Effect of N,N'-Dicyclohexyl Terephthalic Dihydrazide on the Crystallization and Properties of Isotactic Polypropylene

Flóra Horváth,Alfréd Menyhárd,Levente Bihari

doi:10.3311/ppch.19074

Abstract

Application of nucleating agents is a common way to manipulate the structure and properties of crystalline polymers. Our goal was to synthesize N,N'-dicyclohexyl terephthalic dihydrazide (DCTDH) and study it from the viewpoint of applicability as a nucleating agent for isotactic polypropylene (iPP). We used differential scanning calorimetry to investigate the efficiency of DCTDH in samples containing the nucleating agent in a wide concentration range. We used polarized light microscopy to study the crystalline morphology developed in the presence of this nucleating agent. To characterize the mechanical properties of the nucleated samples, we performed tensile and impact tests on injection molded specimens. DCTDH proved to be a non-soluble α-nucleating agent in iPP, with a saturation concentration around 300 ppm. The nucleating agent has a significant effect on the crystalline structure of iPP, microspherulitic structure forms in its presence. Owing to the different structure, a considerable change in the mechanical properties is observable: with increasing nucleating agent content the tensile modulus increases, while impact resistance has a maximum value around 300 ppm nucleating agent content.

Highlights

Isotactic polypropylene is a commodity polymer used in large amounts by industry [1]
We used differential scanning calorimetry to investigate the efficiency of dicyclohexyl terephthalic dihydrazide (DCTDH) in samples containing the nucleating agent in a wide concentration range
In this short summary we focus on those non-soluble nucleating agents, that are selective for the α-modification of isotactic polypropylene (iPP)

Summary

Introduction

Isotactic polypropylene (iPP) is a commodity polymer used in large amounts by industry [1]. As the properties important from the viewpoint of application (such as mechanical and optical properties) depend mostly on the crystalline structure, manipulating the structure is an appropriate way to achieve the required properties To attain this goal, the application of special additives, called nucleating agents, is the most versatile method used in industry. The nucleating agents can be classified from more viewpoints like selectivity or dispersability for example In this short summary we focus on those non-soluble nucleating agents, that are selective for the α-modification of iPP. Other non-soluble nucleating agents commonly used in the industrial practice are sodium-benzoate, NA-11 and NA-21E. These latter two are organic phosphate derivatives [15,16,17].

Objectives

Methods

Results