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compounding with para-aramid fiber engineered elastomers.

by:DMS Seals     2020-06-29
DuPont kaifula fiber brand, the world\'s first
The grass fiber was introduced in the 1970 s.
It is known for its high strength to weight ratio, high modulus and excellent chemical and thermal stability.
Initially, the keffra fiber was provided in the form of continuous filaments, and applications were quickly found in tires, mechanical rubber products, bullet-proof vests and composites.
In 1980 s, short form of fiber-
Staple Fiber, wool and pulp
Was introduced and quickly cut-
Wear-resistant protective clothing, washers and friction materials.
Used to be an abbreviation for Kefla and ACORN.
Fangfangji Twaron was introduced and rubber enhancement evaluation was carried out on them.
In rubber products, it is common to use short fiber to enhance rubber.
They increase the green strength, provide dimensional stability before curing, and improve the mechanical properties of the vulcanization rubber.
Fiber, cotton, denim, polyester and nylon commonly used in the industry.
The company found that they could
The staple food of fangzu or (
We define the wools as staple food less than 6mm long)
It is usually difficult to use a mixer or roller mill to make rubber into rubber.
It turns out that it is very difficult to add pulp products with high surface area.
Only a few people can fully disperse the pulp into rubber compounds.
However, once the dispersion restriction has been overcome, their work does demonstrate the superior enhancement potential of the fanggrass pulp.
DuPont has launched a study to determine a method of decentralized alignment
This effort led to the development of a unique new technology platform to disperse the pulp into the rubber matrix.
The products produced through this technology show the superior dispersion of aromatic pulp in rubber.
Rubber compound samples of the same composition were analyzed using ultrasonic scanning technology, which measured the relative pore rate as shown in Figure 1.
In the sample on the left, the pulp is introduced using engineering rubber;
In the sample on the right, the pulp is directly added to the rubber.
A uniform color indicates a uniform mixture.
The samples made of directly compounding the pulp into the rubber show a significant color difference, indicating that the fiber dispersion is relatively poor;
The samples prepared using engineering elastic materials are almost uniform in color and show their excellent dispersion. [
Slightly] Illustrations
The products made through this new technology make the pulp so well dispersed in the rubber that it is given a new name, Kefla engineering rubber.
Preliminary evaluation of the rubber industry confirmed that engineering rubber is easier to process than dry rubber
The dispersion of pulp was confirmed by the use of the product.
One of the first rubber chemists to evaluate engineering rubber found it to be very effective in rubber enhancement.
The man described the sale as \"yes \". . .
The intimate relationship between rubber and particles has never been achieved through traditional compounding.
\"We also learned that several other customers who can disperse the drying section well
When the pulp was introduced into its compound using engineering rubber, the aromatic pulp in the rubber found a better enhancement.
When using an engineering elastic body instead of a slurry, they obtain a high modulus of up to 20% at the same fiber content.
We propose a hypothesis to explain the basis of this enhancement;
The assumption is based on: * superior dispersion;
* Microstructure of Counterpointaramid fiber;
* There is \"combined rubber\" in engineering elastic materials \";
And * for the process of manufacturing engineering rubber.
Polymer base for alignment
The grass is a rigid rod molecule.
When spun into fiber, the polymer becomes highly oriented and highly crystalline.
High orientation allows carbonyl and \'n-
The h \'function in the amide base of adjacent polymer chains.
The fiber has a structure as shown in Figure 2 (ref. 1).
Morphological studies have shown that the crystal structure is radial oriented, so that the fibers have a backbone of strong bonded bonds along the fiber axis and have hydrogen bonds in the radial direction.
The hydrogen-bound radial sheets are stacked together and combined together by van der Waal\'s force. [
Slightly] Illustrations
Fiber can be considered to have a fiber structure.
The fiber is a highly ordered area oriented along the fiber axis.
The filament is connected by a bundle of strands passing from one filament to another.
This filament structure can form high surface area pulp by mechanical grinding.
Due to the morphology of the fiber, the pulp fiber has an aromatic ring and an amide-based surface.
Kefla fiber is made of high concentrated sulfuric acid. Free [
Mathematical expressions that cannot be reproduced in ASCII]
In the solvent, some aromatic rings were sulfuric acid, and research within DuPont showed that the resulting sulfuric acid base was easily obtained on the surface of the fiber.
Therefore, the surface of the pulp fiber contains a polar base (
Amine and sulfuric acid on the polymer skeleton, as well as amine and acrylic end groups)
This can be associated with a set of elastic materials.
By weight determination of the fiber content of the engineering elastic body, evidence is provided that the elastic body is associated with the charged group on the surface of the fiber.
Polychlorin engineering elastic grade contains 23% fibers on a weight basis;
The average weight analysis is about 26%.
In the NBR matrix with large polarity, the weight analysis of the \"obvious\" fiber content of the engineering rubber averaged 29.
1% of the fiber, at the nominal fiber concentration of 23 weight percentage.
We believe that the weight analysis provides evidence for \"bonding rubber\" in engineering rubber, similar to the bonding rubber in carbon black.
Carbon black binding rubber theory assumes that fragments of elastic molecules adhere to active sites or active sites on filler particles.
LeBron described the theory in a recent publication (ref. 2).
Similar mechanisms can certainly play a role in engineering elastic materials.
One of the key requirements we assume is that the surface of the pulp can be well exposed to rubber.
The patented latex solidification process for the preparation of engineering rubber presents the pulp to the rubber in a way that the fibers are fully open to allow the rubber to fully moisten the fibers.
The designed elastic process maximizes the moisture of the pulp, enabling it to be enhanced with maximum efficiency.
If the pulp is mixed directly in a mixer or roller mill, or if the pulp Masterbatch in the rubber is made with other technologies, the pulp will be compacted to a certain extent, its potential for strengthening has not yet been fully realized.
The process of manufacturing engineering rubber creates a close relationship between rubber and particles.
Engineering rubber is not just a simple master material or dispersion of pulp in rubber.
The experimental compound formulation used in this work is based on the van der Burg manual (ref. 3).
In all cases, the fangzu pulp is introduced into the compound using kaifular engineering rubber.
All compounds are mixed in a laboratory-scale mixer.
Mixing programs are important in order to achieve the correct mixing.
Neat elastic materials and engineering elastic materials were mixed at low speed, with a maximum cooling time of about 1.
5 minutes, then add filler and process assist.
When a dump temperature is reached that is appropriate to the base elastic material being used, the batch is discarded onto the mill, stripped and cooled.
Managers are added on the mill or in the second mixer channel.
Test using standard ASTM or ISO test methods.
The aromatic pulp reinforcement with high Composite modulus is realized with traditional hardening agent (
Carbon Black, silica, resin)
High load is usually required.
At high loads, processing becomes difficult due to high composite viscosity, and dispersion becomes a challenge.
Since short fibers are superior to simple particles as enhancing agents, they are often used when high modulus is required (ref. 4). Para-
Fanggrass pulp is easier to form a modulus than other short fibers, resulting in a decrease in the composite viscosity of a given modulus.
Figure 3 compares the enhancement effect of fangzu pulp from polychlordin GRT power transmission belt compounds with other staple fibers.
The reinforcement of the three-part pulp gives the same modulus as the 6-10 partmm polyester;
The composite viscosity, however, decreased by nearly 15 months per unit.
Reinforced with 7.
5 pulp gives about twice the modulus of 10 parts of 6mm nylon;
Mooney is 10 units lower. [GRAPH OMITTED]
A generalized graph on the counterpoint effect
As shown in figure 4, the modulus of aromatic pulp.
Modulus ratio at 25% and 50% elongation (
Measurement in machine direction)
Function shown as part of the fiber.
The modulus ratio is defined as: the modulus of compounds enhanced with Pulp/The modulus of compounds without pulp [GRAPH OMITTED]
The data points are for a variety of different compounds in several different elastic bodies.
In all cases, the aromatic pulp is introduced into the compound by engineering elastomer.
Adding only 5 pulp, the composite modulus at 25% elongation can be increased by about 10 times. Para-
The aromatic pulp has a higher L/D aspect ratio.
This geometry makes it possible to cut the direction of the particles during machining.
The extended or extruded compound enhanced by fangzu pulp leads to modular heterogeneity-
Modulus difference between Machine direction and cross Machine direction.
The data shown in figure 5 illustrates this modular heterogeneity.
Of the 2mm test pieces of this NR/br fire-proof tread compound, the MD modulus is about 5 times that of the XMD modulus.
Samples that are caldered or squeezed into thinner flakes will show a higher specificity.
Users of some engineering rubber usually reach a MD/XMD ratio greater than 10. [GRAPH OMITTED]
Ability to counterpoint
Fanggrass pulp can build the modulus very effectively and it is relatively easy to disperse it into rubber by engineering elastic body, which provides rubber chemists with the opportunity to go beyond existing limitations when designing rubber compounds
Modular heterosexual is an important feature in many product designs.
Application of compound with body (
Power transmission belt)
In many high-performance, high-load power conveyor belts, fangzu pulp is used as an reinforcing material.
It provides a stiff body in a v-
Belt, and can increase the tooth shear resistance in the synchronous belt and the regular belt.
Pulp reinforcement makes it possible to have a high modulus and a modular specificity for the design of a high performance belt.
The design of the belt can better withstand the deformation under high load.
Figure 6 shows an advantage of using aromatic pulp reinforcement in the belt body.
Aromatic pulp-enhanced compounds have lower lag performance than other compounds with larger load of short fibers or larger load of carbon black.
The lower lag results in a lower heat accumulation, thus prolonging the service life of the belt.
As mentioned earlier, there are also lower Mooney in the band compound enhanced with fangzu pulp. [GRAPH OMITTED]
Tensile glue compounds (
Power transmission belts, conveyor belts, tires)
There are two ways to use fangzu pulp in wires (Gum or adhesion)
A belt or a layer of fire.
It is used as a process aid at low loads to increase the green strength and thus facilitate more efficient processing.
Under higher load, it can improve the belt life.
Compounds in the line (adhesion)
The layer must have sufficient liquidity (
Low composite viscosity)
Fully penetrate and cover the ropes;
The composite modulus is therefore limited.
As mentioned earlier, the band compound must have a high stiffness to prevent deformation or deformation.
The mismatch of the modulus between the two rubber materials can lead to interface cracking and layering.
By using carbon black of short fibers or higher loads to increase the stiffness of the rubber in the rope layer can have a negative impact on the adhesion or fluidity of the rubber. Para-
The aromatic pulp enhancement of the rope layer is a solution;
It can build the modulus with minimal impact on liquidity.
The higher modulus of the rope compound also reduces the difference in modulus between it and the tensile member
We call it the concept of a bridge.
The best preparation of feed rubber for aromatic pulp using latex solidification technology for manufacturing engineering rubber; \". . .
The above rubber layer is made of feed rubber prepared by curing rubber latex, in which short fibers are mixed and dispersed \"(ref. 5).
Reinforcement or replacement of fabrics (
Tire diaphragm)
In several low to medium pressure applications, fangzu pulp reinforced rubber has been successfully used as a fabric replacement.
High modulus that can be achieved in thin segments (
By pressing or squeezing)
Can eliminate the demand for fabric.
Coating the fabric with a compound containing aromatic pulp enhancements can prevent the fabric from layering through the above-mentioned modulus bridging concept.
It has been proved that the roller cap fangzu pulp reinforcement of rubber used in the roller cover can improve the wear resistance and wear resistance of the roller cover.
A mechanism that causes wear of rubber cover rollers (ref. 6)
The result from the pressure on the work roll that causes the rubber cover to produce stress.
This stress causes strain or deformation of the rubber.
When the rubber approaches the pressure point, the strain causes the rubber to bulge (roll nip. )
The shape of the roll cover changes from a dotted line to a solid line, as shown in Figure 7. [
Slightly] Illustrations
When the turning roller approaches the maximum stress point, the rubber moves quickly in the inlet bump.
Rubber is subjected to shear stress and normal friction stress.
Since the shear stress is greater than the friction stress between point A and point B, the rubber in this area slips.
Slip under this stress can cause the roll cover to wear.
A similar situation exists in the outlet bump, where a slide occurs between Point C and point D.
The use of aromatic pulp to reinforce the roll cap compound helps to reduce wear and tear due to slipping and wear.
By designing the rollers so that the fibers are aligned in a weekly direction, the modulus or stiffness of the compound can be increased, reducing the strain at a given stress.
However, due to the possibility that the aromatic pulp reinforcement has a modular asymmetry, the increase in the radial and axial modulus is small.
Increasing the composite die volume by using traditional hardening agent usually leads to an increase in the composite hardness.
Often, the increase in hardness means the sacrifice of the rolling grip, as the harder Rolling may have less desirable friction properties.
The rubber compound is designed by balancing the relative content of aromatic pulp and other reinforcing agents, which can increase the modulus without increasing the hardness.
As shown in figure 8.
Compounds were prepared in silica and Fangfang pulp with different loading amounts. The control (
Fiber-free compound)
Hardness with 81A.
A compound of 80 degrees was prepared [Greater than]
6x high modulus (13. 1 vs. 2. 1 MPa)
Add 9 servings of grass paste while reducing the amount of silica from 45 to 15. [GRAPH OMITTED]
The data sheet of this composite study shows the importance of the re-study
Design a compound that can make full use of aromatic pulp enhancement.
It is difficult to achieve performance goals by simply adding the aromatic paste to the existing formula.
Figure 9 shows other data for this study.
Adding aromatic grass pulp to rubber compounds can improve tear and wear
Two key properties to improve the performance of rubber cover rollers.
As shown in figure 3 with compound properties, fangzu pulp has achieved ideal improvement in modulus, tearing and wear resistance without affecting hardness or processing properties, as shown in Figure 9[GRAPH OMITTED]
Composite material of sub-tread/cap layer (tires)
In many high-grade bicycle tires, the grass paste is used as a booster.
The stable, hard sub-tread reduces the injection of the tire and improves the handling capacity of the bicycle.
Designing a sub-tread compound enhanced by aromatic pulp is a way to reduce rolling resistance, improve turn performance, reduce wear and improve puncture resistance (ref. 7).
Effective use of fangzu pulp enhancement materials in several high-specification sub-tread and rope layers
Improving the handling characteristic of motorcycle tires (ref. 8).
The aromatic pulp enhancement was evaluated in several areas of passenger car tires (ref. 9);
It is particularly effective at the apex and top of the tire.
Recent work shows the advantages of the support strip of the aromatic pulp reinforcement layer (ref. 10).
Recently, a seed tread enhanced by fangzu pulp was designed to eliminate high-
Performance Tires (ref. 11). Footwear (soling)
In order to improve the friction and sliding properties, improve wear and wear resistance, and prevent stitch tearing without sacrificing the flexibility of the sole, shoe sleeve compounds have been formulated.
The key is that the aromatic pulp can be reformulated to achieve the desired performance.
Extrusion and molding components fangzu pulp enhancements increase the modulus of molded and extruded products.
The increased stiffness improves the anti-deflection capability and fine the cross section, reducing the weight of the components.
The increased stiffness of rubber compounds enhanced by fangzu pulp has special advantages in seals and washers, improving the anti-blowout capability.
Conclusion kaifla engineering elastic materials provide a tool for composite materials, which can bring the benefits of counterpoint.
Enhance the aromatic pulp of rubber;
It overcomes the dispersion limit, which is an obstacle to the successful use of pulp in rubber.
The process of manufacturing engineering elastic bodies displays the pulp to the elastic body in a way that the fibers are fully opened;
Rubber can completely wet the fiber.
The designed elastic process maximizes the moistness of aromatic pulp, enabling it to be enhanced with maximum efficiency. Para-
The aromatic pulp enhancement of rubber gives rubber chemists the opportunity to go beyond current limits in designing rubber compounds.
Compounds enhanced with aromatic pulp that have: * increased green strength can be developed;
* Improve processing performance;
* Improved dimensional stability;
* Improve traffic;
* Increase in tensile mold quantity;
* Potential of the attribute of the opposite sex;
* Increase in Dynamic modulus;
* The lower tan delta;
* Enhanced tear resistance;
* Enhanced wear resistance;
And * increase penetration resistance.
Engineering rubber is used to reinforce a variety of finished products, including belts, tires, footwear, roll covers, seals and molded parts. References (1. )H. H.
High aromatic Yang
High strength fiber, Willie-
Interscience, New York, 1989. (2. )J. L. Leblanc, J.
66, 2, 257 (Applied Polymer Science)1997). (3. )R. F.
Ohm, editor, van der Burg rubber Manual, Version 13, R. T.
Van der Bildt Company, Inc. , Norwalk, CT. (4. )S. K. De and J. R.
White, staple
Polymer Composites, Woodhead, Cambridge, 1996, Chapter 9. (5. )M.
Japanese patent application HEI 10 [Ogino]1998]-103413 (1998). (6. )P.
Metlikovic, \"stress, slip and wear of conveyor rollers covered by rubber, review\", 1996, Louisville, ACS Rubber segment conference, document 66. (7. )
Special bicycle parts, \"specifically demonstrated in the tire renovation
Test, \"the press conference, California. July 17, 1998. (8. )G. Armellin, U. S.
Patent 5,975,175 (1999). (9. )R. J. Brown and R. M. Scriver, U. S.
Patent 4,871,004 (1989). (10. )P. R.
EP 931 676, European patent application (1999). (11. )M.
Nahmias Nanni ,. Brunacci and C.
World Patent application WO 00/24596 Zanichelli (2000).
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