The seashells, a serious environmental hazard, are composed mainly by calcium carbonate, which can be used as filler in polymer matrix. The main objective of this work is the use of calcium carbonate from seashells as a bio-filler in combination with eco-friendly epoxy matrices thus leading to high renewable contents materials.Previously obtaining calcium carbonate, the seashells were washed and grinded. The powder obtained and the resin was characterized by DSC, TGA, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and rheology plate-plate. The results show that addition of 30 wt. % of seashell bio-filler increase mechanical properties as flexural modulus (over 50%) and hardness Shore D (over 6%) and thermal properties as an increase around 13% in glass transitions temperature. The results show that the addition of calcium carbonate from seashells is an effective method to increase mechanical properties of bio-composite and to reduce the residue of seashells from industrial production.
The continuous rise in oil prices has led to the use of other ways to obtain polymer materials. This paper proposes a methodology to obtain a thermosetting resin from cottonseed oil by epoxidation process. The cottonseed oil contains as most representative fatty acids: 52.5% of linoleic acid (C18: 2), 23.9% of palmitic acid (C16: 0) and 17.6% of oleic acid (C18: 1); the real iodine index, which is indicative of the number of double bonds, has a value of 107. Epoxidized cottonseed oil (ECSO) has been successfully obtained using conventional epoxidation process with hydrogen peroxide, acetic acid and sulfuric acid, maintaining a constant temperature of 70 ºC with homogeneous magnetic stirring. Average oxirane oxygen content (OOC) of 5.32% can be obtained by conventional epoxidation process which represents a yield over 83%. The epoxidized oil has been crosslinked with mixtures of two cyclic anhydrides to tailor different properties on final crosslinked thermosetting resins: on the one hand, methyl nadic anhydride (MNA) which is characterized by a rigid molecular structure and on the other hand, dodecenylsuccinic anhydride (DDSA) with a long side chain that can confer flexibility. The crosslinking process has been followed by dynamic differential scanning calorimetry (DSC), ionic mobility and oscillatory rheometry (OR) as well as gel time determination.The effect of the hardener mixture (wt. % DDSA:MNA) on mechanical performance of cured materials has been followed by flexural and impact tests as well as the evolution of the storage modulus (G') by dynamic mechanical analysis (DMA) in torsion mode. By selecting the appropriate hardener mixture, it is possible to obtain crosslinked materials with different properties ranging from
RESUMO Com o objetivo de avaliar um protocolo de reabilitação em cães submetidos a homoimplante ortotópico tenopatelar conservado em glicerina a 98%, seguido de imobilização rígida temporária da articulação do joelho, oito cães foram distribuídos em dois grupos de igual número ABSTRACT The objective of this study was to evaluate the influence of a rehabilitation procedure in eight dogs undergone to arthroplasty followed by rigid immobilization of the knee joint. The dogs were alocated into a treated group (Group I) and a control group (Group II). After the removal of the biplanar external skeletal fixation device, the dogs from Group
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