Ana M. C. Grisa

Degradation study of polypropylene (PP) and bioriented polypropylene (BOPP) in the environment

Polymers are vastly employed for numerous purposes in different industrial segments and generate soaring quantities of discarding in the environment. This research analyzed the degradability/biodegradability of polypropylene films (PP) and Bioriented polypropylene (BOPP) polymers after 11 months interred in the Sao Giacomo landfill in Caxias do Sul. Comparing the buried PP film to a sample of virgin PP, two peaks of degrading activity appeared at the TG curve as well as structure modification typified by occurrence of new absorption bands at FTIR, which can be credited to changes in crystallinity. Thermal analysis carried out on the buried PP and BOPP showed decreases in the percentage of crystallinity due to chain scission. The major reduction was observed in the PP, since its crystallinity is a consequence of polymerization instead of chain orientation processes, as in BOPP. Cracks and erosion of the polymer surface were detected in both PP and BOPP, indicating degrading processes by microorganisms.

Acoustic Behavior of Subfloor Lightweight Mortars Containing Micronized Poly (Ethylene Vinyl Acetate) (EVA)

This paper aims to contribute to acoustical comfort in buildings by presenting a study about the polymer waste micronized poly (ethylene vinyl acetate) (EVA) to be used in mortars for impact sound insulation in subfloor systems. The evaluation method included physical, mechanical and morphological properties of the mortar developed with three distinct thicknesses designs (3, 5, and 7 cm) with replacement percentage of the natural aggregate by 10%, 25%, and 50% EVA. Microscopy analysis showed the surface deposition of cement on EVA, with preservation of polymer porosity. The compressive creep test estimated long-term deformation, where the 10% EVA sample with a 7 cm thick mortar showed the lowest percentage deformation of its height. The impact noise test was performed with 50% EVA samples, reaching an impact sound insulation of 23 dB when the uncovered slab was compared with the 7 cm thick subfloor mortar. Polymer waste addition decreased the mortar compressive strength, and EVA displayed characteristics of an influential material to intensify other features of the composite.

Study of oxo-biodegradable polyethylene degradation in simulated soil

This study aims to evaluate the influence of pro-oxidant additive and accelerated aging on the degradation of polyethylene (PE) samples in simulated soil, in accordance with ASTM G160-03. Films of polyethylene with and without pro-oxidant additive were studied, before and after 72 hours of accelerated aging. The films were initially characterized by analyses of Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) (to evaluate the Carbonyl Index (CI)). The films were exposed for 30, 60 and 90 days in simulated soil, with controlled moisture and soil pH. The results showed the degradation of polyethylene films through an increase of CI in samples with additive and accelerated aging after 30 days of exposure, and a decrease, after 60 and 90 days, indicating the uptake of material oxidation by-products by microorganisms. The polyethylene films without pro-oxidant additive after accelerated aging showed greater structural and surface modifications, as compared to films with the additive.

Characterization of polyurethan skin agglomerates for acoustic insulation from impact noise

Polymeric materials are greatly used in industry due to their versatility in application generating therefore, large quantities of solid waste. Population growth in urban areas, with living quarters mainly in residential buildings, face discomfort caused by noise, particularly by impact noise. Aiming at reducing the amount of polymeric material disposed of in the environment and at providing alternatives of reuse, together with the possibility of reducing noise impact from construction works, agglomerates of polyurethane skin (PUs) have been developed. The recycling process of PUs was developed through variations in particle size and pressing temperature of agglomerates. PU agglomerates of coarse particle size, hot pressing process and close cell structure presented reductions in noise level up to 20 dB, showing that it is suitable for acoustic insulation.

Thermogravimetric and Morphologic Analysis of Oxo-degradable Polyethylene Films after Accelerated Weathering

The degradation of polyethylene films containing a prodegradant additive has been studied after exposure to accelerated weathering for 480 hours. After exposure, the effects of photo-oxidation were evaluated by thermogravimetry, infrared spectroscopy and X-ray diffraction. The kinetics of the thermo-oxidative degradation of polyethylene films, with and without the prodegradant additive, was assessed by applying the Flynn-Wall-Ozawa method to thermogravimetric analysis carried out at different heating rates. The values of activation energy for samples with and without the prodegradant additive were in the range of 166-214 kJ/mol, and increased, after exposure to accelerated weathering, to values in the range of 245-279 kJ/mol. After exposure, the crystallinity index increased by 9 percentage points for the polyethylene sample without the prodegradant additive and by 8 percentage points for the sample containing the prodegradant additive. For both samples exposed to accelerated weathering, an increase in the carbonyl index was observed. The use of the prodegradant additive caused more evident changes in the crystalline regions of the polymer than in the amorphous regions; the results of this study are thus important from the standpoint of degradation, since the crystalline regions are considered difficult to degrade.

Evaluation of Metal Biosorption by the Fungus Pleurotus sajor-caju on Modified Polyethylene Films

Metal ions, such as Fe +3 , Mn +2 and Co +2 , are present in the formulations of pro-degrading additives and represent a means to accelerate the degradation of post-consumer plastics. When incorporated into the polymer, the pro- degradant additive serves to accelerate the degradation of the polymeric chain through oxidation initiated by light and/or heat, favouring the action of microorganisms. However, the consequences of the disposal of waste containing polymeric pro-oxidants are not yet known and represent an important area of investigation for environmental technology. In this work, we analysed the growth of the edible fungus Pleurotus sajor-caju and its ability to biosorb metals in culture media containing polyethylene films with and without a pro-degradant additive. In biosorption process metals, there is a contribution from the pro-degradant additive to the development of mushrooms from P. sajor-caju on different substrates. P. sajor-caju was effective in removing the following metals: Al, Ca, Cu, Fe, Mg, Mn, K, Na and Zn that were present in the pro-degradant additive and the masterbatch

Effect of cellulose fibers on morphology and pure water permeation of PSf membranes

Chemical and physical changes are necessary to improve the transport properties of polymeric membranes. Cellulose fiber pulp from Pinus taeda was processed in knives and balls mills in order to reduce the dimensions of the fibers for later application in polysulfone (PSf) membranes. By adding cellulosic fibers in PSf membranes, a composite membrane with improved morphological properties, permeate flux and good resistance to pressure was obtained. The fibers as well as the PSf and PSf/cellulose fibers membranes were morphologically characterized by scanning electron microscopy. Tests of pure water permeate flux were performed with pressure up to 20 bar. The addition of 0.2% (wt) of cellulose fibers in the formation of composite membranes resulted in the elimination of macrovoids, causing an increase in pure water flux (50% ±10) when pressure was risen.

Development of adhesive compositions using powder coating residues

The industry of powder coatings, for base polyester/epoxy, produces about 300 kg.day−1 of residue in a production of 6,000 kg.day−1 (5% residue). Powder coatings with equal or lower to 10 μm of granulometer are considerate residues. The use of these residues in the formulation of adhesives is studied in the present work. Portions of residue with 0.1 a 0.5 g.mL−1 were tested with 7 solvents and 5 kinds of elastomers. Two solvents compatible with the residue and three elastomers, so, three mixtures were obtained: A, B and C; then, 15 g of a petroleum derivated was additioned. The mass of mixtures was homogenized in a mechanic stirrer for 15 minutes. The preliminary tests have demonstrated that the adhesives A, B and C had effective adherence in carpet on cement slab and HDF® (High Density Fiber). The formulations of A, B and C show superior to other 8 tested specially in: fast drying, migration of adhesive upon the surface (carpet) and adherence to the slab. According to the rules ASTM D2094 and D2095 the results of tension test are compared to commercial adhesives, resulting that adhesive C had an efficiency similar to a commercial adhesive for the same utilization.