Processing, Performance Properties, and Storage Stability of Ground Tire Rubber Modified by Dicumyl Peroxide and Ethylene-Vinyl Acetate Copolymers

In this paper, ground tire rubber was modified with dicumyl peroxide and a variable content (in the range of 0–15 phr) of ethylene-vinyl acetate copolymers characterized by different vinyl acetate contents (in the range of 18–39 wt.%). Modification of ground tire rubber was performed via an auto-thermal extrusion process in which heat was generated during internal shearing of the material inside the extruder barrel. The processing, performance properties, and storage stability of modified reclaimed ground tire rubber were evaluated based on specific mechanical energy, infrared camera images, an oscillating disc rheometer, tensile tests, equilibrium swelling, gas chromatography combined with a flame ionization detector, and gas chromatography with mass spectrometry. It was found that the developed formulas of modified GTR allowed the preparation of materials characterized by tensile strengths in the range of 2.6–9.3 MPa and elongation at break in the range of 78–225%. Moreover, the prepared materials showed good storage stability for at least three months and satisfied processability with commercial rubbers (natural rubber, styrene-butadiene rubber).

Addition of divinyl benzene comonomer to glycidyl methacrylate grafting to cyclic natural rubber

The process of thermally grafting glycidyl methacrylate (GMA) on cyclic natural rubber (CNR) compared to the addition of an initiator of organic peroxide, dicumyl peroxide (DCP) and using cross-linker divinyl benzene (DVB) has been carried out by means of melt processing. The main aims of the modified GMA grafted to CNR was to increase the polarity of the polymer to be used as a compatibiliser agent in asphalt modification. The addition of DVB comonomer in the processing was to increase the amount of GMA implanted in cyclic rubber as measured by the degree of GMA grafting. The grafting method was carried out by melting polymer (melt processing) at high temperatures in the reactor internal mixer (Brabender model). The grafting reaction took place at a temperature of 160°C, 60 rpm rotor rotation for 10 minutes of mixing. To determine the GMA grafting reaction on cyclic rubber, characterization was carried out with Fourier Transformed Infra Red (FT-IR) while the degree of GMA grafting on natural rubber was determined by acid-base titration method in organic solvents. It was found that the GMA grafting process on cyclic natural rubber could easily occur in the melting phase at high temperatures and increase with the addition of dicumyl peroxide (DCP) peroxide. Although the addition of divinyl benzene (DVB) comonomer can increase the degree of grafting of GMA on CNR, the addition of comonomer can cause high cross-linking.

EFFECTS OF GRAFTED VINYL TRIETHOXY SILANE ON MOISTURE CROSSLINKED EPDM

ABSTRACT An EPDM terpolymer grafted with silane vinyl triethoxysilane (EPDM-g-VTES) was prepared by melt grafting, with dicumyl peroxide (DCP) as an initiator. Next, dibutyl tin dilaurate was added as a catalyst to promote moisture crosslinking of EPDM-g-VTES. By means of the rheological response of the rubber compound, Fourier transform infrared spectroscopy, and moving die rheometer, the VTES graft ratio and DCP partial crosslinking (pre-crosslinking) of EDPM-g-VTES were characterized to show the feasibility of moisture crosslinking. The mechanical properties of moisture crosslinked EPDM-g-VTES specimens were tested by universal material tester. The results showed that when the weight ratio of VTES to DCP was fixed at 15:1, the VTES graft ratio and DCP partial crosslinking of EDPM-g-VTES increased with the increase of VTES content. But the torque in the moisture crosslinking curve of EPDM-g-VTES increased significantly with the extension of crosslinking time, which proved that EPDM grafted with VTES was cured by moisture successfully. The tensile strength and elongation at break of EPDM-g-VTES were improved by moisture cure. Furthermore, the moisture cured specimen with 3 wt% VTES had the best mechanical performance.

Effect of EVA and DCP addition on injection moldability and tensile properties of recycled PE from disposable drip tapes

The effects of ethylene-vinyl acetate copolymer (EVA) and dicumyl peroxide (DCP) addition on injection moldability and tensile properties of recycled polyethylene (PE) from disposable drip tapes were studied. DCP showed an adverse impact on the injection moldability of recycled PE materials, while EVA had positive effects on it. Tensile properties of the reproduced PE increased with the increasing amount of EVA up to 10 wt.% and decreased beyond it. The DCP addition reduced the elastic properties of the reproduced PE, while it enhanced the tensile strength. Overall, the co-addition of 6 wt.% EVA + 0.4 wt.% DCP could improve the tensile strength of the reproduced PE materials.

Discoloration of green PET bottles recycled with chemical agents by reactive extrusion

This study evaluates the effect of incorporating chemical agents with green polyethylene terephthalate (PET) bottles on extrudate color change and other properties. First, the best type of chemical agent that decolorizes recycled green PET bottles (RGPB) with good processability was determined. RGPB-chemical agent mixtures were evaluated, reducing, photoinitiator, or oxidant, where the best one turned out to be the oxidizing agent, a dicumyl peroxide. Then new mixtures of RGPB-oxidizing agent, dicumyl or benzoyl, were made in a reactive extrusion process employing a drying hopper to avoid hydrolytic degradation. The intrinsic viscosity, crystallinity, and color change of extrudates were determined. It was determined by SEM with EDS that the dye is possibly a chlorinated copper phthalocyanine. The final results show an increase in the intrinsic viscosity of the PET handling dicumyl peroxide, a partial whitening of the extrudates, and an increase in the crystallinity of the PET, which contributed to a decrease the hue and saturation of the green color of RGPB. Where the dicumyl peroxide present in mixtures with RGPB interacts with chlorinated copper phthalocyanine to produce phthalamide or phthalic acid, which are white.

Reaction extrusion of organic-inorganic hybrid gels based on modified polyolefins and dressed mineral fillers

The article discusses the technological features of the reaction extrusion of nanocomposites based on dressed natural minerals and high density polyethylene modified with compatibilizer and polypropylene. Clinoptilolite, vesuviane, bentonite and talc were used as natural minerals. The optimal technological mode of reaction extrusion was selected. Dicumyl peroxide in the amount of 0.25 and 0.5 wt.% was used as a vulcanization agent. The influence of technological features of reaction extrusion on the basic physicomechanical properties of nanocomposites based on polyolefins is considered.