Properties Of Isotactic Polypropylene Research Articles

Effect of polyacrylic salt nucleating agents on the properties of isotactic polypropylene

Effect of polyacrylic salt nucleating agents on the properties of isotactic polypropylene

Influence of chemical structures of bisamide nucleating agents on the crystallization behavior and properties of isotactic polypropylene

Influence of chemical structures of bisamide nucleating agents on the crystallization behavior and properties of isotactic polypropylene

Mechanical Properties of Isotactic Polypropylene with Oriented and Cross-hatched Lamellae Structure

Abstract The mechanical properties of injection moulded unreinforced isotactic, polypropylene depend on the crystalline structure and lamellae orientation. Push-pull processing is an injection moulding technique that allows the user to produce parts with oriented structures. Mostly applied for short fibre reinforced thermoplastics in order to align fibres parallel to the flow direction, this technique can also be used to orient the polymeric matrix of LCP and polypropylene. A comparison of mechanical properties as well as investigations on morphology between the samples produced using conventional injection moulding and push-pull processing are presented trying to improve the knowledge about this so far rather unknown technique.

Effect of a novel bio-based β-nucleating agent on the properties of isotactic polypropylene

Effect of a novel bio-based β-nucleating agent on the properties of isotactic polypropylene

The inhibiting effect of basalt powder on crystallization behavior and the structure-property relationship of α-nucleated polypropylene composites

Basalt powder (BP) is a promising eco-friendly filler for polymeric composites. Due to its chemical composition, it can alter the effectiveness of various modifying agents used in the polymer industry. In this study, the influence of simultaneous addition of 5 wt% of basalt powder and 0.5 or 1 wt% of a sorbitol-based nucleating agent (NA) on the structure and properties of isotactic polypropylene (iPP) composites was analyzed. The potential chemical reactions of BP and NA were evaluated by Fourier transform infrared spectroscopy. The influence of the additives on the crystallization of the polymer was studied by differential scanning calorimetry, optical microscopy in polarized light, and rheological measurements. The kinetics of crystallization was analyzed using Mo and Friedman methods. The structure of the composites was observed by scanning electron microscopy. The mechanical properties were also evaluated. It was found that the BP reacts with the NA, which limits its ability to form the microfibrillated network in the melt. As a result, the crystallization behavior of the nucleated basalt-filled iPP is almost the same as in the case of the composite without the NA. However, the samples containing both NA and BP present good mechanical properties and adhesion between the polymer and the filler.

Analyses of the Adhesion Interphase of Isotactic Polypropylene Using Hot-Melt Polyolefin Adhesives

The interphase structure and properties of isotactic polypropylene (it.PP) have received much attention in the fundamental science and industrial applications for the improvement of the poor adhesion properties of the it.PP. In this work, we focused on the laminates with it.PP substrates and various ethylene–octene rubber (EOR) hot-melt adhesives with different molecular weights and crystallinities. We prepared laminate samples using EOR with low molecular weight, random copolymerized EOR, and block-like copolymerized EOR as adhesives. We performed T-peel tests of the laminate samples and evaluated their thickness of the interphase with confocal Raman scattering imaging, X-ray refraction contrast imaging, and atomic force microscopic imaging. The laminates with larger interphase thicknesses possessed the larger T-peel strengths, which were relatively consistent with these obtained results among all the measurement methods. It is revealed that the adhesion properties and the interphase thicknesses depended on the crystallinities of the it.PP substrates. These results mean that the interphase would be constructed by not only diffusion of molecular chains but also the crystalline growth and the formation of lamellae interlock in the interphase region.

Effect of N,N′-Dicyclohexyldicarboxamide Homologues on the Crystallization and Properties of Isotactic Polypropylene

Application of nucleating agents is the most versatile and industrially applied way to manipulate the crystalline structure of isotactic polypropylene (iPP). Various materials possess a nucleating effect, but from the viewpoint of dispersibility, the partially soluble ones are the most advantageous. Our objective was to synthesize new N,N′-dicyclohexyldicarboxamide homologues and study their applicability as nucleating agents in iPP. Carbon-13 nuclear magnetic resonance (13C NMR) and infrared spectroscopy were used to prove that the synthesis reactions were successful. Thermal stability of the compounds was investigated with simultaneous thermal analysis. Nucleating efficiency and solubility were characterized by polarized light microscopy and differential scanning calorimetry. Polarized light microscopy was also applied to study the effect of novel additives on the morphology of iPP. The properties, important from the viewpoint of applicability, were also investigated. Tensile tests were performed to characterize the main mechanical properties, and standard haze measurements were performed to characterize optical properties. It can be concluded that the investigated compounds are partially soluble nucleating agents and influence the crystalline structure of iPP. Most of the studied compounds have a moderate nucleating efficiency, but a very interesting dendritic structure develops in their presence. Two of them proved to be non-selective β-nucleating agents, which result in a remarkable improvement of impact resistance and higher opacity.

Calcium Salt of L-Isoleucine-Phthalate: An α-Nucleating Agent That Enhances the Crystallization Behavior and Mechanical Properties of Isotactic Polypropylene

In this study we prepared the novel compound L-isoleucine-phthalandione (LIPTA), featuring carboxyl and amide groups, and its calcium salt, the calcium salt of L-isoleucine-phthalate (LIPTA-Ca), and characterized them using 1H nuclear magnetic resonance spectroscopy, thermogravimetric analysis, and differential scanning calorimetry (DSC). LIPTA-Ca has a relatively high melting point and thermostability. We employed DSC and polarized optical microscopy and tests of mechanical properties to examine the effect of LIPTA-Ca on the crystallization behavior and mechanical properties of isotactic polypropylene (iPP). We found that LIPTA-Ca is a highly effective α-nucleating agent that can increase the crystallization temperature of iPP by more than 10 °C during cooling, when present as an additive at a content of 0.15 wt%, while greatly decreasing the spherulite size and accelerating the crystallization rate of iPP. In addition, LIPTA-Ca can improve the rigidity of iPP significantly without decreasing its toughness.

Study of the Relative Variations of the Thermal Properties and Crystallinity of Blends (PP/EPR)/Calcium Carbonate

The objective of this paper is to investigate the relative variations of the constants of the thermal properties and the degree of crystallinity of the mixtures (PP/EPR)/Calcium carbonates elaborated with the Micro Bivis. We have strengthened the basic copolymer PP/EPR of a low level (5%) by three calcium carbonates models socal312, socal322v, Winnofil spm. We then subjected the different mixtures obtained, two cycles of a thermal loading under differential scanning calorimetry DSC. We finally focused on the thermal properties of isotactic polypropylene (TfP, TcP, ΔHfP, ΔHcP) and we calculated the degree of crystallinity of the mixtures. Reducing the energy cost of implementing mixtures is one of the objectives of this work. We quantified the relative variations of the above properties with those of the base copolymer. It shows that at a low loading rate of calcium carbonate, there is a decrease in the enthalpies of crystallization during the second exothermic cycle, with values that can reach 5.53 J/gPP for the basic copolymer PP/EPR. During the second endothermic cycle, there is an overall increase in isotactic polypropylene melting temperature values for all the blends as well as for the basic copolymer PP/EPR. There is evidence that calcium carbonates are useful for lowering the melting energy of isotactic polypropylene, even at a low loading rate for the majority. The number of endothermic cycles accentuates this phenomenon which is linked to the presence in our composites, of a so-called confined amorphous phase.

Thermo‐mechanical and mechanical behavior of hybrid isotactic polypropylene glass fiber reinforced composites (GFRC) modified with calcium carbonate (CaCO3)

AbstractThe study investigates the thermo‐mechanical properties of isotactic polypropylene (iPP) hybrid composites in reference to various amounts of particle‐ and fiber‐shaped inorganic fillers. Three grades of hybrid composites were prepared as a function of filler amount: 5, 10, and 20 wt% and different ratios of glass fiber (GF) and calcium carbonate (CaCO3). The main objective is to describe the relationship between the hybridization efficiency and mechanical performance of polypropylene‐based composites. The analysis of the thermo‐mechanical properties of the composites shows that both the total amount of the filler and the ratio of GF and CaCO3 clearly influence the properties of the composites. Hybrid composites with the highest amount of the GF display improved thermo‐mechanical stability. The presence of well‐dispersed CaCO3 in the composites was found to improve elongation at break and Vicat softening temperature values. Even though it is glass fiber, which shows higher filler effectiveness and visibly reinforces the composite samples, causing an increase in tensile strength or reinforcing efficiency, replacing up to 50% of this filler with calcium carbonate does not result in a considerable deterioration of the properties of the material.

Analysing the Effect of Nucleators on Mechanical, Thermal and Structural Properties of Isotactic Polypropylene

Analysing the Effect of Nucleators on Mechanical, Thermal and Structural Properties of Isotactic Polypropylene

The influence of illite on the crystallization and properties of isotactic polypropylene

The influence of illite on the crystallization and properties of isotactic polypropylene

Microstructural Evolution and Its Effect on Mechanical Properties of Isotactic Polypropylene by Shear Plastic Deformation at Elevated Temperatures

Isotactic polypropylene (iPP) was plastically shear deformed by equal channel angular extrusion (ECAE) at extrusion temperatures varied from 45 to 125°C (25 mm/min). The evolutions of morphology and crystal orientation were studied by reflected optical microscopy (ROM), scanning electron microscopy (SEM), and X-ray diffraction. It was found that the original spherulites were deformed into nearly ellipsoids with their long axis tilted at an angle away from the flow direction. Azimuthal scanning results revealed that two preferred crystal orientations were formed after ECAE. The crystal plasticity was activated by increasing the extrusion temperature, followed by fast rotation of crystallites toward the shear direction. The thermal mechanical analysis (TMA) indicated that low extrusion temperature was favorable to fix the molecular orientation. The iPP samples processed at the investigated temperatures displayed a significant increase in the impact strength, especially for those extruded at 45°C and 65°C. The tensile results revealed a greater elongation at break in the samples deformed at low temperatures (45°C and 65°C) but not in those deformed at high temperatures (85°C or above).

Investigation on the Tensile Behavior and Morphology Evolution of Isotactic Polypropylene Films Polymerized with Different Ziegler-Natta Catalysts

Stereodefect distribution is very important in determining the morphology and properties of isotactic polypropylene (iPP). In this study, two iPPs (PP-A and PP-B) with different uniformities of stereodefect distribution were prepared. The tensile behavior and morphology evolution of their cast films were studied. The morphology study of the cast films showed that compared with PP-B, PP-A with less uniform distribution of stereodefects has smaller spherulites and spheruilitic boundaries and higher degree of crystallinity. In uniaxial tensile measurements, PP-A exhibited higher yield strength and lower elongation at break. When strain was 500%, PP-A exhibits totally transparent appearance and highly oriented structures without cavities, whereas PP-B shows opaque appearance and mass of both nanometer- and micrometer-sized cavities. Moreover, calculation of rigid amorphous fraction (RAF) indicated that PP-B cast film has a higher amount of RAF, which might be the reason for the different morphology evolutions and tensile behaviors of the samples.

Polypropylene/nTiO2 nanocomposites using melt mixing and its investigation on mechanical and thermal properties

This study investigates the preparation of nTiO2 particle using green chemistry approach and its subsequent effect on the properties of isotactic polypropylene (iPP) nanocomposites, which is one of the most suited thermoplastic polymer. The nanocomposite of iPP with TiO2 nanoparticle (0.5, 1, 1.5, 2, and 2.5 wt%) were prepared on Brabender plasticorder, which was then subjected to injection molding to get a dumbbell‐shape specimens. Meanwhile, TiO2 nanoparticles (nTiO2) were prepared using ultrasonic cavitation technique using leaf extract of Murraya koenigii. The extraction of leaf was carried out using distilled water as a solvent. The size and shape of nTiO2 particle was confirmed using transmission electron microscope and found to be spherical shape of diameter ∼10–45 nm. The mechanical properties of nTiO2 reinforced iPP composites were studied using universal testing machine. Moreover, thermal properties were studied using Vicat softening temperature, thermogravimetric analyzer, and differential scanning calorimeter. The extent of dispersion of nTiO2 in iPP matrix was studied using field‐emission scanning electron microscope and X‐ray diffractometer. The mechanical and thermal properties of nTiO2‐iPP composites were found to be improved significantly with increasing amount of nTiO2 particles except elongation at break, which is a marginal increment. This improvement in properties (mechanical and thermal) was due to the uniform dispersion of nTiO2 in iPP matrix, which means that chains of polymers were well adhered with the spherical shaper particles. POLYM. COMPOS., 38:1273–1279, 2017. © 2015 Society of Plastics Engineers

Structure, thermal and mechanical properties of polypropylene composites with nano- and micro-diamonds

The influence of diamond powders on properties of isotactic polypropylene (PP) was investigated. PP composites containing 0.2—5 wt % of the powders with particles of average size between 100 nm and 1 μm were prepared, and their structure and properties were examined. Dispersion of each filler depended on its grain size and content. The presence of fillers raised the crystallization temperature of PP matrix by up to few Celsius degrees. The modulus of elasticity of composites increased with increasing filler content, by up to 40 % in comparison to neat PP. The tensile impact strength of the composites with 1 μm powders and also the other composites at the filler content as low as 0.2 wt % improved by up to 30 %. The composites did not exhibit any decrease in the yield strength and retained good drawability. The elongation at break exceeded 1000 % in most cases. Examination of the uniaxially drawn specimens revealed that the filler grains separated from the PP matrix during drawing.

Effect of an In-Situ Nucleating Agent on the Polymorphs and Mechanical Properties of Isotactic Polypropylene

The influence of glutaric acid (GA)/cadmium hydroxide [Cd(OH)2] mixtures on the crystallization and properties of isotactic polypropylene (iPP) was investigated by means of differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), polarized light microscopy, and mechanical tests. It was found that the β-crystalline form was produced in the samples containing 0.15 wt% GA and more than 0.17 wt% Cd(OH)2. The content of β-crystalline form was maximum, i.e. KDSC = 65.4% and KWAXD = 71.4%, when the sample was doped with GA (0.15 wt%)/Cd(OH)2 (0.20 wt%) (the molar ratio of GA:Cd(OH)2 was 1:1.2). It was also found that GA/Cd(OH)2 mixtures not only induced the β-crystalline form but also made spherulites smaller. The results of mechanical tests showed that the toughness of iPP was greatly improved by bicomponent nucleator, while the stiffness decreased a little. Fourier transform infrared spectroscopy analysis indicated that an “in-situ” chemical reaction occurred between GA and Cd(OH)2 during melt blending, yielding an effective β nucleator (cadmium glutarate).

Synthesis and Influence of Sodium Benzoate Silsesquioxane Based Nucleating Agent on Thermal and Mechanical Properties of Isotactic Polypropylene

Novel sodium benzoate modified silsesquioxane (nbPOSS) for isotactic polypropylene modification was synthesized and characterized. The influence of the novel silsesqioxane based nucleating agent on mechanical and thermal properties of commercial isotactic polypropylene was observed and compared with sodium benzoate. The mechanical investigations revealed changes in polymeric structure indicating that nucleating process had occurred. Synthetic route of 1-(3-benzoyloxypropyl)-3,5,7,9,11,13,15-hepta(isobutyl)pentacyclo-[9.5.1.13,9.15,15.17,13]octasiloxane and its characterization were presented.

Transcrystalline formation and properties of polypropylene on the surface of ramie fiber as induced by shear or dopamine modification

The key for fiber reinforced polymer composites is the interfacial interaction between fiber and polymer matrix. The crystallization of polymer on the surface of fiber as a possible way to enhance the interfacial interaction has received increasingly attention. In this work, the transcrystalline (TC) formation and properties of isotactic polypropylene (iPP) on ramie fiber surface, as induced either by fiber pulling or by dopamine modification, were investigated and compared. It was found that the growth rate of shear induced TC is faster than that obtained via dopamine modification. There exists α–β crystal form transition in the TC formation process as induced by pulling while only α-crystal form is obtained via dopamine modification. By using both dopamine modification and fiber pulling, a formation of TC with two step growth was observed for the first time: the first step growth has much enhanced rate than that induced by fiber pulling, and second step growth has the same rate with that induced by dopamine modification. Thus a unique TC structure was obtained, with α-crystal form presented in the inner layer and the outer layer, and β-crystal form in between. The result from single fiber fragmentation test indicated that interfacial shear stress (IFSS) between iPP and ramie fiber for dopamine modification induced TC is much higher than that of shear induced TC. Our work provides guidance for the preparation of polymer/fiber composites with enhanced interfacial interaction via formation of TC layer by using shear or fiber surface modification.

On Line study of optical and structural behaviour of annealed as spun isotactic polypropylene fibres under creep Deformation

Double-arm of multiple- beam Fizeau system in transmission, attached with a modified creep device was used to investigate the opto-viscoelastic properties of isotactic polypropylene (iPP) fibres under different annealing conditions. The mean refractive index, birefringence, orientation, density and crystallinity were calculated for the annealed iPP fibres during creep deformation. Crystallinity behaviour was investigated during creep experiments at different annealing conditions which indicated a remarkable improvement in the properties of the investigated samples. The creep compliance curves were obtained at three different values of stresses for different annealing temperatures and different times of annealing. An empirical formula was suggested to describe the creep compliance curve of annealed iPP fibre and the constants of this formula were determined from the fitting parameters of the obtained creep curves. Kelvin chain was used to model the mechanical behaviour of iPP fibre under creep process. Illustrations using graphs and microinterferogrames are shown.