For the purpose of renewable materials applications, Curauá fiber treated with 5% sodium hydroxide was added to high-density biopolyethylene, using an entirely Brazilian raw material of sugarcane ethanol. Polyethylene grafted with maleic anhydride was used as a compatibilizer. With the addition of curauá fiber, the crystallinity was reduced, possibly due to interactions in the crystalline matrix. A positive thermal resistance effect was observed for the maximum degradation temperatures of the biocomposites. When curauá fiber was added (5% by weight), the morphology showed interfacial adhesion, greater energy storage and damping capacity. Although curauá fiber additions did not affect the yield strength of high-density bio polyethylene, its fracture toughness improved. With the addition of curauá fiber (5% by weight), the fracture strain was greatly reduced to about 52%, the impact strength was also reduced, suggesting a reinforcing effect. Concomitantly, the modulus and the maximum bending stress, as well as the Shore D hardness of the curauá fiber biocomposites (at 3 and 5% by weight), were improved. Two important aspects of product viability were achieved. First, there was no change in processability and, second, with the addition of small amounts of curauá fiber, there was a gain in the specific properties of the biopolymer. The resulting synergies can help ensure more sustainable and environmentally friendly manufacturing of automotive products.

In this work, recycled poly(ethylene terephthalate) (PETR) was blended with virgin high-density polyethylene (HDPE) in an internal mixer in an attempt to obtain a material with improved properties. A compatibilizer (PE-g-MA) and a chain extender (Joncryl) were added to the PETR/HDPE blend and the rheological and thermal properties of the modified and unmodified blends as well as those of virgin PET with virgin HDPE (PETV/HDPE). All the blends were characterized by torque rheometry, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The data obtained indicate that the incorporation of either the chain extender or the compatibilizer agent led to increases in torque (and hence in viscosity) of the blend compared to that of the neat polymers. The joint incorporation of the chain extender and compatibilizer further increased the viscosity of the systems. Their effect on the crystallinity parameters of HDPE was minimal, but they reduced the crystallinity and crystallization temperature of virgin and recycled PET in the blends. The thermal stability of the PETR/HDPE blend was similar to that of the PETV/HDPE blend, and it was not affected by the incorporation of the chain extender and/or compatibilizer.

Bananas are some of the most consumed fruits throughout the world, providing metabolizable calories and vitamins for humans, along with many other benefits. However, this fruit tends to be easily degraded by microorganisms and other chemical agents because of the high moisture content. Considering the importance, this work focuses on an experimental study regarding banana fruit drying. For such purpose, whole bananas were hand-peeled and sliced longitudinally and then dried by a hot air circulation oven with air temperatures of 40 °C, 50 °C, 60 °C and 70 °C. Measurements of mass, temperature, and dimensions of the sample were done during the drying process. Results of drying, heating, and shrinkage (volume and surface area) kinetics are presented and analyzed. The study revealed that the drying air temperature significantly affected moisture removal, heating, and dimensions’ variation rates, as well as quality of banana fruit. The drying carried out with higher temperature and lower relative humidity of the air gave rise to higher rates of drying, heating and variation of dimensions, and shorter drying time of the product.

Drying and firing of ceramic products are processes that require high energy consumption. Making these processes more efficient can improve product quality, reduce processing time and energy consumption, and promote economic and environmental gains. In this sense, this work aims to quantify heat transfer in an intermittent ceramic kiln during the heating and cooling stages, with and without thermal insulation. All mathematical formulation is based on the first law of thermodynamics. From the results, we conclude that the greatest heat loss occurs by radiation in the sidewalls of the equipment, and that a considerable amount of energy is required to heat the sidewalls, base, and ceiling of the kiln. Further, with the use of thermal insulation, it was concluded that a high reduction in the heat lost through the sidewalls was achieved, thus providing a global energy gain of approximately 35% and a reduction in the maximum external surface temperature from 249.34 to 79.47 °C when compared to the kiln without thermal insulation, reducing the risks of work accidents and thermal discomfort when in operation.

This work aims to experimentally study the drying of agricultural products using microwaves, with particular reference to grains. Microwave drying experiments were carried out with paddy rice grains in natura (BRSMG Conai variety) for three levels of incident microwave power per mass of fresh grain (6.27, 14.63 and 22.99 W/g). Results of grain drying and heating kinetics are presented and analyzed. It was verified that the ideal average moisture content for grain storage and marketing, 15% (d.b.), occurred at 20 min (6.27 W/g), 13 min (14.63 W/g) and 7 min (22.99 W/g), and that the equilibrium moisture content of the samples reached 4.4%, 2.7% and 1.9%, at 310, 180 and 110 min, for each of the three power levels studied, respectively. The drying with the highest absorbed power caused discoloration of the grains at the end of the drying process.

The conformation of a ceramic piece follows the steps of preparing the raw material, molding, lamination, drying, and firing. Drying is a thermodynamic process of heat and mass transfer, with dimensional variations of the product that requires a large amount of energy. Ceramic materials when exposed to non-uniform drying may suffer cracks and deformations, reducing their post-drying quality. Thus, this work aimed to study the drying of industrial ceramic blocks in an oven with forced air circulation. Experiments were carried out to characterize the clay and drying of the ceramic block at temperatures ranging from 50 °C to 100 °C. Results of the chemical, mineralogical, granulometric, differential thermal, and thermogravimetric analysis of the clay, and heating kinetics, mass loss, and dimensional variation of the industrial ceramic block are presented and analyzed in detail. It was found that the clay is basically composed of silica and alumina (≈ 80.96%), with an average particle diameter of 13.36 μm. The study proved that drying at high temperature and low relative humidity of the air generates high rates of mass loss, heating, and volumetric shrinkage in the ceramic product, and high thermo-hydraulic stresses, which cause the appearance and propagation of cracks, gaps, and cleavages, compromising the final quality of the product.