Comprehensively improve the 7 key properties of vulcanized rubber
Improved tensile strength
Polymer body selection
Choose rubbers with high crystallinity or strong molecular chain regularity (such as NR, IR) and crystallization-induced tensile strengthening.
The addition of a high molecular weight (Mn>300,000) rubber compound is conducive to the formation of strong molecular chain entanglements.
Enhance the reinforcing packing system
The use of N220 or N110 high-structure carbon black, with its small particle size and large specific surface area, can form a denser rubber-carbon black network.
Silica + silane coupling agent (TESPT) is used in polar adhesives to enhance rubber/filler interface bonding.
Cross-linking density control
Moderately increase the sulfidation crosslinking density (control the S/A ratio of the CV system at 2.5~3.0) and enhance the network structure.
Avoid under-sulphur or oversulphur and use MDR to precisely control the t90 vulcanization time.
Improved tear strength
Microstructure optimization
The essence of tearing is microcrack propagation, and the construction of an energy-absorbing network structure (polysulfur cross-linking, blended elastomer) can alleviate the stress concentration at the crack tip.
Rubber with high elongation and high elongation at break (such as BR and IR) is added to blend with the main rubber to improve crack elongation absorption.
Reinforce the uniformity of the distribution of the filler
RPA and PAK test the dispersion of the packing to avoid the agglomeration of carbon black to form a tear source.
Optimization of the mixing process, e.g. with the mode of "high and low velocity-multi-stage feeding-final refining with a vulcanizing agent".
Construct multi-scale structures
Short fibers (Aramid/glass fibers) or nanofillers (graphene, CNT) are added to form a multi-scale reinforced backbone.
Abrasion Resistance
High cross-linking density design
SEV/EV cross-linking system is recommended for high wear-resistant occasions, and the cross-linking bond is shorter and more stable (such as NR tire tread compound).
High wear-resistant filler selection
Preference is given to carbon blacks with strong wear resistance, such as N234/N120, and the high structure strengthens the fracture energy consumption mechanism.
In silica systems, products with high hardness and high surface energy are selected and matched with coupling agents to effectively embed them in the network.
Shear-resistant structure construction
Low molecular block copolymers (e.g., SBS) or dynamic crosslinking materials (e.g., TPVs) are added to improve dynamic fatigue resistance.
Hardness control
Vulcanization structure adjustment
Increased crosslinking density = increased stiffness, either by adding sulfur or by using a hard crosslinking system (e.g. peroxide)
For products with low hardness requirements, choose long-chain softeners/plasticizers to adjust the softness.
Control the amount of filler added
The addition of carbon black increases the hardness of Shore linearly, and the addition of N330 increases from 30phr to 60phr, and the hardness can be increased by 10~15 degrees.
If high hardness (80~95A) is required, hard inorganic fillers such as talcum powder, barium sulfate, etc. can be added.
External support material
Design composite structures (such as steel wire skeletons, and glass fiber reinforced fabrics) to achieve the synergy between external hardness and internal elasticity.
Improving Elasticity
High cis/non-polar rubber preferred
NR, BR, and IR are natural highly elastic systems, with soft molecular chains, weak intermolecular forces, and strong recovery ability.
Although EPDM is anti-aging, its elasticity is slightly poor; It needs to be combined with a rubber compound to improve its recovery characteristics.
Reduce the amount of filler
The high ratio of fillers hinders the recovery of molecular chains and reduces resilience. Optimize the structure of the formulation, and replace some ordinary fillers with low-structure carbon black or nanofillers.
Adjust the cross-linking structure
Polysulfide bonds give higher elasticity but are susceptible to aging; It is necessary to weigh the balance between CV system and aging resistance.
Reduced Compression Set
Large compression set = fast stress relaxation, commonly found in high-temperature seals, O-rings, and other working conditions.
Rubber type selection
Rubber with low compression set, such as IIR, EPDM, VMQ, HNBR, etc., is preferred.
NR and SBR are not recommended for use in high-temperature and long-term compression environments.
Vulcanization system optimization
It is recommended to use a peroxide cross-linking system or EV vulcanization system to form a stable short-chain cross-linking structure with strong creep resistance.
In sulfur systems, the accelerator ratio needs to be precisely controlled to avoid scorching and desulphurization.
Add structurally stable filler
The addition of trace amounts of high-specific surface silicate/mica powder can improve the support skeleton and enhance the deformation resilience.
Use heat-stabilized softeners instead of aromatic oils to avoid migration and oil seepage.
Improved Aging Resistance
Including thermal aging, oxidative aging, ozone aging, ultraviolet aging, etc.
Basic Grade Impact
Unsaturated rubbers such as NR and BR have poor aging resistance, and the anti-aging system needs to be strengthened.
EPDM, IIR, and FKM have saturated structures and excellent oxidation and aging resistance.
Anti-aging agent system strengthened
It is recommended to use amines (e.g., 6PPD, TMQ) + phenols (e.g., SP, BHT) in combination.
For ozone aging, the addition of an anti-ozone wax/wax migratory agent can form a protective film.
Improve network stability
For high-temperature applications, peroxide crosslinking or a heat-resistant multifunctional vulcanizing agent such as Bismaleimide is used instead of conventional sulfur systems.
Coating and shielding
The use of UV absorbent coating or coating technology on the surface of the product can significantly extend the service life.
