| Yunnan Province is both one of the main domestic natural rubber latex (NRL)producing region, and a main NRL product base. While, because of techniques beingbackward in the field, product monotonous and lack of market competition. For thissituation, on the basis of the research before, in the paper, a new idea about surfaceconditioning agent of nano-silica (n-SiO_x) has been put forward, a deep research of theprocess that nano-silica enhanced NRL has been studied, and the mechanical properties ofmodified NRL has been explored preliminarily. In NRL industrial field, the results areexpected to give a help to actual process and technology, mean while, to give guidance ontheory.Three kinds of polyols have been selected as surface conditioning agent to nano-silica.Single factor experiment results show that polyol polycondensate NS-2 is the most suitableone for n-SiO_x in NRL. Polyol polycondensate NS-2 as surface conditioning agent forn-SiO_x admixed into NRL, the tear strength is 27.66 kN/m, tensile strength is 5.94MPa,elongation at break is 627.27%, and permanent distortion is 15.91%, which tensile strengthand tear strength are 45.6% and 33.2% separately as high again as the films without n-SiO_x.Besides, elongation at break and permanent distortion have been heightened to some extent.The surface treatment technique of nano-silica has been studied also. Four mainfactors that influencing n-SiO_x homogenized in NRL film have been designed in aorthogonal test. Target assess is the mechanical properties of the film. Intuitionistic analysisof the results show: among the 4 factors, n-SiO_x, homogenized in NRL is most influencedby concentration of n-SiO_x/polyol polycondensate NS-2 disperse system. With 2.0% n-SiO_xin NRL, under the best technique, 16.5% concentration of n-SiO_x/polyol polycondensateNS-2 disperse system, the highest linear velocity at 18.5m/s for 25F homogenizerConducting surface treatment, and 240s duration of mixing with 25G homogenizer,condition, tear strength reaches as high as 36.68 kN/m. While under the best technique,14.5% concentration of n-SiO_x/polyol polycondensate NS-2 disperse system, the highestlinear velocity at 27.2m/s for 25F homogenizer conducting surface treatment, 2700sduration of treatment by ultrasonic, and 240s duration of mixing with 25G homogenizer,tensile strength reach as high as 9.60MPa.n-SiO_x influenced NRL elasticity action has been studied. The relationship curvesbetween elongate rate and stress show, the elongation of film filled n-SiO_x always higherthan film unfilled n-SiO_x, and the film unfilled n-SiO_x has more deformation at fixed stressin the whole test range.The influence of additive quantity of n-SiO_x in NRL films for tear resistance has been studied. The results show that NRL filled with 2.0% n-SiO_x, the film's tear strength in roomtemperature reach the highest, 33.07kN/m, which is 47.0% as high again as the film withoutn-SiO_x. In addition, the trend is: 0～1.0%, tear strength hold the line almost, fall a little;1.0%～2.0%, tear strength rise sharply; 2.0%～3.5%, tear strength fall to some extent, andwith 3.0%, it has a lower value. In the whole additive quantity range, NRL filled with 3.5%n-SiO_x, the tear resistance of the film in thermal load reach the highest, the temperature atbreak is 110℃, which is 150% as high again as the film without n-SiO_x. And the trend oftear resistance in thermal load is: with the load 15 kN/m, 0～2.0%, the variety oftemperature at break is unconspicuous, and 2.0%～3.5%, the temperature at break risesharply, and with 3.0%, it has a lower value also.The mechanism of n-SiO_x enhanced NRL has been discussed. The mechanism hasbeen deemed as follow: two aspects effect together when nano-silica enhanced NRL, thefirst one is, the special properties of n-SiO_x, such as tiny size, much hydroxidion and highactivity, which make it to be homogenized in NRL molecule, exist steadily, and it wouldmove or deform slightly in order to destroy the stress centralized spots, even ease up orconsume a portion of stress after receiving a external force. Another one is, n-SiO_x has amultiporous structure, which can absorb and dissipate redundant energy throughcompressing and restoring the special structure space time and again. |
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