A novel polyhedral oligomeric octadiphenylsulfonylsilsesquioxane (ODPSS) was synthesized from octaphenylsilsesquioxane and benzenesulfonyl chloride via a Friedel–Crafts reaction with a high yield. ODPSS was identified by Fourier transform infrared spectroscopy, ¹H-NMR, ¹³C-NMR, ²⁹Si-NMR, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI–TOF MS), wide-angle X-ray diffraction, and elemental analysis to be a kind of polyhedral oligomeric silsesquioxane of a T₈R₈ structure. ODPSS exhibited superior thermal stability according to thermogravimetric analysis. Its initial thermal decomposition temperature (T_onset) was at 491°C in air and 515°C in nitrogen. Thermal and mechanical properties of epoxy resin (EP) composites with ODPSS added were studied by differential scanning calorimetry and tensile testing. The results show that the incorporation of ODPSS at a low loading content not only improved the glass-transition temperature of the EP composites but also enhanced their tensile strength. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40892.

A series of flame retardant epoxy resins (EPs) containing phosphorus-containing oligomeric silsesquioxane are prepared, and an interesting blowing-out effect is detected in flame retardant EPs. The temperature profiles show that blowing-out effect slows the heat transfer from the fire to the unburned matrix; furthermore, this blowing-out effect can even take away some heat from the surface zone by the spurting gases. The thermo gravimetric analyzer and Fourier transform infrared spectrometer result shows that the spurting gases during the blowing-out effect have a high content of CO₂, which could reduce the combustion capability of the jetting gases. The flame retardancy of these EPs is tested by limit oxygen index and UL-94. The incorporation of 2.5 wt% phosphorus-containing oligomeric silsesquioxane into EP gives a remarkable blowing-out effect, which results in a significant enhancement of limit oxygen index value and UL-94 rating. The flame retardancy mechanism of blowing-out effect is quite different from the traditional mechanisms. The char strength and morphology of EP composites are also investigated to explain the mechanism of the blowing-out effect. Copyright © 2013 John Wiley & Sons, Ltd.

To study flame retardant mechanism of epoxy resin (EP) by octaphenyl silsesquioxane and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, an experimental method is set up to investigate the residue of the EPs, which is extinguished during the cone calorimeter testing at different times. The chemical structures of the residues are investigated by the FTIR and XPS. The breakdown of EPs network and formation of new crosslinking structure are supported by the FTIR analysis. The changes of C and O concentrations in the condensed phase during the combustion are investigated by XPS in detail. Moreover, formation of organic carbon is uncovered by the plasmon loss curves based on XPS that could track the carbon crosslinking. These results exhibited a whole degradation and charring process of EP during the combustion: degradation of EP chain, more crosslinking charring, and thermal oxidation of the char. Furthermore, a program of combustion and degradation process of EPs is described in this research. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4119–4128, 2013

The flame retardancy mechanisms of a novel polyhedral oligomeric silsesquioxane containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-POSS) in polycarbonate (PC) composites are discussed. A nice flame retardancy performance of 6 wt % DOPO-POSS/PC is detected from cone calorimeter testing. The peak heat release rate and total heat released of 6 wt % DOPO-POSS/PC decrease obviously compared with that of PC. The major pyrolysis products detected from the decomposition process of PC and 6 wt % DOPO-POSS/PC are investigated by TGA coupled with Fourier transform infrared spectrometry and mass spectrum (TGA-FTIR and TGA-MS), respectively. It is confirmed that DOPO-POSS catalyzes thermal decomposition of PC, however, reduces the release of flammable volatiles during the decomposition of PC. The condensed phase products after decomposition of PC and 6 wt % DOPO-POSS/PC are investigated by FTIR, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy characterizations. They indicated that DOPO-POSS can accelerate the formation of char during the decomposition of PC composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The flame retardancy mechanisms of a novel polyhedral oligomeric silsesquioxane containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-POSS) in polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blends are discussed. The thermal stability of PC/ABS composites with different DOPO-POSS loadings are investigated by TGA and the enhancement of the thermal stability could be found at high temperature range. Their fire behavior is tested by the LOI, UL-94, and cone calorimeter. Excellent flame retardancy of PC/ABS composites have been discovered with 10 wt% DOPO-POSS loading. TGA-FTIR, FTIR, XPS, and SEM, respectively, are used to characterize the gaseous products and the condensed residue in thermal decomposition, and the micro-structure of the chars from cone calorimeter tests. The decomposition of PC/ABS with 10 wt% DOPO-POSS shows significant changes compared with PC/ABS by TGA, FTIR, TGA-FTIR, and XPS analysis. The enhancement of the thermal-oxidative stability of PC/ABS with DOPO-POSS is attributed to the interaction between DOPO-POSS and PC/ABS at high temperature, which might be the key for improvement of the flame retardancy. Copyright © 2011 John Wiley & Sons, Ltd.

Polyhedral oligomeric azido-octaphenylsilsesquioxane (N₃-OPS) was synthesized from octaaminophenylsilsesquioxane (OAPS) via its diazonium salt. The synthesis included nitration of octaphenylsilsesquioxane (OPS) to octanitrophenylsilsesquioxane (ONPS), conversion of ONPS into octaaminophenylsilsesquioxane (OAPS), and conversion of OAPS into N₃-OPS. The kinetics of the conversion of OAPS into N₃-OPS were studied by recording the volume of N₂ gas released with the reaction time, which revealed it to be a 1st order reaction. The chemical structures of ONPS, OAPS and N₃-OPS were characterized by ¹H-NMR, GPC, FTIR, ²⁹Si solid NMR, ¹³C-NMR, XRD, and elemental analysis. It is proposed that the diazonium salt of OAPS was substituted by the main N₃ group and a few of the OH groups. The ratio of N₃:OH was calculated to be approximately 68:32 in N₃-OPS on the basis of the elemental analysis and ¹H-NMR. XRD suggested that N₃-OPS was a kind of amorphous compound. The two-step conversion mechanism of OAPS to N₃-OPS was briefly discussed. TGA results showed that N₃-OPS was stable at ambient temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Polyphenylsilsesquioxane (PPSQ) of ladder structure synthesized in laboratory was incorporated into polycarbonate (PC) by means of a twin-screw extruder. Scanning electron microscopy (SEM) observations showed that spherical PPSQ particles of size 0.5−1.5 μm dispersed homogeneously in PC. The incorporation of PPSQ into PC improved the elongation at break and flexural strength. Thermal gravimetric analysis and Fourier transform infrared spectroscopy revealed that PPSQ made the initial thermal decomposition of PC happen fast. The early cleavages of CC and CO bonds in the PC chains induced crosslinking reaction in the condensed phase char. According to the cone calorimetry (CONE) tests, loading of 8 wt % PPSQ reduced the peak heat release rate of PC composites from 570 to 153 kW/m². The chars obtained after CONE testing of PC/PPSQ composites showed continuous, smooth, flaky, and cascading char and SiO₂ ceramic layer on the top. These indicated the good flame retardancy of PC/PPSQ, that is the attainment of a UL-94 rating of V-0 (1.6 mm), and limiting oxygen index of 42.0% when PPSQ was in 8 wt % in PC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Poly(l-lactic acid) (PLLA) of high molecular weight was prepared by a chain-extending reaction in a microcompounder. Phosphites were used as chain extenders to increase the molecular weight of the PLLA prepolymer, which was prepared by the bulk polycondensation of l-lactic acid. The effects of the amount of phosphite, the temperature, and the screw speed on the torque of the PLLA melt were studied. Under the optimal conditions, the molecular weight of PLLA increased from 62,100 to 126,000 g/mol. The chemical structure and crystallinity of PLLA were characterized by Fourier transform infrared spectroscopy, ¹H-NMR and ¹³C-NMR, differential scanning calorimetry, and X-ray diffraction. The mechanical properties of PLLA were measured. The results indicate that triphenyl phosphite (TPPi) was an effective chain extender for PLLA. The role of the TPPi in chain extending is suggested to be an esterification-promotion agent. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Variable amounts of transition metal oxides (MO), such as MnO₂, ZnO, Ni₂O₃, etc., were incorporated into blends of polypropylene (PP)/ammonium polyphosphate (APP)/dipentaerythritol (DPER) with the aim of studying and comparing their effects with main-group MO on intumescent flame retardance (IFR). The PP/IFR/MO composites were prepared using a twin-screw extruder, and the IFR behavior was evaluated through oxygen index and vertical burning tests. The progressive enhancement of flame retardancy has proved to be strongly associated with the interaction between APP and MO. With the aid of thermogravimetry (TG) analysis, Fourier transform infrared (FTIR) spectra and scanning electron microscopy, Ni₂O₃ has been shown to be the most effective among the aforementioned three MO. The flame-retardant mechanism of the IFR system is also discussed in terms of catalytic charring, which relates to complex formation through the d-orbitals of the transition metal elements. It is considered that the melt viscosity of a PP/APP/DPER blend containing Ni₂O₃ corresponds well to the gas release with increasing temperature. Copyright © 2009 John Wiley & Sons, Ltd.

A simple route to synthesize a new type of phosphorus-containing polyhedral oligomeric silsesquioxanes (DOPO–POSS) in high yield, by the hydrolytic condensation of a modified silane, is reported. The starting material was a phosphorus-containing triethoxy silane (DOPO–VTES), which was synthesized by addition reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and vinyl triethoxy silane (VTES). This product was subjected to hydrolytic condensation using an HCl catalyst in methanol. The new types of phosphorus-containing POSS were obtained and characterized using ¹H, ¹³C, ²⁹Si-NMR, MALDI-TOF MS, XRD, DSC, and FTIR. All of these results suggested that the DOPO–POSS were amorphous mixtures of T₈, T₉(OH), and TGA curve of DOPO–POSS shows that the cage-like compound has high thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Ammonium polyphosphate (APP)/montmorillonite (MMT) nanocompounds were prepared. The crystal forms and morphologies of the nanocompounds were studied by XRD, FTIR, SEM, and TEM. The APP/MMT nanocompounds were applied to intumescent flame-retarded polypropylene (PP) composites. The PP composites were studied by using oxygen index measurements, UL-94 flame testing, thermogravimetric analysis, and mechanical measurement. It was found that the APP/MMT nanocompounds enhanced the flame retardancy of the IFR/PP compared with the form II APP and its mixture with micro-MMT. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The dynamic viscoelastic properties of poly(vinyl alcohol) (PVA)/H₂O solutions with concentrations of 10 to 25 wt % have been characterized by controlled-stress rheometry at 30°C. Parameters relating to the linear and nonlinear viscoelasticities include complex viscosity (η*), storage modulus (G′), loss tangent (tan δ), relaxation time (λ), thixotropy, and creep. Change curves of η*, G′, tanδ, and λ with frequency (ω) have been obtained for the PVA/H₂O solutions. Creep and recovery testing yielded compliance (J′) curves with loading and unloading. Shear stress versus rate profiles of the PVA solutions have been obtained through thixotropic measurements. The PVA concentration has been found to have a profound influence on the rheological properties of the aqueous solutions. Four aqueous solutions of 10, 15, 20, and 25 wt % PVA at 30°C exhibited shear-thinning and showed different transition behaviors of η* and G′ with frequency, and different degrees of creep under constant stress to recovery with time. The 10 wt % PVA solution was viscous and displayed the lowest η* and G′; the 25 wt % PVA solution was viscoelastic and displayed the highest η* and G′; the 15 and 20 wt % PVA solutions showed η* and G′ values and creep to recovery behaviors intermediate between those of the 10 wt % and 25 wt % PVA solutions. The different rheological properties of these PVA/H₂O solutions are considered to correlate with interchain hydrogen bonds and shear-induced orientation in the solutions. Shearing is able to break the intrachain and interchain hydrogen bonds, and, at the same time, the orientation creates new interchain hydrogen bonding. The reorganization of hydrogen-bonding mode contributes to the transitions of the macroscopic viscoelasticity with frequency. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010