Preparation Of Carboxylic Styrene Butadiene Rubber/Natural Polysaccharide Composite And Preliminary Study Of Its Performances

Rubber composite has attracted much attention because of its high performance,functional diversity and so on.In line with the trend of sustainable development,renewable resources begin to play an important role in rubber composite.Natural polysaccharides have attracted widespread attention due to their wide source,renewability and degradability,etc.For instance,abundant active hydroxyl and amino groups on the surface of chitosan are available for the surface modification.Therefore,chitosan and its derivatives have been widely studied in composite materials.However,at present,there are few studies on chitosan and its derivatives in rubber composites.In order to make full use of natural polysaccharide resources,this paper is introducing CTS or carboxymethyl chitosan（CMCS）into the matrix of carboxy styrene-butadiene rubber（XSBR）based on latex blending and film-forming processing methods.Therefore,we prepared high-performance composite materials through the interface interaction with XSBR,and studied the impact of CTS and CMCS on the performance of XSBR from the microstructure through testing and characterization methods.On the basis of studying XSBR/CMCS composites,Zn O and CMCS are used together to further prepare XSBR/CMCS/Zn O composites,and the effect of Zn²⁺crosslinked regenerated CMCS network on the performance of XSBR was discussed.The specific research contents and main results are as follows:（1）The composite material is prepared by blending CTS acetic acid solution with XSBR latex.The expanded CTS molecular chain and XSBR molecular chain form more hydrogen bonds and other interactions,which has a significant enhancement effect on the XSBR matrix.At the same time,the comparison results of CTS solution blended latex film formation and CTS particles directly added latex film formation two different processes to prepare composite materials show that the supramolecular reinforced network is formed inside the CTS solution blended latex film formation sample and has higher strength;CTS particles directly add latex film-forming samples to form a filler cross-linked network with higher elongation.For example,when the CTS mass fraction is 20%,the Young’s modulus and elongation at break of the solution method samples are 10.7 MPa and 160%,respectively,while the particle method samples are 4.8 MPa and1030%,respectively.（2）The CTS derivative carboxymethyl chitosan（CMCS）aqueous solution was blended with XSBR latex to form a film,unconventional cross-linked rubber composites are obtained through the formation of hydrogen bonds between CMCS and XSBR molecules.The experimental results found that the regenerated CMCS formed a developed capillary-like network structure in the XSBR matrix,which had a reinforcing effect similar to the"reinforced concrete"structure of the composite.For example,when the CMCS mass fraction was 30%,the tensile strength and Young’s modulus of the composite increased in 9.57 MPa and 14.10MPa,respectively,3.5 times and 9.3 times of pure XSBR.The limitation of the regenerative CMCS network on the XSBR matrix increases the apparent maximum shape fixing temperature of the composite so that it exhibits better shape memory behavior at a temperature close to the human body’s suitable temperature.When the CMCS mass fraction is greater than 15%,the composites can obtain a 100%shape fixation rate at 11-14℃,and the shape recovery rate can reach more than 90%at 40℃.In addition,because the CMCS has water solubility,the CMCS can be removed by soaking in water,and the XSBR can be recovered and reused.（3）Based on the XSBR/CMCS system,nano-Zn O was added to the CMCS aqueous solution during the preparation process to react with it during the film formation process to introduce Zn²⁺and complex crosslink the regenerated CMCS,forming a high-strength integrated regenerated CMCS isolation network.The experimental results show that the mechanical properties of the composite material have been further enhanced,when the CMCS mass fraction is 30%,the tensile strength of the composite with 2.5 phr Zn O increased from 9.57 MPa to22.6 MPa.At the same time,it exhibits excellent electrical conductivity and solvent resistance under certain conditions.When the moisture content range is between 0-20%,the volume resistance of composite is reduced from the level of×10⁸Ωcm to×10⁴Ωcm.The ratio of volume resistance to initial volume resistance after immersion in organic solvents such as toluene for 2 h is less than10,indicating that the volume resistance of the composite material changes little,and still retains good electrical conductivity.