The mechanical and thermal behavior of ultra-high molecular weight polyethylene (UHMWPE)/metallic quasicrystal powder (MQP) composites are evaluated at filler volume fractions ( ∅ f) of 0.01, 0.02, 0.06 and 0.15. MQP is based on an aluminum alloy, synthesized and characterized to act as a filler for UHMWPE. The preparation of the composites was conducted by compression molding. Morphological analysis reveals larger and smaller MPQ particles, being well distributed, and mechanically anchored in the matrix. The melting temperature was maintained after adding filler, while the crystallinity values decreased. When adding MQP, an improvement in thermal stability is observed by increases in both the initial and maximum weight loss rate temperatures (Tmax). However, when the temperature is about 700°C all composites present oxidation due to the MQP presence. The Pukansky model shows that the 0.06 MQP composites have better interfacial adhesion. This is confirmed by the Nicolais-Narkis equation. This contributes to an increase in the modulus of elasticity of the 0.06 MQP composite in respect to the others. The elongation at break was reduced for the 0.15 MQP composite. However, the higher volume fraction of MQP increased the stiffness of the UHMWPE, reflecting its potential for use as a reinforcement.

Resumo Observa-se o crescente interesse pela sustentabilidade dos recursos naturais de nosso planeta. A arquitetura, imersa em um dos setores industriais responsáveis por grandes transformações do ambiente construído, mostra-se um canal para a incorporação racional de materiais com viés ecológico. Este artigo aborda pesquisa cujo objetivo foi o desenvolvimento de painéis compósitos de fibra da folha do abacaxizeiro e resina vegetal. O texto contempla a descrição dos procedimentos experimentais adotados e discute os resultados das caracterizações físicas - massa específica, teor de umidade e absorção de água - e mecânicas - resistências à flexão e à tração, e módulo de elasticidade em tração. O compósito foi desenvolvido com a adoção de diferentes teores de fibras, empregadas no sentido longitudinal. A fim de recomendar usos para os compósitos confeccionados, realizou-se comparação com o ANSI A208.1 - American National Standard Institute (ANSI, 2016), procedendo-se à simulação computacional, por meio da modelagem paramétrica via Rhinoceros 3D 5.12, Grasshopper 0.9.0076 e Karamba 3D 1.3.0. Os resultados experimentais indicaram um material com valores médios de massa específica entre 610 kg/m3 e 760 kg/m3, e resistência à tração entre 56,27 MPa e 81,58 MPa, direcionando sua classificação como painel compósito de partícula. A modelagem paramétrica reforçou as aplicações do produto no ambiente construído.

Abstract The sustainability of our planet’s natural resources has been a growing and pressing concern in the past few years. Architecture, as one of the industrial sectors responsible for great transformations in the built environment, is a means for the rational adoption of eco-friendly materials. This paper discusses a research project that employed an experimental procedure to produce composite materials using pineapple leaf fibre and vegetable resin. The article describes the experimental procedures adopted and the results of physical characterisation - specific gravity, moisture content and water absorption - and mechanical ones - flexural and tensile strengths, and tensile modulus of elasticity. The composite was developed with different fibre contents, used in the longitudinal direction. In order to recommend applications for the composites, a comparison was done with ANSI A208.1 (ANSI, 2016), and a computer simulation using parametric modelling with Rhinoceros 3D 5.12, Grasshopper 0.9.0076 and Karamba 3D 1.3.0. The experimental results produced a material with moisture content values between 610 kg/m3 and 760 kg/m3, and tensile strength between 56.27 MPa and 81.58 MPa, classifying of the material as a particle board. The parametric modelling reinforces the applications of the product in the built environment.

The effect of alcaline and hot water surface treatments of piassava Attalea funifera fibers was investigated. The efficiency of each treatment was evaluated by Fourier transform infrared spectroscopy, X-ray diffractometry, optical microscopy, scanning electron microscopy and atomic force microscopy. The alkaline treatments were effective in removing the superficial lignin layer from the fiber, while the hot water treatment was not. Treatment with hot water and NaOH caused fiber defibrillation. NaOH was most effective in promoting both, a decrease in fiber diameter and an increase in fiber surface area. Treatment with Ca(OH)2 led to the formation of a CaCO3 layer deposited on the fiber, preventing defibrillation. The crystalline structure of the fiber was not altered by any of the treatments, maintaining type I cellulose.

RESUMO O objetivo deste trabalho foi investigar as propriedades térmicas, mecânicas e termo dinâmico mecânicas de compósitos de polietileno de alta densidade (PEAD) com a incorporação do pó de conchas de moluscos (5, 10 e 20% em peso). A matriz pura e seus compósitos foram misturados em um misturador interno e em seguida moldados por compressão. A incorporação do pó de concha de molusco diminuiu o índice de fluidez do PEAD em uma faixa de 23 a 53%, já a cristalinidade da matriz praticamente não foi alterada. O pó da concha possui 97, 53% de CaO, tendo estrutura cristalina constituída por aragonita e calcita, ambos polimorfos do carbonato de cálcio. O estudo granulométrico mostrou que o pó da concha apresentou uma distribuição larga do tamanho das partículas, sendo também confirmada na análise da superfície de fratura dos compósitos por microscopia eletrônica de varredura. Os aspectos morfológicos mostram que nenhuma adesão foi observada entre as partículas e o PEAD. A adição da concha causou um aumento na rigidez da matriz e como também diminui a capacidade de amortecimento da matriz. A adição de 10% deslocou a temperatura de transição vítrea (Tg) do PEAD em 6 °C, enquanto o compósito com 20% do pó de concha não apresentou essa transição.

ABSTRACT This work deals with an investigation of thermal, mechanical and dynamic mechanical properties of composites of high density polyethylene(HDPE) with addition of mollusk shell powder (5, 10 and 20%wt). The pure matrix and its composites were first mixed in an internal mixer and then molded by compression. The mollusk shell powder incorporation decreased the melt index within a range of 23% to 53% whereas no relevant changes in crystallinity of matrix were observed. The shell powder was composed by 97.53% of CaO and its crystalline structure was constituted of calcite and aragonite, both polymorphs of calcium carbonate. The granulometric study showed a large distribution of particle size to the mollusk shell powder, which was also confirmed by the scanning electron microscopy (SEM) analysis of the fracture surface of the composites. The morphological aspects of the composites showed a poor adhesion between HDPE matrix and shell powder. The adding of filler increased the matrix rigidity and decreased its damping capacity. The incorporation of 10%wt mollusk shell powder shifted the glassy transition temperature (Tg) of the PEAD in 6 °C, while the composite with 20%wt did not show this transition temperature.

RESUMO O objetivo deste trabalho foi investigar as propriedades térmicas, mecânicas e termo dinâmico mecânicas de compósitos de polietileno de alta densidade (PEAD) com a incorporação do pó de conchas de moluscos (5, 10 e 20% em peso). A matriz pura e seus compósitos foram misturados em um misturador interno e em seguida moldados por compressão. A incorporação do pó de concha de molusco diminuiu o índice de fluidez do PEAD em uma faixa de 23 a 53%, já a cristalinidade da matriz praticamente não foi alterada. O pó da concha possui 97, 53% de CaO, tendo estrutura cristalina constituída por aragonita e calcita, ambos polimorfos do carbonato de cálcio. O estudo granulométrico mostrou que o pó da concha apresentou uma distribuição larga do tamanho das partículas, sendo também confirmada na análise da superfície de fratura dos compósitos por microscopia eletrônica de varredura. Os aspectos morfológicos mostram que nenhuma adesão foi observada entre as partículas e o PEAD. A adição da concha causou um aumento na rigidez da matriz e como também diminui a capacidade de amortecimento da matriz. A adição de 10% deslocou a temperatura de transição vítrea (Tg) do PEAD em 6 oC , enquanto o compósito com 20% do pó de concha não apresentou essa transição.

ABSTRACT This work deals with an investigation of thermal, mechanical and dynamic mechanical properties of composites of high density polyethylene(HDPE) with addition of mollusk shell powder (5, 10 and 20%wt). The pure matrix and its composites were first mixed in an internal mixer and then molded by compression. The mollusk shell powder incorporation decreased the melt index within a range of 23% to 53% whereas no relevant changes in crystallinity of matrix were observed. The shell powder was composed by 97.53% of CaO and its crystalline structure was constituted of calcite and aragonite, both polymorphs of calcium carbonate. The granulometric study showed a large distribution of particle size to the mollusk shell powder, which was also confirmed by the scanning electron microscopy (SEM) analysis of the fracture surface of the composites. The morphological aspects of the composites showed a poor adhesion between HDPE matrix and shell powder. The adding of filler increased the matrix rigidity and decreased its damping capacity. The incorporation of 10%wt mollusk shell powder shifted the glassy transition temperature (Tg) of the PEAD in 6 oC, while the composite with 20%wt did not show this transition temperature.