Effect of a high-efficiency amide transparent nucleating agent on properties of polypropylene
The effect of a novel amide nucleating agent,1,3,5-benzene tricarboxylic acid tris(neopentylamine),on the proper-ties of isotactic polypropylene(iPP)was investigated.The optical and mechanical properties of iPP were characterized.The results show that the nucleating agent exhibits a high nucleation effect at a low concentration.When the addition amount is 0.3‰,iPP haze is reduced by 60.2%.At the same time,the flexural modulus and tensile strength are increased by 19.7%and 13.7%.This indicates that the nucleating agent is a highly efficient transparent nucleating agent for PP.Differential scanning calorimetry and polarizing optical microscopy were respectively applied to characterize the crystalline behavior and crystal morphology of iPP.The results show that the crystallization process of pure iPP can not complete within 30 minutes and the crystallization rate is slow.After adding the nucleating agent,the crystallization process of nucleated iPP can basically complete in about 4 minutes.The crystallization rate is greatly improved,while the size of the spherical crystals is significantly reduced.In addition,the nucleating agent increases the crystallization temperature of iPP from 121.1℃to 130.0℃and the melting temperature from 164.1℃to 165.8℃.Finally,the isothermal crystallization kinetics of iPP were investigated.It is suggested that the nucleating agent can reduce the Avrami index n of iPP and can promote heterogeneous nucleation of iPP,thus accelerating the crystallization rate.
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