Thermal behaviour of benzoxazine blends based on epoxy and cyanate ester

2021 ◽  
Vol 29 (9_suppl) ◽  
pp. S1475-S1485
Author(s):  
Balaji Krishnasamy ◽  
Hariharan Arumugam ◽  
Mohamed Iqbal M ◽  
Alagar Muthukaruppan
Keyword(s):  
High Performance ◽  
Analytical Techniques ◽  
Cyanate Ester ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Limiting Oxygen Index ◽  
Polymeric Matrices ◽  
Bisphenol F ◽  
Degradation Temperature ◽  
Cure Behaviour

In the present work, an attempt has been made to develop high-performance polymeric hybrid binary blends of epoxy/benzoxazine and benzoxazine/cyanate ester with varying weight percentages (25/75, 50/50 and 75/25 wt%) of resins, namely, bisphenol-F epoxy resin (DGEBF), benzoxazines [bisphenol–F/aniline (BF-a) and imidazole core-based bisphenol/aniline (IBP-a)] and cyanate ester [bisphenol-F bifunctional cyanate ester (BF-CE)]. The molecular structure, polymerisation temperature/cure behaviour, glass transition temperature (Tg) and thermal stability of the neat polymeric matrices and binary hybrid blends of polymeric matrices were characterised using different analytical techniques, viz. Fourier Transform infra-red spectroscopy (FTIR), Nuclear Magnetic Resonance spectroscopy (NMR), Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA). Among the binary hybrid blends, the lowest polymerisation temperatures (Tp) were noticed in the case of blends of epoxy/benzoxazine were 219°C for DGEBF/BF-a (25/75 wt%) and 170°C for DGEBF/IBP-a (25/75 wt%). Similarly, in the case of blends of benzoxazine/cyanate ester, the lowest values of Tp observed were 155°C and 153°C for BF-a/BF-CE (75/25 wt%) and IBP-a/BF-CE (75/25 wt%), respectively. The highest values of Tg observed for the blends of epoxy/benzoxazine were 175°C and 254°C for DGEBF/BF-a (25/75 wt%) and DGEBF/IBP-a (25/75 wt%), respectively. Whereas, the highest values of Tg observed in the case of blends of benzoxazine/cyanate ester were 234°C and 278°C for BF-a/BF-CE (25/75 wt%) and IBP-a/BF-CE (75/25 wt%), respectively. From the TGA results of blends, the maximum degradation temperature (Tmax) and limiting oxygen index (LOI) value calculated from the char yield, which ascertain that almost all the binary hybrid blends of epoxy/benzoxazine and benzoxazine/cyanate ester possess good flame retardant behaviour.

scholarly journals Synthesis and characterization of cyanate ester and its blends with bisphenol dicyanate ester

2008 ◽  
Vol 2 (4) ◽  
pp. 239-247
Author(s):  
Samikannu Rakesh ◽  
◽  
Muthusamy Sarojadevi ◽  
Keyword(s):  
Cyanate Ester ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Limiting Oxygen Index ◽  
Dsc Studies ◽  
Degradation Temperature ◽  
Ft Ir ◽  
Flame Retardant Properties ◽  
Lower Temperature

A new keto-ene functionalized 1, 5-bis (4-hydroxyphenyl)penta-1,4-dien-3-one (HPDO) was prepared from p-hydroxy benzaldehyde and acetone using boric acid as a catalyst. The prepared bisphenol was converted into 1,5-bis (4-cyanatophenyl) penta-1,4-diene-3-one (CPDO) by reacting with cyanogen bromide (CNBr) in the presence of triethylamine. The synthesized bisphenol and the dicyanate ester were characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H-NMR and 13C-NMR) and elemental analysis (EA) techniques. CPDO was then blended with a commercial bisphenol-A dicyanate ester (BADCy) at different ratios (100:0, 75:25, 50:50. 25:75, 0:100) and the cure characteristics were studied. CPDO was found to be cured at a lower temperature than BADCy. The cyanate ester blends were cured at 373 K (30 min) → 423 K (30 min) → 473 K (60 min) → 523 K (3h). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to study the thermal properties. DSC studies show that the cure (peak) temperature of CPDO with and without a catalyst was found to be 408 K and 466 K respectively. The initial degradation temperature of the cured resins was found to be in the range from 701 K to 705 K. The Limiting Oxygen Index (LOI) value, determined by Van Krevelen’s equation, shows that these blends have good flame retardant properties.

scholarly journals Synthesis and Characterization of N-Substituted Polyether-Block-Amide Copolymers

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 773
Author(s):  
Jyun-Yan Ye ◽  
Kuo-Fu Peng ◽  
Yu-Ning Zhang ◽  
Szu-Yuan Huang ◽  
Mong Liang
Keyword(s):  
Titanium Isopropoxide ◽  
Decomposition Temperature ◽  
Phenyl Isocyanate ◽  
Cross Linking ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Degradation Temperature ◽  
Melt Polycondensation ◽  
Structural Regularity

A series of N-substituted polyether-block-amide (PEBA-X%) copolymers were prepared by melt polycondensation of nylon-6 prepolymer and polytetramethylene ether glycol at an elevated temperature using titanium isopropoxide as a catalyst. The structure, thermal properties, and crystallinity of PEBA-X% were investigated using nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, wide angle X-ray diffraction, and thermogravimetric analysis. In general, the crystallinity, melting point, and thermal degradation temperature of PEBA-X% decreased as the incorporation of N-methyl functionalized groups increased, owing to the disruption caused to the structural regularity of the copolymer. However, in N-acetyl functionalized analogues, the crystallinity first dropped and then increased because of a new γ form arrangement that developed in the microstructure. After the cross-linking reaction of the N-methyl-substituted derivative, which has electron-donating characteristics, with poly(4,4′-methylenebis(phenyl isocyanate), the decomposition temperature of the resulting polymer significantly increased, whereas no such improvements could be observed in the case of the electro-withdrawing N-acetyl-substituted derivative, because of the incompleteness of its cross-linking reaction.

Synthesis, Characterization and Application of Multi-Generations Hyperbranched Polyurethane Based on Isophorone Diisocyanate

2012 ◽  
Vol 554-556 ◽  
pp. 126-129 ◽  
Author(s):  
Shun Yin ◽  
Ning Sun ◽  
Chun Yun Feng ◽  
Zhi Mou Wu ◽  
Zhao Hua Xu ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Raw Materials ◽  
Degradation Mechanism ◽  
Resonance Spectroscopy ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Isophorone Diisocyanate ◽  
Scanning Calorimetry ◽  
Degradation Temperature ◽  
Hyperbranched Polyurethane

A series of different generation hyperbranched polyurethane(HBPU) was synthesized based on the raw materials of isophorone diisocyanate(IPDI) and diethanolamine(DEOA). Their structure, thermal degradation mechanism and glass transition temperature(Tg) were characterized by fourier transform infrared spectroscopy(FTIR), nuclear magnetic resonance spectroscopy(NMR), thermal gravimetric analysis(TGA) and differential scanning calorimetry(DSC). The results showed that: the yield of each generation HBPU was up to 90%, different generation HBPU had almost the same initial degradation temperature(about at 200°C) and they all had two decomposition platforms; with the increase of generation, Tg increased from 107.2°C to 132.1°C. The gloss and hardness of the HBPU coatings were significantly improved.

scholarly journals Fabrication of thermo-regulating cotton fabric with enhanced flame retardancy via layer-by-layer assembly

2021 ◽  
Author(s):  
Yunbo Chen ◽  
Xiangyu Zhu ◽  
Xiang Li ◽  
Bijia Wang ◽  
Zhiping Mao ◽  
...  
Keyword(s):  
Flame Retardancy ◽  
High Performance ◽  
Cotton Fabrics ◽  
Melting Enthalpy ◽  
Residual Carbon ◽  
Layer By Layer ◽  
Scanning Calorimetry ◽  
Infrared Thermal Imaging ◽  
Limiting Oxygen Index ◽  
Lbl Assembly

Abstract The lack of thermo-regulation functionality and high flammability of cotton fabrics greatly restrict their application in high-performance fields. Herein, we report a versatile layer-by-layer (LbL) assembly strategy for introducing to cotton fabrics a multilayered coating consisted of phase change microcapsules and ammonium polyphosphate, endowing them with thermo-regulating and flame retardancy. The coated fabrics were characterized by limiting oxygen index (LOI), scanning electron microscopy (SEM), thermogravimetry (TG), differential scanning calorimetry (DSC) and infrared thermal imaging. The fabric deposited with 20 bilayers (MCPM/APP-20) showed improved flame retardancy with a LOI of 24.4% and residual carbon of 34.24%. It also shows a melting enthalpy of 30.16 J/g, which transferred to a temperature difference of 6.4 ℃ compared with pristine cotton. The functional endowed by the LbL assembly was reasonably durable, with melting enthalpy and residual carbon of MPCM/APP-20 reduced to 17.14 J/g and 19.82% after 30 laundering cycles. These results suggest that LbL assembly was a convenient way for functionalization of cotton fabrics.

Heat-resistant and photoluminescent indole-based poly(ether sulfone)s

2017 ◽  
Vol 30 (4) ◽  
pp. 475-479 ◽  
Author(s):  
Wenxuan Wei ◽  
Li Yang ◽  
Guanjun Chang
Keyword(s):  
Thermal Stability ◽  
High Performance ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Condensation Polymerization ◽  
High Glass Transition Temperature ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
High Performance Polymers ◽  
Good Agreement

Indole-based poly(ether sulfone)s (PINESs), as novel high-performance polymers, have been obtained by the condensation polymerization of 4-hydroxyindole and hydroquinone with activated difluoro monomers via a catalyst-free nucleophilic substitution reaction. The structures of the polymers are characterized by means of Fourier transform infrared and proton nuclear magnetic resonance spectroscopy, and the results show good agreement with the proposed structures. Differential scanning calorimetry and thermogravimetric analysis measurements exhibit that polymers possess high glass transition temperature ( Tgs > 245°C) and good thermal stability with high decomposition temperatures ( Tds > 440°C). In addition, due to their special structure, PINESs are endowed with significantly strong photonic luminescence in N, N-dimethylformamide.

scholarly journals Corrosion Resistance of Mild Steel Coated with Phthalimide-Functionalized Polybenzoxazines

Coatings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1114
Author(s):  
Kamal I. Aly ◽  
Abdulsalam Mahdy ◽  
Mohamed A. Hegazy ◽  
Nayef S. Al-Muaikel ◽  
Shiao-Wei Kuo ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Mild Steel ◽  
High Performance ◽  
Functional Group ◽  
Curing Temperature ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Mannich Reactions ◽  
Polymerization Behavior ◽  
Thermal Stability Of

Herein, we synthesized two new phthalimide-functionalized benzoxazine monomers, pPP-BZ and oPP-BZ, through Mannich reactions of 2-(4-hydroxyphenyl)isoindoline-1,3-dione (pPP) and 2-(2-hydroxyphenyl)isoindoline-1,3-dione (oPP), respectively, with p-toluidine and paraformaldehyde. The structures of these two monomers were confirmed using Fourier transform infrared (FTIR) and nuclear magnetic resonance spectroscopy. We used differential scanning calorimetry, FTIR spectroscopy, and thermogravimetric analysis to study the polymerization behavior and thermal stability of the monomers and their corresponding polybenzoxazines. Poly(pPP-BZ) and poly(oPP-BZ) were formed on mild steel (MS) through spin-coating and subsequent thermal curing polymerization. We used various corrosion testing methods to examine the effect of the curing temperature on the corrosion resistance of the coated MS samples in 3.5 wt.% aqueous solution of NaCl. Among our tested systems, the corrosion rate reached a low of 2.78 µm·Y−1 for the MS coated with poly(pPP-BZ)180 (i.e., the coating that had been cured at 180 °C); this value is much lower than that (4.8 µm·Y−1) reported for a maleimide-based benzoxazine compound (MI-Bz)/33 wt.% ACAT (amine-capped aniline trimer) blend. Thus, the incorporation of the imide functional group into the PBZ coatings is an effective strategy for affording high-performance corrosion resistance.

NIR spectroscopy vs. food pests: The case of stored rice

NIR news ◽  
2019 ◽  
Vol 30 (5-6) ◽  
pp. 18-21
Author(s):  
Alessandra Biancolillo ◽  
Patrizia Firmani ◽  
Remo Bucci ◽  
Andrea Magrì ◽  
Federico Marini
Keyword(s):  
High Performance ◽  
Nir Spectroscopy ◽  
Analytical Techniques ◽  
Plodia Interpunctella ◽  
Resonance Spectroscopy ◽  
Nutritional Properties ◽  
Physical Sensors ◽  
Food Commodities ◽  
Non Destructive ◽  
Food Commodity

Rice is one of the most widely consumed cereals, and it represents a staple food for several populations all over the world. One of the main peculiarities of this food commodity is that it can be stored for relatively long periods, maintaining its nutritional properties and its organoleptic attributes. Nevertheless, it is not uncommon that pests infest granaries, altering the characteristics of cereals, making them less valuable and/or un-edible. Avoiding the presence of insects in storehouses is a task difficult to accomplish; consequently, different methods for detecting pests’ infestation in food commodities have been developed. In general, they are based on physical sensors, or they exploit analytical techniques such as high-performance liquid chromatography, nuclear magnetic resonance spectroscopy, enzyme-linked immunosorbent assays or other bio-chemical devices to detect insects’ byproducts. Despite these approaches providing accurate results, they all present the same inconvenience: they are destructive. In the light of these considerations, the present work aims at developing a non-destructive NIR-based strategy to detect the presence of Plodia interpunctella, one of the most common intruders of granaries, in rice parcels. In order to achieve this goal, 1525 samples of rice have been analysed by NIR spectroscopy and then partial least squares discriminant analysis was used to discriminate the edible grains from the infested ones. The proposed methodology provided extremely good results, properly assigning 484 test samples over 500.

A new high performance novolac-based polytriazole resin

2016 ◽  
Vol 30 (1) ◽  
pp. 109-115 ◽  
Author(s):  
Lvyuan Ye ◽  
Liqiang Wan ◽  
Farong Huang
Keyword(s):  
Mechanical Property ◽  
Differential Scanning Calorimetry ◽  
High Performance ◽  
Infrared Analysis ◽  
Good Mechanical Property ◽  
Novolac Resin ◽  
Scanning Calorimetry ◽  
Click Polymerization ◽  
Degradation Temperature ◽  
Thermal Degradation Temperature

A novolac-based polytriazole (NPTA) resin was synthesized using 4,4′-diazidomethylbiphenyl and a propargylated novolac resin through catalyst-free click polymerization. Differential scanning calorimetry and Fourier transform infrared analysis results demonstrate that the NPTA resin can be cured at 80°C. The glass transition temperature of the cured NPTA-88 resin is 202°C. The thermal degradation temperature of the cured NPTA resin is 352°C under nitrogen. The composite of the resin exhibits good mechanical property.

Lacidipine: review of analytical methods developed for pharmaceutical dosage forms and biological fluids

Bioanalysis ◽  
2021 ◽  
Author(s):  
Sai Tejasvini Chebrolu ◽  
Lalit Kumar ◽  
Ruchi Verma
Keyword(s):  
High Performance ◽  
Limit Of Detection ◽  
Biological Fluids ◽  
Ultra Violet ◽  
Analytical Techniques ◽  
Dosage Forms ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Limit Of Quantification ◽  
Pharmaceutical Dosage Forms

Lacidipine (LAC) is a calcium antagonist used in the treatment of hypertension. It is a lipophilic drug containing dihydropyridine ring that is responsible for the activity. This review article gives an overview of various analytical techniques proposed for the determination of LAC in pharmaceutical dosage forms, in pure form, in biological fluids and to determine characteristics of LAC in modified release dosage forms. Ultra violet/visible spectrophotometric, spectroflourimetric, high performance liquid chromatography, high performance thin layer chromatography, electro-analytical, bioanalytical and miscellaneous methods such as microbiological assay, X-ray diffraction, differential scanning calorimetry, were discussed. Various parameters such as system suitability, selectivity, linearity, precision, accuracy, limit of detection, limit of quantification and robustness have been discussed for the employed methods.

Hydroxypropylation Reduces Gelatinization Temperature of Corn Starch for Textile Sizing

2021 ◽  
Author(s):  
Yanqin Shen ◽  
Yijun YAO ◽  
Zhongliang Wang ◽  
Hailiang Wu
Keyword(s):  
High Performance ◽  
Corn Starch ◽  
Water System ◽  
Hydroxyl Group ◽  
Resonance Spectroscopy ◽  
Gelatinization Temperature ◽  
Step Method ◽  
Scanning Calorimetry ◽  
Raw Starch ◽  
Substitution Level

Abstract A series of hydroxypropylated starch (HPS) that can be dissolved in water at 60-65℃ was obtained via two-step method in water system from corn starch. The structure and property of the HPS and its gelatinization temperature were characterized by Fourier transform infrared spectrometer (FTIR), nuclear magnetic resonance spectroscopy ( 1 H NMR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and transmission electron microscope (TEM). It was concluded that hydroxypropyl mainly bonded on the hydroxyl group at C 2 position from anhydroglucose unit of starch in the form of C-O-C, and the substitution level at C 6 position was slightly higher than that at C 3 position; and the crystallinity of starch decreased from 52.41% to 29.4% due to the introduction of hydroxypropyl and was confirmed by XRD. At the same time, the grooves on the surface of starch granules were observed by SEM. The above-mentioned two synergism promoted the permeation and transmission of water molecules in the starch microstructure. Moreover, the gelatinization temperatures and enthalpy of synthetic HPS was lower than that of raw corn starch, as further confirmed by DSC. This caused the HPS with a molar substitution greater than 0.1 soluble in water at 65℃, and the dissolution state was similar to that of at 95℃ (transmittance above 55%), as well as exhibited high slurry stability. Interestingly, compared with the raw starch, the HPS film showed excellent mechanical property at the relative humidity of 65%, which could be attributed to the hydrophilic ether bond and the flexible alkyl chain bonded on the structure of starch. This study will provide a new way for the preparation of high performance starch size for sizing yarn at medium low temperature.

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