Synthesis and Characterization of Poly(glycidyl nitrate‐block‐caprolactone‐block‐glycidyl nitrate) (PGN‐PCL‐PGN) Tri‐Block Copolymer as a Novel Energetic Binder

An energetic binder was synthesized through ring opening copolymerization of glycidyl nitrate (GLYN) with polycaprolactone (PCL) as a macroinitiator to form tri‐block copolymer PGN‐PCL‐PGN. Effect of monomer concentration, catalyst, reaction time and solvent was investigated in polymerization. Resulting tri‐block copolymer was characterized by Fourier transform infrared spectroscopy (FT‐IR), nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The DSC result shows that glass transition temperature of tri‐block copolymer (T_g=−56.2 °C) is lower than PGN (T_g=−35 °C). In optimal condition, the M_w of this polymer was obtained 2900 g/mol.     

Synthesis,characterization, thermal stability,and compatibility properties of poly(vinyl p‐nitrobenzal acetal)‐g‐polyglycidylazides

A series of energetic polymers, poly(vinyl p‐nitrobenzal acetal)‐g‐polyglycidylazides (PVPNB‐g‐GAPs), are obtained via cross‐linking reactions of poly(vinyl p‐nitrobenzal acetal) (PVPNB) with four different molecular weights polyglycidylazides (GAPs) using toluene diisocyanate as cross‐linking agent. The structures of the energetic polymers are characterized by ultraviolet visible spectra (UV‐Vis), attenuated total reflectance‐Fourier transform‐infrared spectroscopy (ATR‐FT‐IR), ¹H nuclear magnetic resonance spectrometry (¹H NMR), and ¹³C nuclear magnetic resonance spectrometry (¹³C NMR). Differential scanning calorimetry (DSC) is applied to evaluate the glass‐transition temperature of the polymers. DSC traces illustrate that PVPNB‐g?2^#GAP, PVPNB‐g?3^#GAP, and PVPNB‐g?4^#GAP have two distinct glass‐transition temperatures, whereas PVPNB‐g?1^#GAP has one. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) are used to evaluate the thermal decomposition behavior of the four polymers and their compatibility with the main energetic components of TNT‐based melt‐cast explosives, such as cyclotetramethylene tetranitramine (HMX), cyclotrimethylene‐trinitramine (RDX), triaminotrinitrobenzene (TATB), and 2,4,6‐trinitrotoluene (TNT). The DTA and TGA curves obtained indicate that the polymers have excellent resistance to thermal decomposition up to 200°C. PVPNB‐g?4^#GAP also exhibits good compatibility and could be safely used with TNT, HMX, and TATB but not with RDX. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42126.     

Preparation of polysiloxane with pendant Cr‐bound carbazole chromophore for nonlinear optics

A novel η⁶‐complex of N‐allylcarbazole containing chromium tricarbonyl was synthesized. This complex was hydrosilylated with polymethylhydrosiloxane to afford a substituted polymer. Both the complex and the polymer were characterized by classical spectroscopy techniques (FTIR, NMR, and UV–vis), gel permeation chromatography, elemental analysis, and thermal analysis (TGA and DSC). The glass transition temperature of the polymer was found to be above 100°C and its thermal decomposition temperature was above 280°C. The polymer was amorphous in nature and formed excellent homogeneous films of good optical transparency. The third nonlinear optical properties of this polymer film coated on quartz substrate were studied by time‐resolved forward degenerate four‐wave mixing (DFWM). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of poly(vinyl butyral)s in homogeneous phase and their thermal properties

The condensation reaction of butyraldehyde (BA) with poly(vinyl alcohol) (PVA) to give poly(vinyl butyral) (PVB) was studied in detail using N‐methyl‐2‐pyrrolidone (NMP) as solvent for PVA and PVBs. PVBs having various degrees of acetalization were obtained. The acetalization reaction under a variety of conditions gave at best a polymer with 97% acetalization. The extent of modification and the structure of the polymer, i.e., the ratio of acetal units from meso and racemic dyads of PVA, were determined by ¹H‐NMR. The acetalization degree was reflected in the solubility of PVB; all products were soluble in NMP. PVBs were characterized by IR spectroscopy and ¹H and ¹³C‐NMR. The glass transition temperatures of PVBs, determined by DSC, increased as vinyl alcohol units increased and displayed a positive departure from linearity. Thermal degradation of PVBs was studied using differential thermal analysis (DTA) and thermogravimetry (TGA) under dynamic conditions in nitrogen. The content of hydroxyl groups had an effect on the thermal stability of PVBs; the thermal stability of PVBs decreased as vinyl alcohol units increased. The apparent activation energy of the decomposition was determined by the Kissinger and Flynn–Wall methods, which agree well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5007–5017, 2006     

Thermal characteristics of poly(vinyl alcohol) and poly(vinylpyrrolidone) IPNs

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) (PVA) and 1‐vinyl‐2‐pyrrolidone (VP) were prepared by radical polymerization using 2,2‐dimethyl‐2‐phenylacetophenone (DMPAP) and methylene bisacrylicamide (MBAAm) as initiator and crosslinker, respectively. The thermal characterization of the IPNs was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). Depressions of the melting temperatures of PVA segments in IPNs were observed with increasing VP content via the DSC. The DEA was employed to ascertain the glass transition temperature (T_g) of IPNs. From the result of DEA, IPNs exhibited two T_gs indicating the presence of phase separation in the IPN. The thermal decomposition of IPNs was investigated using TGA and appeared at near 270°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1844–1847, 2002     

聚乙烯醇缩对硝基苯甲醛的合成与热稳定性

以聚乙烯醇（PVA）和对硝基苯甲醛为原料,二甲基亚砜为溶剂,对甲基苯磺酸为催化剂,采用均相工艺合成得到聚乙烯醇缩对硝基苯甲醛（PVPNB）。通过衰减全反射-傅里叶红外光谱（ATR-FTIR）、紫外可见光谱（UV-Vis）、核磁共振氢谱（¹H NMR）等测试手段对聚乙烯醇缩对硝基苯甲醛结构进行了表征。利用差示扫描量热仪（DSC）测定了聚乙烯醇缩对硝基苯甲醛的玻璃化温度（T_g）。采用差热分析（DTA）和热重分析（TGA）对聚乙烯醇缩对硝基苯甲醛热稳定性进行研究。DSC结果表明,聚乙烯醇缩对硝基苯甲醛的玻璃化温度为160 ℃。DTA和TGA结果表明,聚乙烯醇缩对硝基苯甲醛具有较好的热稳定性。     

Degradation of high barrier ethylene–vinyl alcohol copolymer under mild thermal‐oxidative conditions studied by thermal analysis and infrared spectroscopy

A study of the thermal‐oxidative degradation of a high barrier ethylene–vinyl alcohol copolymer with 32 mol% of ethylene (EVOH) has been carried out by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier‐transform infrared spectroscopy (FTIR) under mild temperature conditions above melting. It was found that time exposures of up to 11 h at temperatures between 9 and 33 °C above the EVOH melting point resulted in polymer weight losses of up to 3.6% with colour formation. The weight loss was faster at short times and slowed down with increasing exposure time. DSC showed a small decrease in crystallinity and melting point, melting‐peak broadening and a slight increase in the glass transition temperature of the samples subjected to the more severe thermal‐oxidative treatment. The FTIR experiments showed transformation of the vinyl alcohol hydroxyl groups into carbonyl groups and creation of double bonds. Changes in degradation kinetics and perhaps in mechanisms are thought to occur with increasing exposure time. Moreover, FTIR measurements suggest that transformation of the hydroxyl groups leads to a weakening of the overall hydrogen bonding strength in the degraded samples, and therefore a reduction in intermolecular cohesion can be anticipated. © 2001 Society of Chemical Industry     

Synthesis,characterization and biological activity of 3‐(1‐cyclohexyl)azetidinyl methacrylate monomer and its homopolymer

3‐(1‐Cyclohexyl)azetidiniyl methacrylate (CyAMA), a new methacrylate monomer, was synthesized by reaction of the sodium salt of 1‐cyclohexylazetidin‐3‐ol with methacryloyl chloride. The monomer was polymerized at 60 °C in 1,4‐dioxane solution using 2,2′‐ azobisisobutyronitrile (AIBN) as an initiator. CyAMA and poly(CyAMA) were characterized by FTIR and ¹H and ¹³C NMR spectroscopy. The activation energy of the initiation step of the polymerization was estimated from initial rates, and the number average molecular weight of the homopolymer was determined by gel permeation chromatography (GPC). The antibacterial and antifungal effects of the monomer and homopolymer were investigated on various bacteria and fungi. The thermal stability of poly(CyAMA) was investigated by TGA, and its glass transition temperature was determined by DSC as 93 °C. © 2000 Society of Chemical Industry     

Effect of different aromatic amines on the crosslinking behavior and thermal properties of phthalonitrile oligomer containing biphenyl ethernitrile

To find a proper amine to promote the processability of phthalonitrile‐based composites, three different aromatic amines: 4‐aminophenoxyphthalonitrile (APN), 2,6‐bis (4‐diaminobenzoxy) benzonitrile (BDB) and 4,4′‐diaminediphenyl sulfone (DDS) were used as curing agents to investigate the crosslinking behavior and thermal decomposition behavior of phthalonitrile oligomer containing biphenyl ethernitrile (2PEN‐BPh). Differential scanning calorimeter (DSC) and dynamic rheological analysis were employed to study the curing reaction behavior of the phthalonitrile/amine blends and prepolymers. The studies revealed that BDB was the preferred curing agent and the preferred concentration of BDB was 3 wt %. The thermal properties of the 2PEN‐BPh polymers were monitored by TGA, and the results indicated that all the completely cured 2PEN‐BPh polymers maintained good structure integrity upon heating to elevated temperatures and these polymers could thermal stabilize up to over 550°C in both air and nitrogen atmospheres. Dynamic mechanical analysis (DMA) showed the glass transition temperature (T_g) exceeded 450°C when the 2PEN‐BPh polymer post cured at 375°C for 8 h. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal characteristics of IPNs composed of polyallylamine and chitosan

Interpenetrating polymer network (IPN) hydrogels composed of polyallylamine and chitosan were synthesized by radical polymerization using 2,2‐dimethyl‐2‐ phenylacetophenone (DMPAP) and methylene bisacrylicamide (MBAAm) as initiator and crosslinker, respectively. The IPNs thus obtained were characterized by using Fourier transform infrared (FT‐IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). The melting temperatures of IPNs were observed with increasing chitosan content by DSC. DEA was employed to ascertain the glass transition temperature (T_g) of IPNs. From the result of DEA, IPNs exhibited two T_gs indicating the presence of phase separation in the IPN. The thermal decomposition of IPNs was investigated by TGA and appeared at near 270 °C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1956–1960, 2002     

Thermal characteristics of interpenetrating polymer networks composed of poly(vinyl alcohol) and poly(N‐isopropylacrylamide)

Interpenetrating polymer networks (IPNs) composed of poly(vinyl alcohol) (PVA) and poly(N‐isopropylacrylamide) (PNIPAAm) were prepared by the sequential‐IPN method. The thermal characterization of the IPNs was investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). Depression of the melting temperature (T_m) of the PVA segment in IPNs was observed with increasing PNIPAAm content using DSC. DEA was employed to ascertain the glass‐transition temperature (T_g) of IPNs. From the result of DEA, IPNs exhibited two T_g values, indicating the presence of phase separation in the IPNs. The thermal decomposition of IPNs was investigated using TGA and appeared at near 200°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 881–885, 2003     

Synthesis,polymerization, and properties of the allyl‐functional phthalonitrile

A novel bisphthalonitrile monomer containing allyl groups (DBPA‐Ph) had been synthesized via the reaction of diallyl bisphenol A (DBPA) and 4‐nitrophthalonitrile. The chemical structure of DBPA‐Ph was confirmed by ¹HNMR, ¹³CNMR, and FTIR spectroscopy. The curing behaviors and processability of DBPA‐Ph were studied by differential scanning calorimetry (DSC) and dynamic rheological analysis. The monomer manifested a two‐stage thermal polymerization pattern. The first stage was attributed to the polymerization of allyl groups and the second to the ring‐form polymerization of cyano groups. The result of dynamic rheological analysis indicated the monomer had wide curing window and the self‐catalyzed curing behavior. DBPA‐Ph polymers were prepared from the thermal polymerization with short curing time, showing high glass transition temperature (>350°C) and attractive thermal decomposition temperature (>430°C). The outstanding glass transition temperature, desirable thermo‐oxidative stabilities, good processability and sound process conditions could provide more applications to the DBPA‐Ph polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41203.     

Synthesis and properties of a novel bismaleimide resin containing 1,3,4‐oxadiazole moiety and the blend systems thereof with epoxy resin

A new bismaleimide monomer, 2‐((4‐maleimidophenoxy)methyl)‐5‐(4‐maleimidophenyl)‐1,3,4‐oxadiazole (Mioxd), was designed and synthesized. The chemical structure of the monomer was confirmed by means of Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (¹H NMR) spectroscopy and elemental analysis, and its thermal properties were characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Mioxd as a reactive modifier was blended with epoxy resin based on bisphenol A diglycidyl ether (DGEBA) in weight ratio of 5, 10, and 15%, using 4,4′‐diaminodiphenyl sulfone (DDS) as hardener. The effect of Mioxd addition on the cure behavior and thermal properties of the blend resins was studied by DSC, TGA, and dynamic mechanical analysis (DMA). DSC investigations showed that the main exothermic peak temperature (T_p) of the blend systems did not obviously shift with increasing Mioxd content whereas a new shoulder appeared and gradually grew on the high temperature side of the exothermic peak. The results of DMA measurements exhibited the glassy storage modulus (G') and glass transition temperatures (T_g) increased as the Mioxd content was increased, the cured blends investigated were miscible and no phase separation occurred. Further, the thermal decomposition temperature first decreased and then increased, but the char yield at 600°C increased with an increase in Mioxd content. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Investigation of novel polytriazole resins

2,4,6-Tri(4-propargyloxy-phenyl)pyridine(POPP) was made from 2,4,6-tri (4-hydroxyphenyl)pyridine(HPP) and propargyl bromide. The chemical structures of POPP and HPP were well characterized by means of FTIR, ¹H-NMR, ¹³C-NMR, and elemental analysis. Novel polytriazole resins (P-PTA resins) were prepared from POPP and azide compounds via 1, 3-dipolar cycloaddition reaction and characterized by solubility, FTIR, DSC, and TGA analyses. The P-PTA resins show good solubility in common solvents. The resins could be cured at 80 °C. The glass transition temperature (T_g) and the 5% weight loss temperature (T_d5) of the cured P-PTA-33 resin arrive at 310 and 365 °C in nitrogen atmosphere, respectively.     

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     

Grafting of poly(vinyl chloride) and polypropylene with styrene in a supercritical CO2 solvent medium: Synthesis and characterization

Graft copolymerization of styrene onto poly(vinyl chloride) (PVC) and polypropylene (PP) was carried out in a supercritical CO₂ medium using AIBN as a free radical initiator. The supercritical CO₂ medium served as a reaction medium in addition to being a solvent for the styrene monomer and the free radical initiator. The reaction temperature and pressure were kept above the critical points of the solvent‐monomer mixture to form a homogeneous single‐phase medium. The resulting graft copolymers were characterized using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and nuclear magnetic resonance (NMR) techniques. The weight percent of grafting was determined using IR absorbance ratio technique. TGA results showed that the thermal stabilily of grafted copolymer of PVC was better than that of PVC, while grafted copolymer of PP had poorer thermal stability than PP. DSC results showed that glass transition temperatures (T_g's) of the grafted copolymers were higher than those of the starting polymers PVC and PP. The presence of polystyrene attached to the backbone polymer was confirmed by ¹H NMR and ¹³C NMR analyses.     

Synthesis,characterization, and properties of a linear poly(ester‐amide) containing ethylene glycol lactate sequences

A novel linear lactic acid‐based poly(ester‐amide) (LLPEA) was prepared via polyaddition of toluene‐2,4‐diisocyanate (TDI) with ethylene lactate succinic half‐ester diacid (ELDA), which contained ethylene glycol lactate sequences and derived from lactic acid. LLPEA was characterized with FTIR, GPC, DSC, TGA, and XRD. The weight average molecular weight and its polydisperse index of LLPEA could be 1.0 × 10⁵ and 2.0, respectively. DSC and XRD analysis showed that LLPEA was a semicrystalline polymer. The glass transition temperature, melting temperature, and the thermal decomposition temperature (50 wt %) of LLPEA were ?2, 94, and ～415°C, respectively. The contact angle determination indicated that LLPEA was a hydrophilic polymer. It was found that the yield strength, tensile strength, and elastic module of LLPEA could be 8.8, 9.6, and 176 MPa, respectively. In addition, the weight loss percentage of LLPEA was 2.5% after 157‐days immersion in activated sludge at ambient temperature, which suggested that LLPEA was degradable. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3805–3808, 2006     

Low dielectric thermoset. I. Synthesis and properties of novel 2,6‐dimethyl phenol‐dicyclopentadiene epoxy

A 2,6‐dimethyl phenol‐dicyclopentadiene novolac was synthesized from dicyclopentadiene and 2,6‐dimethyl phenol, and the resultant 2,6‐dimethyl phenol‐dicyclopentadiene novolac was epoxidized to 2,6‐dimethyl phenol‐dicyclopentadiene epoxy. The structures of novolac and epoxy were confirmed by Fourier transform infrared spectroscopy (FTIR), elemental analysis, mass spectroscopy (MS), nuclear magnetic resonance spectroscopy (NMR), and epoxy equivalent weight titration. The synthesized 2,6‐dimethyl phenol‐dicyclopentadiene epoxy was then cured with 4,4‐diaminodiphenyl methane (DDM), phenol novolac (PN), 4,4‐diaminodiphenyl sulfone (DDS), and 4,4‐diaminodiphenyl ether (DDE). Thermal properties of cured epoxy resins were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), dielectric analysis (DEA), and thermal gravimetric analysis (TGA). These data were compared with those of the commercial bisphenol A epoxy system. Compared with the bisphenol A epoxy system, the cured 2,6‐dimethyl phenol‐ dicyclopentadiene epoxy resins exhibited lower dielectric constants (～3.0 at 1 MHz and 2.8 at 1 GHz), dissipation factors (～0.007 at 1 MHz and 0.004 at 1 GHz), glass transition temperatures (140–188°C), thermal stability (5% degradation temperature at 382–404°C), thermal expansion coefficients [50–60 ppm/°C before glass‐transition temperature (T_g)], and moisture absorption (0.9–1.1%), but higher modulus (～2 Gpa at 60°C). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2607–2613, 2003     

Preparation and characterization of poly(methyl methacrylate) nanocomposites containing octavinyl polyhedral oligomeric silsesquioxane

A series of poly(methyl methacrylate) (PMMA) containing octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) nanocomposites were synthesized by solution polymerization. The products were characterized by FTIR, ¹H NMR, GPC, TEM, DSC and TGA. The actual contents of OV-POSS in the obtained products and the reaction degree of the vinyl groups in the POSS were calculated on the basis of FTIR, TGA and ¹H NMR data respectively. The DSC and TGA results indicate that the incorporation of POSS molecules could improve the thermal properties of PMMA nanocomposites significantly. The glass transition temperature (T_g) and thermal decomposition temperature (T_dec1) of the nanocomposite with 12.27 wt % of OV-POSS were increased by 23 °C and 93 °C correspondingly. In our experiment, the improved thermal properties were largely attributed to the nanoreinforcement effect of POSS cages and the formation of star-shaped structures with cubic silsesquioxane core.     

Bismaleimide and bisazomethine high temperature polymers

Conjugated aromatic bisazomethine, resulting from the reaction of terephthaldicarboxaldehyde and aniline, has been found to react with bismaleimidodiphenylmethane to provide polymeric compositions with glass transition temperature higher than 300°C. These two materials form a low viscosity melt at ca. 150°C and the melt shows only a small viscosity increase when maintained at 120°C over a period of 8 h. Differential scanning calorimetry (DSC) of this composition shows that upon heating above 200°C, it cures rapidly to produce a thermally stable polymer. Thermal mechanical analysis (TMA) of the cured composition does not detect any softening up to 350°C. In the thermal gravimetric analysis (TGA), no weight loss is observed up to 400°C in air and the material leaves a rather large amount of residue (ca. 60%) even up to 600°C. Dynamic mechanical thermal analysis (DMTA) shows that the polymer maintains its high modulus with increasing temperature up to 250°C.