Microwave Devulcanized Crumb Rubbers in Polypropylene Based Thermoplastic Dynamic Vulcanizates

Abstract

Because of the chemically crosslinked 3D molecular structure of rubbers, their recycling is a challenging task, especially when cost efficiency is also considered. One of the most straightforward procedures is the grinding of discarded rubber products with subsequent devulcanization. The devulcanized rubber can be used as a feedstock for fresh rubber compounds or can be blended with uncured virgin rubber and thermoplastic polymers to form thermoplastic dynamic vulcanizates (TDVs). TDVs combine the beneficial (re)processability of thermoplastics and the elastic properties of rubbers. Our current work focuses on the development of polypropylene (PP)-based TDVs with the use of a tire model rubber (MR) composed of natural rubber (NR) and styrene-butadiene rubber (SBR) in a ratio of 70/30. The research target was the partial substitution of the above fresh MR by microwave devulcanized crumb rubber (dCR). TDVs were produced by continuous extrusion, and the effects of composition (PP/MR/dCR = 40/60/0…50/35/15) and processing parameters (different screw configurations, temperature profiles, the feeding method of PP) were investigated. Results showed that the fresh rubber compound can be replaced up to 10 wt % without compromising the mechanical properties of the resulting TDV.

Microwave treatment in waste rubber recycling – recent advances and limitations

“…Moreover, authors indicated unsatisfactory compatibility and adhesion between HDPE and microwave treated GTR (regardless of extrusion parameter), what limit potential application of prepared blends. Simon et al [66] investigated polypropylene based thermoplastic dynamic vulcanizates obtained by twinscrew extrusion. At first they prepared materials containing model rubber comprising in 70% of SBR and in 30% of NR, which was then replaced partially (10, 20 and 30 wt%) by microwave-treated crumb rubber.…”

Preparation and properties of novel fluorosilicone thermoplastic vulcanizate with cross‐linking–controlled core‐shell structure

“…With the increasing requirements for environment protection and resource saving, thermoplastic vulcanizates (TPVs) have attracted more attention because of their good processability and easy recyclability . The effective way to prepare TPVs is through dynamical vulcanization, which is the process of cross‐linking an elastomer during its melt mixing with a molten plastic under dynamic condition . A significant number of TPVs are produced through this method, such as polylactide (PLA)/natural rubber (NR), PLA/epoxidized natural rubber (ENR), PLA/nitrile butadiene rubber (NBR), poly(vinylidene fluoride) (PVDF)/acrylic rubber (ACM), ethylene‐propylene‐diene monomer (EPDM)/polypropylene (PP), PVDF/ENR, polyamide 12 (PA12)/hydrogenated acrylonitrile butadiene rubber (HNBR), and ethylene octene copolymer (EOC)/poly dimethyl siloxane (PDMS) rubber …”

“…6,7 The effective way to prepare TPVs is through dynamical vulcanization, [8][9][10] which is the process of cross-linking an elastomer during its melt mixing with a molten plastic under dynamic condition. 11,12 A significant number of TPVs are produced through this method, such as polylactide (PLA)/natural rubber (NR), 13,14 PLA/epoxidized natural rubber (ENR), [15][16][17] PLA/nitrile butadiene rubber (NBR), 18 poly(vinylidene fluoride) (PVDF)/acrylic rubber (ACM), 19 ethylene-propylene-diene monomer (EPDM)/polypropylene (PP), [20][21][22][23] PVDF/ENR, 24 polyamide 12 (PA12)/hydrogenated acrylonitrile butadiene rubber (HNBR), 25 and ethylene octene copolymer (EOC)/poly dimethyl siloxane (PDMS) rubber. 26 The properties of TPVs strongly depended on the final morphology, which were affected by many factors, such as the cross-linking degree of the rubber phase, composition, viscosity and elasticity of individual components, preparation method, and processing condition.…”

The Influence of UV-Accelerated Aging Process on Industrial Waste Containing EPDM

“…Among the most-studied methods, the ultrasound method uses ultrasound waves to produce cavitation in the rubber, which generates tensions that are able to break the chemical bonds [3,5,[11][12][13][14][15][16][17][18]. Another de-vulcanization method based on the action of microwaves presents some advantages that make it one of the most promising for the recycling of rubber [2][3][4]13,15,[18][19][20][21][22], including its physical nature, the volumetric heating of the material by the microwaves, and the possibility of high productivity [23].The aging of elastomers can be defined as the degradation process produced by the interaction between a material and an environment, modifying their structure and properties (i.e., mechanical, electrical, chemical, and/or thermal). It is a complex chemical process that occurs under the influence of heat, oxygen, light, ozone, and mechanical tension, and it results in time-dependent modifications of the chemical and physical properties [24].…”