DETERMINATION OF THE STABILITY OF COMPLEX COMPOUNDS OF COPPER (II), ZINC (II), CADMIUM (II) AND SILVER (I) WITH COVALENTLY IMMOBILIZED SULFUR CONTAIN LIGANDS

"The purpose of this study is to determine the stability of the obtained coordination compounds of some d-metals with covalent immobilized sulfur-containing ligands. To achieve this goal, coordination compounds of copper (II), zinc (II), cadmium (II) and silver (I) ions with covalent immobilized sulfur-containing ligands - О,О-di- (2-aminoethyl) -dithiophosphate potassium - polyester matrix (KD2AEDTP-PEM), O,O-di- (2-aminoethyl) -dithiophosphate potassium - carbamide-formaldehyde matrix (KD2AEDTP-KFM). Studies were carried out to determine the acid-base properties of covalent-immobilized sulfur-containing ligands - KD2AEDTP-PEM, KD2AEDTP-KFM and the concentration stability of the obtained coordination compounds with ions of copper (II), zinc (II), cadmium (II), and silver (I). Based on the results of integral and differential potentiometric titrations, it was established that the ionization constants (pK) of the dithiophosphoric group in KD2AEDTP-PEM and KD2AEDTP-KFM are 3.23 and 3.35, and the ionization constants of the amino group are 9.76 and 9.63, respectively. As a result of studies of polymer ligands by potentiometric titration via the method of individual weighed portions, it was shown that polyfunctional polymer ligands have the ability to form stable coordination compounds with metal ions of copper (II), zinc (II), cadmium (II) and silver (I). "

MECHANICAL CHARACTERIZATION OF A POLYESTER MATRIX COMPOSITE REINFORCED WITH NATURAL FIBERS FROM Luffa cylindrica Hoen

The growing demand for renewable products has led to many studies of alternative materials. The present work describes the production of a composite based in polyester resin reinforced with fibers from the climber plant Luffa cylindrica and evaluates its mechanical performance. The composite was produced with two perpendicularly-crossed layers of vegetable fibers. The lamination was performed in a mold with two glass plates pressed by a hydraulic press. To characterize the properties of the produced composite, density, tensile and bending strength tests were performed. The final composite had a mean density of 1.16 g cm-3, making it light due to the reinforcement with vegetable fibers. Tensile and bending strengths were 13.91 and 26.70 MPa, respectively. The experimental results showed that the composite with vegetable fibers as reinforcement had lower density than the pure polyester matrix and composites produced with glass fibers. The tensile strength was higher than the polyester matrix itself, although it was still low. Also, when submitted to bending stress, the composite presented lower resistance than the matrix. Overall, the composite can be a viable alternative for non-structural applications where light materials are required such as handicrafts and office partition. Keywords: sustainable material; vegetable fibers; mechanical properties; technical feasibility. Caracterização mecânica de um compósito com matriz de poliéster reforçado com fibras naturais de bucha vegetal (Luffa cylindrica Hoen) RESUMO: A crescente demanda por produtos renováveis tem levado a muitos estudos de materiais compósitos reforçado com fibras vegetais. A planta trepadeira Luffa cylindrica, conhecida popularmente como bucha vegetal, também apresenta potencial para este uso. O presente trabalho avalia o desempenho de um compósito à base de resina de Poliéster reforçado com bucha vegetal. O compósito foi produzido com duas camadas de fibras vegetais dispostas perpendicularmente entre si. A laminação foi realizada em um molde com duas placas de vidro prensadas por uma prensa hidráulica. Como propriedade física foi determinada a densidade e para as propriedades mecânicas, foram realizados ensaios de resistência à tração e flexão. O compósito final apresentou densidade média de 1,16 g cm-3, tornando-o leve devido ao reforço com fibras vegetais. As resistências à tração e flexão foram de 13,91 e 26,70 MPa, respectivamente. Os resultados experimentais mostraram que o compósito com fibras vegetais como reforço apresentou densidade menor que a matriz de poliéster pura e compósitos produzidos com fibras de vidro. A resistência à tração foi maior do que a própria matriz de poliéster. Além disso, quando submetido a tensões de flexão, o compósito apresentou menor resistência do que a matriz. No geral, o composto pode ser uma alternativa viável para aplicações não estruturais onde materiais leves são necessários, como artesanatos e paredes divisórias. Keywords: material sustentável; fibras vegetais; propriedades mecânicas; viabilidade técnica.

Phosphonated Poly(ethylene terephthalate) Ionomers as Compatibilizers in Polyester/Polyamide Blends for Packaging Applications

Poly(ethylene terephthalate) (PET) is widely used in the packaging industry. The oxygen barrier properties of PET are acceptable for many food and beverage products, but do not meet the stringent requirements for packaging highly oxygen-sensitive products. Blending PET with aromatic polyamides, such as poly(m-xylyene adipamide) (MXD6), reduces the inherent oxygen permeability of the polyester matrix. Due to the immiscibility of these two parent polymers, a compatibilizer is necessary to achieve an efficient and stable mixing

Synthesis and mechanical behavior of composite material reinforced with Guadua fiber and with a polyurethane or polyester matrix

A reactive hot-melt resin (polyurethane) was used to manufacture Guadua composites with a certain flexibility, high processing speed, good initial rigidity, and high temperature performance. These composites can support a moderate tensile stress, allow for large strains at low stresses, and have a low density and a working temperature range of -40 °C and 110 °C. During the flexural test, bamboo composites with reactive polyurethane matrix do not break or fail during the test. A polyurethane-based reactive hot-melt resin was characterized by tensile tests, Shore hardness tests, differential scanning calorimetry, and thermogravimetry. Besides, a composite material was made with Guadua fiber and polyester matrix, which had a greater strength in the test of tension and flexion, although it had a lower percentage of elongation than the composite material with reactive polyurethane. Guadua fiber can increase the strength by 266% of polyurethane matrix and 228% of polyester matrix.

THERMO-MECHANICAL INVESTIGATION OF HYBRID PARTICULATE BANANA/SISAL FIBER REINFORCED POLYESTER MATRIX COMPOSITE

An increasing desire is to produce eco-friendly materials for varied engineering applications, such as natural fiber-reinforced composites (NFRCs). Although many research works on natural fiber polymer matrix composite exist, not much is known on the thermo-mechanical properties of acetic acid-treated particulate banana-sisal fiber reinforced polyester composite. Additionally, establishing the fiber constituent with a detrimental effect on thermal and mechanical properties for acetic acid-treated particulate banana-sisal reinforced polyester matrix composite is not well known. This work aims to examine the effect of banana-sisal particulate fiber on the thermal and mechanical properties of banana-sisal reinforced polyester matrix composites to address the gap. The composites were produced via the mechanical stir mix technique. Thermal, Fourier-transform infrared spectroscopy (FTIS), compressive, flexural, and impact analysis were conducted according to appropriate test standards. The results revealed that the thermal properties of the developed composites were not dependent on hybridization. Also, hybridization significantly enhanced the compressive and flexural properties, with 70B/30S and 50B/50S particulate fiber reinforced polyester matrix composite found to have the most superior compressive and flexural properties. A major contribution of this study is that the impact properties of the developed composites were dependent on the fiber composition and decreased as the sisal content percentage increased. In general, reinforced polyester matrix composite with 70B/30S particulate fiber has a preferable combination of thermal and mechanical properties.

The Tensile and Flexural Forces of Acropora Reef Waste Particulate-Enchanced Polyester Composites

Composite is a material that combines two or more materials that basically dissimilar chemical or physical properties from one another. In this research, we used Acropora coral reef waste particulate and Resin Polyester BQTN type 157 with Methyl ethyl ketone peroxide (MEKP) 1% as the hardener. The Hand Lay-Up molding technique is used in the process of making the material. The tensile and flexure test is done according to the ASTM D3090 and ASTM D790 – 03 standards. The purpose of this research is to discover the means to produce a composite enhanced by Acropora coral reef waste with polyester matrix and to learn the tensile and flexure strength from the Acropora coral reef waste particulate-enhanced polyester composites with mass fraction varieties of 10%, 20%, 30%, and 40%. The tensile test result of Acroporal coral reef waste particulate with polyester matrix yields average tensile strength at mass fraction variety of 40% with a score of 19,66 MPa, with an Modulus score of 636,75 MPa. The flexure test result of Acropora coral reef waste particulate with polyester matrix yields average flexure stress at mass fraction variety of 40% with a score of 112,56 MPa, with an average Elastic Modulus score of 3098,96 MPa.

Experimental Investigation of Thrust Force, Delamination and Surface Roughness in Drilling Hybrid Structural Composites

Filled hybrid composites are widely used in various structural applications where machining is critical. Hence, it is essential to understand the performance of the fibre composites’ machining behaviour. As such, a new hybrid structural composite was fabricated with redmud as filler and sisal fibre as reinforcement in polyester matrix. The composite was then tested for its drilling performance. A comprehensive drilling experiment was conducted using Taguchi L27 orthogonal array. The effect of the drill tool point angle, the cutting speed, the feed rate on thrust force, delamination, and burr formation were analysed for producing quality holes. The significance of each parameter was analysed, and the experimental outcomes revealed some important findings in the context of the drilling behaviour of sisal fibre/polyester composites with redmud as a filler. Spindle speed contributed 39% in affecting the thrust force, while the feed rate had the maximum influence of ca. 38% in affecting delamination.

Effect of alkaline treatment on mechanical properties of composites: Unsaturated polyester reinforced ZrO2/jute and sisal

Alkali treated (5 wt. % alkali was used on the total weight of the alkali solution and the treatment time was 2 h) discontinuous cellulosic fiber (jute and sisal were used as cellulosic fibers and 35 wt. % filler content was incorporated) reinforced chemically modified ZrO2 (ZrO2 was used as 10 wt. % of total filler content. In this context, it is worthwhile to mention that when both fillers were used, the fiber content was taken in the weight ratio of 1:1.) dispersed hybrid unsaturated polyester composites were fabricated by a compression molding technique. The mechanical behavior of the fabricated composites was evaluated at the sub-micron scale by nanoindentation (indentation with an applied load on the composites surface at the nano-metric range) or depth-sensing instrumented indentation technique. The significant effect of incorporation of the dispersing phases within the unsaturated polyester matrix with respect to mechanical properties at microstructural length scale was observed. A marked improvement in the nanoindentation-derived parameters viz. , nanohardness, reduced modulus, elastic recovery, and indentation creep was observed which may be attributed due to the influence of fillers inclusion within the unsaturated polyester matrix. An extensive effort was laid to analyze the dynamic mechanical properties using the sinus indentation mode associated with nanoindentation measurements to further correlate the influence of fillers addition with the indentation-derived parameters.