Preparation Of Polypropylene Engineering Mandrel Pipe And Its Structure And Properties

In recent years, paper industry is rapidly developed accompanied by the development of national economy and the expansion of paper market demand in china. Annual per capita consumption of paper and paperboard was 45 kilograms in 2005. In the paper industry paper, widely used product types of mandrel pipe are onefold, mainly paper-based pipe. The defects of the paper-based pipe are easy to deform, lack of stiffness and sharp decline in mechanical strength in humid air. Mandrel pipes for paper industry with high stiffness and heat deformation temperature are badly needed. So in this study, the microstructure and properties of two PP pipes made with different catalysts were firstly analysed, then ZNIPP was modified by physical and chemical methods, and applied to engineering mandrel pipe. The molecular weight and its distribution were measured by gel permeation chromatography (GPC). The sequence structure and composition of two kinds of PP were analyzed by nuclear magnetic resonance(NMR) and infrared spectroscopy. Crystallization, crystal type and structural stability of two kinds PP were investigated by X-ray diffraction and differential scanning calorimetry (DSC). The physical and mechanical properties of two kinds of the composite materials were measured by all-purpose test machine. On this basis, two different molecular weight PPs and inorganic fillers were used to improve the strength and stiffness of the composite. Chemical cross-linking reaction of bismaleimide (BMI) and pentaerythritol acrylate were used to increase the stiffness and micro-structural stability of PP. The physical and mechanical properties of the composite materials were measured by all-purpose test machine and pendulum-type impact machine. Sectional morphology of the materials was observed by scanning electron microscope (SEM). The reaction incompleteness after reactive extrusion of BMI with polypropylene was measured by tester of melt flow index (MFI). The main conclusions were drawn by a series of tests:(1) The micro-structure difference of two types of PP resulted in different physical and mechanical properties. In this study, the feature of ZNIPP was higher molecular weight, narrower molecular weight distribution, lower crystallinity. The crystallization ofαandβwas concurrence. In a given ranges of temperature and time, the heating cycle caused moreβ-crystal. Tensile strength, flexural strength and modulus of ZNIPP were lower. The crystallization ofαandγwas concurrence in MIPP, but the content ofγ-crystal was low. The structure of MIPP was stability after heating cycle. The other structures and physical and mechanical properties of MIPP were opposite to ZNIPP. DSC and X-Ray diffraction can be used to distinguish synthetical method of Isotactic PP.(2) The polymer blends by two different molecular weights of PP improved the tensile strength, flexural strength, flexural modulus and toughness. Four different kinds of inorganic fillers enhanced tensile strength, flexural strength and modulus. PP-g-MAH improved the bonding and dispersion of talc in PP, and thus the stiffness and toughness. BMI increased the tensile strength and modulus, flexural strength and modulus while decreased the impact strength of PP filled with glass fiber, however, all the inferior mechanical properties of the composite materials were resulted when BMI was excessive. In addition, during the reactive extrusion process, the grafting and crosslinking reactions of BMI were incomplete. Graft modification by pentaerythritol acrylate gave rise to higher crystallization temperature and lower melting point. It indicated that grafting modification could increase the apparent molecular weight. while inhibited the formation ofβ-crystal, and this would be conducive to the improvement of fatigue resistance of PP. The mechanical property of the modified PP was improved by heat treatment at vacuum. The heat treatment strengthened adhesive force between BMI and glass fiber, and thus mechanical properties. The engineering mandrel pipe was obtained based on the above-mentioned studies. The pipe's inner diameter was about 152mm, tensile strength 49Mpa and ring stiffness 61kN/m2. The innovation checking report displayed that the comprehensive performances of the product reached the leading level in China.The characteristics and innovation of the paper are the following:(1)The method of discrimination of the Z-N and metallocene catalyzed PPs was suggested.(2)The polymer blending, multi-functionality monomer grafting reaction and heat treatment were used to improve stiffness and toughness of PP, and the better mechanical properties were obtained.