线型低密度聚乙烯固相接枝马来酸酐研究

利用固相接枝技术,在自由基引发剂存在下,用2种不同熔体流动速率(MFR)的线型低密度聚乙烯(LLDPE)制备了马来酸酐接枝物(LLDPE-g-MA),研究了工艺条件对产物接枝率(DG)和凝胶含量(DC)的影响,结果表明,在相同工艺条件下,反应6 h后,接枝率都保持在2%以上,但低MFR的LLDPE原料,在接枝反应过程中容易发生交联,产品的凝胶含量接近60%,而用高MFR的LLDPE原料得到的产品凝胶含量低于2%。同时用IR、DSC和X衍射表征了产物的结构,结果表明,MA接枝主要发生在PE的非晶区,对PE的结晶结构没有很大影响。     

Two‐stage grafting onto polyethylene fiber by radiation‐induced graft polymerization and atom transfer radical polymerization

Two‐stage graft polymerization onto polyethylene (PE) fiber was demonstrated. The graft side chain was formed by radiation‐induced graft polymerization. A PE fiber was irradiated with an electron beam and immersed in a vinyl monomer solution. The terminal of the formed graft chain was halogenated using N‐bromosuccinimide. The halogenated graft chain was then extended by atom transfer radical polymerization to obtain block‐copolymer grafted PE fibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Free radical grafting of styrene onto polyethylene in intensive mixer

The graft copolymerization of styrene onto low density polyethylene (LDPE) with dicumyl peroxide as an initiator was studied. The existence of the graft copolymer was verified by infrared spectra. The effects of the initiator concentration, the feed composition, the reaction time, and the reaction temperature were discussed. Grafting efficiency reached a maximum value with the increase of reaction time. The effect of increasing the concentration of dicumyl peroxide was to decrease the grafting efficiency up to a minimum value. Grafting efficiency was not affected much by the variation of the reaction temperature. Grafting efficiency decreased largely with the increase of the feed composition of styrene. The compatibilizing effect of the copolymer prepared in this study was demonstrated by the morphology and mechanical properties of high impact polystyrene/LDPE blends. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1307–1317, 1998     

Elucidation of the nanoparticle effect on the grafting of vinyl monomers onto cotton fabric

The grafting emulsion polymerization of vinyl monomers onto cotton was carried out in the presence of double‐modified montmorillonite clay. The obtained results show that grafting with glycidyl methacrylate/montmorillonite gave a higher rate of grafting than grafting with methyl methacrylate/montmorillonite in all clay percentages, and also, the grafting yield of glycidyl methacrylate monomer onto cotton in the presence of montmorillonite clay had a higher value than that in the absence of the clay for all factors studied. Cotton grafted with glycidyl methacrylate/montmorillonite with a graft yield of about 50% was prepared according to the emulsion polymerization technique and was treated with different concentrations of dibutylamine solutions ranging from 1 to 4%. The obtained samples were characterized according to nitrogen content, thermal stability, scanning electron microscopy, mechanical properties, water absorption, and color strength according to acid, basic, and reactive dyes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

纳米铁粒子表面接枝聚合甲基丙烯酸甲酯

采用直流电弧等离子体法制备纳米铁粉,利用甲基丙烯酸(MAA)和盐酸处理纳米铁粉,通过乳液聚合方法,在纳米铁粉存在下MMA原位聚合,形成纳米铁/聚甲基丙烯酸甲酯复合粒子。分析结果表明,MMA在纳米铁粒子表面接枝聚合,纳米铁粉表面的双键参与了聚合反应,所形成的复合粒子具有核壳结构,这种复合粒子具有较高的稳定性。     

Kinetics and mechanism of free radical grafting of methyl acrylate onto sago starch

The graft copolymerization was carried out by methyl acrylate with sago starch in which ceric ammonium nitrate was used as an initiator. It has been found that the rates of graft polymerization and grafting efficiency were dependent upon the concentration of ceric ammonium nitrate (CAN), methyl acrylate (MA), sago starch (AGU, anhydro glucose unit), mineral acid (H₂SO₄), and as well as reaction temperature and period. A rate equation of polymerization was established from the proposed reaction mechanism, and the rate of polymerization (R_p) was the first‐order dependence of the MA monomer concentration and square root of the CAN concentration. A new kinetic model of the grafting reaction has been proposed, and a normal kinetics of methyl acrylate polymerization was observed. An equation of a predicted model relating the graft fraction of poly(methyl acrylate) with the sago starch has been derived, and validity of the predicted model was verified by the experimental results. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 784–791, 2000     

Grafting of maleic anhydride onto polyethylene through a green chemistry approach

The grafting of a polymer can lead to the improvement and modification of the polymer and thus expand its applications. Grafting methods include solution grafting in organic solvents, melt grafting at high temperatures, and light grafting with radioactive sources. These methods have their advantages and disadvantages. The disadvantages include waste treatment, consumption of energy, and so on. In this study, a hydrothermal process which is called the green approach, was developed to prepare graft copolymers. The effect of various factors on the grafting degree was investigated in detail. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Plasma induced grafting of PSt onto titanium dioxide powder. II

Grafting of polystyrene (PSt) onto titanium dioxide powder was investigated in this study. The graft polymerization reaction was induced by N₂ plasma treatment of the surfaces of the titanium dioxide powder. IR and XPS results showed that PSt was grafted onto the titanium dioxide powder. The crystal structure of the titanium dioxide powder observed by XRD spectra was unchanged after plasma graft polymerization. In the grafting reaction, the grafting yield increased with the plasma power, the plasma treatment time, and the grafting reaction, but it increased first then decreased after reaching 50°C. The type of monomers also has an effect on the grafting yield. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2112–2117, 2005     

Effect of styrene addition on chemically induced grafting of 4‐vinylbenzyl chloride onto low‐density polyethylene for anion exchange membrane preparation

Anion exchange membranes were prepared from graft polymerization of 4‐vinylbenzyl chloride on low‐density polyethylene matrix and subsequent amination with trimethylamine solution. The graft polymerization was initiated by benzoyl peroxide instead of gamma ray radiation. The resulting membranes had insufficient anion exchange functional groups; however, this could be enhanced by adding 10% styrene to 4‐vinylbenzyl chloride in a graft polymerization reaction. Further addition of styrene resulted in a decrease of the ion exchange capacity of anion exchange membranes due to competition with 4‐vinylbenzyl chloride in graft polymerization onto polyethylene. These were evidenced by analytical titration, elemental analysis, infrared spectroscopy and ¹H NMR. © 2019 Society of Chemical Industry     

Effect of MWCNTs irradiation grafting treatment on the surface properties of PBO fiber

The aim of this article is improved the surface properties of Poly[p‐phenylenebenzobisoxazole] (PBO) fiber with epichlorohydrin hybridized carboxylic multi walled carbon nanotubes (MWCNTs‐Ecp) grafting by using γ‐ray irradiation technology. The surface chemical properties, the surface morphology, the amount of the grafted MWCNTs on PBO fiber and the surface free energy of PBO fibers have been analyzed. The results show that MWCNTs‐Ecp have been grafted on the surface of PBO fiber by γ‐ray irradiation treatment. The surface chemical inertness and the surface smoothness of PBO fiber are significantly improved by grafting MWCNTs‐Ecp chains, the amount of the grafted MWCNTs on PBO fiber is about 11.9%, and the surface free energy of PBO fiber has an increase of 42.6% by generating some active groups such as ? COOH, ? OH, and ? C? Cl on the surface of PBO fiber. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Atom transfer radical polymerization of graft chains onto polyethylene film initiated at tribromomethyl unit introduced by electron beam irradiation

A novel process for graft polymerization onto a polyethylene (PE) film using atom transfer radical polymerization (ATRP) was examined. First, a PE film irradiated with an electron beam was treated with carbon tetrabromide, thereby introducing tribromomethyl groups. The number of tribromomethyl groups introduced onto the film could be controlled by adjusting the electron beam irradiation dose. Methyl methacrylate (MMA) was then graft‐polymerized by ATRP in the initiator‐introduced PE film in the presence of a copper catalyst. Based on FTIR spectra from the PMMA grafted films, the behavior of graft polymerization reactions on the film surface and inside the film are discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

PE膜表面接枝间苯二酚

Low density polyethylene film surface-grafted process. Firstly, acrylic acid was grafted to the surface grafting. Secondly, the carboxylic groups in poly （acrylic resorcinol was prepared by a sequential of low density polyethylene by UV photoacid） chains were transferred to acyl chloride groups by the reaction of carboxylic groups with thionyl chloride. The stability of acyl chloride groups in several solvents （alcohol, water, acetone, aqueous NaOH and in N2 atmosphere） was investigated, and N2 atmosphere and acetone were appropriate media to protect acyl chloride groups from side reaction. Finally, resorcinol monomer reacted with acyl chloride to append to the poly（acrylic acid） chains at room temperature. FT-IR ATR was used to characterize the change of carbonyl groups during each step of the grafting process. Furthermore, by the experimental data of gravimetric analysis the grafted resorcinol monomer on the surface of low density polyethylene film was verified to have undergone condensation with acetone further in the resorcinol/acetone solution at 56℃, which might be a useful feature for synthesizing a thermoplastic/thermosetting composition.     

Preparation and characterization of layered membranes constructed by sequential redox‐initiated grafting onto polyacrylonitrile ultrafiltration membranes

Layered membranes were prepared by sequential grafting—by means of redox initiators—of water‐soluble monomers, with oppositely charged ionic groups, onto ultrafiltration (UF) polyacrylonitrile (PAN) membranes at room temperature. Grafting of a single layer of 2‐hydroxyethylmethacrylate (HEMA) onto a PAN membrane gave a highly grafted membrane with a relatively high water flux. Bilayered membranes with various properties containing poly‐2‐(dimethylamino)ethyl methacrylate (p‐2DMAEMA) as the bottom layer and polymethacrylic acid or polystyrenesulfonic acid (p‐SSA) as the upper layer were prepared and compared—by means of infrared spectroscopy and electron microscopy—with single‐layered membranes of grafted polyhydroxyethylmethacrylate. Layered membranes exhibited a significant decline in water flux in comparison with the initial UF membranes. The flux could, however, be manipulated by controlling the concentration of monomers, the time of grafting, and the number of layers. When four layers of p‐2DMAEMA and p‐SSA were sequentially grafted onto a PAN membrane, pure water fluxes were stable over a wide range of pH values and did not change over long storage times. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 509–520, 2005     

过硫酸盐引发棉纤维接枝的研究

以过硫酸盐与硫代硫酸钠为引发剂,使丙烯酰胺与棉纤维进行接枝共聚,研究了过硫酸盐的加入方式和加入量对接枝反应的影响,发现采用过硫酸铵与过硫酸钾两种氧化剂、两步加入的办法能够克服体系中氧气的阻聚作用,又能得到较高的单体转化率和接枝率。     

Reactive extrusion process for the grafting of maleic anhydride onto linear low‐density polyethylene with ultraviolet radiation

In this work, we chemically modified linear low‐density polyethylene with maleic anhydride in the molten state using, in a first step, different doses of ultraviolet irradiation to generate hydroperoxide groups, which were highly reactive at the processing temperature. Then, in a second reactive extrusion step, maleic anhydride was grafted to the linear low‐density polyethylene under different processing conditions. Characterization of the modified and unmodified linear low‐density polyethylene material was performed with Fourier transform infrared spectroscopy, differential scanning calorimetry, and nuclear magnetic resonance. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Homogeneous grafting reaction of vinyl pyrrolidone onto chitosan

Modification of chitosan by grafting of vinyl pyrrolidone (VP) was carried out in homogeneous phase using potassium persulfate as redox initiator. The effect of the reaction variables on the extent of grafting was studied systematically. Values for grafting percentages up to 290% were reached. It was observed that the solubility of chitosan was markedly reduced after grafting with vinyl pyrrolidone. The grafted product is insoluble in common organic solvents as well in dilute organic and inorganic acids. However, the solubility of the grafted chitosan after adsorption of copper ions changed substantially, becoming completely soluble in dilute hydrochloric acid. This was attributed to the effect of complex formation produced by coordination of amino groups of chitosan with copper ions. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1321–1326, 1997     

Irradiation grafting of methyl methacrylate monomer onto ultra‐high‐molecular‐weight polyethylene: An experimental design approach for improving adhesion to bone cement

The grafting of methyl methacrylate (MMA) onto ultra‐high‐molecular‐weight polyethylene (UHMWPE) and chromic acid etched UHMWPE was conducted with a preirradiation method in air in the presence of a Mohr salt and sulfuric acid. The grafted samples were characterized by Fourier transform infrared (FTIR) spectroscopy, a gravimetric method, differential scanning calorimetry, scanning electron microscopy (SEM), and interfacial bonding strength measurements. The FTIR results showed the presence of ether and carbonyl groups in the MMA‐grafted UHMWPE (MMA‐g‐UHMWPE) samples. The Taguchi experimental design method was used to find the best degree of grafting (DG) and bonding strength. The efficient levels for different variables were calculated with an analysis of variance of the results. SEM micrographs of MMA‐g‐UHMWPE samples showed that with increasing DG and chromic acid etching, the MMA‐g‐UHMWPE rich phase increased on the surface; this confirmed the high interfacial bonding strength of the grafted samples with bone cement. The grafting of the MMA units onto UHMWPE resulted in a lower crystallinity, and the crystallization process proceeded at a higher rate for the MMA‐g‐UHMWPE samples compared to the initial UHMWPE; this suggested that the MMA grafted units acted as nucleating agents for the crystallization of UHMWPE. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Optimized condition for grafting reaction of poly(butyl acrylate) onto oil palm empty fruit bunch fibre

Preparation of poly(butyl acrylate)‐grafted oil palm empty fruit bunch fibre (OPEFB) has been successfully carried out using H₂O₂/Fe²⁺ as a redox initiator in aqueous solution. The effects of reaction temperature and period, as well as the amount of monomer, initiator and nitric acid, on the percentage of grafting were investigated. The percentage of grafting increases with amount of monomer and can be controlled by setting the appropriate reaction conditions. The maximum percentage of grafting (about 265%) was obtained when the reaction was carried out without acid under optimum conditions (reaction period: 2 h, reaction temperature: 55 °C, amount of H₂O₂: 5.88 mmol) with 42.2 mmol of monomer. Mechanisms of grafting of butyl acrylate onto OPEFB were proposed. Characterization of the grafted OPEFB was done by Fourier‐transform infrared spectroscopy and scanning electron microscopy. The thermal properties were studied by thermogravimetric analysis. Copyright © 2003 Society of Chemical Industry     

Reactive grafting of glycidyl methacrylate onto polypropylene

This work explored the melt‐phase grafting of glycidyl methacrylate (GMA) onto polypropylene on a closely intermeshing corotating twin‐screw extruder (16‐mm screws, 40 : 1 length/diameter ratio). The modification of the base polypropylene to produce GMA‐grafted polypropylene was achieved via peroxide‐induced hydrogen abstraction from the polypropylene followed by the grafting of the GMA monomer or by the grafting of styrene followed by copolymerization with the GMA. In this study, both the position and order of the reactant addition were investigated as a route to improving graft yields and reducing side reactions (degradation). For the peroxide–GMA system, adding GMA to the melt before the peroxide resulted in significant improvements in the graft levels because of the improved dispersion of GMA in the melt. The addition of a comonomer (styrene) was explored as a second route to improving the graft yield. Although the addition of the comonomer led to a considerable rise in the level of grafted GMA, altering the order of the reactant addition was not found to contribute to an increase in the grafted GMA levels. However, variable levels of grafted styrene were achieved, and this may play an important role in the development of grafted polymers to suit specific needs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Parameters affecting the grafting reaction and side reactions involved in the free‐radical melt grafting of maleic anhydride onto high‐density polyethylene

The parameters affecting the grafting reaction and side reactions in free‐radical melt grafting of maleic anhydride (MA) onto high‐density polyethylene with the aid of 2,5‐dimethyl‐2,5‐di(t‐butyl peroxy)hexane peroxide(DTBPH) have been studied using an internal mixer. MA grafting degree of the maleated samples was measured with titrometry and FTIR spectroscopy methods. The extent of chain‐branching/crosslinking side reactions was evaluated with gel content and MFI determination. The flow behavior and melt viscoelastic properties of the samples were measured using a rheometric mechanical spectrometer. DTBPH and MA concentrations, reaction temperature, rotor speed, the type and concentration of coagents were among the studied parameters. The results show that MA and DTBPH concentration has a major role on the grafting reaction, chain‐branching/crosslinking side reactions and also the grafts microstructure in the final product. The reaction temperature has a complex effect on the maleation reaction. Increasing the rotor speed causes an increase in MA grafting degree of the samples and reduces the competitive side reactions. By using Gaylord additives, gel formation reduces at the expense of a dramatic decrease in the grafting degree. MA grafting degree is increased by the use of comonomers in the reaction and this is accompanied with a decrease in crosslinking side reaction when the vinyl type styrene comonomer is used. The results of processing torque in combination with the measurements of the melt viscoelastic property and gel content of the samples provide a great insight into understanding the gel formation mechanism. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007