Mechanism of the foaming agent‐assisted microwave drying process on the construction of natural raw rubber network and cross‐linking network

Abstract

The drying process of natural rubber latex significantly affects the structure of the raw rubber network and vulcanizate crosslinking network, resulting in various anti-aging performances. In the present study, a microwave generator was used as an efficient source of clean energy; potassium oleate was introduced as a foaming agent to increase the porosity and water loss channel of the latex system. Aiming at dehydrating and drying natural rubber latex efficiently, an aging resistant rubber composite was prepared. Meanwhile, the mechanism of the foaming agent-assisted microwave drying process on the raw rubber network and the cross-linking network was studied. The experimental results show that the prepared rubber using by this process has higher plastic retention and fluidity. Moreover, it contains more non-rubber components (e.g. protein and acetone extract) and better network structure of raw rubber and vulcanized rubber. It is found that applying this process increases the tensile product by 13.5% and the retention rate of the tensile product after aging by 15.3 times. This process is important for the development of the rubber industry in the direction of green environmental protection, energy conservation, and high efficiency.

Preparation of high‐performance natural rubber composites: Plasma‐foaming agent‐modified kaolin and flash‐drying technology

“…However, both plasma treatment and PO foaming have been found to reduce the Mooney viscosity, and under conditions of synergistic effect, the minimum Mooney viscosity is recorded. This is because the long chain of PO acts as an internal lubricant, reducing friction between rubber molecules and resulting in a lower Mooney viscosity 33 . Additionally, the impact force from high‐energy electrons in plasma technology helps to keep kaolin in a highly dispersed state, promoting the dispersion and interfacial bonding of PO to kaolin and ultimately leading to a lower Mooney viscosity in the plasma–PO–Flashing group.…”

“…This is because the long chain of PO acts as an internal lubricant, reducing friction between rubber molecules and resulting in a lower Mooney viscosity. 33 Additionally, the impact force from high-energy electrons in plasma technology helps to keep kaolin in a highly dispersed state, promoting the dispersion and interfacial bonding of PO to kaolin and ultimately leading to a lower Mooney viscosity in the plasma-PO-Flashing group. Table 3 compares the vulcanization characteristics of rubber blends prepared through different processes.…”

Wet continuous mixing technology and extrusion rheological properties of carbon black/natural rubber composites

“…Acid flocculation is the most traditional flocculation method for wet mixing, but acid is detrimental to properties of rubber products such as aging resistance, and the emission of acidic gases and acidic wastewater pollutes the environment and endangers human health. 29,30 In this study, the flocculation extrusion technology based on carbon black is explored without the addition of any chemical additives outside the formulation, and the mechanism of flocculation extrusion technology is shown in Figure 2. On the one hand, CB itself has a certain adsorption force on the rubber particles, compressing the thickness of the double electric layer and increasing the possibility of agglomeration.…”

Mechanism of the green coagulation processes on the construction of raw rubber network structure

“…However, acid is corrosive to mechanical equipment, and acidic gases and waste liquids can also have adverse effects on the environment and human health. 21,22 Meanwhile, acid coagulation requires long, high-temperature drying, which leads to a longer vulcanization time and poor antiaging properties. Inorganic salt flocculants such as calcium chloride, magnesium chloride, and sodium chloride can also solidify the NRL, but the presence of metal ions can also be detrimental to the aging resistance of rubber.…”

“…NR, a renewable biopolymer, is often prepared by acid coagulation of NRL. However, acid is corrosive to mechanical equipment, and acidic gases and waste liquids can also have adverse effects on the environment and human health 21,22 . Meanwhile, acid coagulation requires long, high‐temperature drying, which leads to a longer vulcanization time and poor antiaging properties.…”