Synthesis and characterization of polypropylene-based polymer hybrids linking poly(methyl methacrylate) and poly(2-hydroxyethyl methacrylate)

Isotactic polypropylene-based polymer hybrids linking poly(methyl methacrylate) (PMMA) and poly(2-hydroxyethyl methacrylate) (PHEMA) were successfully synthesized by a graft copolymerization from maleic anhydride-modified polypropylene (PP-MAH). PP-MAH reacted with ethanolamine to produce a hydroxyl group containing polypropylene (PP-OH) and the thus obtained PP-OH was treated with 2-bromoisobutyryl bromide and converted to a 2-bromoisobutyryl group containing polypropylene (PP-Br). The metal-catalyzed radical polymerization of MMA with PP-Br was performed using a copper catalyst system in o-xylene solution at 100 °C to give the PP-based polymer hybrids linking PMMA segments (PP-PMMA hybrids). Thus obtained PP-PMMA hybrids demonstrated higher melting temperature than PP-Br and microphase-separation morphology at the nanometer level owing to the chemical linkage between both segments. On the other hand, the polymer hybrids linking PHEMA segment (PP-PHEMA hybrids) were also obtained by the radical polymerization of HEMA with PP-Br in o-xylene slurry at 25 °C. TEM observation suggested that the polymerization mainly initiated on the surface of the PP-Br powder, led to the peculiar core-shell-like morphology. These PP-PHEMA hybrid powders showed a good affinity with water due to the hydrophilicity of the PHEMA segments.     

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.     

Influence of miscibility on the morphology and properties of polycarbonate/(maleic anhydride)-grafted-polypropylene blend

Maleic-anhydride-grafted polypropylene (MAH-g-PP) was added to polycarbonate (PC) as a processing agent. Its influence on the morphological, thermal, rheological, and mechanical properties of PC/MAH-g-PP blends was investigated by differential scanning calorimetry (DSC), dynamic mechanical spectroscopy (DMS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), dynamic contact angle goniometry, and tensile and impact strength experiments. The results indicated that the processability and miscibility of the blends were improved significantly by addition of 5–20 wt% MAH-g-PP to PC. The melting temperature of MAH-g-PP increased as the relative composition of MAH-g-PP in the blends increased mainly because of enlargement of the crystallite size. The DSC, FTIR as well as SEM results strongly suggested that a chemical reaction might have taken place between the PC and MAH-g-PP. This chemical reaction could have contributed to the improvement of the mechanical properties of the blends and the miscibility between the PC and MAH-g-PP components.     

Synthesis and hydrophilic property of polypropylene-graft-poly(polyethylene glycol-methacrylate) (PP-g-P(PEGMA))

Polypropylene-graft-poly(polyethylene glycol-methacrylate) (PP-g-P(PEGMA)), which is a hydrophobic-hydrophilic graft copolymer, was synthesized by a combination of an atom transfer radical polymerization (ATRP) of PEGMA with brominated polypropylene (PP-Br), which was synthesized from PP-OH prepared by metallocene-catalyzed copolymerization. Its structure was confirmed by ¹H NMR and GPC analyses. Transmission electron microscope (TEM) micrographs of PP-g-P(PEGMA) revealed the nanometer level microphase-separation morphology between the PP segment and the P(PEGMA) segment. The obtained PP-g-P(PEGMA) showed water-absorbing property as well as thermostability.     

Mechanical behavior of CaCO3 particulate-filled β-crystalline phase polypropylene composites

β-crystalline phase polypropylene (PP) composites containing 5, 10, 20, 30, and 40% (by weight) of CaCO₃ filler were prepared by injection molding. The β-form PP was produced by adding a bicomponent β-nucleator consisting of equal amounts of pimelic acid and calcium stearate. The morphology, static tensile, and impact properties of these composites were investigated in this study. Scanning electron microscopy (SEM) observations revealed that the β-spherulites of the polymer matrix of the composites exhibit curved lamellae and sheaf-like structures. The fillers were observed to disperse within the inter-lamellar spacings of the β-PP composite containing 10% calcium carbonate addition. However, the filler particles tend to link together to form larger aggregates when the filler content reaches 20%. Static tensile measurements showed that the elastic modulus of the composites increases with increasing filler content but the yield strength decreases with increasing filler addition. The falling weight Charpy impact test indicated that the β-PP polymer exhibits the highest critical strain energy release rate (G_c) value. However, there was a drastic drop in G_c of the β-PP composites with increasing filler content. The results are discussed and explained in terms of materials morphology.     

Polypropylene microfibers via solution electrospinning under ambient conditions

Uniform beadless fibers of chlorinated polypropylene (PP-Cl) are prepared by electrospinning of PP-Cl solutions in tetrahydrofuran at different concentrations, feed rates, applied voltages, and tip-to-collector distances (TCDs) under ambient conditions for the first time. Average fiber diameter and morphology of the electrospun PP-Cl fibers are determined by scanning electron microscopy. On the other hand, the wettability of the fibers is examined by water contact angle (WCA) measurements. Furthermore, thermal behavior of fibers is investigated by differential scanning calorimetry and thermogravimetric analyses, respectively. Obtained results show that the higher concentrations and feed rates of polymer solutions not only enhance the average diameter of the electrospun fibers ranging from 2.2 ± 0.5 to 2.8 ± 0.3 μm but improve the hydrophobicity of the fiber surfaces from 128° ± 1.1 to 141° ± 1.0 as well. On the other hand, when applied voltage is increased or TCD is decreased, diameters of achieved fibers are enhanced. It is suggested that PP-Cl is an useful material for solution electrospinning process at under ambient conditions, exhibiting great scientific merit and good industrial expectation in the potential PP applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48199.     

New hydrophilic polypropylene membranes; fabrication and evaluation

This article discusses a new method to prepare polypropylene membrane that has hydrophilic surfaces and asymmetric porous structure. This membrane is based on a newly developed hydroxylated polypropylene (PP-OH), which has a “brushlike” microstructure, high molecular weight, high melting point, and relatively high concentration of hydroxy groups. Under the leaching process conditions, various asymmetric hydrophilic PP/PP-OH membranes are prepared with controllable pore structures. The PP-OH polymer becomes the surface modifier of asymmetric PP membrane with flexible functional groups located on the membrane surfaces, including pore surfaces. This new hydrophilic PP/PP-OH membrane is useful in ultrafiltration, not only offering good selectivity and flux but also showing excellence in antifouling property. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 567–575, 1997     

Synthesis and characterization of a macromolecular surface modifier for polypropylene

A novel macromolecular surface modifier, a polypropylene‐graft‐poly(butyl methylacrylate) copolymer, was synthesized through the coupling of polypropylene containing maleic anhydride with monohydroxyl‐terminated poly(butyl methylacrylate). The effects of the raw ratio, reaction temperature, and molecular weight of the branches on the graft reaction were studied. The graft copolymers were characterized with IR, ¹H‐NMR, thermogravimetry, and differential scanning calorimetry. The results of attenuated total reflection/Fourier transform infrared and contact‐angle measurements indicated that polypropylene‐graft‐poly(butyl methylacrylate) could diffuse preferably onto the surface and be used as a surface modifier for polypropylene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3413–3419, 2006     

Compatibility effect of reactive copolymers on polypropylene/polyamide 6 blends from commingled plastic wastes

We report the compatibility effect on a recycled polypropylene/nylon (75/25) blend processed with reactive copolymers on the basis of morphological, mechanical, and rheological characteristics. Via a scanning electron microscopy investigation, we found improved surface morphologies with regular and fine domains in a recycled polypropylene/nylon (75/25) blend compatibilized with copolymers containing maleic anhydride as a reactive functional group [styrene–(ethylene/butylene)–styrene‐graft‐maleic anhydride copolymer and polypropylene‐graft‐maleic anhydride]. Large increases in both the mechanical and rheological properties with the addition of the styrene–(ethylene/butylene)–styrene‐graft‐maleic anhydride copolymer could be interpreted with respect to a specific structure at the interface, showing a strong interfacial adhesion between recycled polypropylene and nylon. To confirm the existence of this structure, we used various dynamic rheological parameters: the Cox–Merz rule, storage modulus, and phase angle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1188–1193, 2006     

Effect of polyhedral oligomeric silsesquioxane on water sorption and surface property of Bis‐GMA/TEGDMa composites

2,2‐Bis[4‐(2‐hydroxy‐3‐methacryloxypropoxy)phenyl]propane (Bis‐GMA), one of the most important light‐curable dimethacrylate resins, is widely used as dental restorative material. However, one problem of Bis‐GMA is the high water sorption due to the hydrophilic hydroxyl (–OH) group, resulting in a short life in actual application. In this study, to overcome the drawback stated above, novel organic–inorganic dimethacrylate monomer containing polyhedral oligomeric silsesquioxanes (POSS), Bis‐GMA‐graft‐POSS, is synthesized via the nucleophilic addition reaction of isocyanate functionalized POSS (IPOSS) and pendent hydroxyl group of Bis‐GMA. Then the as‐synthesized Bis‐GMA‐graft‐POSS, of which hydroxyl group was substituted by hydrophobic POSS, is also introduced into the Bis‐GMA/TEGDMA matrix to prepare a series of methacrylate‐based hybrids for dental materials under visible light with camphorquinone and ethyl‐4N,N‐dimethy‐laminobenzoae (EDMAB) as initiator and coinitiator, respectively. Compared to Bis‐GMA/TEGDMA composites, water sorption of modified composites can be significantly reduced with the addition of Bis‐GMA‐graft‐POSS. Moreover, the Bis‐GMA/TEGDMA/POSS hybrids show hydrophobic surfaces, leading to much higher water contact angles than that of Bis‐GMA/TEGDMA composites. The morphology of hybrids containing POSS was furthermore studied by X‐ray diffraction (XRD) analysis and X‐ray photoelectron spectroscopy (XPS). The results show that POSS disperses in the matrix in noncrystalline form and tend to migrate to the surface of the modified composites that lead to the lower water sorption and higher water contact angles. These results are very useful for design of novel methacrylate monomers and clinical application. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Novel strategy for ternary polymer blend compatibilization

A novel strategy for compatibilization of ternary polymer blends was described. PP (polyolefins)/PA6 (engineering plastics)/PS (styrene polymers) was selected as a model ternary blend system, and the compatibilization effect was investigated by means of SEM, rheometer, dynamic mechanical thermal analysis and mechanical testing. The results indicated that, as a ternary polymer blend compatibilizer, styrene and maleic anhydride dual monomers melt grafted polypropylene [PP-g-(MAH-co-St)] showed more effective compatibilization in the PP/PA6/PS ternary blend system than PP-g-MAH, PP-g-St and their mixture. The good compatibilizing effect of PP-g-(MAH-co-St) can be explained by two mechanisms. One is the in situ formation of [PP-g-(MAH-co-St)]-g-PA6 copolymer at the PP/PA6 interface, and the other is that it also contains styrene blocks, resulting in chemical affinity with PS and PP homopolymers.     

Non-isothermal crystallization kinetics of calcium carbonate-filled β-crystalline phase polypropylene composites

The non-isothermal crystallization behaviour of high purity β-phase and α-phase polypropylene (PP) and their calcium carbonate-filled composites was investigated by means of differential scanning calorimetry. High purity β-PP polymer was prepared by adding an effective β-nucleator consisting of equal amounts of pimelic acid and calcium stearate. The crystallization temperature and crystallization rate coefficient of pure β-PP polymer were considerably higher than those of the α-PP polymer. This was due to the β-PP polymer containing nucleating agents, which act as nuclei for β-spherulites. The calcium carbonate content had little or no effect on the crystallization rate coefficient and Ozawa exponent of the β-phase PP in the composites. On the other hand, the crystallization temperature, crystallization rate coefficient and Ozawa exponent of the α-phase PP composites depended on the calcium carbonate loading. The effect of calcium carbonate additions on the crystallization of α-PP and β-PP is discussed. ©1997 SCI     

Synthesis of polypropylene graft copolymers from a hydroxyl‐groups‐containing polypropylene precursor via atom‐transfer radical polymerization

Isotactic polypropylene graft copolymers, isotactic[polypropylene‐graft‐poly(methyl methacrylate)] (i‐PP‐g‐PMMA) and isotactic[polypropylene‐graft‐polystyrene] (i‐PP‐g‐PS), were prepared by atom‐transfer radical polymerization (ATRP) using a 2‐bromopropionic ester macro‐initiator from functional polypropylene‐containing hydroxyl groups. This kind of functionalized propylene can be obtained by copolymerization of propylene and borane monomer using isospecific MgCl₂‐supported TiCl₄ as catalyst. Both the graft density and the molecular weights of i‐PP‐based graft copolymers were controlled by changing the hydroxyl group contents of functionalized polypropylene and the amount of monomer used in the grafting reaction. The effect of i‐PP‐g‐PS graft copolymer on PP‐PS blends and that of i‐PP‐g‐PMMA graft copolymer on PP‐PMMA blends were studied by scanning electron microscopy. Copyright © 2006 Society of Chemical Industry     

Melt rheological properties of polypropylene–wood flour composites

This article presents study of melt rheological properties of composites of polypropylene (i-PP) filled with wood flour (WF), at filler concentrations of 3–20 wt%. Results illustrate the effects of (i) filler concentration and (ii) shear stress or shear rates on melt viscosity and melt elasticity properties of the composites. Incorporation of WF into i-PP results in an increase of its melt viscosity and a decrease of melt elasticity such as die swell and first normal stress differences; these properties, however, depend on filler concentration. Processing temperature of the filled i-PP increases as compared to the nonfilled polymer.     

γ‐Irradiation effects on the thermal and structural characteristics of modified,grafted polypropylene

The effects of both the degree of grafting and γ irradiation on the thermal stability and structural characteristic of polypropylene‐graft‐polyvinylpyrrolidone and polypropylene‐graft‐polyvinylpyrrolidone modified with α‐cyano‐δ‐(2‐thienyl) crotononitrile were investigated. The employed techniques were thermogravimetric analysis, differential thermogravimetry, and X‐ray diffraction. The thermal stability of various polymeric substrates was investigated through the determination of the degradation temperature and activation energy of degradation. The effects of different parameters on the structural characteristics of different films were investigated through the determination of possible changes in the degree of ordering of the polymeric substrates. The results revealed that the thermal stability of the trunk polymer, grafted polymer, and polymer modified by α‐cyano‐δ‐(2‐thienyl) crotononitrile increased progressively with an increasing degree of grafting. The increase was, however, more pronounced for the sample undergoing the lowest degree of grafting. The activation energy of the thermal degradation process remained almost unchanged, and this indicated that the degradation processes of the different films followed almost the same mechanism. The γ irradiation at a dose of 60 kGy of the sulfur‐treated polymeric films [i.e., the polymeric films treated with α‐cyano‐δ‐(2‐thienyl) crotononitrile] reduced their thermal stability. This conclusion was reached by the consideration of the changes observed in the pre‐exponential factor of the Arrhenius equation due to different chemical and γ‐irradiation treatments. The degree of ordering, evidenced by X‐ray diffraction measurements of the trunk polymer, grafted polymer, and modified polymer, suffered a significant drop. This drop was much more pronounced for the sulfur‐containing polymeric materials. The observed drop in the degree of ordering of the polymeric substrates was taken as a measure of the structure collapse due to a certain treatment (degree of grafting and sulfur inclusion). The γ irradiation of the sulfur‐containing polymeric materials greatly increased their degree of ordering, which reached a value greater than that measured for the trunk polymer. Therefore, it was concluded that the thermal stability increased as the degree of ordering decreased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 506–515, 2006     

Evaluation of interfacial compatibility in wood flour/polypropylene composites by grafting isocyanate silane coupling agent on polypropylene

In this paper, the polypropylene was functionalized by isocyanate silane coupling agent grafted polypropylene (IS-g-PP), various characterization methods were conducted to evaluate the interfacial compatibility of WF/PP. The results indicated that IS-g-PP remarkably enhanced the interfacial adhesion between WF and PP with improved mechanical property, tensile strength was improved by 96.1%, and flexural strength was also increased apparently. According to the DSC results, the crystallization temperature of PP was decreased due to its enhanced interfacial adhesion. Most importantly, the use of IS-g-PP reinforced the storage modulus, loss modulus, and complex viscosity of WF/PP. These results demonstrated that IS-g-PP enhanced the interfacial interaction, and the mobility of PP chain was restrained, and was further confirmed by SEM analysis.     

Functionalization of Isotactic Polypropylene with Citraconic Anhydride

Summary Functionalization of isotactic polypropylene i-PP) with citraconic anhydride (CA) was carried out in 1,2,4-trichlorobenzene solution with dicumyl peroxide as an initiator at 160 °C under nitrogen atmosphere.atmosphere. Chemical and physical structures and thermal behavior of the synthesized graft copolymers with different anhydride units were determined by volumetric titration (acid number), FTIR and ¹H-NMR spectroscopy, X-ray powder diffraction, DSC and TGA thermal analyses. It was shown that the crystallinity and thermal behavior of grafted i-PP’s depend on anhydride unit concentration in grafted i-PP; grafting reaction proceeds selectively which is not accompanied by oligomerization of CA and degradation main chain as in known maleic anhydride/PP system. This fact was explained by inhibition effect of α-methyl group in CA grafted unit on the chain β-scission reactions and no homopolymerization of CA in chosen grafting conditions. Functionalized i-PPs showed high thermal stability in comparison with virgin i-PP.     

Open-pore morphology of i-PP copolymer crystallized from a gel state in supercritical propane

Open-pore morphology was produced in low-density polypropylene (i-PP) by first crosslinking the i-PP and then crystallizing it from a highly swollen state in supercritical propane. The extent of crosslinking, expressed by an increasing gel fraction and an increasing compression modulus, was found to have a strong effect on pore size but less so on crystal structure. The resulting pore structure, studied using scanning electron microscopy, showed a decrease in pore size with an increase in gel fraction. Typical pore sizes are between 1 and 10 μm. The polymer morphology in the wall, analyzed using wide-angle X-ray diffraction, indicated the presence of α-PP crystals. The experimental results showed that mostly loose chains (sol fraction) contribute to the crystallinity of the polymer. For our specific i-PP, the crosslinked network devoid of sol fraction (after extraction) collapses during cooling and does not produce any open pore structure.     

Structural development and mechanical properties on immiscible and miscible blends from isotactic polypropylene and ethylene-1-hexene copolymers under uniaxial drawing

Isotactic polypropylene and ethylene-1-hexene copolymers containing 32 and 57 mol% of 1-hexene copolymers blends (i-PP/EH32 and i-PP/EH57) were prepared by solution blending, precipitating followed by drying and hot pressing. The two blends were subject to investigation on structure and mechanical properties of these blends under uniaxial drawing. The i-PP/EH32 and i-PP/EH57 represented the immiscible and miscible blends, respectively. The tensile stresses and strains at breaking point of i-PP/EH57 were remarkably higher than those of i-PP/EH32 at room temperature. From wide-angle X-ray diffraction (WAXD) measurement, it was observed that the orientation of crystallites occurred early and then propagated gradually up to about drawing ratio 8 because chains of EH57 copolymer were incorporated into the amorphous regions between lamellae of i-PP. In the WAXD patterns of i-PP/EH57, the oriented spot reflections coexsisted with unoriented ring reflections up to draw ratio higher than in pure i-PP. On the other hand, the two-phase structure was observed from TEM and AFM in i-PP/EH32, and on the drawing, separation at the interface between two-phase was observed in i-PP/EH32 even at the low strain.     

Biologically active polymers. IV. Synthesis and antimicrobial activity of polymers containing 8‐hydroxyquinoline moiety

Polymers containing 8‐hydroxyquinoline moiety were prepared. Modifications of the base polymer of glycidyl methacrylate were carried out in order to introduce chloromethyl groups, either by the hydrolysis of the poly(glycidyl methacrylate) and the chloroacetylation of the hydrolyzed polymer by the reaction with chloroacetyl chloride or by aminating the poly(glycidyl methacrylate) either with ethylenediamine or with hexamethylenediamine, followed by reacting the aminated polymers with chloroacetyl chloride. The polymers containing 8‐hydroxyquinoline moiety were prepared by reacting the chloromethyl groups containing polymers with potassium salt of 8‐hydroxy quinoline. The antimicrobial activity of the polymers obtained was examined against gram‐negative bacteria (Escherichia coli) and gram‐positive bacteria (Bacillus subtilus) as well as the fungus Trichophyton rubrum. Generally, all three polymers proved effective against the tested microorganisms, but growth inhibitory effects varied from one another. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1364–1374, 2001