Chemical Modification Of Polypropylene Research Articles

MODIFICAÇÃO QUÍMICA DO POLIPROPILENO ATRAVÉS DA INTRODUÇÃO DE GRUPOS SULFÔNICOS PARA APLICAÇÃO COMO CATALISADOR EM REAÇÕES DE ESTERIFICAÇÃO

CHEMICAL MODIFICATION OF POLYPROPYLENE THROUGH THE INTRODUCTION OF SULPHONIC GROUPS FOR APPLICATION AS CATALYST IN ESTERIFICATION REACTIONS. In this work, the chemical modification of pristine polypropylene was carried out through sulfonation reactions with concentrated sulfuric acid (PPS1) and fuming sulfuric acid (PPS2), for production of heterogeneous catalysts used in esterification reactions. Fourier transform infrared spectroscopy, elemental analysis, degree of substitution and ion exchange capacity showed that both sulfonation agents were effective to promote the functionalization of polypropylene, with the fuming sulfuric acid capable of promoting a greater chemical modification. The materials catalytic activity in esterification reaction of oleic acid with methanol was evaluated at 100 ºC, methanol: oleic acid molar ratio of 78:1 and with 5 wt% of catalyst (referred to oleic acid weight). It was observed that reaction catalyzed by PPS1 converted 68.02% of oleic acid to methyl oleate in 3 hours of reaction, while PPS2 reached 86.47% conversion in five hours, showing even greater catalytic efficiency than the commercial ion exchange resin, Amberlyst 15. Therefore, the conditions employed for the sulfonation of polypropylene were satisfactory to produce materials with acid characteristics necessary to catalyze the esterification reaction of oleic acid with methanol.

FIBAN fibrous ion exchangers: Synthesis, modification, application

Methods for synthesis and production of FIBAN ion exchange fibers, which are based on the radiation chemical and chemical modification of polypropylene and polyacrylonitrile fibers were developed. The possible applications of FIBAN materials for water and air purification from harmful impurities, separation of valuable products from the liquid media, and catalysis are considered.

Chemical Modification of Polypropylene by Maleic Anhydride: Melt Grafting, Characterization and Mechanism

 Abstract—Polypropylene (PP) was functionalized with maleic anhydride (MAH) in the presence of dicumyl peroxide (DCP) via melt grafting in a batch mixer, where the maleic anhydride and peroxide concentrations were varied. The effect of concentration of monomer and initiator on the degree of functionalization and properties of the products was investigated by FT-IR spectroscopy, contact angle measurement, thermal analysis and titration. It was found that the degree of functionalization depends on the initial concentration of monomer and initiator that used in reaction. Finally a mechanism of melt grafting MAH onto PP proposed on the basis of our experimental results and other experimental finding published in the literature.

Chemical modification of polypropylene by nitroxide-mediated radical graft polymerization of styrene

Nitroxide-mediated free radical polymerization (LREP) was employed for the first time to prepare graft copolymer by having arylated polypropylene (Cl-PP) as a backbone and polystyrene (PS) as branches. The graft copolymerization of styrene was initiated by arylated PP carrying 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) groups as a macroinitiator. Thus, maleic anhydride was grafted onto polypropylene by peroxide-catalyzed swell grafting method (PP-MAH). Next, PP-MAH reacted with ethanolamine to produce a hydroxyl group containing polypropylene (PP-OH) and the obtained PP-OH was treated with α-phenyl chloroacetyl chloride and converted to a chloroacetyl group containing polypropylene (PP-Cl). Finally, 1-hydroxyl-2,2,6,6-tetramethylpiperidine (TEMPO-OH) was synthesized by reducing TEMPO with sodium ascorbate and this functional nitroxyl compound was coupled with α-phenyl chloroacetylated polypropylene. The resulting macroinitiator (PP-TEMPO) for free radical polymerization was then heated in the presence of styrene for the formation of the graft copolymer. The prepared graft copolymer was characterized by Fourier transform infrared spectroscopy and 1H NMR techniques. Glass transition temperature of grafted copolymer was investigated using thermogravimetric analysis and differential scanning calorimetric techniques. This approach using nitroxide-mediated macroinitiators is an effective method for the preparation of new materials.

Chemical modification of polypropylene with diisocyanates for improved gas barrier and mechanical properties

AbstractIn this investigation, modification of polypropylene (PP) with an objective to obtain packaging film with improved gas barrier properties has been studied. The chemical reaction of PP resin with hexamethylene diisocyanate and toluene diisocyanate was monitored by Fourier transform infrared spectroscopy, wherein the appearance of new peaks at 3333 cm−1 for NH stretching, 1620–1641 cm−1 for (CO)NH stretching and 1552–1578 cm−1 corresponding to NH bending in an amide moiety was observed for both the modified PP films. Films of excellent clarity and uniform thickness were obtained by the extrusion of cross‐linked polypropylene. The barrier, mechanical, optical, and thermal properties of the modified PP films were studied. The results clearly indicated significant changes in gas barrier and mechanical properties. Food compatibility of the films was evaluated by overall migration in to different food simulants. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 28:233–245, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20168

Chemical Modification of Polypropylene and Polystyrene through Fluorocarbon Ion Beam Deposition

Classical molecular dynamics (MD) simulations are used to examine the deposition of polyatomic fluorocarbon (FC) beams on polypropylene (PP) and polystyrene (PS) surfaces. The goal is to investigat...

Chemical Modification of Polypropylene by Decomposition of Unsaturated Peroxides

Chemical modifications of polypropylene were studied via the decomposition of β,γ-unsaturated peroxides. Six peroxy derivatives were used to test the influence of the more important structural parameters (type of peroxide, nature of the unsaturation, and substituents in the allylic position) of such compounds on the efficiency of the grafting of a function and on the degradation of the polymer. Grafting of ester and epoxide functions on the chains of the polyolefin occurred with a slight degradation of these last ones with the use of acrylic peroxides. The decomposition of a styrenic peroxide allowed the grafting of phenyl entities on the backbone and induced structural modifications of the chains (branching). However, no epoxidic groups were detected in this case. Allylic peroxide did not permit any functionalization of the polyolefin but provoked some changes in the structure of the polymer. Mechanisms for the grafting and the degradation of the polypropylene were proposed.

Chemical modification of polypropylene with peroxide/pentaerythritol triacrylate by reactive extrusion

To explore the possibility of producing branched polypropylene (PP) by a reactive extrusion (REX) process, isotactic PP was reacted with a polyfunctional monomer, pentaerythritol triacrylate (PETA), in the presence of 2,5-dimethyl-2,5(t-butylperoxy) hexane peroxide (Lupersol 101). Experiments were carried out in an intermeshing, corotating twin-screw extruder at 200°C using three concentrations of peroxide (200, 600, and 1000 ppm) and four concentrations of PETA (0.64, 1.8, 2.8, and 5.0%, by weight). Shear viscosity and MFI of the whole polymers was found to increase with PETA concentration and decrease with increasing the peroxide concentration at a given PETA concentration. The macrogel amount in the materials produced was determined in refluxing xylene using Soxhlet extraction and at PETA concentrations higher than 1.8wt % the macrogel content increased with increasing peroxide concentration. No macrogel was detected at low PETA concentrations (<0.64%) at all three peroxide levels, suggesting that low concentrations of PETA and peroxide should be used in order to minimize the formation of macrogels. The xylene soluble portions (sols) of the modified materials were characterized by FTIR and DSC. Generally, the relative intensities A1740/A841 in the FTIR spectra increased with increasing PETA incorporated into PP. Two melting peaks (Tm1 and Tm2) were observed in the DSC traces of some of the sols, and the crystallization temperatures (Tc) were higher than those of the virgin and degraded polypropylenes. The DSC behavior of the sols suggests that the modified PPs contain branched and/or lightly crosslinked chain structures. © 1996 John Wiley & Sons, Inc.

Yielding and impact behaviour of pp/sgf/epr ternary composites with controlled morphology

Dependencies of the yield strength (σyc), yield strain (ɛyc) and Charpy notched impact strength (CNIS) of polypropylene (PP) reinforced with 30 wt% short glass fibres (SGF) and ethylene — propylene random copolymer (EPR) inclusions on EPR volume fraction (ve) were investigated within the interval of ve varying from 0–0.2. Only one limiting phase morphology has been attained reproducibly using a procedure based on chemical modification of PP. Adhesion enhancement between SGF and PP and complete separation between SGF and EPR was achieved by grafting PP with 2wt % maleic anhydride (MAH). Two regions existed on σyc versus ve curves in the case of complete separation of the reinforcement and elastomer. The observed increase of σyc with increasing ve within the interval 0<ve < 0.05 was attributed to the change in the mode of fracture from brittle to quasi-ductile. Such an explanation has been supported by a several fold increase in ɛyc. Above ve=0.05, a monotonic decrease of σyc with increasing ve was observed corresponding well with an explanation based on a reduction of matrix effective cross-section. In this interval of ve the concentration dependence of σyc was described quantitatively using existing composite models and satisfactory agreement between predictions and experimental data was obtained. The CNIS increased monotonically up to ve=0.1 for both homo- and copolymer based composites. Above ve=0.1, CNIS, measured at -20°C using 6 × 4 × 50 mm bars, notched accordingly ASTM D256 standard, increased for copolymer based composites while it remained constant for homopolymer based materials. Physical meaning of these data is, however, obscured by the inability to separate effects of ve from those of specimen geometry using only a single standard impact strength data.

Mechanical properties of particulate filled polymers

AbstractThe mechanical properties of several types of inorganic fillers were investigated in a number of different thermoplastic polymers. The fillers included minerals, such as talc and silicon carbide, and metals, such as aluminum flake and stainless steel fibers. The polymers included General Electric's Noryl, acrylonitrile‐butadiene‐styrene terpolymer, polypropylene, and modified polypropylene. The talc and some of the aluminum flake were treated with coupling agents to improve interfacial adhesion to the polymers. The results showed that the modulus of the filled polymers was a function only of the concentration of filler used up to 40 volume percent filler. The tensile strength of the filled compositions depended very strongly on the degree of interfacial bond developed between the polymer and the filler. The interfacial bond strength depended on the effectiveness of the coupling agents and the inherent wetting ability of the polymer. Of the polymers investigated in this study, Noryl showed the greatest degree of inherent wetting to inorganic fillers. Chemical modification of polypropylene also resulted in greater adhesion to fillers. The impact strength of filled compounds had an even more complex response, because, in addition to the concentration of the filler, and strength of the polymerfiller interface, it depends on the mechanism of crack propagation.