No abstract

As garrafas PET conquistaram o mercado graças às suas propriedades de leveza, razoável resistência mecânica e moldabilidade a baixa temperatura, aliadas ao preço baixo. Porém, em seu pós-consumo, devido à pouca degradabilidade e baixa densidade, ocupam vastos espaços no ambiente por um longo tempo e se tornam uma preocupação ambiental. Nos últimos anos, não só aumentou o percentual de garrafas recicladas no Brasil, como também foram criadas legislações para utilização deste material em embalagens de alimentos e bebidas. Além disso, refrigerantes com garrafas produzidas totalmente com resina proveniente de garrafa PET pós-consumo (bottle-to-bottle) já vêm sendo vendidas comercialmente. Neste contexto, o presente trabalho visou, através de uma revisão de literatura, fazer um levantamento de informações sobre o PET com enfoque em dados atualizados sobre sua reciclagem, o contexto social relacionado ao reaproveitamento desse material e seu uso para produção de novas garrafas PET (tecnologia bottle-to-bottle).

Abstract:The solid state polymerization (SSP) of PET/PC reactive extrusion blends -with and without cobalt catalyst -at different polymer ratios was studied. Thermal and rheological evaluations were performed. DSC results showed changes in the PET's T g , T ch , T m and X c . The melt flow rate (MFR) decreased for PET and the blends. The intrinsic viscosity increased. The variation in calorimetric and rheological properties might be attributed to the PET's chain extension reactions -esterification and transesterification. These reactions led to an increase in the PET's molar mass, consequently shifting the PET's T g to lower temperature and PET's crystallization, besides reducing the blend miscibility and flowability.

ABSTRACT

A systematic study of solid state polymerization (SSP), concerning the melt extruded blend of poly(ethylene terephthalate)/polycarbonate (catalyzed PET/PC, 80/20 wt %), as a function of temperature range (180-190°C) for a fixed time (6 h) is presented. The materials obtained were evaluated by differential scanning calorimetry (DSC), thermogravimetry/derivative thermogravimetry (TG/DTG), optical microscopy (OM) and intrinsic viscosity (IV) analysis. After SSP, at all reaction temperatures, PET glass transition and heating crystallization temperatures slightly decreased, melting temperature slightly increased, while degree of crystallinity was practically invariable. The DTG curves indicated that, at least, three phases remained. The OM images revealed that the morphology is constituted of a PET matrix and a PC dispersed phase. In the interfacial region we noticed the appearance of structures like bridges linking the matrix and the dispersed domains. These bridges were correlated to the PET/PC block copolymer obtained during blending in the molten state. IV increased for all polymerization temperatures, due to the occurrence of PET chain extension reactions -esterification and transesterification. The IV range for bottle grade PET was achieved.

No abstract

Wood-plastic composite based on post-consumer HDPE and vermiculiteCompósito madeira-plástico à base de HDPE pós-consumo e vermiculita

The recycling process is the best way to manage waste polymers. From an economic standpoint, more investigation is needed of the whole recycling process to enhance the competitiveness in these systems. A first step is improved interaction and interfacial adhesion of blends. Polyethylene (PE) and polyethylene terephthalate (PET) are incompatible polymers, so their blends in general have poor properties. Compatibilization is thus a necessary step to obtain blends with good mechanical and barrier properties. In this work, blends of recycled (high density polyethylene) (HDPE) and post-consumer PET, with organophilic bentonite clay acting as compatibilization agent at the interface of the two polymers, were obtained. The proportions of HDPE/PET/bentonite (0, 5, 10 and 15% weight percentage of bentonite) were processed by extrusion. The processed materials were characterized regarding density (ASTM D792-13), melt flow index (MFI, ASTM D1238-13), hardness (ASTM D2240–10), infrared absorption spectroscopy (FTIR), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results indicated the occurrence of some compatibilization.