Sati Manrich

Tendências e desafios da reciclagem de embalagens plásticas

In the management of municipal solid waste (MSW), recycling emerges as one of the ways to reduce the solid wastes deposited in landfills. Plastics are one of the classes of materials with the lowest recycling index. The present study deals with the main difficulties encountered in different countries to increase plastics recycling and the procedures adopted to change this scenario. Additionally, the general requirements and the restrictions about the use of recycled plastic for food contact are presented. This application represents a whole market share to be explored, which could add value and increase the recycling indexes in a sustainable way, provided that investments in innovative technologies are made.

Studies on thermo-mechanical properties of post-consumer high impact polystyrene in five reprocessing steps

This study consisted of an investigation of the thermo-mechanical properties of post-consumer high impact polystyrene (HIPS) through five consecutive injection moulding steps to simulating the recycling cycles. The selectively collected HIPS residue was ground, washed only in water, dried, agglutinated and then moulded as a set of mechanical test specimens before the first step. The melt flow index (MFI), glass transition temperature (Tg), complex viscosity (η*), deflection temperature under flexural load (HDT), tensile, flexural and impact strength tests were determined at each reprocessing cycles. The results revealed that the degradative effect of consecutive recycling on the materials thermal properties was low and may be considered negligible. After five reprocessing cycles, the results showed an ∼8°C decrease of Tg in DSC, an increase of MFI, a decrease in viscosity and a slight decrease of HDT, which could be attributed to chain scission caused by consecutive cycles of exposure to shear stresses and high temperature. The material became slightly more rigid and fragile, as indicated by the mechanical tests.

Estudo da influência de resíduos catalíticos na degradação de plásticos reciclados (Blenda HDPE/PP e PET) provenientes de lixo urbano

The degradation derived from processing, use, disposable, washing and reprocessing was characterized in this study. The post-consumer HDPE/PP degradation was studied as a function of the presence of reprocessed (recycled) HDPE/LDPE bottles and of the presence of labels and cap of LDPE and PP. Those materials only showed a significant influence in the total degradation of HDPE/PP when they were present together. The residues that exhibited lower thermal-oxidative stability were the labels and cap of LDPE and PP. The analysis used to characterize their influence were Infrared Spectroscopy (IR) and Differential Scanning Calorimetry (oxidation induction time - OIT). Furthermore, the degradation of recycled PET. Furthermore, the PET degradation was studied as a function of washing conditions and of the presence of washing caustic residue and label adhesive. Intrinsic viscosity and titration measurements was used to characterize PET degradation. In spite of the use of high temperature (80 oC) in the washing step, the time extent of that step (5 or 15 min) has not affected PET degradation, at least not detectable by the analysis used to characterize. The removing of adhesive residue played a helpful role, inhibiting the catalytic degradation of PET.

Sacolas plásticas: destinações sustentáveis e alternativas de substituição

Regardless of the material adopted as the best strategy for use in plastic bags, each material has an ideal final disposal, which may be composting, mechanical recycling, energy recycling, sanitary landfills, and others. Therefore, the infrastructure of collection, identification and disposal of post-consumer waste of this material should be tied to the choice made to ensure its socio-economic sustainability. Moreover, solutions that are still controversial in terms of their real environmental impact should be neither condemned nor encouraged - rather, they should be evaluated. In this context, it is up to the scientific community to provide solid and reliable foundations to ensure that such evaluations are based on a global vision of the problem. This was the objective that guided the present work, with an analysis of critical issues and description of the diverse solutions adopted around the world, including environmental impact assessments of the different alternatives to minimize and/or solve the problems pertaining to the use of plastic bags.

Films of post-consumer polypropylene composites for the support layer in synthetic paper

Composite films were studied as possible candidates for the central or support layer of synthetic paper in a multilayer structure. Recycled post-consumer polypropylene films were reinforced with inorganic fillers at various compositions and under several processing conditions, with the aim of optimizing the physical and mechanical properties of rigidity and low density. Three types of CaCO 3 , with and without surface treatment of the particles, were used, but only the treated ones were suitable for use in paper films. These samples were then used to analyze possible correlations of properties with composition and processing conditions, varying the CaCO 3 particle size distribution and the film processing method, from casting extrusion (flat die) to blown-film extrusion (tubular die). An increase in film stiffness was observed as a function of CaCO 3 content and a concentration of 30% CaCO 3 was found to be best for the specific application. The flat films were stiffer than the tubular ones. The densities of all the composite films were considered high, compared to a pulp-based paper and a commercial synthetic paper. No significant effect on the physical-mechanical properties analyzed was observed when the CaCO 3 particle size distribution was varied. Microcavities were found to form at the surface of flat films submitted to a bi-orientation process performed at laboratory scale; no other sample showed this surface morphology.

Efeito da Adição de Diferentes Copolímeros em Blendas HDPE/HIPS Pós-Consumo: Morfologia de Fases e Propriedades Térmicas

Blending of post-consumer polyolefins/HIPS has been exploited for obtaining special films with a desired set of properties, which has required studies to understand the behavior of these materials. In this work the effects of commercial multiblock styrene-butadiene (SBS) and linear triblock styrene-(ethylene-co-butylene)-styrene (SEBS) copolymers in blends of post-consumer high density polyethylene (HDPE) and HIPS are reported. Thermal properties and phase morphology were comparatively analyzed for the additives aiming at verifying possible correlations between them. Decreased dimensions of the minor micro phase along with HDPE surface roughness after HIPS selective extraction, independently of the matrix being HIPS or HDPE, showed better effectiveness for SEBS as interfacial tension modifier or as surfactant at the different domains interface when compared with SBS. The results of thermal characterizations, e.g. lower HDPE melting temperature, lower degree of crystallinity, and higher polystyrene glass transition temperature in the presence of SEBS corroborated with this conclusion as it will be discussed further.

Evaluation of sub-critical water as an extraction fluid for model contaminants from recycled PET for reuse as food packaging material

Recycling of plastics for food-contact packaging is an important issue and research into meaningful and cost-effective solutions is in progress. In this paper, the use of sub-critical water was evaluated as an alternative way of purifying poly(ethylene terephthalate) (PET) flakes for direct food contact applications. The effects of temperature, pressure and flow rate were assessed on the extraction efficiency of two of the most challenging classes of contaminants (toluene and benzophenone) from PET by sub-critical water using a first-order fractional experimental design. Extraction yield was quantified using GC/FID. The most important parameter was flow rate, indicating that the decrease in sub-critical water polarity with temperature was insufficient to eliminate partition effects. Temperature was also important, but only for the optimization of toluene extraction. These results may be explained by the poor solubility of higher molar mass compounds in sub-critical water compared to lower molar mass compounds under the same conditions, and the small decrease in dielectric constant with temperature under the experimental conditions evaluated. As cleaning efficiency is low and PET is very susceptible to hydrolysis, which limits the use of higher temperatures vis-à-vis physical recycling, the proposed extraction is unsuitable for a standalone super-clean process but may be a step in the process.

Filmes tubulares de compósitos de termoplásticos pós-consumo: análise térmica e mecânica

Resumo: Compositos ternarios de residuos pos-consumo de polipropileno (PP), poliestireno de alto impacto (HIPS) e carbonato de calcio (CaCO 3 ) foram preparados para obter filmes de papel sintetico e avaliar suas propriedades termicas e mecânicas. Estes filmes compositos altamente carregados com 10, 20 e 30 % em peso de CaCO 3 foram extrudados na extrusora sopro de filme (matriz tubular), em duas condicoes de velocidade da rosca: 32 e 51 rpm. A orientacao dos filmes compositos foi determinada por meio dos parâmetros das razoes de processo: R l (ao longo da direcao da maquina), R t (na direcao transversal da maquina) e R c (razao entre R L /R t ). Ensaios de caracterizacao por Calorimetria diferencial de varredura (DSC) e resistencia a tracao e ao rasgo foram usados para estudar as propriedades termicas e mecânicas dos filmes, observando-se a dependencia da composicao e do grau de orientacao. Resultados da analise termica por DSC indicaram que a concentracao de carga, assim como a orientacao do filme, exerce pouca influencia tanto na temperatura de fusao Tm quanto no grau de cristalinidade. Resultados do ensaio de tracao mostraram que o modulo de elasticidade dos filmes compositos com maior concentracao de carga diminui na direcao longitudinal e aumenta na transversal. Quanto a resistencia ao rasgo, o efeito do aumento da concentracao de carga e de orientacao foi o de incrementar essa propriedade. Abstract: Ternary composites from post-consumer waste of polypropylene (PP), high impact polystyrene (HIPS) and calcium carbonate (CaCO 3 ) were prepared to obtain films of synthetic paper and to evaluate their thermal and mechanical properties. These composites filled with 10, 20 and 30 % wt of CaCO 3 were film blown extruded under two conditions of screw rotation: 32 and 51 rpm. The composite film orientation was determined with the parameters along the longitudinal axis (Rl), transverse axis (Rt) and Rl/Rt ratio (Rc). Differential scanning calorimetry (DSC) and tensile and tear strength tests were used to study the thermal and mechanical properties of the films, showing their dependence on composition and orientation degree. Composite films with higher filler concentration exhibited a decreased tensile strength, but a less significant effect on tensile modulus. The tear strength was strongly dependent on the degree of film orientation.

Response Surface Analysis for Competition between Thermooxidation and Polycondensation Reactions of PET Flakes. Part 1: Low Vacuum Atmosphere

This work was accomplished employing solid-state polymerization (SSP) under less severe vacuum intensity (30 mmHg) in static mode at different times and temperatures. The influence of these parameters on intrinsic viscosity measurements was performed using Response Surface Methodology. The effect of temperature on intrinsic viscosity gains showed to be less pronounced than expected due to SSP being surface diffusion-controlled. The SSP efficiency for temperature as high as 230°C and dwell times higher than approximately 330 min showed lower increment on intrinsic viscosity than at immediately lower temperatures, although above approximately 215°C. This effect is a consequence of higher conversion rates of side reactions with increasing temperatures, their cumulative effect with increasing dwell time, and lower increment of polycondensation convertion rate with temperature under less severe vacuum intensity. The process temperatures and intervals determined, which allow PET recycling into new injected bottles, were moderates.

Estudo de Mercado em Duas Áreas Específicas de Aplicação de Papel Sintético

This paper assesses the potential demand for synthetic paper in Brazil. Advertising by outdoor panels, and panels in public transportation vehicles, taxis and personal document manufacture were considered. An annual demand between 2,500 and 2,800 tons was found for the scenario in which synthetic paper would replace cellulosic paper in all applications considered. The Brazilian synthetic paper market, still in an early stage, may show a steady increase in demand if investments are made on campaigns to familiarize the users with this new type of material.