Issue 10/2015 - Research progress on the application of new rubber reinforcing fillers

Research progress on the application of new rubber reinforcing fillers

□ Xiaoming

Reinforcing filler has an important and unique role in rubber processing, it can improve the mechanical properties of rubber, meet the requirements of rubber processing technology, reduce the shrinkage of rubber material, conducive to molding, and help the shape and dimensional stability of rubber material after vulcanization, some varieties also have such as flame retardant, electrical and heat resistance, in addition to reducing costs
.
In addition to the research on commonly used reinforcing fillers such as carbon black and silica, many new reinforcing fillers
have also been developed.

Carbon nanotubes
(CNTs) have ultra-high strength, greater toughness and excellent electrical conductivity, and filling a small amount can significantly improve the mechanical and electrical properties of
rubber materials.
In addition, by modifying CNT, the winding of CNT can be reduced, so that it and rubber macromolecules produce strong chemical or physical interaction, thereby improving the dispersion state of CNT in rubber and improving the interface effect
.

Geng Jieting et al.
of Qingdao University of Science and Technology studied the preparation of terminal hydroxypolybutadiene (HTPB) coated multi-walled carbon nanotubes (MWNTs) and its reinforcing effect
on cis-butadiene rubber (BR).
The results show that grinding MWNTs and HTPB can coat the surface of MWNTs, which significantly improves the solubility of MWNTs in solvents such as toluene.
Carboxylation of MWNTs can further improve the coating effect of HTPB on MWNTs, improve the dispersion of MWNTs in BR, and make them show better reinforcement effect
in BR matrix.

Li Guoxi et al.
of Anhui Medical College studied the effect of modified MWNTs dosage on the properties of
modified MWNTs/acrylate rubber (ACM) composites.
The results show that the properties of the materials prepared by filling ACM with MWNTs are far superior to those of
ACM rubber reinforced with carbon black.
With the increase of the amount of modified MWNTs, the conventional mechanical properties, heat aging resistance, oil resistance, wear resistance and thermal decomposition temperature of the composite materials gradually increase, the energy storage modulus shows an increasing trend, the glass transition temperature (tg) gradually decreases, the loss factor first decreases and then increases, and the minimum
when the amount of MWNTs is 10.
0%.

Attapulgite attapulgite
(AT) is a semi-reinforcing type filler, the surface of which is organically modified, which can improve its dispersion and affinity in the rubber matrix, and improve the 300
% elongation stress and elongation of rubber products.

Yang Hui of Xuzhou Industrial Vocational and Technical College and others studied the effects of
AT, modifier and vulcanizing agent bis-2,5 and hydroxy silicone oil on the properties of AT/silicone rubber (MVQ) composites.
The results show that AT has a good reinforcing effect on silicone rubber, and the physical and mechanical properties of the composite material are better when its content is 80 parts.
The tensile strength of AT/MVQ composites was increased by 31.
6%, tear strength by 19.
3%, and 100% tensile stress by 131
% by modifying AT with silane coupling agent KH550 1.
2 parts.
When the vulcanizing agent bis-2,5 is 2.
0 parts and the hydroxyl silicone oil is 5.
6 parts, the tensile strength of AT/MVQ composites can reach up to 8.
38MPa
.

Wang Yuan of Shanghai University of Engineering Science and others used AT as a reinforcing agent to fill it into a mixture of natural latex (NR) and styrene-butadiene latex (SBR) to prepare composite materials
.
The results show that the addition of AT to mixed latex will cause the vulcanization performance of the rubber material to decrease, prolong the vulcanization time, and the tensile strength will decrease with the increase of the addition amount
.
When the mass addition amount of AT is 1%, the performance of the composite material is the best, and the tensile strength can reach 20.
2 MPa
.

Zhou Chunbing of Wuxi Meifeng Rubber Products Manufacturing Co.
, Ltd.
and others studied the effects of
AT dosage and coupling agent type on the vulcanization characteristics and mechanical properties of AT/NBR nanocomposites.
The results show that with the increase of AT, the t10 and t90 of AT/NBR are shortened, the vulcanization rate increases, and the hardness, tensile strength, tensile stress and tear strength first increase and then gradually decrease or remain unchanged.
When the amount of AT is 40 parts, the comprehensive performance is the best
.

Nanocrystalline cellulose
cellulose can not only strengthen natural latex, but also help to improve the mechanical properties and aging resistance of rubber composites, reduce heat generation, improve processing properties and the difficult degradation of vulcanized rubber
.

Suhua Xu et al.
of South China University of Technology prepared (NCC-SiO2)/NR composites
by replacing silica (SiO2) with nanocrystalline cellulose (NCC) as a filler.
The results show that while maintaining the basic mechanical properties of SiO2 to enhance NR, the compression set is reduced from 11.
4% to 5.
9%, and the compression fatigue heat generation is reduced from 19.
9°C to 10.
6°C
.
After aging, the tensile strength, tear strength and hardness increased by 40%, 21% and 25%, respectively, the permanent deformation decreased by 25%, and the tensile strength and elongation at break remained basically unchanged
.

Gu Ju of South China University of Technology et al.
studied the effect of
NCC partially substituting carbon black (CB) on NR performance.
The results show that the CB network structure of the NR/NCC/CB composite is weakened, t10 is extended, t90 is shortened, and the torque is reduced.
With the increase of NCC dosage and vulcanization temperature, the vulcanization rate constant of composite materials increased.
When CB is replaced with 10 NCCs in equal quantities, the activation energy of the composite material is reduced, and the heat resistance and high temperature aging resistance are better
.

Montmorillonite Natural Montmorillonite (OMMT) is a layered silicate containing inorganic cations between the layers, which are modified by organic cations, and then compounded with rubber, so that the montmorillonite
sheet layer is dispersed in the rubber matrix at the nanoscale, so as to achieve the purpose of
improving performance.

Zheng Hua of Shandong University of Science and Technology et al.
studied the effect of
OMMT on NR/BR/SBR/organic montmorillonite composites.
The results show that the composite is an intercalated composite material, and the addition of 5phr OMMTT is beneficial to improve the mechanical properties, wear resistance and thermal stability of the composite, promote vulcanization and reduce the minimum torque
.

Hongran Zhao et al.
of Hunan Normal University prepared composites of butyl rubber (IIR) and ethylene propylene diene (EPDM) using black liquor-montmorillonite (BL-MMT) as filling reinforcing agent
.
The results show that the reduction of the ratio of IIR to EPDM can improve the processability of the composite and improve the thermal oxygen aging resistance
.
When the ratio of IIR to EPDM is 80/20, the comprehensive performance of the composite material is better; The comprehensive physical properties of vulcanized rubber obtained by ordinary vulcanization system are the best; The vulcanized rubber obtained by the effective vulcanization system has the best
heat and oxygen aging resistance.

Lignin lignin
is a kind of polymer with phenylpropane monomer as the skeleton and a network structure, and the molecular side chain contains methoxy, phenolic hydroxyl, aldehyde, carboxyl and other groups
.
These groups are prone to chemical reactions with rubber, so that lignin molecules or hydroxymethyl groups between lignin molecules are further condensed during vulcanization to form a network structure
.
This network structure and rubber network form a double network structure, and the reinforcing effect is greatly improved
.

Li Haijiang et al.
of Nanjing University prepared a lignin/NR complex by co-precipitation method
.
The compound partially replaces silica, the commercial rubber reinforcing agent, and mixes
styrene-butadiene rubber by a three-stage mixing method.
The results show that this lignin/NR composite has a certain reinforcing effect on styrene-butadiene rubber, which improves its tensile strength and elongation at break, and improves the rolling resistance and cold resistance of rubber materials
.

Xu Jianshuang et al.
of Hunan Normal University used lignin to partially replace phenol to synthesize lignin phenol (LPF) to prepare LPF/SBR composites
.
The results show that when the amount of LPF is greater than 25 parts, LPF and SBR are interspersed with each other to form an interpenetrating network structure
.
When the lignin/phenol dosage ratio in LPF is 30/70 and the LPF dosage is 25, the comprehensive performance of LPF/SBR composites is the best
.

In
addition to the above substances, new rubber reinforcing fillers include diatomaceous earth, kaolin, starch and talc.


Liao Jinghui et al.
, China University of Geosciences (Beijing) replaced silica as a reinforcing agent for filling the
rubber after surface treatment of diatomaceous earth.
The results show that diatomaceous earth can improve the mechanical properties of rubber, and diatomaceous earth treated by the composite modified formula of 0.
6% (mass percentage) silane and 1.
0% stearic acid has the best reinforcing effect on rubber, and the tear strength reaches 42.
1kN/m
.

Wang Xu of Southwest Petroleum University and others studied the effect of
talc on the mechanical properties of NBR vulcanizate.
The results show that the comprehensive performance of rubber is further improved by treating talc with KH550 with a mass fraction of 1%, and its tensile strength can reach 14.
1MPa and tear strength 48.
1kN/m
.

Yang Huiqun of Wuhan University of Technology and others blended quartz, kaolinite and muscovite at 15:4:1, crushed by airflow milling ultrafinely, and filled with SBR after surface modification of silane KH570
。 The results show that the reinforcing effect of mineral powder is improved after modification.
When the filling volume is 60 parts, the comprehensive mechanical properties of the composite material are high, and its tensile strength and tear strength are increased by 76.
7% and 39.
9%,
respectively.

Gao Yangjianshu of Hainan University et al.
studied the effect of xanthanelate modified starch (MH) instead of
silica on NR performance.
The results showed that when the total dosage of silica and modified starch was 30 parts, the modified starch/silica/NR rubber t10 was extended and t90 shortened as the dosage of modified starch increased.
The content of MH and binder rubber first increased and then decreased, and the tensile stress, tensile strength, tear strength and wear resistance of vulcanized rubber first increased and then decreased.
When the starch dosage is 15 parts, the comprehensive performance of the rubber material is the best
.

Zhang Yude of Henan Polytechnic University and others used wet ball milling modified kaolin, carbon black and silica as raw materials to fill NR and SBR to prepare rubber composite materials
.
The results show that the tensile strength and tear strength of rubber are greatly improved after filling with kaolin.
The reinforcing effect of kaolin is obvious, which is comparable to silica, and there is still a certain gap with carbon black; When the filler is filled with SBR, kaolin can partially replace carbon black and completely replace silica, effectively reducing the production cost of
products.

Conclusion
In the rubber industry, the application of reinforcing fillers can not only improve rubber performance, but also give rubber many new characteristics, while facilitating processing, reducing costs, and greatly improving the cost performance of
rubber products.
The continuous emergence of new fillers provides a large number of new materials for rubber modification, and expands the research ideas
in the field of rubber reinforcement technology and functional rubber materials.
However, at present, the more commonly used varieties such as carbon black and silica are still used, and new reinforcing fillers such as kaolin, attapulgite, carbon nanotubes, nanocrystalline cellulose have not been widely promoted and applied
, although some research has been carried out.
In the future, in addition to strengthening the research on the mechanism of action between particles and rubber matrix in the process of rubber reinforcement and expanding the characterization and detection methods of reinforced composite materials, it is more important to accelerate the development and promotion of relevant applications to promote the healthy and steady development of
the industry.