Synthesis,characterization, and curing behavior of carborane‐containing benzoxazine resins with excellent thermal and thermo‐oxidative stability

Two benzoxazine precursors bearing carborane moiety ( 1 and 2 ) were designed and synthesized successfully by the Mannich reaction of corresponding carborane bisphenol ( 3 and 4 ) with aniline and formaldehyde in 1,4‐dioxane. The obtained precursors were characterized by using multiple spectroscopic techniques including GPC, FTIR, ¹H NMR, ¹³C NMR, and ¹¹B NMR. Nonisothermal DSC studies showed that precursor 1 owned lower apparent activation energies (E_a) than 2 . The optimum curing processes of benzoxazine precursors were also obtained on the basis of DSC data. TGA analyses manifested that the incorporation of carborane moiety endowed the obtained benzoxazine resins (cured 1 and 2 ) with excellent thermal stability and unique thermo‐oxidative stability. The T_d data showed that the initial degradation of both cured 1 and 2 under nitrogen and air was postponed to some extent owing to the shielding effect of carborane moiety on adjacent organic fragments. At higher temperature three‐dimensional polymer networks with B‐O‐B and B–C linkages were formed as chars by the reaction of carborane cage with atmospheric moisture, degradation products such as phenolic hydroxyl, and oxygen (under air). Under nitrogen this network hindered the motion of radicals formed at elevated temperature and thus inhibited further polymer degradation processes. While under air, the formed boron‐rich networks could hardly be further oxidized into carbon dioxide so that the carborane‐containing benzoxazine resins also showed very high char yields. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43488.     

Synthesis,structure, and properties of segmented carborane‐containing polyurethanes

Novel segmented carborane‐containing polyurethane (PUR 2–5) is synthesized from hydroxyl‐terminated carborane‐containing prepolymer (P3) as soft segment and isocyanate‐terminated carborane‐containing prepolymer (P5) as hard segment by different ratio of P3 and P5. The prepared carborane‐containing polyarylesters and polyurethanes (PURs) are characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). Their mechanical properties and thermal stability are measured, while the dosage of carborane biphenol is 5–10 wt %, the tensile strength is up to 20 MPa, and thermal gravimetric analyzer (TGA) curves indicate that the carborane group effectively reduces the degradation rate of carborane‐containing polyurethane, which is fairly stable above 300°C and with char yield exceeding 40%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42227.     

Novel phenyl acetylene terminated poly(carborane‐silane): Synthesis,characterization, and thermal property

Phenyl acetylene terminated poly(carborane‐silanec) (PACS) was synthesized by the couple reaction of methyldichlorosilane with 1,7‐dilithio‐m‐carborane and lithium phenylacetylide. The structure was characterized using FTIR, ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR, and gel permeation chromatography. PACS exhibits solubility in common organic solvents. Thermal and oxidative properties were evaluated by thermogravimetric analysis (TGA). Thermoset exhibits extremely thermal and oxidative property and TGA curves show that the temperature of 5% weight loss (Td₅) is 762°C and char yield at 800°C is 94.2% in nitrogen. In air, surprisingly, both Td₅ and char yield at 800°C show slight increase, which is greater than 800°C and 95.6%, respectively. After pyrolysis, the char has no additional weight loss up to 800°C in air. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2498–2503, 2007     

Thermal degradation studies of molybdenum containing polyester thermosets

A study has been made of the effect of molybdenum trioxide on the thermal degradation of a series of chlorinated and brominated polyester thermosets. Like antimony oxide, it showed flame retardant activity in all the halogenated polyesters. It was shown to affect the char yield, and the temperature and weight loss of each degradation step. X-Ray diffraction studies of the degraded dibromoneopentyl glycol polyesters showed that in air a near-quantitative yield of molybdenum trioxide was present above 550 °C. Some dioxide was present before the final char oxidation step occurred. In a nitrogen atmoshphere the trioxide was reduced to the dioxide at first, but this finally reacted to give the carbide at around 900 °C. Infrared spectroscopy showed that inclusion of the molybdenum trioxide resulted in structural changes in the high-temperature polyester residues which were more prominent when bromine was present. Elemental analysis of the residues indicated that the presence of the trioxide in the brominated polyesters accelerated the release of bromine at high temperatures and confirmed its char-promoting tendencies.     

Synthesis and characterization of new fluorinated aromatic polyesters containing trifluoromethylphenoxy pendant groups

A series of novel fluorinated aromatic polyesters containing trifluoromethylphenoxy pendant groups was synthesized by interfacial polycondensation of 2‐(4‐trifluoromethylphenoxy)terephthalyl chloride with various bisphenols in dichloromethane. The polyesters obtained in good yields had weight‐average molecular weights of 70,600–29,800 g/mol, polydispersities of 1.81–2.08, and were all amorphous. All polyesters were easily soluble in organic solvents such as N,N‐dimethylformamide, tetrahydrofuran, o‐chlorophenol, pyridine, and dichloromethane. These fluorinated polyesters showed glass transition temperature of 133–210°C, and good thermal stability with almost no weight loss up to 378°C, the 10% weight loss temperature of 472–523°C as well as char yield of 32–63% at 600°C in nitrogen. These polyester films cast from chloroform solutions exhibited tensile strengths ranging from 102 to 126 MPa, elongation at break from 6.3% to 11.7%, and tensile moduli from 2.1 to 3.3 GPa. The resulting polyester films also displayed low dielectric constants between 2.18 and 2.49 (1 MHz), high transparency with an ultraviolet‐visible absorption cut‐off wavelengths in the 332–355 nm range, and excellent electric strengths (50.4–65.6 kV/mm) and volume resistivity (2.51–6.03 × 10¹⁶ Ω cm). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and enzymatic degradation of high molecular weight aliphatic polyesters

The aliphatic polyesters with high molecular weight have been prepared according to two methods. First is the synthesis of the polyesters by polycondensation of dimethyl succinate (DMS) with 1,4‐butanediol (BD) using various metal alkoxides as a catalyst. Among the metal alkoxides used, titanium tetraisopropoxide [Ti(OiPr)₄] gave the best results (highest molecular weight and yield). Thus, we have prepared aliphatic polyesters using a variety combinations of diesters [MeOOC—(CH₂)_x—COOMe, x = 2–8] with BD by the catalysis of Ti(OiPr)₄. The polyesters with high number‐average molecular weight (M_n > 35,000), except dimethyl adipate (DMA, x = 4)/BD polyester (M_n = 26,900), were obtained in high yield. The melting temperatures (T_m) of polyesters were relatively low (43.4–66.8°C) except that (115.6°C) of the DMS/BD polyester. Second is the synthesis of high molecular weight polyesters by chain extension reaction of lower molecular weight (M_n = 15,900–26,000) polyesters using hexamethylene diisocyanate (HDI) as a chain extender. The M_n values of chain‐extended polyesters consequently increased more than two times (M_n = 34,700–56,000). The thermal properties of polyesters hardly changed before and after chain extension. Enzymatic degradations of the polyesters were performed using three different enzymes (cholesterol esterase, lipase B, and Rhizopus delemar lipase) before chain extension. The enzymatic degradability varied depending on both thermal properties of polyesters [melting temperature and heat of fusion (crystallinity)] and the substrate specificity of enzymes, but it was the following order: cholesterol esterase > lipase B > R. delemar lipase. The ¹H‐NMR spectrum of water‐soluble degraded products of the polyester indicated that the polyester was degraded into a condensation product of diol with diester in a monomer form. The enzymatic degradation of chain extended polyesters was slightly smaller than that before chain extension, but proceeded steadily. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 340–347, 2001     

光敏性含磷聚氨酯丙烯酸酯(P-PUA)阻燃预聚物的合成与性能

合成了4种不同结构的光敏性含磷聚氨酯丙烯酸酯阻燃预聚物,并对其结构进行了表征。研究了以所制预聚物为基料的光固化涂料的柔韧性、附着力、硬度等基本物理性能和耐热防火性能。结果表明,该涂料能达到市售PUA涂料的基本物理性能,并具有较高的分解温度,800℃下形成的炭渣能达到涂层原重的20%左右,具有一定的耐热防火性能;以结构相似的阻燃预聚物为基料的涂层,其耐热防火性能随含磷量的增加而提高;预聚物主链中芳环含量也影响涂层的耐热防火性能,相对分子质量相近的预聚物,其主链上的芳环数量增加一倍,涂层在800℃下w(炭渣)能增加5个百分点。     

New coating systems based on vinyl ether‐ and oxetane‐modified hyperbranched polyesters

A series of hyperbranched aliphatic‐aromatic polyesters has been synthesized which contain vinyl ether or oxetane functionalities as curable groups. We investigated the curing behavior of these multifunctional polymers in the presence of reactive diluents in order to analyze the possibility of their application in high solids coatings. The vinyl ether‐modified hyperbranched polyesters with a high degree of modification yield the best coatings. Furthermore, coating systems containing vinyl ether‐modified hyperbranched polyesters and triethyleneglycol divinyl ether (DVE‐3) as reactive diluent showed a better performance compared to those containing 4‐hydroxybutyl vinyl ether (HBVE). Real time FT‐IR studies revealed a high conversion of functional groups (76%) for the cationic curing with DVE‐3. On the other hand, the curing reaction of the functional hyperbranched polymers without the presence of any reactive diluent stopped at 32% conversion of functional groups due to the reduced mobility of the polymer. The vinyl ether‐modified hyperbranched polyester could be cured also radically in the presence of diethyl maleate (DEM) as reactive diluent, whereas the curing of the oxetane‐modified polyesters was very slow and incomplete in all attempts.     

Crystallization kinetics,mechanical properties,and hydrolytic degradation of novel eco‐friendly poly(butylene diglycolate) containing ether linkages

The basic thermal properties, isothermal melt crystallization kinetics, spherulitic morphology, mechanical properties, and hydrolytic degradation behavior of a novel eco‐friendly polyester poly(butylene diglycolate) (PBDG) containing ether linkages were systematically studied with several techniques in this research. PBDG is an aliphatic polyester with high thermal stability. It had a glass transition temperature (T_g) of ?25.7 °C, a melting point temperature of 65.1 °C, and an equilibrium melting point of 73.2 °C. During the isothermal melt crystallization, PBDG crystallized slowly with increasing crystallization temperature, but the crystallization mechanism did not change. Negative spherulites were observed for PBDG. The mechanical properties of PBDG were investigated from the tensile testing. As a ductile polyester, PBDG possessed good mechanical properties. PBDG also showed a fast hydrolytic degradation rate. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44186.     

Ionic polymers with tunable liquid‐crystalline properties

Side‐chain polyesters were synthesized from N‐octyl‐, N‐dodecyl‐ or N‐hexadecyl‐diethanolamine and succinic acid anhydride. These polyesters were then transformed into polyester hydrochlorides by protonation of the amino groups using different amounts of HCl (20–100 mol%). Above 60 mol% the reaction is not quantitative and a degree of protonation of up to 88% is obtained. The structures of the synthesized polyesters and their hydrochlorides were determined by ¹H nuclear magnetic resonance spectroscopy. The thermal properties of the synthesized polyesters and their hydrochlorides were also studied using differential scanning calorimetry in relation to the side‐chain length and the degree of polyester protonation. The polyester with octyl side chains and its hydrochlorides were amorphous liquids at room temperature, while the polyester and polyester hydrochlorides with hexadecyl side chains formed a smectic crystalline phase, S_mB, or its tilted analogues. The polyester with a dodecyl side chain was also an amorphous liquid at room temperature, while its hydrochlorides with various degrees of protonation were smectic liquid crystals, as determined by X‐ray diffraction. By simply varying the degree of protonation the liquid crystal isotropization temperature was increased from 32 °C to 82 °C. Copyright © 2011 Society of Chemical Industry     

Influence of ultrafine zinc borate on the thermal degradation behavior of a(low‐density polyethylene)/(intumescent flame retardant) system

The thermal degradation behavior of low‐density polyethylene (LDPE), LDPE treated with an intumescent flame retardant (LDPE/IFR), and LDPE treated with an intumescent flame retardant and ultrafine zinc borate (LDPE/IFR/UZB) was studied by (thermal gravimetric)‐(differential thermal) analysis (TG‐DTA) and cone calorimetry. The results of TG‐DTA showed that the initial degradation temperature increased, thermal degradation rate decreased, and the residual char amount increased substantially during the Pyrolysis process when ultrafine zinc borate was introduced into the LDPE/IFR system. The mass‐loss rate (MLR) curves and mass curves obtained by cone calorimetry showed that UZB could decrease the MLR and significantly enhance the residual char amount of LDPE/IFR during the combustion process. The results of Fourier transform infrared spectroscopy implied that a graphite‐like char and aromatic structures containing P‐O‐P, P‐O‐C, and B‐O‐B bonds were formed when LDPE/IFR/UZB was heated at high temperature. Scanning electronic micrographs of residual chars showed that ultrafine zinc borate improved char quality. X‐ray diffraction Studies implied that boron orthophosphate (BPO₄) formed in the residual char may play an important role in improving the structural properties of the char and is responsible for its good quality. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Synthesis and properties of aliphatic spirodilactam diphenol containing polyesters

A series of aromatic polyesters containing 1,6-diazaspiro[4,4]-nonane-2,7-dione were synthesized under phase-transfer conditions. The copolymers were obtained in essentially quantitative yield, theses were soluble in common organic solvents, and would readily form clear, colorless films from solution. The optimum conditions of polymerization, was obtained via polycondensation at room temperature and reaction time of 4 h in chloroform. All polymers were characterized by FTIR, GPC, viscosity, water contact angle, water absorption, TGA, DSC and TMA. The prepared polyesters showed excellent thermal stability, as measured by TGA (10 wt% loss), are only moderate due to the alicyclic component and range from 365 to 401 °C in air; however, glass transition temperatures are quite high (245-309 °C). The inherent viscosities of these solutions ranged from 0.77 to 1.40 dl g⁻¹, depending on the polyester structure. The structures of the polyesters were confirmed by FTIR spectroscopy.     

Preparation,thermal, and flammability of halogen‐free flame retarding thermoplastic poly(ether‐ester) elastomer/montmorillonite nanocomposites

In this article, the nanocomposites thermoplastic polyester‐ether elastomer (TPEE) with phosphorous–nitrogen (P–N) flame retardants and montmorillonite (MMT) was prepared by melt blending.The fire resistance of nanocomposites was analyzed by limiting oxygen index (LOI) and vertical burning (UL94) test. The result shows that the flame retardants containing P–N increased the LOI of the material from 17.3 to 27%. However, TPEE containing P–N flame retardants just got UL94 V‐2 ranking, which resulted in the flaming dripping phenomenon. On the other hand, TPEE containing P–N flame retardant and organic‐modified montmorillonite (o‐MMT) achieved UL94 V‐0 rating for the special microstructure. The XRD and TEM morphology has demonstrated that the formation of multi‐ordered structure regarding restricted segmental motions at the organic–inorganic interface and stronger interactions between the clay mineral layers and the polymer chains. The structure was supported by the results of rheological properties and DSC analysis. The thermal degradation and char residue characterization was studied by thermal gravimetric analysis (TGA) and SEM‐EDX measurements, respectively. The TGA and SEM‐EDX have demonstrated that o‐MMT results in the increase of char yield and the formation of the thermal stable carbonaceous char. POLYM. COMPOS., 37:700–708, 2016. © 2014 Society of Plastics Engineers     

Polymer/clay nanocomposite plasticization: Elucidating the influence of quaternary alkylammonium organic modifiers

The potential of nanoclay organic modifiers to induce plasticizing effects in resin and coatings systems was studied. In previous work, it was found that while low amounts of incorporation of organomodified clays significantly improved the physical and mechanical properties of a ultraviolet (UV)‐curable nanocomposite, further increasing the organomodified clay content could result in the reduction of properties. To investigate the potential impact of the organic modifier composition and concentration on polymer properties, a series of experiments were carried out using only the organic modifier. Methyl, tallow, bis‐2‐hydroxyethyl ammonium (MTEtOH), the organic modifier used in montmorillonite clay Cloisite® 30B, was dispersed with precursor polyester oligomers at 1–10 wt % through an in situ synthesis process and via sonication, and UV‐curable coatings were prepared from these MTEtOH‐containing resins. The organic modifier cetyltrimethylammonium bromide (CTAB) was also studied to examine the impact of the organic modifier structure. According to differential scanning calorimetry, small decreases in the glass transition temperatures (T_g) of the MTEtOH‐containing polyesters were observed, but CTAB‐containing polyesters had small T_g increases. Polyester molecular weight and viscosity were also affected by both the structure of the organic modifier as well as its concentration. The mechanical performance of the UV‐curable coatings diminished with increased MTEtOH concentration for the films containing the organic modifier compared to a control film. Furthermore, the crosslink density was found to reduce ～ 50% with increased MTEtOH loading into the UV‐curable films. The cure characteristics, thermal stability, and optical clarity were also studied. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The thermal stability investigation of microencapsulated ammonium polyphosphate/siloxane‐modified epoxy resin composites

In this investigation, epoxy resin composites containing phosphate and silicone were prepared from microencapsulated ammonium polyphosphate (MFAPP) and poly(methylphenyl siloxane) (PMPS). Silicone‐containing epoxy (E‐S) copolymers were gained by the grafting reaction between ? OCH₃ of PMPS and ? OH of E51. And, a fixed weight of MFAPP was introduced to epoxy systems via the physical blending method. The chemical structure of the E‐S copolymer was determined by Fourier transform infrared spectroscopy (FTIR) and ¹H‐NMR. The impact testing results revealed that the impact toughness was improved slightly. The thermogravimetric analysis (TGA) results demonstrated that the thermal degradation property in high temperature region and solid residue yield at 800 °C were enhanced remarkably with increasing PMPS content, whether the testing atmosphere was in nitrogen or oxygen. Moreover, an obvious synergistic effect of silicon and phosphorus on promoting the thermo‐oxidative degradation stability and solid residue at 800 °C was proved. Furthermore, the scanning electron microscope micrographs and FTIR result of residual charred crusts of EA‐S systems after the TGA testing in air manifested that the bubbled charred layer and silicon‐ and phosphorus‐containing residue took chief responsibility for thermo‐oxidative degradation property and solid residue yield. So the MFAPP/siloxane‐modified epoxy resin composites have a significant development prospect in high‐temperature resistant organic adhesives and coatings. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45272.     

Synthesis and properties of novel star-shaped polyesters based on l-lactide and castor oil

The topology of biodegradable polyesters can be adjusted by incorporating multifunctional polyols into the polyester backbone to obtain branched polymers. The aim of this study was to prepare the biodegradable-branched polyester polyols based on l-lactide and castor oil using the trifluoromethanesulfonic acid as a catalyst. FTIR and ¹H NMR spectroscopy measurements were used to estimate the molecular structure of the novel materials. The polyester polyol was synthesized by ‘‘core-first” method which involves a polymerization of l-lactide by using a castor oil as multifunctional initiator. Molar masses estimated by gel permeation chromatography and vapor pressure osmometry were in good correlation with calculated values based on hydroxyl number of obtained polymers. DSC measurements confirmed high crystallinity degree of the synthesized material. It was assessed that the molar masses of obtained polymers-influenced glass transition temperature significantly. The thermal stability was investigated by TG analysis, and the results have shown the dependence of weight loss on the arm length of the star-shaped polyesters. The thermal stability of star-shaped polyesters significantly decreased with degradation of polyester polyol obtained in acid solution.     

Ethynyl aromatic siliconhybridized resin: Synthesis,characterizations, and thermal properties

A novel silicon‐containing resin (ESA resin) was successfully synthesized by the condensation reaction of lithium arylacetylide with chlorosilane in high yields. The resin was characterized by the techniques of FTIR, ¹H‐NMR, ²⁹Si‐NMR, and gel permeation chromatography. Thermal cure process was monitored by DSC and FTIR methods. This resin could melt at around 100°C and thermally cured at 200–250°C with low exothermal enthalpy. Owing to the high aryl groups containing and the complete crosslinking of ethynyl groups, the cured ESA resin exhibited excellent thermal stability and high char yield. The decomposition temperature $T_{d_5}$ of the cured resin was at 510°C, and the residue yield at 900°C was 82.9% in N₂. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Flame‐retardant polyesters. II. Polyester polymers

Two flame‐retardant polyesters were polymerized with two types of phosphorous flame retardants. 3‐(Hydroxyphenyl phosphinyl)propanoic acid (HPP) was used as a main‐chain type, and 9,10‐dihydro‐9‐oxa‐10‐2,3‐dicarbonylpropyl‐10‐phosphophenanthrene‐10‐oxide (DI) was used as a pendant type. Polymerization was accomplished on a commercial scale with a three‐reactor system to exclude the compositional variation of oligomeric ethylene terephthalate. A longer polycondensation time and a higher dosage of the catalyst were necessary for DI with respect to HPP because of the high content and relatively low reactivity of the flame retardant. However, the content of diethylene glycol (DEG) in the polyester, which formed during the polymerization, was much higher in the case of HPP. The produced polyesters had almost the same molecular weight, but the DEG contents in the polyesters were quite different. The higher DEG content in the HPP polyester reduced the thermal stability. The greater flexibility of the HPP polyester chain resulted in easier crystallization and a lower crystalline temperature. The HPP polyester had higher susceptibility to thermal degradation because of low resistance to thermal chain scission, degraded at a lower temperature, and was more easily degraded because of a weak P? O bond linkage in the main chain. The DI polyester, whose phosphorous atom was highly sterically hindered, showed better alkaline resistance than the HPP polyester because of the lower acidity and lower hydrophilic DEG content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Flame retardancy and thermal degradation behaviors of epoxy resins containing bisphenol a bis (diphenyl phosphate) oligomer

Bisphenol A bis(diphenyl phosphate) oligomer (BBO) as flame retardant was synthesized, whose structure was characterized by IR and NMR. In all, 20% weight mixture polyphosphoric acid (APP) and BBO was doped into epoxy resins (EPs) to get 26.0% of limiting oxygen index and UL 94 V‐0. The degradation behavior of EP‐containing BBO/APP was studied by thermogravimetry, differential thermogravimetry, scanning electron microscopy, and cone calorimeter. The activation energies for the decomposition of EP samples are obtained using the method of Kissinger. The experimental results exhibited that for EP‐containing BBO/APP, compared with EP, initial decomposition temperature, maximum temperature at the peak position (T_m), and the activation energy for the decomposition are decreased, whereas the maximum weight loss rate (R_max), char yields, and the inherent thermal stability are increased. Meanwhile, heat release, smoke production, and CO yield and CO₂ yield of EP‐containing BBO/APP are much decreased compared with those of EP. The thermal degradation mechanism of EP‐containing BBO/APP has been proposed. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

Synthesis and thermal property of boron–silicon– acetylene hybrid polymer

Inorganic–organic boron–silicon–acetylene hybrid polymer (PABS) was prepared by the polycondensation reaction between phenylboric acid and diphenyldichlorosilane and then terminated by phenylacetylene. The structure was characterized by using FTIR, ¹³C‐NMR, ¹H‐NMR, and GPC. PABS was a kind of resin exhibited high viscous at room temperature and good solubility in common organic solvents. The thermal and oxidative properties were evaluated by DSC and TGA. Exothermal peak at 370°C observed by DSC was attributed to reaction of the acetylene units. PABS showed excellent thermal and oxidative stability, and TGA exhibited the temperature of 5% weight loss (Td₅) was 625°C and char yield at 900°C was 90.0% in nitrogen. Surprisingly, both Td₅ and char yield at 900°C showed slightly increase in air, which was 638°C and 90.9%, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011