Method for evaluating reinforcement effect and efficiency of filler on natural rubber based on particle size of bound rubber particle formed by the filler and natural rubber latex

A method for screening a filler with a reinforcement effect on natural rubber based on a particle size of bound natural rubber particles formed by the filler and a natural rubber particle in a natural rubber latex, comprising:

• (SI) mixing the natural rubber latex respectively with a plurality of to-be-tested fillers in a weight ratio of 100:5-0.1 to produce a plurality of mixtures, wherein bound natural rubber particles are formed by an interaction between the natural rubber particle in the natural rubber latex and each of the plurality of to-be-tested fillers, diluting the plurality of mixtures to obtain a plurality of first emulsions, respectively;
• (SII) measuring an average particle size of the bound natural rubber particles in each of the plurality of first emulsions by using a particle size measurement instrument;
• measuring an average particle size of natural rubber particles in a second emulsion, wherein the second emulsion is a pure natural rubber latex emulsion without the filler, and the second emulsion is the same as the first emulsion in terms of a concentration of the natural rubber particles in the natural rubber latex;
• calculating a particle size ratio x according to x=d/d1, wherein d represents the average particle size of the bound natural rubber particles in each of the plurality of first emulsions, and d1 represents the average particle size of the natural rubber particles in the second emulsion;
• (SIII) evaluating a reinforcement effect of the plurality of to-be-tested fillers on natural rubber based on the particle size ratio, wherein when the particle size ratio x is equal to or larger than 1.14, the reinforcement effect of a corresponding to-be-tested filler on the natural rubber is determined to be strong;
• when the particle size ratio x ranges from 1 to 1.07, the reinforcement effect of the corresponding to-be-tested filler on the natural rubber is determined to be weak;
• and when the particle size ratio x is larger than 1.07 and less than 1.14, the reinforcement effect of the corresponding to-be-tested filler on the natural rubber is determined to be medium;
• and
• screening a filler with the particle size ratio x equal to or larger than 1.14 from the plurality of to-be-tested fillers;
• (SIV) preparing at least two modified fillers from the screened filler respectively through at least two different modification techniques used for calculating constants;
• measuring an average particle size x of bound natural rubber particles formed by the natural rubber particles in the natural rubber latex and one of the at least two modified fillers used for calculating constants according to steps (SI)-(SII), respectively;
• preparing at least two natural rubber vulcanizates respectively filled with one of the at least two modified fillers used for calculating constants;
• measuring a value y of stress at definite elongation of one of the at least two natural rubber vulcanizates filled with one of the at least two modified fillers used for calculating constants;
• plugging one of the at least two obtained y values and the corresponding one of the at least two particle size ratio x values into the following formula to calculate constants a and b, so as to obtain a function expression for evaluating the reinforcement efficiency of the screened filler on the natural rubber:
• y
• =
• a
• +
• bx
• ;
• (SV) measuring an average particle size of bound natural rubber particles formed by the natural rubber particles in the natural rubber latex and each of a plurality of to-be-tested modified fillers from the screened filler respectively obtained through a plurality of to-be-tested modification technologies according to steps (SI)-(SII), and then obtaining a particle size ratio xt;
• substituting the particle size ratio xt into the function expression obtained in step (SIV) to calculate a corresponding value yt of stress at definite elongation of each of a plurality of natural rubber vulcanizates respectively filled with the plurality of to-be-tested modified fillers;
• measuring a value y′ of stress at definite elongation of a filler-free natural rubber vulcanizate;
• and
• calculating the reinforcement efficiency R according to the following formula:
• R
• =
• [
• (
• y
• t
• -
• y
• ′
• )
• /
• y
• ′
• ]
• ·
• 100
• ⁢
• %
• ;
• wherein when R≤10%, the reinforcement efficiency of a corresponding to-be-tested modified filler on the natural rubber is determined to be weak;
• when R>20%, the reinforcement efficiency of the corresponding to-be-tested modified filler on the natural rubber is determined to be strong;
• and when 20%>R>10%, the reinforcement efficiency of the corresponding to-be-tested modified filler on the natural rubber is determined to be medium;
• and
• screening a modified filler with the reinforcement efficiency R equal to or larger than 20% from the plurality of to-be-tested modified fillers for compounding with the natural rubber latex and vulcanization to prepare a filler-modified natural rubber vulcanizate.