Dynamic reaction inside co‐rotating twin screw extruder. I. Truck tire model material/polypropylene blends

Abstract

Waste ground rubber tire (WGRT) is a complex composite containing various elastomers, carbon black, zinc oxide, stearic acid, processing oils, and other curatives. Most of the waste ground rubber tire is composed of mainly natural rubber (NR) and styrene butadiene rubber (SBR) in varying proportions. Blending it with other thermoplastic materials is difficult due to the inherent thermodynamic incompatibility. But, the compatibility can be increased by making the reactive sites in WGRT with suitable chemicals under optimum condition of shearing inside a twin screw extruder and it is said to undergo a dynamic reaction inside the extruder. To understand the mechanism of dynamic reaction process of a rubber/polyolefin blend, the blending of a truck tire model material rubber with polyolefin was first tried before it was applied to waste WGRT material. It was observed that the blends of a truck tire model rubber material and PP thermoplastic are physical mixture of two incompatible polymers in which a continuous plastic phase is largely responsible for the tensile properties. The rubber particles are the dispersed phase. The large particle size and the poor adhesion of these rubber particles are believed to be liable for the poor tensile properties. In case of blends of truck tire model material with isotactic polypropylene the tensile properties are found to be lower than that of its PP-g-MA counterpart which can be attributed to the reaction of the MA with the carbon black particles. A schematic representation of the possible interactions has been proposed. The effect of addition of compatibilizers such as SEBS and SEBS-g-MA has also been studied. The tensile and TGA studies indicate that the polarity of SEBS and SEBS-g-MA induces an increase in the performance characteristics for both types of polyolefins but the intensity of this increase is higher in the PP-g-MA based blends.

Otimização de propriedades mecânicas de misturas ternárias de polipropileno (PP)/borracha de etileno-propileno-dieno (EPDM)/pó de pneus (SRT) sob tração e impacto usando a metodologia da superfície de resposta (MSR)

“…Na literatura [10][11][12] é reportado que a adição de SRT na forma de carga particulada ao PP reduz a resistência à tração e o alongamento na ruptura como consequência da fraca adesão entre as fases e a concentração de tensões ao redor das partículas de SRT. SRT apresenta uma pobre capacidade de suportar a transferência de tensões a partir da matriz de PP e, portanto, as misturas ternárias ricas em SRT exibem uma diminuição acentuada desta propriedade.…”

“…Observa-se que o material exibe uma textura mais homogênea, na qual a fase dispersa não pode ser claramente identificada. Há claras evidências de um mecanismo de fratura mais dúctil, ou seja, com uma deformação plástica mais visível [9,11,12] . Além disso, a estrutura fibrilar é novamente verificada (Figura 7e.1), porém, desta vez, de forma bem mais acentuada do que o verificado anteriormente para a mesma composição (Figura d.1).…”

“…Os resíduos de borracha oriundos de pneus inservíveis tornaram-se um passivo ambiental de grande preocupação. A adição de resíduos de pneus moídos (SRT) ou desvulcanizados em composições poliméricas é apresentada na literatura como uma maneira de gerar misturas de fácil processamento, vantajosas economicamente e com aumento da tenacidade da matriz termoplástica de interesse [9][10][11][12] . Porém, na literatura, o estudo das diferentes misturas entre o PP e borrachas é conduzido de forma aleatória, ou seja, um grande número de composições diferentes .…”

Blends of ground tire rubber devulcanized by microwaves/HDPE - Part A: influence of devulcanization process

“…The thermoplastic matrix is responsible for the processability of TPVs, while the cross-linked elastomer particles are responsible for the elasticity at room temperature. The final morphology of this kind of material is the main responsible for the rheological and physical properties beyond being controlled by the processing conditions and characteristics of the constituting materials [13] .…”

Degradation of non-vulcanized natural rubber renewable resource for fine chemicals used in polymer synthesis

“…One approach to minimize the problem of rubber waste is to use the ground tire rubber in formulations with other polymers [72][73][74][75][76] and also with asphalt [77] . Other interesting solution is the devulcanization of the NR to produce lower molar mass products.…”