyes, intercalation. IntroduçãoMateriais nanocompósitos poliméricos tiveram o seu descobrimento nos laboratórios de pesquisa da Toyota no Japão (Toyota Central Research Development Laboratories-TCRDL), no início dos anos 90 do século passado [1][2][3] . Primeiramente os materiais utilizados como cargas foram os argilominerais trocadores catiônicos do tipo 2:1, os quais para compatibilização com polímero hidrofóbicos foram submetidos a reações de troca iônica, com cátions de s...

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Pheromones U 1280Chemoenzymatic Synthesis of the Aggregation Pheromones (S)-2-Methyl-4-octanol and (4S,2E)-6-Methyl-2-hepten-4-ol. -The title pheromones (V) and (VII) are prepared using enzymatic resolution of alkynol (I) as the key step. A second enzymatic resolution is used for the preparation of enantiomerically enriched alcohol (S)-(I). -(MARQUES*, F. A.; ZIMMERMANN, A.; DELAY, C. E.; SALES MAIA, B. H. L. N.; Lett. Org. Chem. 5 (2008) 1, 69-72; Dep. Quim., Univ. Fed.