Page 84 - 《橡塑技术与装备》英文版2026年3期

HINA R&P TECHNOLOGY AND EQUIPMENT

The reason lies in the fact that silicone oil, as a small molecule extrudability. The reason may be that when additional 107
substance that does not participate in the reaction in the system, silicone rubber compound is introduced, these newly added
fills the voids in the polymer network chains. The presence of long-chain molecules with active silanol groups at both ends
silicone oil dilutes the effective molecular polymer to some competitively adsorb onto the active sites on the surface of
extent, reducing the number of effective polymer chains per silica filler particles. This behavior is equivalent to diluting
unit volume, leading to a decrease in crosslinking density, the originally tightly bridged network nodes with fewer
further loosening of the molecular network, and weakening polymer chains and higher strength into nodes with more
of the tensile strength. However, the silicone oil molecules polymer chains sharing connections and lower strength. As a
themselves are inert, they do not participate in the formation of result, the overall connection strength and density of the entire
hydrogen bonds, nor do they competitively bind to the silanol filler-polymer network are significantly weakened. From a
groups on the surface of silica. Their presence, to some extent, rheological perspective, when this diluted network structure
increases the average distance between polymer chains, slightly is subjected to shear forces (such as extrusion through a die),
weakens the intermolecular forces (mainly van der Waals it collapses more easily and thoroughly, leading to a sharp
forces), and has a negligible dilution effect on the density decrease in the apparent viscosity of the rubber compound,
of the hydrogen bond network. This dilution and lubrication making extrusion effortless and smooth.
effect does indeed reduce the overall viscosity of the system, 2.2 Market comparison
manifested as a slight decrease in consistency. However, since During the actual construction process, not only must
it does not affect the fundamental structure of the hydrogen the tensile strength and extrudability of silicone rubber be
bond network that determines consistency, this reduction effect considered, but its surface drying time and 24-hour curing
is limited and mild. depth also affect the construction progress during application.
The content of 107 silicone rubber compound has a Therefore, to verify the feasibility of the formula presented in
significant and positive impact on the extrudability of silicone this article, we selected two commercially available silicone
rubber. When the content of 107 silicone rubber compound sealants, X1 and X2, for testing. The test results are shown in
increases from 30% to 35%, there is a noticeable jump in table 5.

Table 5 Performance comparison between optimized formula and commercial silicone sealant
Tensile strength (MPa) Extrusion rate / (mL·min⁻¹) Surface drying time/min 24-hour curing depth ( mm)
X1 2.00 31.46 15 3.2
X2 2.52 56.90 20 3.0
Premium Formula 2.63 68.20 10 3.5

The test results in table 5 indicate that, compared preparing silicone adhesive was determined as follows: 40%
with commercially available formulations, the optimized 107 silicone rubber, 60% mixed nano-calcium, and 3% silicone
formulation presented in this paper exhibits superior oil. At this point, the tensile strength reached 2.63 MPa, and the
performance and can better meet customer requirements. extrusion rate was 68.2 mL/min. Compared to commercially
available silicone adhesives, the tensile strength, extrusion rate,
3 Experimental conclusions surface drying time, and 24-hour curing depth of this formula
Through orthogonal experiments, the optimal formula for were superior.

·38· Vol.52，No.3