Research on Rheology and Micro-properties of Modified Room Temperature Biological Asphalt

In order to explore the rheological property and principles of modified room temperature biological asphalt made with petroleum asphalt, vegetable asphalt, and unsaturated fatty acids as raw materials, waste rubber powder as modifier, and calcium hydroxide powder as curing agent, this paper compared and tested the rheological properties and the original petroleum asphalt by using DSR and BBR, and the micro-properties of the asphalt were studied by using SEM. The PG classification of modified room temperature biological asphalt has been upgraded from PG58-28 of the original petroleum asphalt to PG82-28. Compared with the original petroleum asphalt, the high temperature rheological property of the modified room temperature biological asphalt has been greatly improved. Its low temperature rheological property is equivalent to the original one, but the possibility of cracking is lower. SEM test showed that the components of the modified room temperature biological asphalt are well combined. The calcium hydroxide curing agent reacts with fatty acid and the rubber particles cross link with each other to form a mesh package in the asphalt, which provides strength for the modified temperature biologic asphalt at room temperature.

Preparation of High-Performance Composite Hydrogel Reinforced by Hydrophilic Modified Waste Rubber Powder

In order to reduce the environmental pollution caused by waste rubber and to realize the recycling of resources, we proposed a facile method for the hydrophilic modification of waste rubber powder (HRP) and used it to reinforce a composite hydrogel. In the presence of toluene, dibenzoyl peroxide (BPO) diffused into the waste rubber powder. After the solvent was removed, BPO was adsorbed in the rubber powder, which was used to initiate the grafting polymerization of the acrylamide monomer on the rubber–water interface. As a result, the polyacrylamide (PAM) molecular chains were grafted onto the surface of the rubber powder to realize hydrophilic modification. The success of the grafting modification was confirmed by FTIR, contact angle testing, and thermogravimetric analysis. The hydrophilic modified waste rubber powder was used to reinforce the PAM hydrogel. Mechanical tests showed that the tensile strength and elongation at the break of the composite hydrogel reached 0.46 MPa and 1809%, respectively, which was much higher than those of pure PAM hydrogel. Such a phenomenon indicates that the waste rubber particles had a strengthening effect.

Enhanced Storage Stability and Rheological Properties of Asphalt Modified by Activated Waste Rubber Powder

Segregation of waste crumb rubber powder (WR) modified asphalt binders the large-scale application of WR in asphalt. The method of microwave activation combined with chemical activation (KMWR) was proposed to improve storage stability and rheological properties of WR modified asphalt in this work. Storage stability and rheological properties of virgin asphalt, MWR modified asphalt, and KMWR modified asphalt were comparatively studied by the standard segregation test, bending beam rheometer (BBR) test, and dynamic shear rheometer (DSR) test. The effect of composite activation on waste rubber powder particles was studied by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and Brunauer–Emmett–Teller (BET) tests. The main results showed that after the physical and chemical composite activation, the storage stability of waste rubber powder modified asphalt was significantly improved, WR modified asphalt had better crack resistance, better rutting resistance, and better fatigue performance. After physical and chemical activation, WR was desulfurized, and a large number of active groups was grafted on the WR particles.

EFFECTS OF CROSSLINK BOND TYPE OF IIR-BASED WASTE RUBBER POWDER ON THE EPDM-ASSISTED DEVULCANIZATION REACTION

ABSTRACT Isobutylene–isoprene rubber (IIR)–based waste rubber powder (WRP) present in WRP/ethylene–propylene–diene monomer (EPDM) blends was devulcanized through a stress-induced reaction by increasing the screw rotation speed in the presence of subcritical ethanol. The effects of crosslink bond type (which was cured using phenolic resin, sulphur, or zinc oxide) of WRP and the screw rotation speed on devulcanization were investigated. The results showed that the Mooney viscosity and gel content of the devulcanized blends (DWRP/EPDM) decreased with an increase in the screw rotation speed, and the optimal screw rotation speed maximized the molecular weight (Mη) of sols and enhanced the mechanical properties of the revulcanized material. The optimal screw rotation speed for the phenolic resin-cured WRP1 and zinc oxide-cured WRP3 was 500 r min−1 and that for sulphur-cured WRP2 was 300 r min−1. At the optimal screw rotation speed, crosslink bonds severely fractured, and the main chain structure remained relatively intact. The 1H-NMR spectra of the sol in the devulcanized blends (DWRP/EPDM) confirmed that the content of the alpha and double-bond protons of sols are the highest at the optimal screw rotation speed, and many promoting agent (480) molecules penetrate and participate in devulcanization. Scanning electron microscopy images indicated that the size of the unfused gel particles in the mixed-revulcanized materials of IIR/(DWRP1/EPDM), IIR/(DWRP2/EPDM), and BIIR/(DWRP3/EPDM) was the smallest at the optimal screw rotation speed.