Grafting Degree Of Maleic Anhydride Research Articles

STYRENE ASSISTED MELT FREE RADICAL GRAFTING OF MALEIC ANHYDRIDE ONTO HIGH DENSITY POLYETHYLENE AND PROPERTIES OF THE GRAFT COPOLYMER

Free radical melt-grafting of the multi-monomer system of maleic anhydride(MAH) /styrene(St) onto high density polyethylene(HDPE) prepared by a single-screw extruder was studied.It was found that the addition of St monomer could significantly improve the MAH grafting level of the grafted HDPE.With increasing the St concentration,the graft degree of MAH first increased and then decreased a little.The maximum MAH grafting degree and the minimum melt flow rate were obtained when the molar ratio of MAH to St was approximately 1∶ 1.The higher the graft degreet,he smaller MFR value was,suggesting that the grafted PE chains induced intermolecular entanglements.The mechanical properties of the grafted polymer with the addition of small portions of St monomer were better than those of the neat HDPE in this case.The mechanism of the multi-monomer melt grafting HDPE system was also discussed.It was proposed that MAH and St interacted and copolymerized with each other in the melt grafting system.The grafting of St-MAH copolymer(SMA) onto HDPE greatly increased the grafting degree of the grafted HDPE.When the amount of St is larger than MAH,St would be first grafted onto the PE backbonei,nhibiting the grafting of SMA.Besidest,he cross-linking of PE was well depressed due to the increase of graft degree in the multi-monomer melt grafting systems.And no obvious gel was obseved in the reflux process.

Melt‐grafting mechanism study of maleic anhydride onto polypropylene with 1‐decene as the second monomer

AbstractAlthough polypropylene (PP) grafted by maleic anhydride (MAH) has been successfully commercialized, the grafting mechanism under the existence of a second monomer is not very clear. To simulate the grafting process of MAH onto PP with 1‐decene as the second monomer, the MAH/1‐decene copolymer and Alder ene reaction product were prepared and grafted onto PP with dicumyl peroxide as the initiator. We found that the grafting of the copolymer and the reactive product greatly improved the grafting degree of MAH. Particularly, the grafting degree with a 3% content of the Alder ene reactive product was 1.89%, which was 178% higher than that of pure MAH‐g‐PP, the maximum value of which was 0.68%. The molecular weight of the synthesized product affected the grafting efficiency and crystallization behavior of the grafted system. The system grafted with the Alder ene reaction product showed a higher crystallization temperature and crystalline degree. When the molecular weight of the copolymer was higher than 1700, the improvement of the grafting degree could be neglected. For MAH‐g‐PP with 1‐decene as the second monomer, the possible grafting mechanisms were as follows: first, the formation of MAH/1‐decene copolymer or the Alder ene reaction product, and second, the grafting of the previously formed product onto PP, in which, the effect of the Alder ene reaction product was more pronounced. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Enhancement of graft yield and control of degradation during polypropylene maleation in the presence of polyfunctional monomer

AbstractFree‐radical initiated grafting of maleic anhydride (MAH)/polyfunctional acrylate (PFA) multimonomer system onto polypropylene (PP) via reactive extrusion was studied. The effects of PFA and initiator concentration on the grafting reaction were investigated. It was shown that PFA as a comonomer could greatly enhance MAH grafting degree, which increased monotonically as the molar ratio of PFA to MAH increased. The rheology test demonstrated that the viscosity of grafted PP was also promoted as more PFA was used. The formation of branched structure during the grafting process was proved by oscillatory shear rheological analysis. The mechanism of grafting in the presence of PFA was discussed, suggesting PFA had higher reactivity with PP macroradicals than MAH and therefore forming stabilized macroradicals, thus resulting in depression of β‐scission and favoring the formation of branched structure. Higher initiator concentration gave higher MAH grafting degree but more severe degradation. The mechanical properties of the grafted PP were comparable with those of unmodified PP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Preparation and properties of bitumen modified with the maleic anhydride grafted styrene‐butadiene‐styrene triblock copolymer

AbstractA procedure to improve the properties of styrene‐butadiene‐styrene (SBS) copolymer modified bitumen by grafting of maleic anhydride (MAH) onto SBS in the presence of benzoyl peroxide (BPO) as initiator was proposed. The effects of the grafting degree (GD) on the properties of modified bitumen were investigated. FTIR spectroscopy was employed to verify the grafting of MAH onto SBS. The GD of MAH onto SBS was determined by a back titration procedure. To assess the effects of the GD of grafted SBS on properties of modified bitumen, the softening point, penetration, ductility, elastic recovery, penetration index, viscosity, storage stability, and dynamic shear properties were tested. Experimental results indicated that the SBS grafted with maleic anhydride (SBS‐g‐MAH) copolymer was successfully synthesized by solvothermal method, and different GD of the SBS‐g‐MAH was obtained by control the MAH concentration. The GD of the MAH onto SBS has great effect on the rheological properties of the modified bitumen, and the high temperature performance and storage stability of modified bitumen were improved with the GD of the MAH onto SBS increasing. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Melt grafting of maleic anhydride onto polypropylene with 1‐decene as a second monomer

AbstractThe influence of 1‐decene as the second monomer on the melt‐grafting behavior of maleic anhydride (MAH) onto polypropylene (PP) was studied with differential scanning calorimetry and Fourier transform infrared spectroscopy. We found that the value of the grafting degree increased from 0.68% for pure MAH‐g‐PP to 1.43% for the system with a 1‐decene/MAH molar ratio of 0.3, whereas the maximum value with styrene (St) as the second monomer was 0.98% under an St/MAH molar ratio of 1.0. Compared with the contribution of St/MAH‐g‐PP to the peeling strength between the PP and polyamide (PA) layer for a PP/PA laminated film, the introduction of 1‐decene/MAH‐g‐PP increased the peeling strength from 180 g/15 mm to 250 g/15 mm. 1‐Decene inhibited the chain scission behavior of PP. 1‐Decene reacted with MAH to form a 1‐decene/MAH copolymer or the Alder‐ene reaction product before the two monomers grafted onto PP. The grafting of the reactive product onto PP greatly improved the grafting degree of MAH. What is more, because of the similar chemical structures of 1‐decene and PP, the affinity of 1‐decene with PP was higher than that of St. Compared with St, the introduction of less 1‐decene led to a higher grafting degree and higher peeling strength. Therefore, we concluded that 1‐decene was more effective for improving the grafting degree of MAH onto PP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Exfoliation of organically modified montmorillonite driven by molecular diffusion in maleated polypropylene

AbstractThis work is focused on the factors influencing the intercalation of maleated polypropylene (PPMA) into organically modified montmorillonite (OMMT). Two kinds of PPMA were used to explore the optimal candidate for effective intercalation into OMMT. The grafting degree of maleic anhydride and the viscosity of PPMA have effects on the diffusion of polymer molecules. Moreover, the loading level of surfactant was varied to optimize the modification of montmorillonite because the appropriate loading level can provide a balance between interlayer distance and steric hindrance. The kind of surfactant changes the interaction between OMMT and PPMA, and accordingly the intercalation of PPMA is different, resulting in the discrepancy of the intercalation of PPMA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

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

AbstractMelt 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

Radiation grafting of maleic anhydride onto polypropylene in suspension system

This paper studies the grafting of maleic anhydride (MAH) onto polypropylene (PP) performed in suspension through co-irradiation in the absence of an initiator. The effect of radiation dose and MAH concentration on the graft degree of MAH onto PP was investigated. The graft degree and relative viscosity of grafted MAH were investigated by means of chemical titration and viscosity measurements. The results show that the co-irradiation in suspension systems can obviously cause the increase of the amount of grafted MAH, implying that the grafting reaction consists of chain scission and the grafting reaction of the produced macroradicals with MAH. The percentage of grafting of the product amounts to 4.82%. The molecular structures of the prepared grafted MAH were characterized by Fourier-transform infrared spectroscopy (FT-IR). Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WXRD) were used to determine the degree of crystallinity and crystalline structure.

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

AbstractThe 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

Neodymium oxide co-catalyzed melt free radical grafting of maleic anhydride onto co-polypropylene by reactive extrusion

Rare earth oxide, neodymium oxide (Nd2O3), CO-catalyzed melt grafting of maleic anhydride (MAH) onto co-polypropylene (co-PP) in the presence of dicumyl peroxide (DCP) was carried out by reactive extrusion. The experimental results reveal that the addition of Nd2O3 as a coagent leads to an enhancement in both MFR and the grafting degree of MAH, along with a simultaneous decrease in the gel content. When the Nd2O3 concentration is 6.0 mmol%, the increment of the grafting degree of MAH maximally is up to about 20% compared with the related system without adding Nd2O3, and the gel content decreases simultaneously to a very low level of about 3%. Attenuated total reflection FTIR (ATR-FTIR) indicates that the gel in the graft copolymers mainly arise from the cross-linking reaction between ethylene units of co-PP. A reasonable reaction mechanism has been put forward on the basis of our experimental results and other mechanisms reported in the literature. We also tentatively explain above results by means of synergistic effect between DCP and Nd2O3, which causes a higher concentration of the macroradical, in particular the tertiary macroradical.

Nano-reactors for controlling the selectivity of the free radical grafting of maleic anhydride onto polypropylene in the melt

This paper reports on a successful application of the concept of nanoreactors to effectively controlling the selectivity of the free radical grafting of maleic anhydride (MAH) onto polypropylene (PP) in the melt, an industrially relevant process. More specifically, a free radical initiator of type ROOR was first confined into (or encapsulated by) the galleries of an organically modified montmorillonite (o-MMT) whose interdistance was 2.4 nm. Primary free radicals (RO center dot) formed inside the o-MMT galleries had to diffuse out before they could react with the PP backbone. The controlled release of the primary free radicals significantly increased the grafting degree of MAH onto PP and greatly reduced the level of the chain scission of the latter. Those results were better understood by electron spin resonance studies on model systems and by Monte Carlo simulations.

Neodymium oxide‐assisted melt free‐radical grafting of maleic anhydride on isotactic‐polypropylene by reactive extrusion

AbstractRare earth oxide, neodymium oxide (Nd2O3), ‐assisted melt free‐radical grafting of maleic anhydride (MAH) on isotactic‐polypropylene (i‐PP) was carried out by reactive extrusion. The experimental results reveal that the addition of Nd2O3 into reactive system leads to an enhancement of the grafting degree of MAH, along with an elevated degradation of i‐PP matrix. When Nd2O3 content is 4.5 mmol %, the increment of the grafting degree of MAH (maximally) is up to about 30% compared with that of the related system without adding Nd2O3, while the severest degradation of i‐PP matrix simultaneously occurs. On the basis of the reaction mechanism of PP‐g‐MAH proposed before, the sequence of β‐scission and grafting reaction is discussed in detail. It is found that, for the reactive system studied, most tertiary macroradicals first undergo β‐scission, and then, grafting reaction with MAH takes place at the new radical chain ends. The imported Nd2O3 has no effect on the aforementioned reaction mechanism, whereas it enhances the initiating efficiency of the initiator, dicumyl peroxide (DCP). We tentatively explain the experimental results by means of synergistic effect between DCP and Nd2O3. It is calculated that the synergistic effect is maximal when the molar ratio of DCP to Nd2O3 is approximately 1:6. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 134–142, 2006

Preparation of a maleated Fischer–Tropsch paraffin wax and FTIR analysis of grafted maleic anhydride

Grafting of maleic anhydride (MA) onto Fischer–Tropsch paraffin wax was performed by a melting process in the presence of dibenzoyl-peroxide (DBP). It was confirmed that suitable reaction conditions can give a product which does not contain unbound maleic anhydride. Washing of the final product in boiling water is not suitable in this case, due to the relatively high solubility of the final product in water. A simple method, using Fourier transform infrared spectroscopy (FTIR), was developed for the determination of the grafting degree of MA. The method is based on the evaluation of the ratio of the C–H wax vibration absorbance to that of the carbonyls of the grafted succinic anhydride ring. The identification of the main peaks was done and suitable peaks were chosen for FTIR analysis. The concentration of grafted maleic anhydride was calculated by an iteration technique based on a function derived from the Lambert–Beer law. The regression and statistical parameters of the calculated function, as well as the accuracy of the determined grafted anhydride content, were computed.

Microstructure of Maleic Anhydride Grafted Polyethylene by High-Resolution Solution-State NMR and FTIR Spectroscopy

The microstructure of maleic anhydride (MA) grafted polyethylene (PE), MA-g-PE, has been successfully characterized by high-resolution NMR and FT-IR spectroscopy. The carbonyl asymmetric and symmetric stretchings of MA-g-PE exhibit lower shifts with an increase in the grafting degree of MA, suggesting stronger inductive interactions between different grafts in a solid state. The 1H and 13C NMR spectroscopy of [2,3-13C2]MA grafted PE with a low molecular weight (lmPE), [2,3-13C2]MA-g-lmPE, demonstrates that [2,3-13C2]MA-g-lmPE contains fewer succinic anhydride (SA) oligomeric grafts with a terminal unsaturated MA ring (oligo-MA) in addition to more SA oligomeric grafts terminated with a saturated SA ring (oligo-SA), the only structure that had been observed prior to this study. The formation of oligo-MA and oligo-SA can be explained by a mechanism based on two different termination processes: disproportionation between a grafting radical and a macroradical on a secondary carbon in lmPE or another grafting...

Study on styrene-assisted melt free-radical grafting of maleic anhydride onto polypropylene

Free-radical melt grafting of the multi-monomer system of maleic anhydride (MAH)/styrene (St) onto polypropylene (PP) was studied using a single-screw extruder. The effects of St and initiator concentrations on the grafting reaction were investigated. It was shown that the addition of St to the melt-grafting system as a comonomer could significantly enhance MAH graft degree onto PP. The maximum MAH graft degree was obtained when the molar ratio of MAH to St was approximately 1:1. However, the melt flow rate (MFR) value of the grafted PP was the highest at this ratio. This implies 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 also reacts with MAH to form the St–MAH copolymer (SMA) before the two monomers graft onto PP. Grafting of SMA onto PP greatly enhanced the graft degree of MAH. When the molar ratio of MAH to St is 1:1, the main grafting reaction in the system is the grafting of SMA to PP; therefore, the graft degree of the grafted PP is the highest. When the concentration of MAH is higher than that of St, some MAH monomer reacts with St to form SMA, but others can directly graft onto PP macroradicals. When the amount of St added is higher than that of MAH, part of the St monomer may preferentially react with PP macroradicals to form more stable styryl macroradicals, while others copolymerize with MAH to yield SMA. The MFR value of the grafted PP is lower in this case.

Modification of polypropylene with maleic anhydride: Ultrasonic irradiation effects

The mechanochemical reaction of modificated of polypropylene (PP) with maleic anhydride (MAH) has been studied by ultrasonic irradiation as an energy source at 60°C. Through 23 factorial experimental design, three variables and their interactions were studied: the percentage of MAH, the percentage of benzoyl peroxide (BPO), and ultrasonic irradiation intensity (Watts). According to the results, an increase of wt % of MAH gave a negative effect in the grafting yield; in addition, this negative effect was observed in the interaction of MAH : BPO at a high range of wt %, this behavior is attributed to the homopolymerization of MAH at the experimental conditions employed. The higher positive effect onto the grafting yield was observed for the variable watts (ultrasonic irradiation intensity), even at low intensity. The better interaction of variables gave a MAH grafting degree of 4.65 wt % (93% yield). In addition, the effect of ultrasonic irradiation on the number-average molar mass (Mn), weight-average molar mass (Mw), and polydispersity index (Mw/Mn) was measured. It was observed that the Mw decreased 13.73% and the Mw/Mn also decreased by 11.98%. The o observed effect was attributed to the degradation mechanism induced by the ultrasound, which consists in the generation of macroradicals and their recombination. The product PP-g-MAH was characterized by infrared spectroscopy, also was used to prepare polypropylene–nylon-6 blends. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:45–52, 1998

Modification of polypropylene with maleic anhydride: Ultrasonic irradiation effects

The mechanochemical reaction of modificated of polypropylene (PP) with maleic anhydride (MAH) has been studied by ultrasonic irradiation as an energy source at 60°C. Through 23 factorial experimental design, three variables and their interactions were studied: the percentage of MAH, the percentage of benzoyl peroxide (BPO), and ultrasonic irradiation intensity (Watts). According to the results, an increase of wt % of MAH gave a negative effect in the grafting yield; in addition, this negative effect was observed in the interaction of MAH : BPO at a high range of wt %, this behavior is attributed to the homopolymerization of MAH at the experimental conditions employed. The higher positive effect onto the grafting yield was observed for the variable watts (ultrasonic irradiation intensity), even at low intensity. The better interaction of variables gave a MAH grafting degree of 4.65 wt % (93% yield). In addition, the effect of ultrasonic irradiation on the number-average molar mass (Mn), weight-average molar mass (Mw), and polydispersity index (Mw/Mn) was measured. It was observed that the Mw decreased 13.73% and the Mw/Mn also decreased by 11.98%. The o observed effect was attributed to the degradation mechanism induced by the ultrasound, which consists in the generation of macroradicals and their recombination. The product PP-g-MAH was characterized by infrared spectroscopy, also was used to prepare polypropylene–nylon-6 blends. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:45–52, 1998