Mixture Of Polypropylene Research Articles

Synthesis, structure and α-olefin polymerization activity of group 4 metal complexes with [OSSO]-type bis(phenolate) ligands

The tetradentate [OSSO]-type bis(phenol) ligands, [{2,2′-(HOC 6H 2-4,6-R 2) 2CH 2SCH 2CH 2SCH 2}] (R = t Bu, 2; Br, 3) react with MBz 4 (M = Zr, Hf) to yield the corresponding dibenzyl complexes, [M{2,2′-(OC 6H 2-4,6-R 2) 2CH 2SCH 2CH 2SCH 2}Bz 2] (R = Br, M = Zr, 4 Br ; Hf, 5 Br ; R = t Bu, M = Hf, 5) in a good to very good yield. Zirconium diamido complexes, [Zr{2,2′-(OC 6H 2-4,6-R 2) 2CH 2SCH 2CH 2SCH 2}(NMe 2) 2] (R = t Bu, 6; Br, 6 Br ) were prepared in a reaction of the corresponding disodium salt of 2 or 3 generated in situ with ZrCl 2(NMe 2) 2(THF) 2. Heating of 6 with TMSCl at 35 °C afforded zirconium dichloro complex, [Zr{2,2′-(OC 6H 2-4,6- t Bu 2) 2CH 2SCH 2CH 2SCH 2}Cl 2] ( 7), whereas the titanium analog 8 was prepared in a direct reaction with TiCl 4. While for complexes 4 Br , 5, 5 Br , 6, 6 Br and 7 single C 2-symmetric isomers were observed in solution at room temperature, as revealed by the NMR spectroscopic data, titanium complex 8 formed as a mixture of cis-α ( 8a) and cis-β ( 8b) isomers in a ratio of approx. 20:80% (measured in CD 2Cl 2). The VT NMR studies revealed a reversible conversion of 8a into 8b above 60 °C. The X-ray crystal structure determination of complexes 4 Br , 5 Br and 7 confirmed their C 2-symmetrical configuration in the solid state with cis-arranged benzyl/chloro groups and the trans-coordination of two bulky phenolato moieties. The zirconium dibenzyl complexes exhibit good catalytic activities in homopolymerization of 1-hexene (atactic poly(1-hexene), PDI = 1.5–1.7) and vinylcyclohexane (isotactic poly(vinylcyclohexane), PDI = 1.2–1.8) upon activation with a co-catalyst. In both polymerizations no increase of activity was observed for the complex 4 Br with electron-withdrawing substituents on phenolate rings. Moreover, polymerization of liquid propylene catalyzed by the titanium dichloro isomeric mixture 8 afforded at 5 °C ultrahigh molecular weight atactic/isotactic polypropylene mixtures.

Plastic–plastic transition in mixtures of isotactic polypropylene and ethylene propylene diene Elastomer

The deformation behavior of unvulcanized and dynamically vulcanized mixtures of isotactic polypropylene and from 10 to 50 wt % ethylene propylene diene elastomer was studied. It was discovered that the transition from the extension with the formation and growth of the neck to the uniform straining of these materials with an increase in the concentration of elastomer is related to the change in its dispersion structure and crystalline structure of the matrix polymer upon dynamic vulcanization. It was demonstrated that the analysis of the mechanical characteristics of the systems under study within the model considerations is effective for the determination of the correlation between the structure of the material and its deformation behavior.

Study of the Pyrolysis Kinetics of a Mixture of Polyethylene, Polypropylene, and Polystyrene

The principal aim of this study was the identification of possible routes for the reaction mechanism of a plastic waste mixture pyrolysis. Kinetic studies of a mixture of equal percentages of polyethylene (PE), polypropylene (PP), and polystyrene (PS) were performed in order to analyze if the direct conversion of plastic wastes into gaseous, liquid, and solid products was favored, or if parallel reactions and/or reversible elementary steps should be considered. The experiments were carried out in a six microautoclave system. On the basis of the experimental results obtained at different temperatures and reaction times, a reaction pathway was proposed. The fitting of a kinetic model to the experimental data was performed. The models reasonably fit the results and gave a satisfactory explanation of several experimental data of thermal degradation of the plastic waste mixture tested. The kinetic parameters were estimated, and a dependence of the activation energy and of the pre-exponential factor on temperat...

Polymerization of epoxidized soybean oil with maleinized soybean oil and maleic anhydride grafted polypropylene mixtures

AbstractIn this study, maleinized soybean oil triglycerides (SOMA) were reacted with epoxidized soybean oil triglycerides (ESO) to give plant oil‐based thermoset polymers. To increase fracture toughness of the product, different amounts of SOMA was replaced by maleic anhydride grafted polypropylene (MMPP) (Epolene E43, maleate content 2.9%, Mn = 3900 and Polybond 3200, maleate content 1%, Mn = 1,10,000). The improvement in mechanical properties was monitored. The characterizations of the products were done by DMA, DSC, TGA, and IR spectroscopy. ESO‐SOMA and ESO‐SOMA‐MMPP polymers are crosslinked rigid infusible polymers. ESO‐SOMA‐MMPP(E43) and ESO‐SOMA‐MMPP(PB3200) showed a phase change at 146 and 169°C, respectively, probably due to the melting transition of the MMPP backbone. Storage moduli of the two polymers at 35°C were 54.6 and 246.1 MPa, respectively. Storage moduli and the impact strength of the polymers increased with MMPP content and with MMPP molecular weight. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Dechlorination of fuels in pyrolysis of PVC containing plastic wastes

The objective of this work is the study of several dechlorination methods devoted to reduce the chlorine content of the liquids obtained in pyrolysis of PVC containing plastic wastes. A mixture of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET) and polyvinyl chloride (PVC) has been pyrolysed in a 3.5 dm 3 semi-batch reactor at 500 °C for 30 min. Stepwise pyrolysis carried out at several temperature and time conditions, the addition of CaCO 3 for chlorine capture and a combination of both methods have been studied. Additionally, some thermogravimetric analyses have been carried out in order to establish the best conditions for PVC dehydrochlorination in the presence of other plastics. It has been proved that the application of dehydrochlorination methods plays a significant role in the characteristics of pyrolysis liquids. Stepwise pyrolysis is an effective method for reduction of the chlorine content of pyrolysis liquids; additionally, heavier hydrocarbons and lower quantity of aromatics in the liquids than in conventional pyrolysis are obtained. The addition of CaCO 3 leads to the retention of a significant amount of chlorine in the solid, but more chlorine than in a conventional run is found in the liquids, which contains a higher amount of aromatics.

Analysis and optimization of polypropylene (PP)/ethylene–propylene–diene monomer (EPDM)/scrap rubber tire (SRT) mixtures using RSM methodology

Response surface methodology (RSM) is a collection of statistical and mathematical techniques useful for developing, improving and optimizing processes. In this work, RSM was applied to the investigation of ternary mixtures of polypropylene (PP), ethylene–propylene–diene monomer (EPDM) and scrap rubber tires (SRT). After appropriate processing in a co-rotating twin extruder and injection moulding, mechanical properties, such as tensile strength and impact strength, were determined and used as response variables. Scanning electron microscopy (SEM) was also used for investigation of the morphology of the different blends and interpretation of results. With specific statistical tools, a minimum number of experiments allowed development of the response surface model and optimization of the concentrations of the components according to mechanical performance.

Effect of Particles on the Flow-Induced Crystallization of Polypropylene at Processing Speeds

The effect of particles with different diameters on flow-induced crystallization from low shear rates to processing speeds is studied using mixtures of polypropylene and zinc oxide with diameters between 35 nm and 1 μm. The nucleating efficiency of the particles was characterized by means of the Lotz efficiency scale using DSC. Flow-induced crystallization at processing speeds was studied by means of the birefringence and transmitted intensity measurements using a specially designed sliding-plate flow cell. For crystallization under quiescent conditions and after shear steps at low shear rates, there are significant differences between the kinetics of the neat polymer, the mixture with the 1 μm zinc oxide, and the mixtures with the midrange particles, which are in agreement with the nucleating efficiency of the particles. As the shear rate is increased, the crystallization kinetics of the mixtures and neat polymer become similar, independent of particle diameter. The transition to highly oriented shish-ke...

Synthesis of Early Transition Metal Bisphenolate Complexes and Their Use as Olefin Polymerization Catalysts

Bisphenolate ligands with pyridine- and benzene-diyl linkers have been synthesized and metalated with group 4 and 5 transition metals. The solid-state structures of some of the group 4 complexes have been solved. The titanium, zirconium, hafnium, and vanadium complexes were tested for propylene polymerization and ethylene/1-octene copolymerization activities with methylaluminoxane as cocatalyst. The vanadium(III) precatalyst is the most active for propylene polymerization and shows the highest 1-octene incorporation for ethylene/1-octene copolymerization. The zirconium(IV) precatalyst was the most active for propylene polymerization of the group 4 precatalysts. Titanium(IV) and zirconium(IV) precatalysts with pyridine-diyl linkers provided mixtures of isotactic and atactic polypropylene while titanium(IV) precatalysts with benzene-diyl linkers gave atactic polypropylene only. The hafnium(IV) precatalyst with a pyridine-diyl linker generated moderately isotactic polypropylene.

Dynamic Scaling and Fractal Behavior of Phase Dispersion in Multicomponent Polymer Blends

Dynamic scaling and fractal behavior of phase dispersion in a binary polymer mixture of polypropylene with poly(cis-butadiene) rubber during processing in a batch mixer was studied by means of a back small-angle laser scattering (BSALS) online system. In the late stage of phase dispersion, a special fractal behavior was found; different overlapped line groups existed simultaneously and the temporal distribution was stochastic. We defined the special behavior as quasi-self-similarity and calculated the fractal dimension, D p, by using the power spectrum method. The results show that the evolution of different fractal dimensions with time is consistent with average chord length of the dispersed phase.

Pyrolytic decomposition and model-free kinetics analysis of mixture of polypropylene (PP) and low-density polyethylene (LDPE)

Thermal decomposition behaviour of mixtures of polypropylene (PP) and low-density polyethylene (LDPE) with different weight ratios (20:80, 35:65, 50:50, 65:35, 80:20) is studied under non-isothermal conditions at five different heating rates. Presence of synergistic effect is observed for mixture samples with PP composition >40 wt.%. Formation of hydrocarbons (<C 6) and (C 6–C 10) fractions are the highest in case of (PP(65%) + LDPE(35%)). The nonlinear Vyazovkin model-free analysis is used to understand the variation of activation energy, E α with conversion, α. For almost all the mixtures, initially E α is a slow but increasing function of α and then becomes a very strong function of α towards the end of the decomposition phenomenon. E α is much lower for the mixtures (PP(50%) + LDPE(50%)), (PP(65%) + LDPE(35%)) and (PP(80%) + LDPE(20%)). The plastic mixture PP:LDPE = 65%:35% is the most preferable one during pyrolysis due to its low activation energy and formation of significantly high amount of hydrocarbons of range (≤C 10).

Chemical and ecotoxicological characterization of solid residues produced during the co-pyrolysis of plastics and pine biomass

A mixture of 70% (w/w) pine biomass and 30% (w/w) plastics (mixture of polypropylene, polyethylene, and polystyrene) was subjected to pyrolysis at 400 °C, for 15 min, with an initial pressure of 40 MPa. Part of the solid residue produced was subjected to extraction with dichloromethane (DCM). The extracted residue (residue A) and raw residue (residue B) were analyzed by weight loss combustion and submitted to the leaching test ISO/TS 21268-2 using two different leachants: DCM (0.2%, v/v) and calcium chloride (0.001 mol/L). The concentrations of the heavy metals Cd, Cr, Ni, Zn, Pb and Cu were determined in the eluates and in the two residues. The eluates were further characterized by determining their pH and the concentrations of benzene, toluene, ethylbenzene and xylenes (BTEX). The presence of other organic contaminants in the eluates was qualitatively evaluated by gas chromatography, coupled with mass spectrometry. An ecotoxicological characterization was also performed by using the bio-indicator Vibrio fischeri. The chemical and ecotoxicological results were analyzed according to the French proposal of Criteria on the Evaluation Methods of Waste Ecotoxicity (CEMWE). Residue A was not considered to be ecotoxic by the ecotoxicological criterion (EC 50 (30 min) ≥10%), but it was considered to be ecotoxic by the chemical criterion (Ni ≥ 0.5 mg/L). Residue B was considered to be ecotoxic by the ecotoxicological criterion: EC 50 (30 min) ≤ 10%. Besides that, residue B was considered to be hazardous according the European legislation (BTEX concentrations higher than 100 ppb). The results indicate that volatile organic contaminants can be present in sufficient amounts in these residues and their eluates to induce ecotoxicity levels. The extraction of the pyrolysis residue with DCM was an efficient method for removing lighter organic contaminants.

Elasticity and dynamics of particle gels in non-Newtonian melts

We investigate the relation between the structure and the viscoelastic behavior of a model polymer nanocomposite system based on a mixture of titanium dioxide (TiO2) nanoparticles and polypropylene. Above a critical volume fraction, Φ c, the elasticity of the hybrids dramatically increases, and the frequency dependence of the elastic and viscous moduli reflects the superposition of the independent responses of the suspending polymer melt and of an elastic particle network. In addition, the elasticity of the hybrids shows critical behavior around Φ c. We interpret these observations by hypothesizing the formation of a transient network, which forms due to crowding of particle clusters. Consistent with this interpretation, we find a long-time, Φ-dependent, structural relaxation, which emphasizes the transient character of the structure formed by the particle clusters. For times below this characteristic relaxation time, the elasticity of the network is Φ-independent and reminiscent of glassy behavior, with the elastic modulus, G′, scaling with frequency, ω, as G′∼ω 0.3. We expect that our analysis will be useful for understanding the behavior of other complex fluids where the elasticity of the components could be superimposed.

Influence of some additives on the performance of wood flour/polyolefin composites

AbstractThe main objective of this study was to investigate the effect of different additives, namely, maleic anhydride, alumina trihydrate (ATH), and a mixture of both on wood flour/polyolefin (50/50) composite samples. The polyolefins used were polyethylene (PE), polypropylene (PP), and a mixture of both PE and PP (50/50 w/w). The effects were studied in terms of the percentage water absorption, volumetric swelling efficiency, and mechanical and electrical properties. We found that the absorption of water and volumetric swelling were greatly retarded after 3 weeks in all of the wood flour/polyolefin composite samples containing various additives. It is also clear from the results that the mechanical properties were enhanced. The presence of ATH improved the electrical properties and enhanced the thermal stability of the wood flour composites. Generally, the PE composite samples gave better results compared to the PP ones. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Characterization of liquid products from the co-cracking of ternary and quaternary mixture of petroleum vacuum residue, polypropylene, Samla coal and Calotropis Procera

The co-cracking of the petroleum vacuum residue (XVR) with polypropylene (PP), Samla coal (SC) and Calotropis procera (CL) has been carried out in a batch reactor under isothermal conditions at atmospheric pressure. The liquids obtained by co-cracking have been characterized by Fourier transform infrared spectroscopy, high performance liquid chromatography, 1H nuclear magnetic resonance (NMR), 13C NMR, gel permeation chromatography (GPC), and inductively coupled argon plasma analyses. It was found that the liquid products obtained from the co-cracking of ternary and quaternary mixtures of the petroleum vacuum residue with polypropylene, coal and C. procera contained less than 1ppm of Ni and V. The HPLC analyses indicates that the liquids obtained from the cracking of ternary mixture of XVR+PP+CL were mainly aliphatic in nature (saturates content 87.4%). NMR analyses showed that the aromatic carbon contents decreased (15.0%) in the liquid products derived from the co-cracking of quaternary mixtures of XVR+PP+SC+CL compared to their theoretical averages (taking the averages of aromatic carbon contents of the liquids from XVR, PP, SC and CL individually). The overall results indicated that there exists a definite interaction of reactive species when XVR, PP, SC and CL were co-cracked together.

Interfacial adhesion enhancement of polyethylene–polypropylene mixtures by adding synthesized diisocyanate compatibilizers

AbstractImmiscible and incompatible binary blends of commercial polypropylene (PP)/polyethylene (PE) display poor mechanical properties. The addition of compatibilizer to reinforce and enhance an adhesion at the interfaces between PE–PP mixtures has been conducted. The compatibilizer chosen was in the group of Ziegler–Natta's PE–PP block copolymer with diisocyanate linkage. The effects of adding the compatibilizers were assessed by morphology studies, thermal analysis, and mechanical testing. DSC curves of crystallization and FTIR provided evidences to support the formation of PP/PE block copolymer. Significant improvements in the mechanical properties of 50/50 PE/PP blends containing compatibilizer have been noted. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3766–3773, 2007

Foamed and Oriented Polypropylene Films

Foamed polypropylene films that are made by extruding mixtures of polypropylene (PP) and a chemical blowing agent are described in this study. The films are prepared by a cast extrusion process, followed by machine direction orientation. This article describes the structure–property relationships of the resultant foamed PP films and the varied applications of the foamed films.

Coprocessing of Petroleum Vacuum Residue with Plastics, Coal, and Biomass and Its Synergistic Effects

Thermal decomposition of petroleum vacuum residue (XVR), polypropylene (PP), Bakelite (BL), Samla coal (SC), bagasse (BG), Calotropis procera (CL, a petrocrop), and their mixtures with petroleum residue was studied in a batch reactor under isothermal conditions at atmospheric conditions. The product distribution patterns have been determined. Kinetics of their thermal decomposition were also studied in order to compare the kinetics of cracking of individual materials with that of the mixture. Activation energy as well as rate constants have been calculated for the materials as well as their mixtures. Cocracking of a mixture of XVR, PP, and CL was found to show synergism of activation energy. The detailed results obtained are reported.

Processing and thermal, mechanical and morphological characterization of post-consumer polyolefins/thermoplastic starch blends

Mixtures of high density polyethylene (HDPE) and polypropylene (PP), both post-consumer polymers were blended with thermoplastic starch (TPS). Corn starch plastification was carried out by extrusion with glycerin addition. The behaviour of TPS produced was investigated in the processing and thermal, mechanical and morphology characterization of post-consumer HDPE/PP blends (100/0, 75/25, and 0/100 wt.%) in different proportions of TPS (30%, 40% and 50% wt.%) by melting flow index (MFI), tensile property measurements, and scanning electron microscopy (SEM), respectively. The addition of TPS reduced the MFI of PP and increased of HDPE and HDPE/PP blends. TPS also decreased the tensile strength and elongation at break, and increased the rigidity of the materials. SEM showed separation of phase between the poliolefins and TPS.

回転円錐型容器を用いた２成分混合粒子群の静電分離

In order to develop a simple electrostatic separator for solid mixtures, discharge rates of particles through orifices in each end-wall of a horizontal rotating conical vessel were measured for a binary mixture of polypropylene and polystyrene particles which were loaded in the vessel. Acrylic resin (PMMA), stainless steel and polypropylene were used as the end-wall materials of the conical vessel. The particle discharge rates were strongly dependent on the humidity of surrounding air, the electrification characteristics of particles againt end-wall materials (e. g., polarity of particle charge), and the axial segregation characteristics of particles in the vessel. The binary solid mixture with almost the same density could be separated effectively by using the both effects of the electrification and segregation of each component particles in the mixture during their cascading flow in the rotating conical vessel.

Polypropylene as a carbon source for the synthesis of multi-walled carbon nanotubes via catalytic combustion

Multi-walled carbon nanotubes (MWCNTs) were efficiently synthesized by catalytic combustion of polypropylene (PP) using nickel compounds (such as Ni 2O 3, NiO, Ni(OH) 2 and NiCO 3 · 2Ni(OH) 2) as catalysts in the presence of organic-modified montmorillonite (OMMT) at 630–830 °C. Morphologies of the sample undergoing different combustion times were observed to investigate actual process producing MWCNTs by this method. The obtained MWCNTs were characterized by X-ray diffraction (XRD), transmission electron microscope and Raman spectroscopy. The yield of MWCNTs was affected by the composition of PP mixtures with OMMT and nickel compounds and the combustion temperature. The proton acidic sites from the degraded OMMT layers due to the Hoffman reaction of the modifiers at high temperature played an important role in the catalytic degradation of PP to supply carbon sources that are easy to be catalyzed by nickel catalyst for the growth of MWCNTs. The XRD measurements demonstrated that the nickel compounds were in situ reduced into the Ni(0) state with the aid of hydrogen gas and/or hydrocarbons in the degradation products of PP, and the Ni(0) was really the active site for the growth of MWCNTs. The combination of nickel compounds with OMMT was a key factor to efficiently synthesize MWCNTs via catalytic combustion of PP.