Synthesis and thermal behavior of some brominated bismaleimides and polyaspartimides

Brominated bismaleimides were synthesized by the reaction of brominated bisphenols with 3‐ or 4‐maleimidobenzoyl chloride. The reaction of these maleimides with various aromatic diamines yielded brominated polyaspartimides. The monomers and polymers were characterized by Fourier transformed infrared and proton nuclear magnetic resonance spectroscopy. Thermal behavior of these brominated polyaspartimides was studied and compared with that of related polyaspartimides having other substituents instead of bromine or other bridges in the bisphenolic segment. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

扩链双马来酰亚胺的合成与表征

分别合成了一系列酰胺键扩链的双马来酰亚胺和酰亚胺键扩链的双马来酰亚胺，通过ＩＲ，ＨＮＭＲ对其结构进行了表征，并通过ＴＧ－ＤＴＡ对其热性能进行了研究。结果发现它们具有良好的耐热性。     

Syntheses and thermal properties of ether-containing bismaleimides and their cured resins

Aromatic bismaleimides (BMIs) were prepared by the condensation of malefic anhydride with multiring diamines containing ether bridges. The thermal behavior of the bismaleimides was investigated by differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) and thermomechanical analysis (TMA) were utilized to characterize the thermal properties of the cured resins. The effect of the structures of bismaleimides on their thermal behavior and the thermal properties of the cured resins is discussed. Increasing molecular weight between reactive endgroups lowered melting points of BMIs, leading to a large temperature range between their melting point and the initial polymerization temperature. The introduction of ether bonds together with other flexible partners to bismaleimide resins decreased the glass transition temperatures or softening temperatures and the brittleness of the cured bismaleimide resins without extreme loss of their thermal stability. The cured bismaleimides were stable up to 450°C in both air and nitrogen.     

Syntheses and properties of polyimides derived from diamines containing 2,5‐disubstituted pyridine group

A series of novel homo‐ and copolyimides containing pyridine units were prepared from the heteroaromatic diamines, 2,5‐bis (4‐aminophenyl) pyridine and 2‐(4‐aminophenyl)‐5‐aminopyridine, with pyromelltic dianhydride (PMDA), and 3,3′, 4,4′‐biphenyl tertracarboxylic dianhydride (BPDA) via a conventional two‐step thermal imidizaton method. The poly(amic acid) precursors have inherent viscosities of 1.60–9.64 dL/g (c = 0.5 g/dL in DMAC, 30°C) and all of them can be cast and thermally converted into flexible and tough polyimide films. All of the polyimides show excellent thermal stability and mechanical properties. The polyimides have 10% weight loss temperature in the range of 548–598°C in air. The glass transition temperatures of the PMDA‐based samples are in the range of 395–438°C, while the BPDA‐based polyimides show two glass transition temperatures (T_g1 and T_g2), ranging from 268 to 353°C and from 395 to 418°C, respectively. The flexible films possess tensile modulus in the range of 3.42–6.39 GPa, strength in the range of 112–363 MPa and an elongation at break in the range of 1.2–69%. The strong reflection peaks in the wide‐angle X‐ray diffraction patterns indicate that the polyimides have a high packing density and crystallinity. The polymer films are insoluble in common organic solvents exhibiting high chemical resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1844–1851, 2006     

Bismaleimide monomers with amide units: Synthesis and properties

A series of bismaleimide monomers with amide groups were prepared and characterized. Structurally different bismaleimides (with amide units) were synthesized by a reaction between 4‐maleimidobenzoyl chloride and various diamines. The monomers were characterized by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and elemental analysis. The thermal characterization of the bismaleimides was accomplished with differential scanning calorimetry and dynamic thermogravimetric analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 567–572, 2006     

Polycondensation of bismaleimides with aromatic diamines

Summary The polycondensation (Michael addition) of a bismaleimide (BMI, N,N-4,4-[(1-methylethylidene) bis (phenyleneoxyphenylene)] bismaleimide) with an aromatic diamine (DA, 4,4-[1,3 phenylene bis (1-methylethylidene)] bisaniline), in a 1:1 molar ratio, was followed using SEC and FTIR techniques. The polycondensation followed a 2nd-order kinetics with an activation energy, E=51 kJ mol^–1. The mass fraction of dimer varied with conversion following the statistical prediction for an ideal A₂+B₂ polycondensation. At 60% conversion, gelation was observed. This was ascribed to a small advance in the BMI homopolymerization. Thermal degradation took place at T>200 °C. The first step was, possibly, a reversal in the Michael addition reaction as revealed by the decrease in the concentration of CH₂ groups observed in FTIR spectra.This paper is dedicated to Prof. Eloisa B. Mano (IMA, UFRJ, Brazil) for her pioneering work in the development of the polymer field in Latin America.     

Effect of structure on mechanical properties of vinyl ester resins and their glass fiber‐reinforced composites

The article describes the effect of structure of vinyl ester resins (VE) on the mechanical properties of neat sheets as well as glass fabric‐reinforced composites. Different samples of VE were prepared by reacting ester of hexahydrophthalic anhydride (ER) and methacrylic acid (MAA) (1 : 1 molar ratio) followed by reaction of monomethacrylate terminated epoxy resin with glutaric (E) or adipic (F) or sebacic acid (G) (2 : 1 molar ratio). The neat VE were diluted with styrene and sheets were fabricated by using a glass mold. A significant reduction in the mechanical properties was observed by increasing the methylene content of resin backbone (i.e., sample E to G). Glass fabric‐reinforced composites were fabricated by vacuum assisted resin transfer molding (VARTM) technique. Resin content in the laminates was 50 ± 5 wt %. Increase in the number of methylene groups in the vinyl ester resin (i.e., increasing the bridge length) did not show any significant effect on limiting oxygen index (LOI) value (21 ± 1) of the laminates but tensile strength, tensile modulus, flexural strength, and flexural modulus all increased though these values are significantly lower than observed in laminates based on resin B. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Properties of crosslinked polyurethanes obtained by acrylic side‐group polymerization and of their blends with various plant oils

Novel polyurethane elastomers have been developed to incorporate plant oil into their matrix. Bisphenol A glycerolate diacrylate was used as a chain extender for the polyurethane prepolymer obtained from poly(tetramethylene oxide) glycol and 1,6‐hexane diisocyanate. The curing of the polyurethane acrylate matrix in the presence of the plant oil results in a network matrix which includes renewable resources in their structure. The effects of the inclusion of different vegetable oil (such as soybean oil, rapeseed oil, cotton oil, or sunflower oil) into the crosslinked polyurethane acrylates matrix were studied by evaluating various properties of the films such as the thermal behavior, the tensile properties, and the surface properties. The increases in chain extender content determine an increase of the thermal stability (the 10% weight loss decomposition temperatures increase from 325 to 375°C) and mechanical strength (from 3 to 9 MPa). Contact angle measurements have shown that the hydrophobic property of the films surface slightly increased with the incorporation of plant oil into the crosslinked polyurethane matrix. In addition, polyurethane/plant oil blends exhibit enhanced mechanical strength (from 3 to 9.8 MPa), as well as an increased roughness reaching a maximum average (113 nm) in the case of cotton oil. All polyurethane/plant oil blend present higher values for glass transition temperature and slightly enhanced values for thermal stability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Benzoxazine monomers based on aromatic diamines and investigation of their polymerization by rheological and thermal methods

In the present article with the aim to find new polybenzoxazines with improved thermal properties, new benzoxazine monomers based on phenol and the following aromatic diamines were synthesized: 3,4′-oxydianiline (P-3,4′oda); o-tolidine (P-ot); m-tolidine (P-mt) and 4,4′-(1,3-phenylenedioxy)dianiline (P-tper) and their comparison with the previously known benzoxazines based on 4,4′-diaminodiphenylmethane (P-ddm); 4,4′-oxydianiline (P-4,4′-oda) and 2,2-Bis[4-(4-aminophenoxy)phenyl]propane (P-bapp). The dependence of the thermal and rheological characteristics on the structure of benzoxazine monomers based on various diamines was estimated and possible methods for their processing were identified. All the polybenzoxazines obtained in this work have high char yield and reduced flammability. It was found that the structure of the diamine can have a fundamental effect on both the rheological properties and heat resistance of polybenzoxazines. The benzoxazine monomers P-ddm, P-tper and P-4,4′oda retain viscosity up to 1 Pa s. at 110°C for 2 h, the P-tper monomer with a resorcinol bridge has about five times lower viscosity compared to the P-bapp monomer with a bisphenol A bridge. Polybenzoxazines based on the monomers P-ddm, P-mt, P-bapp and P-tper show excellent thermal stability with a temperature of 10% weight loss above 400°C. In particular, T_g of P-3,4′oda and P-mt monomers is relatively high (202 and 239°C, respectively), while P-ot's is unusually low (115°C), which may be caused by the specific effect of the substituents in the aromatic ring of the amine and their position.     

Synthesis and thermal properties of bismaleimides with mesogen aromatic amide–ester and flexible polymethylenic group

Four bismaleimides with mesogen “amide–ester” aromatic and flexible polymethylenic group variable length (8 ≤ n ≤ 11) were synthesized in two stages, producing yields exceeding 80%. These bismaleimides (BMIs) were obtained after several purifications by dissolution—precipitation in dimethylformamide–methanol (1/4) with over 94% purity (high‐performance liquid chromatography). These pure BMIs were characterized by nuclear magnetic resonance, Fourier transform infrared spectroscopy, and elemental analysis and studied by differential scanning calorimetry, thermogravimetric analysis, polarized light microscopy, and X‐ray diffraction. Solubilities and thermal properties show effects of parity. The even BMIs are more difficult to solubilize than the odd BMI. The melting points of the even BMI (approximately, 220°C) are far higher than those of odd BMI (approximately, 160°C). Crosslinking temperatures of even BMI are close to 230°C, whereas odd BMI crosslinking temperatures are higher (approximately, 250°C). Even BMIs give rise to a liquid crystal state upon melting. Under the same conditions, odd BMIs give rise to an amorphous state; however, after crosslinking, the four bismaleimides give rise to an ordered liquid crystal state of smectic type. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Bismaleimides blend with a synthesised phosphorus-containing benzoxazine and its mechanical and tribological properties

ABSTRACT

The phosphorus-containing benzoxazine-bismaleimides (PBOZ-BMI) resin was fabricated by blending the synthesised phosphorus-contained benzoxazine monomer (PBOZ) with bismaleimides (BMI). The influence of PBOZ content on the mechanical and tribological properties of PBOZ-BMI resin was researched. The results showed that suitable addition of PBOZ can enhance the mechanical properties and decrease the frictional coefficient and wear rate of PBOZ-BMI resin to some extent. The improvement of mechanical properties of PBOZ-BMI can be attributed to the cross hydrogen bonding and network interpenetrating. The wear mechanism of the PBOZ-BMI resin was converted from fatigue wear to adhesive wear after the addition of PBOZ, observed from the wear surface of the materials by scanning electron microscopy (SEM). The enhancement of tribological properties is due to the high heat resistance of PBOZ, which can inhibit the adhesive wear during the wear effective.     

Preparation and characterization of metal-containing bismaleimides from divalent metal salts of p-aminobenzoic acid

A series of novel metal-containing bismaleimides monomers BMI(M) (M = Ca, Sr, Ba, Pb, Co, Ni) were prepared by reacting maleic anhydride with diaminodiphenyl carboxylate to form bismaleamic acid precursors, and subsequently by imidizing them chemically or thermally to form bismaleimides. The samples were characterized by IR, ¹H-NMR, and TG-DTA. The results of thermal analysis show that the BMI(M) have high thermo-oxidiative stability and their temperatures of initial decomposition have a relationship with metals introduced and the imidization methods. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1827–1831, 1997     

Curing behavior and thermal mechanical properties of cyanate ester blends

Cyanate esters are a class of important thermally resistant polymers. To tailor their processability and thermomechanical properties, a series of cyanate ester blends based on a trifunctional novolac cyanate ester (HF‐5), a difunctional bisphenol E cyanate ester (HF‐9), and a reactive catalyst [2,2′‐diallyl bisphenol A (DBA)] were formulated. The effect of the blend composition on the rheology and curing behavior of these cyanate ester blends and the corresponding thermal and mechanical properties of the cured cyanate ester blends was studied. The results showed that HF‐5 contributed to good mechanical property retention at high temperatures because of its trifunctionality, whereas HF‐9 imparted processability by reducing the viscosity and extending the pot life of the formulated cyanate ester blends at the processing temperature. On the basis of the results, an optimal cyanate ester blend suitable for resin transfer molding was determined: the HF‐5/HF‐9/DBA weight ratio of 80 : 15 : 5 exhibited good processability and thermomechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4284–4290, 2006     

Modification of unsaturated polyester resin with bismaleimide

The modification of a commercially available unsaturated polyester resin with 4,4′‐bismaleimidodiphenylmethane is presented. The properties of the modified resins were compared with those of the nonmodified resin, and the resins were characterized in the noncured state and after curing. The results indicate that the addition of bismaleimide to unsaturated polyester resin not only improves its properties but also accelerates the curing reactions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2003–2007, 2001     

Mechanical and Morphological Behavior of Bismaleimide-Modified Soy-Based Epoxy Matrices

This study is concerned with the preparation and mechanical characterization of bio-based polymers from renewable resources. Epoxidized soybean oil at various concentrations is cured with an amine curing agent. The prepared matrices have been chemically modified with three types of bismaleimides, namely N, N′-bismaleimido-4, 4′-diphenyl methane (BMI-1), 1,3-bis(maleimido)benzene(BMI-2) and 3,3′-bis(maleimido phenyl)phenyl phosphineoxide (BMI-3). The crosslinked matrices thus developed were characterized for their mechanical properties such as tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength. The incorporation of bismaleimides in the soy-based matrices significantly enhances the mechanical properties. The morphological behavior of matrices is also studied using a scanning electron microscope. The results indicate that the bismaleimide-modified soy-based epoxy resin at appropriate concentration holds great potential as a replacement for petroleum-based materials in engineering applications.     

Synthesis and properties of novel aromatic copolyamides containing chloro‐substituted phthalazinone moiety in the main chain

A series of novel copolyamides were synthesized by the direct polycondensation of 1,2‐dihydro‐2‐(4‐carboxyphenyl)‐4‐[3‐chloro‐4‐(4‐carboxyphenoxyl)phenyl]‐phthalazinone ( 1 ), terephthalic acid (TPA) with three commercial diamines. The inherent viscosities of the polyamides were between 0.82 and 1.86 dL/g. When the molar ratios of 1 and TPA were higher than 1 : 1, the polymers were soluble in some polar aprotic solvents such as N‐methyl‐pyrrolidone and N,N‐dimethyl acetamide etc. These polymers were amorphous with 10% weight loss temperatures in N₂ above 490°C and their glass transition temperatures were above 269°C. Some films of the polymers were pale yellow and transparent with tensile strengths up to 147.8 MPa, initial modulus up to 2.56 GPa and elongations at break values up to 9.8%, which depended on the repeating unit structures. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis and characterization of novel chain‐extended bismaleimides containing fluorenyl cardo structure

Novel fluorenyl cardo chain‐extended bismaleimides (FCCEBMIs) were synthesized by reacting maleic anhydride with fluorenyl cardo diamine and different dianhydrides. FCCEBMIs were characterized by FT‐IR spectra (FT‐IR), ¹H NMR, and elemental analysis. All FCCEBMI monomers were readily soluble in a variety of organic solvents, such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethyl acetamide, chloroform (CHCl₃), methylene chloride (CH₂Cl₂), dimethyl sulfoxide, and tetrahydrofuran when compared with 9,9‐bis(4‐maleimidophenyl) fluorene. Curing process was investigated by differential scanning calorimetry. Thermal properties of the cured FCCEBMIs were characterized by thermogravimetry analysis, the cured products are stable up to 430°C. The results show that the FCCEBMIs with imide structure improve significantly the solubility of bismaleimide (BMI) in organic solvents without sacrificing thermal properties of cured BMIs. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal and mechanical evaluation of cyanate ester resin catalyzed by nonylphenol and stannous octoate

Nonylphenol (NP), stannous octoate [Sn(Otc)₂], and a mixture of NP and Sn(Otc)₂ were employed for catalyzing cyanate ester resin. The curing reaction was studied by differential scanning calorimetry. A water‐absorption test at 85 °C was utilized to study the resistance to warm and humid conditions. The thermal properties were evaluated through measuring thermal weight loss and the glass‐transition temperature (T_g), and the mechanical properties were evaluated through three‐point bending tests and tensile tests. The results show that the mixture of NP and Sn(Otc)₂ exhibits the best catalytic efficiency by decreasing the exothermic peak temperature by almost 148 °C. The mixture of NP and Sn(Otc)₂ has unfavorable effects on the thermal stability. Nevertheless, all catalyst systems have good water‐absorption resistance. The mechanical investigation confirms that the tensile properties show a little reduction that is due to the plasticization of the catalyst, while the excellent flexural properties are maintained. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43959.     

High‐performance polymeric materials with greatly improved mechanical and thermal properties from cyanate ester/benzoxazine resin reinforced by silane‐treated basalt fibers

This present article investigates the effect of silane‐treated basalt fibers (TBFs) on the morphological, mechanical and thermal properties of cyanate ester/benzoxazine (CE/BOZ) resin composites. The characterization was made using a scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), flexural test, impact strength (IS) test, microhardness test, dynamic scanning calorimetry, and thermogravimetric analysis. The mechanical test results inferred the distinctive improvements in the values of the flexural strength and modulus, IS, and microhardness of the CE/BOZ composites. The thermal stabilities in terms of the T_g, T_5%, T_10%, and T_HRI were appreciably improved and were higher than those of the pure CE/BOZ resin. Data from the SEM and FTIR tests ascertained the good dispersion and adhesion between the TBFs and the resin matrix, which might be behind the significant enhancement in the ultimate performances of the composites, with respect to the distinguished properties of BFs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46283.     

Syntheses and characterization of maleic anhydride–styrene–allyl propionate terpolymer ester derivatives

In this study, maleic anhydride (MA)–styrene (St)–allyl propionate (AP) was produced with MA, St, and AP. It was then reacted with n‐propyl alcohol (Pr), n‐butyl alcohol (Bu), n‐pentyl alcohol (Pn), and benzyl alcohol (Bz) under certain conditions to produce ester derivatives of the terpolymer. These ester derivatives were designated alkyl maleate terpolymers (PrMA–St–AP, BuMA–St–AP, PnMA–St–AP, and BzMA–St–AP). The polymers were investigated by solubility and viscosity experiments, with the number of ester groups in the polymers determined by chemical analysis. They were also characterized by Fourier transform infrared spectroscopy, with thermomechanical properties measured via stress–strain curves. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 296–299, 2003