Polypropylene Graft Copolymers Research Articles

Polyolefin graft copolymers through a ring-opening metathesis grafting through approach

A series of polyethylene-g-atactic polypropylene graft copolymers were synthesized by grafting through copolymerization of a cyclooctene terminated aPP macromonomer with cyclooctene monomer and subsequent hydrogenation.

Detailed analysis on thermal, microstructural, mechanical, and morphological features of side chain liquid crystalline polymer/isotactic polypropylene graft copolymers: Effect of grafted and ungrafted polymer units

AbstractThe main scope of this comprehensive study is to investigate the effects of poly(p‐benzophenoneoxycarbonylphenyl acrylate), poly(BPOCPA), which presenting as only graft units or both graft and ungrafted units in the matrix, on the fundamental features of isotactic polypropylene (IPP). The graft copolymerization of BPOCPA onto IPP was performed with the aid of bulk melt polymerization at varying monomer content levels ranging from 5% to 40%. The thermal behavior, crystal quality, mechanical performance, and surface morphology of the samples were investigated by means of differential scanning calorimeter, X‐ray diffractometer (XRD), universal mechanical test, and scanning electron microscope (SEM) techniques. Thermal analyses depicted that there existed the noteworthy enhancements in both crystalline melting temperatures and percent crystallinities of matrix polymers. Furthermore, according to XRD results, a and b parameters increased significantly at low percentages of the graft units, while the parameter c decreased in all products in consistence with the content. As for the mechanical characterization, the grafting led to remarkable improvements in modulus, tensile and impact strength of the products. SEM micrographs indicated that the samples were completely homogeneous without any phase separation and the products exhibited brittle nature with some ductility.

Dynamically vulcanized elastoplastics based on the technologically compatible random polypropylene and butadiene-nitrile rubber

The basic physicomechanical properties of dynamically vulcanized elastoplastics based on random polypropylene and nitrile butadiene rubber are considered. It is shown that the higher the concentration of nitrile groups in the nitrile-butadiene rubber, the higher the limiting concentration of the elastomer to appear rubber-like properties in elastoplastics. In order to improve the compatibility of the components of the mixture, a graft copolymer of polypropylene with methacrylic acid was used as a compatibilizer. In contrast to sulfuric vulcanization, peroxide one contributes to a signifi cant deterioration of the melt fl ow index of elastoplastics.

Design of a super‐ductile polypropylene/polycarbonate blend with high heat resistance by using reactive plasticizer

AbstractHigh‐performance blend of polypropylene (PP) and polycarbonate (PC) has not been explored. The difficulty is caused by the big differences in melt viscosity (PP: low viscosity vs. PC: high viscosity) and polarity (PP: nonpolar vs. PC: polar). We put forth a new approach using a reactive plasticizer which is preferentially soluble with PC and polymerizable by organic peroxide. As the plasticizer, diallyl phthalate and triallyl cyanurate (TAC) were used. By reactive extrusion of PP/PC/plasticizer/dicumyl peroxide (e.g., 80/14/6/0.12 wt. ratio), reaction‐induced phase decomposition took place in the dispersed PC particles to develop a regularly phase‐separated nanostructure and the graft copolymer of PP and polymerized plasticizer was in situ generated at the interface. The extruded blend showed an excellent ductile behavior with about 500%‐elongation at break. TAC was very effective to elevate the heat resistance. Then, a super‐ductile PP/PC blend with high heat resistance was successfully developed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Preparation and Chemical Structure of RIC of PP/ Modified PA66 <i>In Situ</i> Microfibrillar Composite

Reactive interface combination agent (RIC) was synthesized by using reaction mixture technique starting from polypropylene（PP）, ethylene-propylene or butadiene-styrene elastomer, epoxy compound and monomer-assisted in the presence of a free radical initiator. The chemical structure of the RICs and the effects of change in the ratio of raw material during its preparation on constitute and structure was investigated using fractional extraction and infrared spectroscopy. The prepared RICs consisted of unreacted PP and/or elastomers, homo-and/or copolymerization of monomer, and graft copolymer of PP and elastomers, and crosslinked copolymer of PP and/or elastomers in conjunction with polymer bridge chains derived from monomer.

Reactive blending of polypropylene and butadiene-acrylonitrile elastomer

Graft copolymer of polypropylene and butadiene-acrylonitrile random copolymer was prepared by reactive polymer blending in a melt without solvents. The process was performed by preliminary grafting of maleic anhydride groups to polypropylene and of isocyanate groups to butadiene-acrylonitrile copolymer, followed by blending of the modified polymers. The chemical reactions occurring in the process and the fraction composition of the copolymer were studied.

Real time assessment of the compatibilization of polypropylene/polyamide 6 blends during extrusion

The reactivity of maleic anhydride and acrylic acid polypropylene graft copolymers with amine groups and their effect in the compatibilization of polymer blends was analyzed in real time during the reactive processing of compatilized polypropylene/polyamide 6 (PP/PA6) blends. The presence of compatibilizers in the blend produces a block copolymer PP-PA6, which stays in the blends interface, lowering the interfacial tension and reducing the PA6 particle size, affecting the light extinction phenomena. The in-line optical detector is able to indirectly quantify the conversion of the compatibilization reaction of the blends. The signal intensity of the detector increases with the increase of the PA6 content due to the increase in the number of particles. Quantitative off-line FTIR analyses of the compatibilized blends have shown that the amount of block copolymer formed when polypropylene grafted with acrylic acid (PP-g-AA) is used as compatibilizer increases with its content in the blend. There is a good correlation between the in-line optical measurement and the off-line amidic bond content formed. Non-reacted compatibilizers are always present in the reactive blends whose content is proportional to its initial concentration. The PA6 particle size data obtained from scanning electron microscopy analysis showed good correlation with the in-line measurements. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers

Catalytic synthesis and characterization of well-defined polypropylene graft copolymers

Abstract Isotactic polypropylene graft copolymers including isotactic-polypropylene- graft -polystyrene (PP- g -PS) and isotactic-polypropylene- graft -poly(methyl methacrylate) (PP- g -PMMA) were prepared by atom transfer radical polymerization (ATRP) initiated by hydrochlorinated polypropylene (PP-Cl), a macroinitiator synthesized from pendant vinylbenzene group-containing functional polypropylene. The functional polypropylene was formed by copolymerization of propylene and 4-(3-butenyl)styrene (4BuSt) upon the addition of hydrogen using a rac -Me 2 Si[2-Me-4-naph(Ind)] 2 ZrCl 2 /MAO catalytic system. The PP- g -PS and PP- g -PMMA copolymers were obtained and characterized with proton nuclear magnetic resonance ( 1 H NMR), differential scanning calorimetry (DSC), and high-temperature gel permeation chromatography (GPC) etc.

Influence of Adjustable Grafted Side Chains on the Non-Isothermal Crystallisation of a Ternary-Monomer Solid Phase Graft Copolymer of Polypropylene

A solid phase graft copolymer with an adjustable structure was prepared by grafting maleic anhydride, methyl methacrylate and butyl acrylate onto polypropylene (PP). How the grafted side chains affected the crystallisation of the graft copolymer was studied by differential scanning calorimetry and polarised optical micrographs. Results show that the grafted side chains not only promoted heterogeneous nucleation but also hindered the whole crystal growth of the copolymers. The Jeziorny method and Mo method were successful in describing the non-isothermal crystallisation kinetics. The Jeziorny method showed that the Avrami exponent ranged from 2 to 3, indicating that the crystal tended to grow in a three-dimensional mode. The Mo method showed that the graft copolymer (known here as PPTM) needed a lower crystallisation rate than PP to attain the same crystallinity at unit time, due to the hetero-nucleation of the grafted side chains. Meanwhile, the hetero-nucleation of the grafted side chains caused a decrease in the crystallisation half-time and in the spherulite size of PPTM. Hindrance of the grafted side chains was shown by the incomplete crystallisation images and by the increase in the non-isothermal crystallisation activation energy of PPTM.

Investigation on preparation and property of nano‐CaCO3/PP masterbatch modified by reactive monomers

AbstractNano‐CaCO3/polypropylene (PP) masterbatch containing above 80 wt % nano‐CaCO3 was prepared by nano‐CaCO3 coated PP modified by reactive monomers. The chemical interaction, crystallization and melting behavior, thermal stability, morphology, and surface contact angle of masterbatch were investigated with IR, DSC, TEM, TGA, ESCA, and surface contact angle. The results indicated that nano‐CaCO3 was coated by PP graft copolymers in the masterbatch modified by reactive monomers. The graft ratio and crystallization and melting behavior of PP in the masterbatch depended on the type and content of reactive monomer. The crystallization temperatures of masterbatch modified by reactive monomer is methyl methacrylate > butyl acrylate > methyl acrylate ≈ mixture of acrylic acid and styrene > unmodified ≈ maleic anhydride ≈ acrylic acid > styrene. Modification by reactive monomer increased the thermal stability and surface contact angle of masterbatch. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3907–3914, 2006

Design and synthesis of structurally well-defined functional polypropylenes via transition metal-mediated olefin polymerization chemistry

Functionalization of polyolefins is an industrially important yet scientifically challenging research subject. This paper summarizes our recent effort to access structurally well-defined functional polypropylenes via transition metal-mediated olefin polymerization. In one approach, polypropylenes containing side chain functional groups of controlled concentrations were obtained by Ziegler-Natta-catalyzed copolymerization of propylene in combination with either living anionic or controlled radical polymerization of polar monomers. The copolymerization of propylene with 1,4-divinylbenzene using an isospecific MgCl2-supported TiCl4 catalyst yielded polypropylenes containing pendant styrene moieties. Both metalation reaction with n-butyllithium and hydrochlorination reaction with dry hydrogen chloride selectively and quantitatively occurred at the pendant reactive sites, generating polymeric benzyllithium and 1-chloroethylbenzene species. These species initiated living anionic polymerization of styrene (S) and atom transfer radical polymerization (in the presence of CuCl and pentamethyldiethylenetriamine) of methyl methacrylate (MMA), respectively, resulting in functional polypropylene graft copolymers (PP-g-PS and PP-g-PMMA) with controllable graft lengths. In another approach, chain end-functionalized polypropylenes containing a terminal OH-group with controlled molecular weights were directly prepared by propylene polymerization with a metallocene catalyst through a selective aluminum chain transfer reaction. Both approaches proved to be desirable polyolefin functionalization routes in terms of efficiency and polymer structure controllability.

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

AbstractIsotactic 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

Rheological properties of maleated natural rubber/polypropylene blends with phenolic modified polypropylene and polypropylene- g-maleic anhydride compatibilizers

Maleated natural rubber was prepared using natural rubber (air-dried sheet) and maleic anhydride by a melt mixing process under high shearing action. Two types of blend compatibilizers: graft copolymer of polypropylene and maleic anhydride (PP- g-MA), and phenolic modified polypropylene (Ph-PP) were also synthesized in a molten state. The 60/40 MNR/PP blends were later prepared by a melt mixing process using PP- g-MA and Ph-PP at various loading levels of 3, 5, 10, 15 and 20 wt% of PP. Shear flow properties of the blends were later characterized. We found that the apparent shear stress and shear viscosity increased with an increase in apparent shear rate over a range of loading levels of compatibilizers of 0–5%. This may be attributed to the chemical interaction between different phases of the blend caused by compatibilizers. They consist of segments chemically reactive to their respective counterparts in the polymer pairs. The increase in chemical interaction between the interface caused an improvement of interfacial tension and led to decreasing size of dispersed domains of the minor phase (PP) in the MNR matrix. Increasing loading level of compatibilizers higher than 5 wt% caused a decreasing trend of the flow properties. This may be attributed to the formation of micelles dispersed in the MNR matrix. Therefore, the apparent shear stress and shear viscosity decreased because the micelles act as a lubricant in the polymer melt flow. The log additive rules was applied to the flow properties and it was found that the 60/40 MNR/PP blends with PP- g-MA and Ph-PP compatibilizers indicated positive deviation blends. That is, the blends were partially compatible blends. The power law equation was also applied to the shear flow properties. We found that at a loading level of compatibilizers of 5 wt%, the lowest n value was observed. This indicates the highest pseudoplasticity of the polymer melts.

Synthesis of polypropylene graft copolymers by the combination of a polypropylene copolymer containing pendant vinylbenzene groups and atom transfer radical polymerization

AbstractThis article discusses a facile and inexpensive reaction process for preparing polypropylene‐based graft copolymers containing an isotactic polypropylene (i‐PP) main chain and several functional polymer side chains. The chemistry involves an i‐PP polymer precursor containing several pendant vinylbenzene groups, which is prepared through the Ziegler–Natta copolymerization of propylene and 1,4‐divinylbenzene mediated by an isospecific MgCl2‐supported TiCl4 catalyst. The selective monoenchainment of 1,4‐divinylbenzene comonomers results in pendant vinylbenzene groups quantitatively transformed into benzyl halides by hydrochlorination. In the presence of CuCl/pentamethyldiethylenetriamine, the in situ formed, multifunctional, polymeric atom transfer radical polymerization initiators carry out graft‐from polymerization through controlled radical polymerization. Some i‐PP‐based graft copolymers, including poly(propylene‐g‐methyl methacrylate) and poly(propylene‐g‐styrene), have been prepared with controlled compositions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 429–437, 2005

A novel reactive extrusion process for compatibilizing immiscible polymer blends

A novel reactive extrusion process was developed to obtain compatibilized A/B immiscible polymer blends. It consisted of polymerizing a monomer of polymer A in the presence of polymer B. A fraction of polymer B chains bore initiating sites either at the chain end(s) or along the chain backbones, from which polymer A chains could grow. In the process, polymer A and a graft or block copolymer of A and B were formed simultaneously leading to in situ polymerized and in situ compatibilized A/B polymer blends. This paper shows the feasibility of this novel process in a batch mixer using polypropylene (PP) and polyamide 6 (PA 6) blends as an example. Specifically, ε-caprolactam (ε-CL) was polymerized anionically in the presence of PP. A fraction of the PP chains bore 3-isopropenyl-α,α-dimethylbenzene isocyanate (TMI) which acted as growing centers to initiate PA 6 chain growth from the PP chains and to form a graft copolymer of PP and PA 6.

Well-Defined Polystyrene Grafted to Polypropylene Backbone by “Living” Radical Polymerization with TEMPO

A stable free radical (2,2,6,6-tertamethylpiperidinyl-1-oxy, TEMPO) polymerization technique was applied to a graft polymerization of styrene (ST) to polypropylene (PP). PP peroxides produced by γ-irradiation (7.2, 12, and 35 kGy) in air were used as macromolecular initiators for grafting. Grafted polystyrene (PSgraft) was cleaved from the main PP chain by reaction with trifluoroacetic acid. The molecular weight (Mn) and polydispersity of the PSgraft and the free (nongrafted) polystyrene (PSfree) were determined by GPC. These PS's have almost the same Mn (nearly theoretical Mn) and narrow polydispersity. Nitroxide-terminated PS grafted to the PP was chain extended by sequential activation of the dormant chain ends in the presence of additional ST monomer. The polydispersity of the extended PSgraft remained narrow. A controlled random graft copolymer of PP with ST and n-butyl methacrylate was also synthesized using this technique.

Synthesis and characterization of solid‐phase graft copolymer of polypropylene with styrene and maleic anhydride

Polypropylene (PP) was modified by solid-phase graft copolymerization with maleic anhydride (MAH) and styrene (St), using benzoyl peroxide as the initiator and xylene as the interfacial agent. Effects of various factors such as monomer concentration, monomer ratio, initiator concentration on grafting percentage, and acid value were investigated. The graft copolymer was characterized by Fourier transform infrared, pyrolysis gas chromatography—mass spectroscopy, and dynamic mechanical analysis, and the intrinsic viscosity of the extractive from the reaction product was investigated. The results showed that the grafting percentage and acid value of the graft copolymer of PP with two monomers (MAH and St) were considerably higher than those of the graft copolymer of PP with MAH alone. The graft segments were shown to be the copolymer of St and MAH with a substantial molecular weight. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2482–2487, 2000

Toughened polypropylene with balanced rigidity (I): preparation and chemical structure of toughening master batch

The title toughening master batch (TMB) was synthesized in a low-viscosity reaction system by using dynamic vulcanization technique starting from polypropylene (PP) as the matrix resin and ethylene–propylene or butadiene–styrene elastomer as the toughening agent through a polymer–bridge conjunction derived from a monomer containing a carbonate group in the presence of a free radical initiator. The chemical structure of the TMBs and the effects of technological conditions on structural parameters were investigated using fractional extraction and infrared spectroscopy. The prepared TMBs consisted of unreacted PP, unreacted elastomers, graft copolymer of PP and/or elastomers containing branched chains formed by bridging agent, and crosslinked copolymer of PP and/or elastomers in conjunction with polymer bridge chains derived from bridging agent. Results showed that the PP existed in graft and crosslinked forms was in the range of 3–21 wt% and that of the elastomer toughening agent was in the range of 50–70 wt%, grafting and bridging efficiency of bridging agent was in the range of 62–88 wt%, graft copolymer content in the total TMB was in the range of 0.18–3.65 wt% and crosslinked copolymer content was in the range of 22–42 wt%. Copyright © 2000 John Wiley & Sons, Ltd.

Synthesis and characterization of solid-phase graft copolymer of polypropylene with styrene and maleic anhydride

Synthesis and characterization of solid-phase graft copolymer of polypropylene with styrene and maleic anhydride

Reactive Extrusion: Toward Nanoblends

By nanoblends, it is meant that the scale of dispersion of one polymer phase in the other is below 100 nm. A novel method was developed to prepare nanostructured blends (nanoblends) of polypropylene (PP) and polyamide-6 (PA-6) directly in a screw extruder. It consisted of polymerizing a monomer of PA-6, e-caprolactam (e-CL), in the matrix of PP. A fraction of the latter bore 3-isopropenyl-α,α-dimethylbenzene isocyanate (TMI) which acted as growing centers to initiate PA-6 chain growth. As such, formation of PA-6 and a graft copolymer of PP and PA-6 took place simultaneously in the matrix of the PP, leading to compatibilized PP/PA-6 blends. The size of the particles of the dispersed phase (PA-6) was between 10 and 100 nm, which could not be achieved otherwise by melt blending premade PP and PA-6.