Melt grafting of maleic anhydride onto elastomeric ethylene‐octene copolymer by reactive extrusion

Melt grafting of maleic anhydride onto elastomeric ethylene‐octene copolymer was carried out in a twin‐screw extruder, in the presence of dicumyl peroxide as an initiator. Dimethyl formamide was used as an inhibitor to reduce crosslinking and as a solvent for peroxide initiator. The aim of the work is to produce the copolymer with reactive functionality without the expense of elastomeric characteristics. Particular consideration was, therefore, given to the effects of initiator and monomer concentrations, and of screw speed on the degree of grafting, percentage of conversion, amount of crosslinked products, and on the stress‐strain behaviors of the grafted products. The degree of grafting was found to be dependent mainly on the initiator and monomer concentrations. Increasing the initiator concentration increased the degree of grafting, and at the same time, increased the amount of gel (crosslinking). An increase in gel content of the grafted products resulted in a change of tensile behaviors from uniform deformation followed by strain‐hardening at high strains to low extensibility and fracture at low strains.     

Melt grafting of poly(ethylene‐vinyl acetate) copolymer with maleic anhydride

Poly(ethylene‐vinyl acetate) (EVA) copolymer was melt grafted with maleic anhydride (MAH) in a twin screw extruder in the presence of peroxide. It is confirmed that MAH has been melt grafted on the backbone of EVA by FTIR using the method of hydrolysis. The NMR analysis suggests that the grafting reaction occurs on the tertiary carbon of main chain of EVA other than the methyl moiety of vinyl acetate (VA) group. The incorporation of VA groups onto the matrix shows a competitive effect on the grafting. The existence of VA groups promotes the extent of MAH graft onto EVA; nevertheless, it also weakens the crystallizability of main chain. When the content of peroxide initiator is 0.1 wt % based on the polymer matrix, the grafting degree increases with increasing the concentration of monomer. When the peroxide content is higher than 0.1 wt %, side reactions such as crosslinking or disproportionation will be introduced into this system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 841–846, 2006     

Block copolymer formation from the melt reaction between polycarbonate and poly(ethylene‐co‐butylene) diol

The block copolymer formation from the exchange reaction between polycarbonate (PC) and poly(ethylene‐co‐butylene) diol (POH) occurring during melt mixing was studied. The exchange reaction proceeded by the attack of active chain ends of hydroxyl‐terminated POH on the inner carbonate groups of PC. The reaction was accelerated in basic condition in the presence of a hindered amine. The formation of block copolymer was confirmed by ¹H–NMR analysis. The proceeding of the exchange reaction was analyzed with UV spectrometry by measuring the absorbance at 285 nm of the less‐reactive phenolic end group of PC oligomers produced. The reaction was terminated when the hydroxyl end groups of POH were completely consumed. It was found from the analyses by GPC and DSC that the exchange reaction between PC and POH takes place rather uniformly by random scission of the chain. The block copolymer obtained here will be employed as a compatibilizer of PC/polyolefin blends in a future study. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1725–1732, 2001     

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     

Maleic anhydride/styrene melt grafting and crosslinking onto ethylene‐octene copolymer

Melt grafting of the multimonomer system of maleic anhydride (MAH)/styrene (St) onto ethylene‐octene copolymer (POE) was performed by a twin‐screw extruder. The effects of St and initiator contents as well as MAH/St on the grafting reaction were investigated. The structure and properties of the grafted POE were characterized by the Fourier transform infrared spectroscopy, melt flow index, dynamic rheological behaviors, and thermogravimetric analysis. It is shown that the addition of St can significantly enhance MAH grafting degree onto POE. MFI values of grafted POE are affected not only by MAH/St copolymer concentration, but also by initiator concentration. These data indicate that the interaction and reaction between MAH and St monomers plays an important role in the grafting reaction. St improves the grafting reactivity of MAH and reacts with MAH before the two monomers graft onto POE. And high grafting degree can be obtained while the gel content is still low. Compared with neat POE, grafted POE shows different dynamic rheological behaviors and high thermal stability. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

马来酸酐熔融接枝全同聚1-丁烯

采用马来酸酐(MAH)熔融接枝全同聚1-丁烯,研究了MAH及第二单体苯乙烯(St)、复配引发剂、温度对接枝率的影响,用傅里叶变换红外光谱法表征接枝产物。结果表明:2种单体和复配引发剂用量对接枝率有较大影响,加入St提高了接枝率,引发剂过氧化二异丙苯与过氧化二苯甲酰质量比为3:1时接枝率最高,接枝率随着温度的升高而增大。     

Styrene‐assisted grafting of maleic anhydride onto isotactic poly butene‐1

Grafting of maleic anhydride (MAH) onto isotactic poly butene‐1 (iPB‐1) was carried out by thermal decomposition of dicumyl peroxide (DCP) using electron‐donating monomer styrene (St), and were carried out in the molten state in a twin‐screw extruder according to an experimental design in which the content of MAH and St were varied. The calibration curve was constructed from FTIR measurements and titration which can obtain the absolute amounts of grafted MAH according to FTIR data. The proposed mechanism was that when St is added to the iPB‐1/MAH/peroxide grafting system, St reacted first with MAH to form a charge‐transfer complex (CTC). Then CTC react (or copolymerize) with macroradicals. The grafting of MAH onto iPB‐1 (iPB‐1‐MAH) accelerated crystalline transformation rate of form II to I. The contact angle decreased with the increase of grafting degree, which indicated that surface polarity increased. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Comparison of maleic anhydride grafting onto powder and granular polypropylene in the melt by reactive extrusion

The grafting of powder and granular polypropylene (PP) with maleic anhydride (MA) was investigated in a reactive extrusion process with dicumyl peroxide (DCP) as an initiator. The effects of the MA and DCP contents in the feed on grafting were investigated. Under the experimental conditions applied in this study, the grafted monomer unit content was varied from 0.023 to 0.5%. The MA grafting efficiency of powder PP was higher than that obtained for the granular form of PP. In general, the grafting degree first increased with the MA or DCP content in the feed, then reached a maximum value, and finally decreased because of several possible alternative reactions during the grafting. The grafting of powder PP was more successful because of better initial mixing and less diffusional resistance during the grafting. An increase in the MA content in the feed caused significant reductions in the melt‐flow index of the graft copolymers. The results obtained with Fourier transform infrared, differential scanning calorimetry, and X‐ray powder diffraction analyses indicated that the structure, macrotacticity, crystallinity, crystallization, and thermal behavior of PP changed with grafting and depended on the grafting degree. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3675–3684, 2004     

Solvothermal process for grafting dibutylmaleate onto poly(ethylene‐co‐1‐octene)

Solvothermal process was successfully developed to graft dibutylmaleate (DBM) onto poly(ethylene‐co‐1‐octene) (POE) with dicumyl peroxide (DCP) as free radical‐initiator. FTIR spectra demonstrate that DBM is successfully grafted onto the backbone of POE by this novel method. The influences of DBM content, DCP concentration, POE concentration, reaction temperature and reaction time on the grafting copolymerization have been investigated in detail through grafting degree (GD). It is worthy to indicate that high grafting degree (above 15%) can be achieved through the one‐pot way when the graft reaction is carried out in 40 mL toluene at 150°C for 5 h with 1.6 g DBM, 6–8 g POE and 0.35 g DCP. This developed solvothermal process is becoming an effective way to prepare POE‐g‐DBM graft copolymers, and can be extended to other systems. In addition, TGA results show that the thermal properties of POE are enhanced after the grafting reaction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Property enhancement in polypropylene ternary blend nanocomposites via a novel poly(ethylene oxide)‐grafted polystyrene‐block‐poly(ethylene/butylene)‐block‐polystyrene toughener–compatibilizer system

Synthesis and characterization of a novel toughener–compatibilizer for polypropylene (PP)–montmorillonite (MMT) nanocomposites were conducted to provide enhanced mechanical and thermal properties. Poly(ethylene oxide) (PEO) blocks were synthetically grafted onto maleic anhydride‐grafted polystyrene‐block‐poly(ethylene/butylene)‐block‐polystyrene (SEBS‐g‐MA). Special attention was paid to emphasize the effect of PEO‐grafted SEBS (SEBS‐g‐PEO) against SEBS‐g‐MA on morphology, static/dynamic mechanical properties and surface hydrophilicity of the resultant blends and nanocomposites. It was found that the silicate layers of neat MMT are well separated by PEO chains chemically bonded to nonpolar SEBS polymer without needing any organophilic modification of the clay as confirmed by X‐ray diffraction and transmission electron microscopy analyses. From scanning electron microscopy analyses, elastomeric domains interacting with MMT layers via PEO sites were found to be distributed in the PP matrix with higher number and smaller sizes than the corresponding blend. As a benefit of PEO grafting, SEBS‐g‐PEO‐containing nanocomposite exhibited not only higher toughness/impact strength but also increased creep recovery, as compared to corresponding SEBS‐g‐MA‐containing nanocomposite and neat PP. The damping parameter of the same nanocomposite was also found to be high in a broad range of temperatures as another advantage of the SEBS‐g‐PEO toughener–compatibilizer. The water contact angles of the blends and nanocomposites were found to be lower than that of neat hydrophobic PP which is desirable for finishing processes such as dyeing and coating. © 2018 Society of Chemical Industry     

Synthesis and characterization of poly(butylene terephthalate)‐co‐poly(butylene succinate)‐block‐poly(ethylene glycol) segmented block copolymers

Poly(butylene terephthalate)‐co‐poly(butylene succinate)‐block‐poly(ethylene glycol) segmented random copolymers, with poly(butylene succinate) (PBS) molar fraction (M_PBS) varying from 10 to 60 %, were synthesized through a melt polycondensation process and characterized by means of GPC, NMR, DSC and mechanical testing. The number‐average relative molecular mass of the copolymers was higher than 4 × 10⁴ g mol^?1 with polydispersity below 1.9. Sequence distribution analysis on the two types of hard segments by means of ¹H NMR revealed that the number‐average sequence length of PBT decreased from 2.80 to 1.23, while that of PBS increased from 1.27 to 4.76 with increasing M_PBS. The random distribution of hard segments was also justified because of the degree of randomness around 1.0. Micro‐phase separation structure was verified for the appearance of two glass transition temperatures and two melting points, respectively, in DSC thermograms of most samples. The crystallinity of hard segments changed with the crystallizability controlled by the average sequence length and reached the minimum value at an M_PBS of about 50–60 mol%. The results can also be ascribed to the co‐crystallization between two structurally analogous hard segments. Mechanical testing results demonstrated that incorporating a certain amount of PBS moieties (less than 30 mol%), at the expense of a minute depression of the elastic modulus, that higher relative elongation and more flexibility of polymer chain could be expected. Maximum equilibrium water absorption and faster degradation rates were observed on samples with higher M_PBS values and lower crystallinity of hard segments were better hydrophilicity of the polymer chain, through in vitro degradation experiments. Copyright © 2003 Society of Chemical Industry     

Bulk grafting of poly(styrene‐alt‐maleic anhydride) onto preirradiated polyolefin membranes in supercritical carbon dioxide

To take advantage of the property of supercritical carbon dioxide as both a solvent and swelling agent, the bulk grafting of poly(styrene‐alt‐maleic anhydride) [P(MAH‐alt‐St)] onto preirradiated polyolefin membranes was performed by a combination of γ‐ray‐preirradiation‐induced graft copolymerization and supercritical fluid‐swollen polymerization. The trapped radicals on the polyolefin backbones were uniformly distributed by γ‐ray irradiation under a nitrogen atmosphere. Subsequently, these polymeric trapped radicals initiated the alternating copolymerization of styrene (St) and maleic anhydride (MAH) infused into the swollen polymer matrix with the aid of supercritical CO₂. It was important that the graft copolymers were relatively pure without any contaminants, including homopolymers, monomers, and initiators. The experimental results show that the degree of grafting could be easily controlled. In addition, St/MAH could synergistically promote the bulk grafting process and strongly effect on the alternating trend; this was confirmed by element analysis and differential scanning calorimetry. Soxhlet extraction, X‐ray diffraction, and Fourier transform infrared spectroscopy indicated that the P(MAH‐alt‐St) was covalently bonded to the polymeric backbones. Scanning electron microscopy showed that the alternating graft chains were uniformly dispersed throughout the 5‐mm thickness of the polymer membranes on the nanometer scale. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Peroxide‐catalyzed swell grafting of maleic anhydride onto polypropylene

A new grafting method was developed to incorporate maleic anhydride directly onto solid‐state polypropylene powders. Maleic anhydride grafts altered the nonpolar characteristics of polypropylene so that much better mixing was achieved in blends and composites of polypropylene with many other polymers and fillers. Maleic anhydride was grafted onto polypropylene by the peroxide‐catalyzed swell grafting method, with a maximum extent of grafting of 4.60%. Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, tensile testing, and impact testing were used to characterize the isotactic polypropylene (iPP), maleic anhydride grafted polypropylene (MAH‐g‐iPP), and (isotactic polypropylene)/(calcium carbonate) composites (iPP/CaCO₃). The crystallinity and heat of fusion of the MAH‐g‐iPP decreased as the extent of grafting increased. The mechanical properties of the CaCO₃ filled polypropylene were improved by adding MAH‐g‐iPP as a compatibilizing agent. The dispersion of the fillers in the polymer matrix and the adhesion between the CaCO₃ particles and the polymer matrix were improved by adding the compatibilizer.     

Highly porous starch/poly(ethylene‐alt‐maleic anhydride) composite nanofiber mesh

In this study, starch‐based hybrid electrospun nanofiber meshes were fabricated by electrospinning. Spinning solutions were prepared by mixing starch and certain amounts of poly(ethylene‐alt‐maleic anhydride). Starch‐based nanofiber meshes became insoluble in water with thermal‐induced esterification of hydroxyl groups onto starch backbone. Morphologic and structure analysis of the electrospun nanofiber meshes were investigated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Thermal properties of nanofiber meshes were characterized by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Thermal stability of nanofiber meshes were increased with formation of intermolecular bonds between starch and poly(ethylene‐alt‐maleic anhydride). POLYM. COMPOS. 34:1321–1324, 2013. © 2013 Society of Plastics Engineers     

Reactive compatibilization of the poly(butylene terephthalate)–EVA blend by maleic anhydride. II. Correlations among gel contents,grafting yields,and mechanical properties

Correlations among the degree of crosslinking of ethylene vinyl acetate copolymer (EVA), the grafting yield of maleic anhydride (MAH) onto EVA, and the mechanical properties of the blends of poly(butylene terephtalate) (PBT) with EVA‐g‐MAH were investigated. The EVA was functionalized by melt grafting reaction in the presence of MAH and dicumyl peroxide (DCP) using a plasticorder. The grafting yield of MAH was increased by increasing the concentration of MAH and DCP. The flexural strength of PBT–EVA‐g‐MAH blends depends on both the grafting yield of MAH and the degree of crosslinking of EVA, while the crosslinked parts of EVA‐g‐MAH hindered rather than improved the tensile strength regardless of the increase of the grafting yield of MAH. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1305–1310, 2003     

Dynamic mechanical properties of polystyrene‐block‐poly[ethylene‐co‐(ethylene‐propylene)]‐block‐polystyrene triblock copolymer/hydrocarbon oil blends

Blend systems of polystyrene‐block‐poly(ethylene‐co‐(ethylene‐propylene))‐block‐polystyrene (SEEPS) triblock copolymer with three types of hydrocarbon oil of different molecular weight were prepared. The E″ curves as a function of temperature exhibited two peaks; one peak at low temperature (? ?50°C), arising from the glass transition of the poly[ethylene‐co‐(ethylene‐propylene)] (PEEP) phase and a high temperature peak (? 100°C), arising from the glass transition of the polystyrene (PS) phase. The glass transition temperature (T_g) of the PEEP phase shifted to lower temperature with increasing oil content. The shifted T_g depended on the types of oil and was lower for the low molecular weight oil. The T_g of PS phase of the present blend system, were found to be constant and independent of the oil content, when molecular weight of the oil is high. However, for the lower molecular weight oil, the T_g of the PS phase also shifted to lower temperatures. This fact indicates that the oil of high molecular weight is merely dissolved in the PS phase. The E′ at (75°C, at which temperature both of PEEP and PS phases are in glassy state, was found to be independent of oil content. In contrast, at 25°C, at which temperature the PEEP phase is in rubbery state, the E′ decreased sharply with increasing oil content. This result indicates that the hydrocarbon oil was a selective solvent in the PEEP phase. It mainly dissolved in the PEEP phase, although slightly dissolved into the PS phase as well, when molecular weight of oil is low. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Controllable self‐assembly of polystyrene‐block‐poly(2‐vinylpyridine)

Block copolymers can form various ordered structures by self‐assembly, and their composites with inorganic materials may give surprising properties. This review summarizes recent developments in the preparation, mechanism and application of various types of self‐assembly of polystyrene‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP). The focus of the review is on how to control the self‐assembly of the dynamic and ordered structure of PS‐b‐P2VP based materials by applying effective factors such as thermal annealing, solvent annealing, block composition and blending. Moreover, the combination of the self‐assembly of PS‐b‐P2VP and various nanoparticles, with potentials in drug delivery, sensors and catalysis, is highlighted. © 2018 Society of Chemical Industry     

Study on toughening effect of maleic anhydride‐grafted‐poly(ethylene‐octene) to EVOH and their compatibility

Blends of poly(ethylene‐co‐vinyl alcohol) (EVOH) with maleic anhydride‐grafted‐poly(ethylene‐octene) (POE‐g‐MAH) were prepared by blending extrusion in order to improve the toughness and flexibility of EVOH. The compatibility behavior of these blends with POE‐g‐MAH content range from 0 to 25 wt% was studied using mechanical, thermal, infrared, and morphology characterization techniques. The mechanical test results showed that POE‐g‐MAH can significantly improve the impact toughness of EVOH with a brittle‐tough transition appeared at the POE‐g‐MAH content of 20 wt%. A huge increase of toughness of the blend was also observed when the POE‐g‐MAH content was increased to 15 wt%. The thermal analysis of the blends demonstrated that the thermal stability of EVOH is improved with the addition of POE‐g‐MAH, adding 20 wt% or more POE‐g‐MAH can effectively decrease the crystallinity of EVOH and greatly improve compatibility between the two components. The existence of esterification between anhydride groups in POE‐g‐MAH and hydroxyl groups in EVOH in melt processing was confirmed using Fourier transform infrared technique. Morphology analysis of the Izod impact fractures has clearly shown the mechanisms for these blends to change from brittle to tough with increasing the POE‐g‐MAH content. POLYM. ENG. SCI., 53:2093–2101, 2013. © 2013 Society of Plastics Engineers     

Solid‐state grafting of succinic anhydride onto poly(vinyl alcohol)

The graft reaction of succinic anhydride onto poly(vinyl alcohol) (PVA) was catalyzed by p‐toluenesulfonic acid monohydrate in solid state. The infrared spectra and ¹H‐NMR spectra confirmed that succinic anhydride was successfully grafted onto PVA backbone. The influences of reaction temperature, reaction time, the amount of succinic anhydride, and the amount of catalyst on the graft reaction were studied. Uncrosslinked PVA graft copolymer with grafting degree up to about 6.5% could be obtained under low reaction temperature, short reaction time, and low amount of catalyst, whereas crosslinked PVA with high gel content could be obtained under high reaction temperature, long reaction time, and high amount of catalyst. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 848–852, 2007     

Crystallization kinetics,melting behavior,and morphologies of poly(butylene succinate) and poly(butylene succinate)‐block‐poly(propylene glycol) segmented copolyester

This article investigated the crystallization kinetics, melting behavior, and morphologies of poly(butylene succinate)(PBS) and its segmented copolyester poly(butylene succinate)‐block‐poly(propylene glycol)(PBSP) by means of differential scanning calorimetry, polarized light microscopy, and wide angle X‐ray diffraction. Avrami equation was used to describe the isothermal crystallization kinetics. For nonisothermal crystallization studies, the Avrami equation modified by Jeziorny, and the model combining Avrami equation and Ozawa equation were employed. The results showed that the introduction of poly(propylene glycol) soft segment led to suppression of crystallization of PBS hard segment. The melting behavior of the isothermally and nonisothermally crystallized samples was also studied. Results showed that the isothermally crystallized samples exhibited two melting endotherms, whereas only one melting endotherm was shown after nonisothermal crystallization. The spherulitic morphology of PBSP and wide angle X‐ray diffraction showed that the polyether segments were excluded from the crystals and resided in between crystalline PBS lamellae and mixed with amorphous PBS. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010