Rosmary Nichele Brandalise

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.

Grinding and Characterization of Scrap Rubbers Powders

SBR and EPDM extruded profile scraps are ground under ambient conditions for further utilization in recycling and reclaiming processes. The obtained powders (SBR-r and EPDM-r, respectively) are physically, thermally, and chemically characterized and the results are analyzed as for its suitability for reuse methods. It is possible to obtain powdered SBR and EPDM rubber with irregular shape and high surface roughness. The grinding process has not deteriorated the material. The obtained powder is suitable for utilization in new formulations and in regeneration processes.

Evaluation of the solubility of the HPMC: PVA blends in biological fluids in vitro

Received: September 22, 2010; Revised: April 28, 2011Polymers are often used to coat tablets for controlled drug release. The purpose of this study is to evaluate the solubility of the HPMC and PVA blend compared to isolated polymers in solutions with a pH of biological fluids (6 and 1.2) and the dissolution of capsules obtained using theophylline granules produced with the HPMC/PVA 25/75 blend as a matrix and as coating. HPMC is completely solubilized in the medium that simulates the pH of the stomach and intestine, and PVA is the polymer that allows controlling the solubility of the blend in the medium, with a differents pH. The dissolution time was monitored by UV absorbance with maximum theophylline at 269 nm. The theophylline was released immediately in the granules, and in the capsules 78.4% after 30 minutes and 97.4%, after 120 minutes. Thus, PVA can potentially control the drug solubilization, contributing to obtaining modified release systems.

Influence of different sterilization processes on the properties of commercial poly(lactic acid)

This study aims at analyzing the modifications in the morphological, physical, chemical and thermal properties of commercial poly(lactic acid) (PLA) films after exposure to five different sterilization processes. Films were obtained by compression molding, hygienized and sterilized by ethylene oxide (SEtO), hydrogen peroxide plasma (SH2O2), saturated steam (SSS), electron beam radiation (SEB) and gamma radiation (SGR). The samples of PLASEtO, PLASH2O2, PLASEB and PLASGR exhibited thermal and physical changes after being submitted to sterilization processes. PLASSS showed morphological, chemical, thermal and physical changes. It is concluded that processes by SEtO, SH2O2, SEB and EGR can be applied for the sterilization of PLA films and the SSS process is not recommended in view of the data obtained and test conditions reported in this study for PLA films.

Behavior in simulated soil of recycled expanded polystyrene/waste cotton composites

Composites consisting of waste cotton yarn (CF) from the textile industry and postconsumer expanded polystyrene (EPS) was followed during 90 days of exposure in simulated soil. The mechanical properties, morphologies and chemical natures of the composites were determined before and after exposure in simulated soil. The composites were made using a single-screw extrusion, a twin-screw extrusion and injection molding. The composites showed an increase of the mechanical properties nearly 50% in relation to the recycled expanded polystyrene (rEPS). After exposure in simulated soil the composites presented losses of mechanical properties. Evidence of the oxidation of the samples was demonstrated by the increase in the values of the carbonyl index after 30 days of exposure in simulated soil. Changes in the color of the surface of the sample were observed after 90 days of exposure and are due to the fungi and bacteria colonization on the surface.

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.

Photostabilized LDPE films with UV absorber and HALS as protection against the light for rosé sparkling wine.

Rose sparkling wines are photosensitive products thus subject to degradation by photo-oxidation over time when they are exposed on shelves. Consequently, its color gradually loses the most vibrant hues coupled with changes in aroma and flavor. An alternative to increase the shelf life of sparkling wines is the usage of light stabilizers, such as UV Absorbers (UVA) and Hindered Amine Light Stabilizers (HALS), substances that, when added to the packaging used for sparkling wines has the purpose of stabilizing the material, protecting the product. The purpose of this study was to evaluate the quality of rose sparkling wines looking at the following properties: hue, colorimetric intensity, anthocyanins index and chemical characteristics using FTIR and visible-UV of Low Density Polyethylene films (LDPE) used as a protective layer for the exterior of colorless bottles. The stabilization system of LDPE films proposed in this study allowed the rose sparkling wine to retain its chromatic characteristics longer, allowing for extensive periods of exposure on shelves, accounting for 60.4% reduction in the anthocyanins index for films with combined UVA/HALS, and 77.8% for films without photoprotection.

Chemical and Thermal Evaluation of Commercial and Medical Grade PEEK Sterilization by Ethylene Oxide

Many polymers have been used as biomaterials due to their physicochemical characteristics and structural versatility. However, usage on the human body requires sterilization in order to prevent microbial contamination and diminish the risk of rejection or inflammation. This study presents the use of thermogravimetric analysis (TGA) as an alternative to monitor the presence of residual ethylene oxide from polymers sterilization processes. This is a simple technique and does not require sample preparation stages which can imply in some ethylene oxide loss. Ethylene oxide has been used to sterilize polymeric biomaterials, but with restrictions in the amount used due to the difficulty in removing the toxic waste after the sterilization procedure. Samples of commercial (PEEKc) and medical (PEEKm) grade poly(ether ether ketone) (PEEK) were manufactured in the form of cylindrical tubes, hygienized and sterilized with ethylene oxide. PEEKs showed no chemical changes, but exhibited thermal changes by TGA, which evidenced weight loss between 100 and 500oC that was attributed to the removal of residual ethylene oxide, so this technique, at a 10oC‧min-1 heating rate, can be used to monitor the sterilization processes.

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