Nucleating Agent For Polypropylene Research Articles

Novel nucleating agents for polypropylene and modifier of its physical-mechanical properties

In this paper, we demonstrate that dicalcium salt of 1-hydroxyethane-1,1-diphosphonic acid (HEDP) can be used as a component of nucleating agents for isotactic polypropylene (iPP) - one of the most widely used commercial polymers. Based on dicalcium HEDP salt novel nucleators show high efficiency in the nucleation of iPP α-crystals. At a concentration of 0.25 wt% the nucleators demonstrate an increase in crystallinity (+ 1.5 % in composition with calcium stearate and + 4% - with zinc stearate). When the dicalcium HEDP salt based nucleator is added to the iPP, the flexural modulus increases by 8–12 %. Assumptions are suggested about the mechanism of action of the new nucleator, based on its core-shell structure. The main component of the nucleating agent, the dicalcium HEDP salt, is synthesized by the one-step reaction in a non-toxic aqueous medium with commercially available reagents. The synthetic protocol gives a finely friable product that does not require further grinding. The synthesis is cheap and environmentally friendly since only deionized water is used as a solvent.

Properties and Structure of Polypropylene/ Polyethylene-Octene Elastomer/Nano CaCO 3 Composites

Polypropylene (PP)-based nanocomposites were developed by the incorporation of a novel nano-sized precipitated calcium carbonate (NPCC) nanoparticles and polyethylene—octene elastomer (POE). The NPCC filler loading selected were 10 and 15wt.% while the POE contents were varied between 0 and 30wt.%. A slight decrease in the tensile strength of the PP nanocomposites was observed with increasing NPCC content. Results of impact strength indicated that the NPCC filler imparted some toughening effects on the PP and PP/POE blends. Maximum impact strength enhancement was achieved for the PP when blended with 30wt.% POE and filled with 15wt.% NPCC. However, the essential property balance between toughness and stiffness was still lacking in the nanocomposites developed. Differential Scanning Calorimeter results showed that NPCC acted as a nucleating agent for PP, increasing the crystallization temperature of PP by approximately 9°C.

Effect of the Compatibiliser on the Morphology and Properties of Dynamically Cured PP/EPDM/Epoxy Blends

Dynamic vulcanisation was successfully applied to epoxy resin reinforced polypropylene (PP)/ethylene-propylene diene elastomer (EPDM) blends, and the effects of different compatibilisers on the morphology and properties of dynamically cured PP/EPDM/epoxy blends were studied. The results show that dynamically cured PP/EPDM/epoxy blends compatibilised with maleic anhydride-grafted polypropylene (MAH-g-PP) have a three-phase structure consisting of EPDM and epoxy particles dispersed in the PP continuous phase, and these blends had improved tensile strength and flexural modulus. While using maleic anhydride-grafted EPDM (MAH-g-EPDM) as a compatibiliser, the structure of the core-shell complex phase and the PP continuous phase showed that epoxy particles could be embedded in MAH-g-EPDM in the blends, and gave rise to an increase in impact strength, while retaining a certain strength and modulus. DSC analysis showed that the epoxy particles in the blends compatibilised with MAH-g-PP were more efficient nucleating agents for PP than they were in the blends compatibilised with MAH-g-EPDM.

Polypropylene/polypropylene‐grafted acrylic acid copolymer/ethylene–Acrylic acid copolymer ternary blends for hydrophilic polypropylene

AbstractTernary blends of polypropylene (PP), a polypropylene‐grafted acrylic acid copolymer (PP‐g‐AA), and an ethylene–acrylic acid copolymer (EAA) were prepared by melt blending. The surfaces of films with different contents of these three components were characterized with contact‐angle measurements. Scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis were used to characterize the microstructure, melting and crystalline behavior, and thermal stability of the blends. The contact angles of the PP/PP‐g‐AA blends decreased monotonically with increasing PP‐g‐AA content. With the incorporation of EAA, the contact angles of the PP/PP‐g‐AA/EAA ternary blends decreased with increasing EAA content. When the concentration of EAA was higher than 15 wt %, the contact angles of the ternary blends began to increase. Scanning electron microscopy observations confirmed that PP‐g‐AA acted as a compatibilizer and improved the compatibility between PP and EAA in the ternary blends. Differential scanning calorimetry analysis suggested that acrylic acid moieties could act as nucleating agents for PP in the polymer blends. Thermogravimetric analysis and differential thermogravimetry confirmed the optimal blend ratio for the PP/PP‐g‐AA/EAA ternary blends was 70/15/15. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 436–442, 2006

Effect of Modified Abietate Nucleating Agents on the Properties of Polypropylene

ABSTRACT Two kinds of modified abietates, cocrystals of dehydroabietic acid with sodium dehydroabietate and tetrahydroabietic acid with sodium tetrahydroabietate, were prepared, respectively. The properties and crystallization behavior of polypropylene (PP) with the modified abietate cocrystals as nucleating agents were investigated by the measurement of mechanical properties and heat distortion temperature (HDT), testing of differential scanning calorimetry (DSC), X-ray diffraction (XRD), and polarizing light microscopy (PLM) observation. The results show that the heat distortion temperature (HDT), transmittance, crystallizing point, the degree of crystallinity, and mechanical properties, especially the flexural strength and modulus of PP are enhanced obviously, but the size of spherulites measured by polarizing optical microscopy decrease, by adding modified abietate cocrystals. By adding the modified abietates, the typical α-form monoclinic structure of PP was formed, which was proved by the results of X-ray diffraction. It is concluded that the modified abietates can be used as effective nucleating agents for PP.

Morphology and mechanical properties of biaxially oriented films of polypropylene and HDPE blends

AbstractBiaxially oriented films of blends of high‐density polyethylene (HDPE) with polypropylene (PP) homopolymer and PP copolymers prepared by twin‐screw extrusion and lab‐stretcher have been investigated by scanning electron microscopy (SEM), polarized microscopy, differential‐scanning calorimeter, and universal testing machine. Three different kinds of PP copolymers were used: (i) ethylene–propylene (EP) random copolymer; (ii) ethylene–propylene (EP) block copolymer; (iii) ethylene–propylene–buttylene (EPB) terpolymer. In the SEM study of the morphology of films of HDPE with various PP blends, phase separation is observed between the PP phase and the HDPE phase for all blends and compositions. In all blends, HDPE serves to reduce the average spherulites size, probably acting as a nucleating agent for PP. The reduction of spherulite size appeared most significantly in the blend of EPB terpolymer and HDPE. A large increase of crystallization temperature was found in the blend of EPB terpolymer and HDPE compared with the unblended EPB terpolymer. For the blend of EPB terpolymer and HDPE, the improvement of tensile strength and modulus is observed with an increase of HDPE content, and this can be considered as a result of the role of HDPE in reducing average spherulite size. © 1994 John Wiley & Sons, Inc.

Crystallinity in the polypropylene/cellulose system. I. Nucleation and crystalline morphology

AbstractThe amount of research on lignocellulosic/thermoplastic composites has increased dramatically. Little attention, however, has been directed towards the subject of crystallinity at the interface (interphase). Optical microscopy and differential scanning calorimetry were used in this work to study crystallinity in the cellulose/polypropylene system. The results verify that cellulose acts as a nucleating agent for polypropylene, producing a transcrystalline region around the fiber. Treatment of the fibers with alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), or stearic acid, inactivates the surface features responsible for transcrystallinity. These treatments also affect the overall degree of crystallinity of the sample. Morphological features, resulting from a transcrystalline or nontranscrystalline interphase, may have a significant effect on mechanical properties. A possible mechanism for the appearance of transcrystallinity involving crystal structure matching is also proposed. © 1993 John Wiley & Sons, Inc.