Holmer Savastano Junior

Treatments of non-wood plant fibres used as reinforcement in composite materials

This paper presents a summary of the knowledge on fibres and pulps of non wood tropical plants used as reinforcement in cementitious composites accumulated during the recent years by Guadeloupean and Brazilian teams participating in collaborative work. Vegetable fibres represent a good alternative as non-conventional materials for the construction of ecological and sustainable buildings. The use of such renewable resources contributes to the development of sustainable technologies. The main objective of the paper is to emphasize the use of agricultural wastes in the production of cement based composites. The botanical, chemical, physical, morphological and mechanical properties of fibres from various plants are described. The effects of different treatments on physical, chemical and mechanical properties of fibres are presented. The most effective treatments in influencing the mechanical and physical properties are pyrolysis and alkaline ones, according to the type of plant. The final choice will have to consider fibre availability, and treatment costs.

Sugarcane bagasse and castor oil polyurethane adhesive-based particulate composite

This paper discusses the potential use of sugarcane bagasse in two different fiber lengths (5 mm and 8 mm) of the same density as a raw material for the production of particleboards, using castor oil-based two-component polyurethane adhesive. The quality of the product that can be manufactured industrially was evaluated based on density, thickness swell (TS), absorption (WA), modulus of elasticity (MOE), modulus of rupture (MOR) in static bending and internal bond (IB), according to the Brazilian NBR 14.810:2006 standard. The results revealed a significant difference between the particleboards made with 5-mm-long fibers and those made with 8-mm-long fibers. An analysis by scanning electron microscopy (SEM) indicates that the interparticle spaces are filled with castor oil-based two-component polyurethane adhesive, contributing to improve the physicomechanical properties of the particleboards. A durability assessment based on accelerated aging tests shows that waterproofed particleboards can be used in moist environments.

Alternative body sites for heat stress measurement in milking cows under tropical conditions and their relationship to the thermal discomfort of the animals.

This study was conducted to determine the relationship among temperatures measured at different anatomical sites of the animal body and their daily pattern as indicative of the thermal stress in lactating dairy cows under tropical conditions. Environmental dry bulb (DBT) and black globe (BGT) temperatures and relative humidity (RH) were recorded. Rectal temperature (RT), respiratory frequency (RF), body surface (BST), internal base of tail (TT), vulva (VT) and auricular temperatures (AT) were collected, from 37 Black and White Holstein cows at 0700, 1300 and 1800 hours. RT showed a moderately and positive correlations with all body temperatures, ranging from 0.59 with TT to 0.64 with BST. Correlations among AT, VT and TT with RF were very similar (from 0.63 to 0.64) and were greater than those observed for RF with RT (0.55) or with BST (0.54). RF and RT were positively correlated to TT (0.63 and 0.59, respectively), AT (r = 0.63 for both) and VT (r = 0.64 and 0.63, respectively). Positive and very high correlations were observed among AT, VT and TT (from 0.94 to 0.97) indicating good association of temperatures measured in these anatomical sites. Correlations of BST with AT and VT were positive and very similar (0.71 and 0.72, respectively) and lower with TT (0.66). The AT, TT, VT and BST presented similar patterns and follow the variations of DBT through the day. Temperatures measured at different anatomical sites of the animal body have the potential to be used as indicative of the thermal stress in lactating dairy cows.

Respostas fisiológicas e produtivas de vacas holandesas em lactação submetidas a diferentes ambientes

This work was carried out during the summer of 2002 to evaluate the influence of some cooling systems on the milk yield and animal thermoregulation. Ten heifers and seventeen milking cows were assigned to the control housing (ICO), mist & fan housing (ICL) and shade cloth (80%) (IT). The milk yield and the individual intake were daily measured for each animal. The rectal temperature was measured three times a day with three animals from each treatment. The skin surface temperature was collected three times a day for all the animals and the respiratory frequency two times a day for all the animals. The climatic data of each housing were registered to calculate the temperature humidity index (ITU) and the black globe humidity index (ITGU). Twenty six days of high enthalpy were selected and analyzed. The study showed that temperature humidity index from 75 to 76 was not associated with stress conditions for the animals, although many researches propose this situation as stressing. The milking cows in the mist & fan treatment showed respiratory frequency and skin surface temperature significantly lower than the cows in the other treatments. The heifers presented respiratory frequency and rectal temperature higher than the cows in all the registration times. The higher milk yield of the cows was observed in the shade cloth treatment.

Effects of Methane Cold Plasma in Sisal Fibers

One of the main problems in using vegetable fibers as reinforcement in aggressive cement matrix is the penetration of alkaline products in the porous structure of the filaments, making them very fragile with the time. In this sense a series of physical and chemical methods of surface modification has been used in order to improve its characteristics. The plasma surface modification technique is a physical method surface modification that utilizes ionized gas at low pressure to change the chemical nature and the substrate surface morphology of both organic and inorganic materials without changing their intrinsic properties. This is considered an environmentally friendly process without generation of contamination and has a low operating cost compared to some chemical (such as silane based) treatments. In the present study, the sisal fibers were treated with methane plasma generated by direct electric current during 10, 20 and 30 min with gas flow of 5 cm3/s and current of 0.10 A. The study presents some mechanical, physics and chemical characteristics of sisal fiber after being subjected to treatment with methane cold plasma. The results presented indicate that treatment with methane cold plasma induced changes in sisal fibers at all times of exposure to treatment (10, 20 and 30 min). However, the major changes in structural and mechanical components may be seen in fibers treated with 10 min of exposure to plasma.

Sisal organosolv pulp as reinforcement for cement based composites

The present work describes non-conventional sisal (Agave sisalana) chemical (organosolv) pulp from residues of cordage as reinforcement to cement based materials. Sisal organosolv pulp was produced in a 1:1 ethanol/water mixture and post chemically and physically characterized in order to compare its properties with sisal kraft pulp. Cement based composites reinforced with organosolv or kraft pulps and combined with polypropylene (PP) fibres were produced by the slurry de-watering and pressing method as a crude simulation of the Hatschek process. Composites were evaluated at 28 days of age, after exposition to accelerated carbonation and after 100 soak/dry cycles. Composites containing organosolv pulp presented lower mechanical strength, water absorption and apparent porosity than composites reinforced with kraft pulp. The best mechanical performance after ageing was also achieved by samples reinforced with kraft pulp. The addition of PP fibres favoured the maintenance of toughness after ageing. Accelerated carbonation promoted the densification of the composites reinforced with sisal organosolv + PP fibres.

Grinding process for the production of nanofibrillated cellulose based on unbleached and bleached bamboo organosolv pulp

Nanofibrillated cellulose (NFC) is a type of nanomaterial based on renewable resources and produced by mechanical disintegration without chemicals. NFC is a potential reinforcing material with a high surface area and high aspect ratio, both of which increase reinforcement on the nanoscale. The raw materials used were unbleached and bleached bamboo organosolv pulp. Organosolv pulping is a cleaner process than other industrial methods (i.e. Kraft process), as it uses organic solvents during cooking and provides easy solvent recovery at the end of the process. The NFC was produced by treating unbleached and bleached bamboo organosolv pulps for 5, 10, 15 and 20 nanofibrillation cycles using the grinding method. Chemical, physical and mechanical tests were performed to determine the optimal condition for nanofibrillation. The delamination of the S2 layer of the fibers during nanofibrillation contributed to the partial removal of amorphous components (mainly lignin), which have low polarity and improved the adhesion of the fibers, particularly the unbleached cellulose. The transverse modulus of elasticity of the unbleached NFC was highest after 10 nanofibrillation cycles. Further treatment cycles decreased the modulus due to the mechanical degradation of the fibers. The unbleached NFC produced by 10 cycles have a greater transverse modulus of elasticity, the crystallite size showed increase with the nanofibrillation, and after 5 nanofibrillation cycles, no differences are observed in the morphology of the fibers.

Microstructure and mechanical properties of gypsum composites reinforced with recycled cellulose pulp

The use of waste fibers for the reinforcement of brittle matrices is considered opportune for the sustainable management of urban solid residues. This paper examines the microstructure and mechanical properties of a composite material made of gypsum reinforced with cellulose fibers from discarded Kraft cement bag. Two different kinds of gypsum were used, natural gypsum (NG) and recycled gypsum (RG), both with an addition of 10% by mass of limestone. For the production of samples, slurry vacuum de-watering technique followed by pressing was evaluated revealing to be an efficient and innovative solution for the composites under evaluation. The composite was analyzed based on flexural strength tests, scanning electron microscopy (SEM) imaging, secondary electron (SE) detection, and pseudo-adiabatic calorimetry. The morphology of the fractured surfaces of flexural test samples revealed large gypsum crystals double the original size surrounding the fibers, but with the same overall aspect ratio. Natural fibers absorb large amounts of water, causing the water/gypsum ratio of the paste to increase. The predominance of fiber pullout, damaged or removed secondary layers and incrusted crystals are indicative of the good bonding of the fiber to the gypsum matrix and of the high mechanical resistance of composites. This material is a technically better substitute for the brittle gypsum board, and it stands out particularly for its characteristics of high impact strength and high modulus of rupture.

Índices de conforto térmico e respostas fisiológicas de bezerros da raça holandesa em bezerreiros individuais com diferentes coberturas

This work was focused in the efficiency of housing for calves, based on thermal comfort indexes (radiant thermal load, black globe humidity index and black globe index). It was compared animal housing covered with commercial corrugated sheets produced with asbestos cement and cellulose cement tiles. The experiment was carried out in a system of conventional housing, box type, with five treatments: roofs with asbestos cement tiles, cellulose cement tiles, cellulose cement painted tiles and double layer of cement cellulose tiles, all of them exposed to the sunlight and cement cellulose roof under shade. The experiment involved five replications (one calf per replication), during the spring time of 2002, in Pirassununga, State of Sao Paulo, Brazil. Physiological variables of thermoregulation (respiration rate and rectal temperature) were registered. The housing directly exposed to the sunlight and covered with asbestos cement sheets presented the less satisfactory results for the animal thermal comfort in comparison with the other treatments also exposed to the sun. The housing covered with cellulose cement tiles under shade showed the best results of thermal comfort. The results of the physiological variables were significantly better for the treatment positioned under shade. A satisfactory relation between the thermal comfort indexes and the physiological results (especially respiration rate) were found for the conditions of the present work.

Desempenho de telhas de escória de alto forno e fibras vegetais em protótipos de galpões

The substitution of cement asbestos by safer and equally economical alternatives has being searched for throughout the world. The usage of vegetal staple fiber as agglomerate in tropical countries where these residues are abundant has shown it self to be viable. In this study, roofing tiles fabricated with cement base Portland CPII 32Z (ABNT NBR-5735), blast furnace slag (EAF), active silica reinforced with cellulose pulp staple fibers of sisal (Agave sisalana) were compared with cement asbestos roofing tiles with white paint and ceramic roofing tiles. Prototypes of poultry facilities were used and lamps simulated the heat produced by the birds. Indices ITU, ITGU, CTR and entalpy (H) were employed for the characterization of the thermal atmospheric comfort and the results showed that the alternative roofing tiles were similar to the ceramic tiles and could be used as a substitute for asbestos roofing tiles.