The Nucleation Performance Of L-isoleucine And N-isoleucine Benzamide Acid Calcium In Polypropylene

As a thermoplastic,the intrinsic semicrystalline character and typical polymorphism of iPP make its crystallization behavior particularly important because it affects the crystallization kinetics.the final crystalline morphology,and the polymorphic behavior of the polymer,thereby effectively modulating the properties of the final product.Studies have shown that dispersing nucleating agents(NAs)into the polymer matrix during melt processing is one of the most efficient way.However,most of the nucleating agents can not be used in food and medicine because of their toxicity.In this way,the nucleation performance of an amino acid in polypropylene is explored in this paper.It is found that it has the inhibiting effect of polypropylene nucleation crystallization,and it is found that a derivative of isoleucine has a promote effect on the crystallization of polypropylene.First of all,in this paper,L-isoleucine were firstly applied in polypropylene processing,and the effect of L-isoleucine on melting and crystallization behaviors of polypropylene were investigated systematically.It was found that L-Ile can inhibit the crystallization of iPP,since the crystallization temperature of polypropylene increased when the concentration of isoleucine was less than 0.1 wt%,and the inhibitory effect will increase with the increase of the amount of L-Ile.But when the concentration is higher than 0.1 wt%,isoleucine can promote the crystallization of iPP,and the promoting effect increases with the increase of the addition amount of L-Ile.In order to explain this phenomenon,the L-Ile/iPP systems were further studied by means of POM,DSC and rotary rheometer,and the "solution dilution" theory of L-Ile to isotactic polypropylene was proposed and confirmed in the further studies.Secondly,a new nucleating agent,2-(1,3-dioxoisoindol-2-yl)-3-methylpentanoic acid calcium(DIMA-Ca),was synthesized.The effects of DIMA-Ca on the melting and crystallization behaviors and mechanical properties of polypropylene were studied.The results showed that DIMA-Ca can effectively raise the crystallization temperature of polypropylene and reducing the crystal size of iPP.The DSC and POM results show that DIMA-Ca is one of c-NA which can not change the crystal form of neat iPP.The results of mechanical properties shown that as a-nucleating agent,DIMA-Ca can increase the tensile strength of polypropylene by 7%,increase the flexural modulus by 17%and increase the impact strength by 7%at the same time.Finally,the isothermal crystallization processes of the mixed systems of iPP/L-Ile and iPP/DIMA-Ca had been studied by avrami equation,and the non-isothermal crystallization processes had been studied by Mo Zhishen method,which could provide theoretical basis for exploring the nucleation mechanism of nucleating agent/polypropylene systems.