Enhancement of thermoelectric and mechanical properties of thermoplastic vulcanizates (TPVs) with hydroxylated graphene by dynamic vulcanization

In order to obtain higher thermoelectric and mechanical properties in nonpolar thermoplastic vulcanizates (TPVs), the butyl rubber/polypropylene (TPVs)/hydroxylated graphene (HGE) composites with nanosheet network were prepared through masterbatch technique and based on thermodynamic calculations, using polypropylene-graft-maleic anhydride (PP-MA) as a compatibilizer. The Fourier transform infrared (FTIR) and Raman spectra revealed the introduced maleic anhydride group on PP-MA can form strong interfacial interaction with hydroxyl-containing functional groups on HGE. Morphology study indicated the rubber particles in the composites occupied the most volume of the PP phase, as expected to hinder the aggregation of HGE and form the effective nanosheet network. The nanosheet network can be combined with the butyl rubber (IIR) cross-linked particles during the dynamic vulcanization process to improve the interface bonding between PP and IIR, thus increasing the tensile strength of TPVs. The prepared TPVs/HGE composites have significantly improved in mechanical properties, thermal properties and dielectric properties, which provides a guarantee for their potential application as multifunctional TPVs polymers.

Preparation of polyoxymethylene/methyl vinyl silicone rubber/thermoplastic polyurethane ternary thermoplastics vulcanizates with good toughness properties

Novel thermoplastic vulcanizates (TPVs) based on polyoxymethylene (POM) and methyl vinyl silicone rubber (MVQ) have been prepared by dynamic vulcanization process through a batch mixer. During the preparation of TPV blends, Di-(tert butyl peroxyisopropyl) benzene (BIBP) was used as the curing agent in order to make MVQ cross-linked and TPU was used to coat MVQ for improving the compatibility of MVQ and POM. In order to understand the influence of different compositions on TPV blends, five groups of experimental processes were described in detail. During these experiments, the amount of POM was reduced from 70phr to 30phr, that of MVQ was gradually increased from 18phr to 42 phr, and TPU was increased from 12phr to 28phr. In addition, the morphology and properties of TPVs were studied by DSC, FTIR, SEM, DMA and mechanical tests. The mechanical testing results showed that with the amount of POM decreasing and the total amount of MVQ and TPU increasing, the tensile strength of the TPV blends gradually was decreased, and the elongation at break was increased accordingly from 35.2 ± 6% of pure POM to 142.8 ± 11% of sample 5#.

PP/POE thermoplastic elastomer prepared by dynamic vulcanization and its flame retardant modification

Flame retardant thermoplastic elastomer (TPE) with excellent mechanical properties and thermal oxidative aging resistance was prepared by dynamic vulcanization technology with ethylene-octene copolymer (POE) and polypropylene (PP) as raw materials. The paper first discussed the effect of the amount of vulcanizing agent on the properties of PP/POE TPE. Based on the study of tensile strength, elongation at break, cross-section morphology, processability and aging properties of TPE, it was found that the TPE prepared with 0.6 phr of bis(1-(tert-butylperoxy)-1-methylethyl)-benzene (BIPB) and 40/60 of PP/POE had the best properties. Then silicone powder (GM) is added to the traditional low-halogen bromine-phosphorus flame retardant system for flame retardant modification. The results show that the addition of GM can effectively enhance the stability of the carbon layer, prevent the material from dripping during combustion, and increase the residual carbon content of TPE at 800°C. When 3 phr of GM is combined with a bromine-phosphorus system. The comprehensive performance is the best, the limiting oxygen index (LOI) of TPE increased to 29.8%, reaching the V-0 level. At the same time, the processing fluidity and aging resistance of TPE materials have also been improved.

Enhance Thermoelectric and Mechanical Properties of Thermoplastic Vulcanizates (TPVs) by Constructing Nanosheet Network of Hydroxylated Graphene

In order to obtain higher thermoelectric and mechanical properties in non-polar thermoplastic vulcanizates (TPVs), the Butyl rubber/Polypropylene (TPVs)/hydroxylated graphene (HGE) composites with nanosheet network were prepared through masterbatch technique and based on thermodynamic calculations, using polypropylene-graft-maleic anhydride (PP-MA) as a compatibilizer. The FTIR and Raman spectra revealed the introduced maleic anhydride group on PP-MA can form strong interfacial interaction with hydroxyl-containing functional groups on HGE. Morphology study indicated the rubber particles in the composites occupied the most volume of the PP phase, as expected to hinder the aggregation of HGE and form the effective nanosheet network. The nanosheet network can be combined with the IIR cross-linked particles during the dynamic vulcanization process to improve the interface bonding between PP and IIR, thus increasing the tensile strength of TPVs. When the content of HGE reached the percolation threshold (2 wt.%), the nanosheet network of HGE was formed, and the AC conductivity, dielectric permittivity and thermal conductivity increased sharply. The prepared TPVs/HGE nanocomposites have significantly improved in mechanical properties, thermal properties and dielectric properties, which provides a guarantee for their potential application as multifunctional TPVs polymers.

Development of elasto-plastic eco-nano-materials for the footwear industry

The paper refers to the obtaining of new types of eco-nano elasto-plastic materials with high-performance characteristics based on ethylene-propylene-terpolymer rubber (EPDM), high-density polyethylene (HDPE), plasticized starch and organically modified montmorillonite (OMMT). The new materials were obtained by the technique of dynamic vulcanization and melt intercalation in a Plasti-Corder Brabender internal mixer, at 80 rpm and a temperature of 170°C. The influence of using the OMMT type nanofiller and the plasticized starch filler on the characteristics was observed. The new materials have a melt flow index of over 12g/10 min at 180°C for a force of 10 kg, which allows injection processing - an ecological method of processing polymeric materials. The samples show very good physical-mechanical characteristics both in the normal state and after accelerated aging at 168 hours at 170°C (tensile strength over 16 N/ mm2, tear strength over 102 N/mm, hardness 55-59°ShD, elasticity over 30%, etc.). The materials show high values of abrasion resistance (below 30 mm3), and very good results for mass and volume variation after 22 hours at 23°C in: water, acids and concentrated bases. These characteristics are due both to the composition of the new materials and to the obtaining technology. For evaluating the structural modification, analysis of the FT-IR spectral of the samples was carried out. The new materials can be used in different fields such as: in the footwear industry (soles, heels and plates), safety equipment (boots, etc), obtaining gaskets, hoses, technical rubber products for cars etc.