| Latex foam material is a porous rubber material,most of its internal pores are open pore structure.Its continuous bubble structure makes it highly elastic,lightweight,good cushioning performance and many other advantages,is widely used in mattresses,pillow cushions,sofas and sports protection equipment and other areas of life production.The existing latex foam is produced with natural rubber latex(NRL)as the main raw material,but with the increasingly wide range of latex foam application scenarios and people’s individual needs,for the pure natural latex foam material,it is no longer able to combine a variety of properties.In this context,in addition to the modification of natural latex,it is also possible to look at other latexes.For example,eucommia ulmoides latex(EUL)and nitrile-butadiene latex(NBL),EUG belongs to a kind of natural rubber and is a unique strategic rubber resource in China,it is not like natural latex which can be obtained by cutting rubber tree or synthetic latex which can be obtained by emulsion polymerization,EUL can only be obtained by emulsification method,so it is less researched in the field of latex foam;NBL is a polar synthetic latex that has not been widely used in latex foam materials,a type of latex product.Based on these backgrounds,this paper will carry out the following three parts of work:In the first part,the formulations of EUL and NBL when foaming alone and the basic properties of the formed sponge samples were investigated and compared with the existing mature optimal formulations of pure NRL foaming,and it was found that both EUL and NBL could be foamed with NRL using the same formulations and the samples could be uniformly formed.The amount of potassium oleate in the formulation was 1.5 phr,sodium fluorosilicate was 0.5phr,and ammonium sulfate was 2 phr.However,the performance of the samples made of EUL and NBL foam alone cannot meet the basic needs,such as eucommia ulmoides latex foam(EULF),its tensile strength and compression properties than pure natural latex foam(NRLF)has been significantly increased,tensile strength from 0.41 MPa to 1.68 MPa,compression stiffness from 2.76N/mm to 6.91 N/mm,indentation hardness from 4.7 to 12.8,but its resilience is only 18%,can not meet the minimum requirements of international standards,so the EULF has good mechanical properties and supportability,but its resilience is not good.The compression performance of nitrile-butadiene latex foam(NBLF)than NRLF has improved,from 2.76 N/mm to 3.56 N/mm,but its tensile strength is the lowest of the three only 0.27 MPa,the foam micropores inside the sponge material are easily ruptured by the force.Therefore,in the next work,the latex blending method was used to make up for the lack of performance of the single latex foam in some aspects.In the second part,the EUL/NRL composite latex foam materials were prepared,and the effects of the dosage of EUL and sulfur on the foaming properties,apparent density,cross-link density,crystallinity,two-phase structure,mechanical properties,and dynamic thermo-mechanical properties of latex sponge materials were investigated.The experimental results show that the use of EUL in NRL can significantly improve the indentation hardness,tensile strength,stiffness and modulus and other mechanical properties of latex foam materials,improving the pure NRLF with poor support,the disadvantages of easy deformation and depression under force.It was found that when the addition amount of EUL was 30 phr and the addition amount of sulfur was 2phr,the overall performance of the products reached the best.At this time,compared with the NRLF,the tensile strength saw a dramatic rise from 0.41 MPa to 1.05 MPa,a 156% increase,while the indentation hardness also rose,from 4.7 to 6.7,an increase of 42.6%;the average stiffness increased from 2.69N/mm to 3.18 N/mm,an increase of 18.2%;the compression modulus increased from 1420 KPa to 1789 KPa,an increase of 26%;EUL/NRL composite latex foam material can be applied to mattresses,pillow cushions and sofas such as large sponge products,it has a better support for the human body,the force will not produce a substantial depression and reduce the reaction force on the human body,making it much more comfortable.In the third part,the EUL/NBL composite latex foam materials were prepared,and the effects of the dosage of EUL and sulfur on the foaming properties,apparent density,cross-link density,crystallinity,two-phase structure,mechanical properties,and dynamic thermo-mechanical properties of latex sponge materials were investigated.The experimental results show that the use of EUL in NBL can also significantly improve the indentation hardness,tensile strength,stiffness and modulus and other mechanical properties of latex foams,improving the disadvantages of NBLF with low tensile strength,but also make NBLF with a better support.It was found that when the addition amount of EUL was 20 phr and the addition amount of sulfur was 2 phr,the overall performance of the products reached the best.At this time,compared with the NBLF,the tensile strength increased from 0.27 MPa to 0.72 MPa,an increase of 166.7%;the hardness of indentation rose from 5.1 to 6.5,a 27.5% increase;the mean stiffness rose from 3.96 N/mm to 4.31 N/mm,a 8% rise;and the compression modulus rose from 1671 KPa to 1856 KPa,a 11.1% rise.EUL/NBL composite latex foam material can be used in shoe mats,yoga mats and other small foam products,which need moderate softness and hardness to play a good role in supporting the bottom of the feet. |
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