Page 58 - 《橡塑技术与装备》英文版2025年12月

HINA R&P TECHNOLOGY AND EQUIPMENT

figures in Figure 2 demonstrate the disappearance of loose the surface becomes rougher. This is because HDA interacts
particles in DCR, with surface adhesion and the appearance with the rubber molecular chains, gradually destroying the
of holes and gaps. This is due to the destruction of the internal cross-linking network, making the originally compact structure
cross-linking network of DCR. Figures 2(b)(e)(f) show the looser, and thus forming more pores. The increase in HDA
apparent morphology of DCR at different desulfurization content is accompanied by a deeper degree of desulfurization
temperatures. From Figure 2(b) to (e), it can be observed reaction, leading to more severe breakage of rubber molecular
that the surface of DCR becomes increasingly rough, and the chains. This makes DCR particles more prone to crushing
particle size decreases. When the desulfurization temperature under the shear force of the internal mixer, resulting in particles
is increased from 140℃ to 160℃, it accelerates the chemical with blurred and irregular edges, unlike CR which has a clearer
reaction between HDA and CR, allowing the desulfurizing outline and regular shape.
agent to fully contact and react with the sulfur cross-linking 2.3 The impact of desulfurization process on
bonds on the rubber molecular chains, thereby accelerating the conventional physical properties of PMA
the breakage of the cross-linking bonds. On the other hand, The impact of the desulfurization process on the
high temperatures intensify the thermal motion of rubber conventional physical properties of PMA is illustrated in
molecules, increasing the flexibility of the molecular chains, Figures 3 and 4. It can be observed that as the desulfurization
making them more prone to breakage and rearrangement. temperature and rotational speed increase, both ductility
Simultaneously, the mechanical shearing effect of the internal and penetration increase, but the softening point and elastic
mixer becomes more effective at high temperatures, further recovery decrease, indicating a strong correlation with its
promoting the breakage of rubber molecular chains and the degree of desulfurization. When the degree of desulfurization
refinement of rubber powder particles. From Figure 2(e) to (f), is low, the interaction between rubber powder and asphalt is
it can be observed that the surface of DCR tends to become weak, with little impact on the softening point. As the degree
smoother. When the desulfurization temperature is increased of desulfurization increases, the rubber powder disperses and
from 160℃ to 180℃, it may be due to the excessively high swells better in the asphalt, reducing the high-temperature
temperature inside the internal mixer, leading to a more stability of the asphalt, and the softening point tends to
thorough desulfurization reaction. At the same time, a large decrease. The softening point represents the temperature at
number of cross-linking bonds in the rubber molecular chains which asphalt transitions from a solid state to a paste with
break, becoming smaller and more uniform, rearranging on certain fluidity. After desulfurization of rubber powder, the
the surface of the rubber powder, thus presenting a smooth crosslinking density decreases, weakening its ability to absorb
appearance. Figures 2(c)(d)(e) show the apparent morphology light components in asphalt. This results in a relative increase
of DCR at different desulfurization speeds. It can be observed in light components in asphalt, making it more prone to flow at
that as the speed increases, the surface of DCR becomes high temperatures, leading to a decrease in softening point.
increasingly rough, with more and more holes and gaps Generally, when the degree of desulfurization is
appearing. This is due to the increased mechanical shearing low, due to less damage to the CR cross-linked structure,
effect caused by the higher speed of the internal mixer, which its dispersibility in asphalt is poor, and its impact on the
subjects DCR to greater shearing and friction inside the penetration of asphalt is small. As the degree of desulfurization
chamber, leading to more wear and tear on the surface of the increases, the cross-linked structure is largely destroyed, CR
rubber powder, forming more irregularities, holes, and cracks, swells fully in asphalt, and the plasticizing effect of organic
and significantly increasing surface roughness. Figures 2(e) small molecules in DCR on asphalt is enhanced, resulting in
(g)(h) show the apparent morphology of DCR with different an increase in the penetration of asphalt. Penetration reflects
contents of desulfurizing agent HDA. It can be observed that the hardness and consistency of asphalt. DCR's ability to
as the content of desulfurizing agent increases, the pores inside absorb light components in asphalt weakens, and the content of
the rubber powder become more abundant and connected, and organic small molecules increases, playing a plasticizing role,

·52· Vol.51，No.12