Maria José O. C. Guimarães

Effect of molecular weight and long chain branching of metallocene elastomers on the properties of high density polyethylene blends

Abstract In this work, rheological properties and morphological characteristics of blends based on high density polyethylene (HDPE) and two different grades of poly(ethylene-co-octene) metallocene elastomers (EOC) were studied. These elastomers were commercial samples differing in molecular weight, and rheology index (DRI). Blends were processed in a single screw extruder (L/D=32), at 230 °C and 50 rpm, using mass fraction weight percent of EOC in the range from 5–80%. The rheological properties were evaluated in dynamic experiments at 190 °C and frequency range from 10 -1 s -1 –10 -2 s -1 . The blends exhibited pseudoplasticity and complex rheological behavior. That complex behavior was intensified by increasing molecular weight and long chain branching proportion (DRI) of EOC elastomers. The morphological characterization was carried out by using scanning electron microscopy (SEM). The blends exhibited dispersed morphologies with EOC domains distributed homogeneously and with particle size inferior to 2 μm.

Degradação de poliolefinas utilizando catalisadores zeolíticos

In this work the degradation of some of the main plastics responsible for waste, viz. high density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene (PP), was studied using a spent FCC catalyst (fluid cracking catalyst) and a zeolitic catalyst (ADZ3) synthesized in laboratory. Using thermogravimetry (TG-DTG) and gas chromatography (GC) techniques, it was possible to evaluate the products from these polyolefins cracking. The catalytic degradation of polyolefins led to a preferential production of LPG, diesel and gasoline, which are important products of the Brazilian energetic matrix. The spent FCC catalyst was more selective for production of LPG and gasoline, whereas the diesel production was more favored with the ADZ3 catalyst.

Efeito da temperatura e taxa de cisalhamento nas propriedades de escoamento da polpa de Cupuaçu (T. grandiflorum Schum) integral

The rheological behavior of the entire cupuassu pulp was determined in the temperature range 10 - 60oC. The effects of temperature and deformation rate were evaluated by means of shear flow tests. Rheometry analyses were conducted with a Thermo Haake RheoStress 1 system. Rheograms were described by models by Ostwald-of-Waelle and Herschel-Bulkley. The Ostwald-of-Waelle model successfully represented pulp flow behavior. The product presented shear-thinning behavior and the flow behavior index (n) decreased with the increase of temperature. The effect of temperature on the apparent viscosity in cupuassu pulp was described by an Arrhenius equation and discussed in terms of activation energy. The increase in shear rate caused an energy increase, and values were obtained in the range of a line from 1 to 2 kcal/gmol.

Patenteamento em Nanotecnologia: Estudo do Setor de Materiais Poliméricos Nanoestruturados

In this work a study of technological tendencies in nanotechnology applied to polymeric materials sector was carried out, based on information extracted of paten documents. The patent office of USPTO (United States Patent Trademark Office) was used as a data source. The data were supplied via web, using several keywords. A mapping was made of the major countries contributing, types and year of patent deposition, application sectors, polymer types used, main additives and fillers incorporated to the polymeric matrices.

Estudo comparativo de diferentes tipos de polibutadieno na tenacificação de poliestireno

In this work, an evaluation was made of the toughening of polystyrene (PS) with three types of polybutadiene (PB): low-cis polybutadiene (PBl), high-cis polybutadiene (PBh ) and styrene-butadiene block (SBS) copolymer (PBco). The impact strength increased 138, 208 and 823% when low-cis polybutadiene, high-cis polybutadiene and styrene-butadiene block copolymer, were used, respectively. The materials presented dispersed morphology with domains smaller than 1 µm, randomly distributed in the polystyrene matrix. The flow activation energy, calculated by Arrhenius equation, varied from 34 to 71 kJ/mol. In the rheological experiments all polymer blends presented pseudoplastic behavior.

Management of plastic wastes at Brazilian ports and diagnosis of their generation

This study evaluated the management of plastic wastes at 20 Brazilian maritime ports, from three sources: vessels, leased and non-leased areas. The data were obtained from documents on port wastes organized in a relational database with defined protocols (closed form). Analysis of the spreadsheets prepared and field visits revealed that the main bottleneck in managing plastic wastes at ports is their segregation. In general, more material is segregated and sent for recycling from leased areas than non-leased ones (administered by the government). This relatively better performance in managing the wastes generated in leased areas is probably due to the need for private operators to comply with the international standards such as the Code of Environmental Practice to satisfy the international market.

Catalisadores metalocênicos: aspectos gerais e heterogeneização

Este trabalho apresenta uma discussao sobre aspectos gerais da nova tecnologia de sintese de polimeros com microestrutura e propriedades controladas, obtidos via sistema catalitico metaloceno/MAO. Mostra a importância da heterogeneizacao desses sistemas para possibilitar o seu emprego na producao industrial de uma ampla classe de materiais polimericos. Sao discutidas ainda as principais caracteristicas dos suportes mais empregados para esses catalisadores.

Reologia de Polietileno de Alta Densidade Tenacificado com Polietileno Elastomérico

In this work rheological properties of high density polyethylene toughened with two different grades of metallocene elastomers based on poly(ethylene-co-octene) were studied. These elastomers were commercial polymers differing in molecular weight, and Dow Rheology Index (DRI). Blends were processed in a Wortex single screw extruder (L/D=32), at 230 °C and 50 rpm, using mass fractions of EOC in the range from 5% to 80%. The rheological properties were evaluated in steady and dynamic experiments at 190 °C and shear rates in the range from 90 s -1 to 1500 s -1 with frequencies from 10 -1 s -1 to 10 -2 s -1 . The blends exhibited pseudoplasticity and complex rheological behavior. The complex rheological behavior was intensified with increasing molecular weight and long chain branching proportion (DRI) in the EOC elastomers.

Desenvolvimento de Materiais à Base de Poliolefinas e Elastômeros Metalocênicos

The aim of this work was to evaluate the mechanical, thermal and morphological properties of systems based on polyolefins (PP and HDPE) and ethylene/1-octene metallocene copolymer (EOC), produced by Dow Chemical. The effect of a propylene/1-octene metallocene copolymer (POC), obtained in the laboratory was also investigated as a compatibilizer agent for the PP/EOC blend. The results showed that the addition of certain contents of EOC to PP and HDPE may carry the production of materials with good mechanical properties. The data obtained also revealed that the POC copolymer can be used as compatibilizer agent of the PP/EOC blends.

Polietileno de Alta Densidade Tenacificado com Elastômero Metalocênico: 1. Propriedades Mecânicas e Características Morfológicas

The mechanical and morphological properties of high density polyethylene (HDPE) toughened with two different grades of metallocene elastomers based on ethylene/1- octene (EOC) were studied. These elastomers were commercial polymers differing in molecular weight, melt flow index and Dow rheology index (DRI). Blends were processed in a Wortex single screw extruder (L/D=32), at 230°C and 50 rpm, using mass fraction weight percent of EOC in the range from 5% to 80%. A synergistic effect on the tensile properties and supertough behavior for blends with EOC concentrations higher than 5% was observed. Cavitation, plastic deformation and fibrillized cavitation were observed in the deformation processes. Materials containing up to 50% of EOC exhibited dispersed morphologies with EOC spherical domains uniformly distributed with particle size in the range from 0.30 to 0.45 µm. The toughening of HDPE with ethylenic elastomers produced materials with good properties and technological compatibilization.