LLDPE films containing monoester of oleic acid grafted to silica particles as durable antifog additives

Antifog additives (AF) are incorporated into polymeric systems to improve their wettability. When added to a polyethylene (PE) film, the AF molecules migrate to the films' surface and their concentration decreases; over time the additive's effect desists. Extended additives' performance is necessary to avoid frequent substitution of PE films for different applications (e.g. greenhouses coverings), as a result, reducing plastics' waste and contributing to environmental sustainability. This paper presents a simple, low cost, one‐step reaction to create durable AF for PE films, as well as a thorough study of AF migration rate, fog activity, and film properties. Films are prepared by compression‐molding (laboratory scale) and cast‐extrusion (pilot scale). FTIR (Fourier Transform IR) and TGA (Thermal Gravimetric Analysis) measurements confirm the existence of AF grafted particles. Aging tests depict a significant decrease of the AF migration rate. An evaluation test procedure for AF performance shows an extended duration of the AF's activity; the cast‐extrusion films exhibit improved AF durability, compared with the compression‐molded films. Copyright © 2016 John Wiley & Sons, Ltd.     

Rheo-optical FT-IR Spectroscopy of LLDPE: Effect of Comonomer and Composite Materials

Summary: In order to further evaluate the potential of FT-IR spectroscopic investigations on molecular processes during tensile testing experiments, the behavior of monolayer LLDPE films, made with ethylene-butene and ethylene-octene copolymers, was studied. Additionally, multilayer LLDPE films based on the same C4 and C8 copolymers were investigated. The stress-strain data obtained from the monolayer films indicate differences in the strain hardening region. It seems that the film samples PE 469-30-2 (C4-gas phase process) and PE 469-30-5 (C8 solution process) behave similarly whereas the strain hardening for the PE 469-30-3 (C4 solution process) requires lower stress values. The orientation function changes during the stretching of the films indicating that unfolding of the polymer chains occurs at lower strain for PE 469-30-5 (C8) than in the C4 materials. In the multilayer systems the Primplast 44 material (C8) shows a lower tendency for reorientation in the strain hardening region than the Coex 82 (C4) material. In this region of the stress-strain curve the lamellar structure is already transformed into the fibrillar arrangement. Regarding the orientation behavior of the material above 200% strain, a small increase in f_b was observed, which led to a decrease of f_c. In the octene product possibly the bulky side chains influence the unfolding significantly, producing a higher resistance to unfolding and alignment along the stretching direction. In part, this is potentially caused by the more perfect lamellae in the octene copolymer, which do not include the side chains, while the butene copolymer may have weaker lamellae because they contain a fraction of the side chains which create defects. Consequently, the octene copolymer requires higher stress values to be stretched and finally results in a lower stretchability of this material, as observed on an industrial scale during pallet wrapping tests. Based on the ratio of the structural absorbance parameters of the signals at 729 and 719 cm⁻¹ changes in the crystallinity were studied. For the continuous stretching experiment, no monoclinic phase was detected even after Fourier self-deconvolution and peak fitting approaches. Literature data, however, describe that this crystalline transformation takes place as a result of mechanical deformation. Therefore, stepwise stretching experiments which allow an improvement of the spectral resolution to 1 cm⁻¹ were carried out. In the deconvoluted spectra the monoclinic, orthorhombic and amorphous LLDPE modifications could be assigned. Ultimate stretchability and stretching force of the films, both monolayer and multilayer, was well correlated to the development of crystalline orientation in the films upon stretching. Other mechanical properties like Elmendorf tear and dart impact can also be better understood with these results.     

The molecular structure of SEBS grafted with maleic anhydride through ultrasound initiation

The molecular structure of SEBS grafted with maleic anhydride(SEBS-g-MAH) through ultrasound initiation was investigated by nuclear magnetic resonance(NMR). It can be confirmed that the grafting groups mainly exist on the terminus of the ultrasound initiated SEBS-g-MAH. However, it was difficult to detailedly confirm the block of the SEBS on which MAH is grafted through characterization of 1H-NMR due to the complex structure of the SEBS. Moreover, the temperaturedependent infrared spectra of the ultrasound initiated SEBS-g-MAH were also analyzed by the perturbation correlation moving window 2D(PCMW2D) correlation spectroscopy. It could confirm that the broken point existed at the joint between poly(ethylene-co-1-butene)(EB block) and polystyrene block(S block). Therefore, the grafting groups were attached to not only the S block but also the EB block. In addition, in order to well understand the aggregation structure of the ultrasound initiated SEBS-g-MAH, the possible grafting mechanism and aggregation model of the ultrasound initiated SEBS-g-MAH at room temperature were also proposed.     

A novel technique for preparing of maleic anhydride grafted polyolefins

A novel mechanochemical method of preparation of maleic anhydride grafted polypropylene (MAPP) was developed. The preparation was performed by ball milling of polypropylene (PP) powder, maleic anhydride (MA), and peroxide initiator in balls-containing jars with a planetary ball mill for a certain time. Compared with the conventional melt-mixing method, MAPP obtained through ball-milling technique reveals higher graft degree, particularly alleviated degradation of PP, or even increased molecular mass of the resulting MAPP. Maleic anhydride grafted polyethylene (MAPE) was obtained via this technique, and the optimization of the technique is in progress. The novel technique offers new opportunities in modification of polyolefins, which has also the advantages of solventless, lower process temperature, energy efficient, low cost, and simple running process. Furthermore, it is very easy to obtain purified products.     

Morphology- and phase-controlled iron oxide nanoparticles stabilized with maleic anhydride grafted polypropylene

About phase: Ferromagnetic γ-Fe(2) O(3) nanowires (left in the figure) with a saturation magnetization (M(s) ) of 54.0?emu?g(-1) and coercivity of 518?Oe at room temperature, and superparamagnetic hollow α-Fe(2) O(3) nanoparticles (right) with a room-temperature M(s) of 2.9?emu?g(-1) were synthesized by the thermal decomposition of [Fe(CO)(5) ] but with the stabilizing action of maleic anhydride grafted polypropylene.     

Synthesis of maleic anhydride grafted polyethylene and polypropylene,with controlled molecular structures

This article discusses a new chemical route to prepare maleic anhydride (MA) grafted polyethylene and polypropylene polymers with controlled molecular structure, that is, MA grafted content and polymer molecular weight and composition distributions. The chemistry involves a free radical graft reaction of maleic anhydride with poly(ethylene‐co‐p‐methylstyrene) and poly(propylene‐co‐p‐methylstyrene) copolymers. Under a suspension reaction condition, the grafting reaction takes place selectively on the p‐methylstyrene units in the copolymer, due to high reactivity of p‐methyl group and favorable mixing between p‐methylstyrene units and chemical reagents in the swollen amorphous phases. The resulting polymer shows no detectable molecular weight change during the reaction, and the MA grafted content increases with the increase of initiator and p‐methylstyrene concentrations. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1337–1343, 2000     

Solution properties of chlorinated polypropylene and maleic anhydride grafted chlorinated polypropylene

The solution behaviors of the chlorinated polypropylene (CPP) and its grafted polymers (CPP-g-MAH) were systematically studied to characterize their polar change with grafting maleic anhydride (MAH) onto the chain of CPP. The molecular weights of the polymers were determined with light scattering measurements, and the Mark–Houwink equation of CPP in toluene was also obtained. The result showed that the Mark–Houwink equation of CPP was suitable for estimating the molecular weight of the polydisperse samples of CPP and not suitable to CPP-g-MAH because the molecular polarity of the graft polymers had changed with grafting MAH onto CPP. The solubility result of CPP and CPP-g-MAH in various solvents indicated that the polarity of CPP gradually increased with grafting MAH onto its chain, which would cause the solubility of poorly hydrogen bonded solvents for CPP-g-MAH to gradually become poor, whereas that of moderately hydrogen bonded solvents for the polymers becomes better with an increase of the MAH graft content. This is consistent with the results of their dilution ratio and solubility parameter. Stabilities of the 344^# resin–CPP-g-MAH–toluene solutions showed that the miscibility of CPP-g-MAH and 344^# resin was improved with increase of the MAH grafted content.     

线型低密度聚乙烯的快速鉴定

采用对样品进行液氮淬火及溴化处理的制样方法,以期达到消除分子晶体场及分子链烯类端基对分析谱带的影响和干扰,结果表明:(1) 1 378 cm-1甲基对称变形振动谱带强而尖锐,和1 368 cm-1亚甲基面外摇摆振动谱带清晰分开,表明分子链上只存在一种单一的支链;(2)890 cm-1附近不存在表征长支链的甲基面内摇摆振动峰,只有772 cm-1附近存在表征乙基支链的亚甲基面内摇摆振动峰.成功地鉴定了以1-丁烯为共聚单体的线型低密度聚乙烯,方法简便、快速,为鉴定其他类的以烯烃为共聚单体的线型低密度聚乙烯(LLDPE)提供了重要思路.     

Chemical initiation mechanism of maleic anhydride grafted onto styrene-butadiene-styrene block copolymer

The mechanism of grafting styrene-butadiene-styrene (SBS) tri-block copolymer with maleic anhydride (MAH) initiated by benzoperoxide (BPO) or 2,2^′-azo-bis-isobutyronitrile (AIBN) was studied by FTIR and ¹H NMR spectroscopies. The variation of CC (double bond) content in SBS-g-MAH was used to verify the different graft mechanisms of BPO and AIBN, indicating that the chemical initiation mechanisms of MAH grafted onto SBS of AIBN is different from that of BPO. The graft reaction occurs by addition on CC for AIBN, while by removal of an allylic hydrogen atom from SBS and by addition on CC at the same time for BPO. The graft efficiency of AIBN is higher than that of BPO in this system.     

Use of maleic anhydride compatibilization to improve toughness and other properties of polylactide blended with thermoplastic elastomers

Polylactide (PLA) being a very brittle biopolymer could be toughened by blending with thermoplastic elastomers such as thermoplastic polyurethane elastomer (TPU) and thermoplastic polyester elastomer (TPE); unfortunately, these blends are immiscible forming round domains in the PLA matrix. Therefore, the purpose of this study was to investigate the effects of using maleic anhydride (MA) compatibilization on the toughness and other properties of PLA blended with TPU and TPE. MA grafting on the PLA backbone (PLA‐g‐MA) was prepared separately by reactive extrusion and added during melt blending of PLA/thermoplastic elastomers. IR spectroscopy revealed that MA graft might interact with the functional groups present in the hard segments of TPU and TPE domains via primary chemical reactions, so that higher level of compatibilization could be obtained. SEM studies indicated that PLA‐g‐MA compatibilization also decreased the size of elastomeric domains leading to higher level of surface area for more interfacial interactions. Toughness tests revealed that Charpy impact toughness and fracture toughness (K_IC and G_IC) of inherently brittle PLA increased enormously when the blends were compatibilized with PLA‐g‐MA. For instance, G_IC fracture toughness of PLA increased as much as 166%. It was also observed that PLA‐g‐MA compatibilization resulted in no detrimental effects on the other mechanical and thermal properties of PLA blends. Copyright © 2014 John Wiley & Sons, Ltd.     

4-PEG接枝苯乙烯-马来酸酐交替共聚物的合成及功能化

采用普通自由基聚合和可逆加成一断裂链转移（RAFT）自由基聚合方法合成了对位PEG取代苯乙烯（PEG-g-St）和马来酸酐的交替共聚物（P（（PEG—g—St）-alt-MA））,”CNMR分析表明PEG-g-St和马来酸酐单元采取交替的序列结构．利用反应性基团-马来酸酐单元的水解以及胺解可以制备功能性的PEG聚合物．以月桂胺为模型小分子研究了该聚合物的胺解,得到4-PEG-苯乙烯与羧酸基团以及疏水烷烃的交替序列聚合物,该双亲聚合物在水溶液中形成组装体．     

Enhancement of mechanical properties of natural rubber with maleic anhydride grafted liquid polybutadiene functionalized graphene oxide

An effective procedure has been developed to synthesize the functionalized graphene oxide grafted by maleic anhydride grafted liquid polybutadiene(MLPB-GO). Fourier transform spectroscopy and X-ray photoelectron spectroscopy indicate the successful functionalization of GO. The NR/MLPB-GO composites were then prepared by the co-coagulation process. The results show that the mechanical properties of NR/MLPB-GO composites are obviously superior to those of NR/GO composites and neat NR. Compared with neat NR, the tensile strength, modulus at 300% strain and tear strength of NR composite containing 2.12 phr MLPB-GO are significantly increased by 40.5%, 109.1% and 85.0%, respectively. Dynamic mechanical analysis results show that 84% increase in storage modulus and 2.9 K enhancement in the glass transition temperature of the composite have been achieved with the incorporation of 2.12 phr MLPB-GO into NR. The good dispersion of GO and the strong interface interaction in the composites are responsible for the unprecedented reinforcing efficiency of MLPB-GO towards NR.     

Effects of poly-(p-phenylene terephthamide) powder coated with polydopamine on ethylene-propylene-diene-terpolymer grafted maleic anhydride

In this paper, we reported a technique for the surface modification of poly-(p-phenylene terephthamide) (PPTA) powder coated with polydopamine (PDOPA). We used air oxidation to self-polymerize dopamine (DOPA) to ensure that the PPTA powder was coated. Our results indicate that the modified surface of PPTA powder enhances compatibility with the polymer matrix without damaging its structure. Additionally, it is possible to control the coating thickness of PDOPA by regulating the reaction time. The modified PPTA powder improved the comprehensive property of ethylene-propylene-diene-terpolymer grafted maleic anhydride (EPDM-g-MAH), and it proved that this method can enhance the strength and electric insulativity of EPDM-g-MAH.     

Chemical modification of E. coli L-asparaginase with polyethylene glycol grafted vinylpyrrolidone–maleic anhydride copolymer

A series of polyethylene glycol grafted vinylpyrrolidone–maleic anhydride copolymers [P(VMP)] was synthesized by radical copolymerization of vinylpyrrolidone, maleic anhydride and polyethylene glycol maleic acid monoester. Escherichia coli l -asparaginase was chemically modified with these copolymers. The modified l -asparaginase exhibited the complete loss of antigenicity towards anti-asparaginase serum from rabbit. The highest enzyme activity of the modified l -asparaginase without antigenicity was retained by 59% of the nonmodified one. The modified enzyme was also more resistant to trypsin in vitro. When tested in vivo, the native l -asparaginase was quickly cleared from the plasma of rabbits (half-life time: t_1/2=1.2 hr), whereas the modified enzyme showed prolonged clearance from plasma (t_1/2=53 hr). © 1997 John Wiley & Sons, Ltd.     

热重法测定高马来酸酐含量苯乙烯-马来酸酐共聚物的组成

高马来酸酐含量苯乙烯-马来酸酐共聚物(SMA)是一种具有优良耐热性、刚性和尺寸稳定性的新型高分子材料.由于SMA分子中含有极性很强、反应活性很高的酸酐官能团,所以它被广泛应用于涂料、粘合剂的改性剂、地板抛光的乳化剂、复合材料和颜料的分散剂、水处理剂等领域[1-5].     

Morphology of nylon 6/polypropylene blends compatibilized with maleated polypropylene

Transmission electron microscopy (TEM) was used to examine the morphology of blends of nylon 6 and polypropylene (PP) containing various maleated polypropylenes (PP-g-MA). The size of the dispersed polypropylene particles decreases as the content of maleic anhydride in the PP-g-MA increases for binary blends of nylon 6 and the maleated polypropylenes. Ternary blends of nylon 6, PP, and PP-g-MA show morphologies that depend on the content of maleic anhydride of the PP-g-MA and on the miscibility of PP and PP-g-MA. Blends where PP and PP-g-MA are immiscible show a bimodal distribution of particle sizes. Miscibility of the PP and PP-g-MA was determined by TEM using a special staining technique. Experimental observations of miscibility were further corroborated by thermodynamic calculations. The morphology of the ternary blends was also found to be dependent on the ratio of PP/PP-g-MA. By changing this ratio it was possible to induce drastic changes of morphology, going from a continuous nylon 6 phase to a continuous PP phase at a fixed composition. The mechanical properties of these blends were found to be dependent on their morphology. ©1995 John Wiley & Sons, Inc.     

Studies on dynamic mechanical and mechanical properties of vinyloxyaminosilane grafted ethylene propylene diene terpolymer/linear low density polyethylene (EPDM-g-VOS/LLDPE) blends

The dynamic mechanical properties of vinyloxyaminosilane grafted ethylene propylene diene terpolymer/linear low density polyethylene (EPDM-g-VOS/LLDPE) blends have been evaluated with special reference to the effect of blend ratio. It has been found that increasing the proportion of LLDPE in the blends decreases the T_g values and increases the storage modulus (E^′) and loss modulus (E^′′) due to increase in crystallinity. A gradual increase in the values of tanδ_max is observed for the blends with increase in EPDM-g-VOS concentration, which indicates that no phase inversion occurs. But however the higher increase in tanδ_max after 50 wt.% of EPDM-g-VOS composition is due to small change in crystallinity and is ascertained by SEM micrographs. Mechanical properties such as tensile strength, Young’s modulus and hardness increase with increases in LLDPE concentration in the blends and with dicumyl peroxide (DCP) concentration whereas the values of elongation at break are decreased with increase in LLDPE and DCP concentration.     

Laser-Initiated copolymerization of N-vinylpyrrolidone with maleic anhydride and maleimide

This article describes the laser-initiated copolymerization of N-vinylpyrrolidone with maleic anhydride and maleimide via charge transfer complexes. The dependence of copolymer yield on the molar ratios of the monomers in the feed and on the irradiation time is described. Based on the ultraviolet and infrared spectroscopy, and chemical analysis results, a tentative mechanism of polymerization is suggested. The rates of polymerization of several monomer systems are compared. The N-vinylpyrrolidone and maleimide system shows the highest rate of polymerization.     

Functionalization of polyesters with maleic anhydride by reactive extrusion

Maleic anhydride (MAn) was grafted onto aliphatic and aromatic/aliphatic copolyesters by reactive extrusion in the presence of a free radical initiator using a twin‐screw extruder. The grafting reaction was confirmed by spectroscopic analyses. The presence of succinic anhydride groups was shown by FT‐IR spectroscopy, and NMR spectra indicate that the grafts consist of single succinic anhydride units. The 2D ¹H‐NMR spectra (COSY) indicate that grafting reactions take place at aliphatic dicarboxylic acid units of copolyesters. The graft content was determined by a nonaqueous titration method. The effects of concentration of initiator and monomer and reaction temperature on the graft content and intrinsic viscosity were studied. The low percentage grafting in poly(lactic acid) was observed due to the presence of limited free radical sites in the polymer backbone. Temperature and monomer and initiator concentrations affect the graft content, and the desired graft content with minimal degradation can be obtained by controlling these factors. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1693–1702, 1999     

Effective adsorption of U(VI) from aqueous solution using magnetic chitosan nanoparticles grafted with maleic anhydride: equilibrium,kinetic and thermodynamic studies

The in situ formed magnetite nanoparticles was encapsulated by maleated chitosan to synthesize a novel magnetic chitosan nano-sorbent (MCN-MA) for the effective sorption of uranium. The sorption kinetics could be described by the pseudo-second-order model, whereas the sorption isotherms could be fitted to the Langmuir model (q _m = 187.9 mg/g). The MCN-MA showed higher U(VI) sorption capacities (compared to MCN) due to high affinity of carboxylate groups introduced from grafting maleic anhydride. Thermodynamic parameters indicate that U(VI) sorption is endothermic and feasible. The nano-size and magnetic property of the MCN-MA allow its efficient U(VI) sorption and facile magnetic separation from wastewaters.