Study on effect of polydimethylsiloxane in intumescent flame retardant polypropylene

The effect of polydimethylsiloxane (PDMS) in intumescent flame retarded polypropylene (PP) containing melamine phosphate (MP) was studied using limiting oxygen index (LOI), UL-94 test, thermogravimetric analysis (TG), real time Fourier transform infrared (FTIR) and pyrolysis/gas chromatogram/mass spectrometry (Py–GC/MS). It was found that the addition of PDMS into the PP/MP composites leads to a decrease in the LOI values of the PP/MP/PDMS composites, and the values increase gradually with the increase of the PDMS content. The UL-94 test results indicate that the PP/MP/PDMS composite with 30% PDMS reaches the V-0 rating compared with no rating of the PP/MP composite at the same MP loading. The water resistance of the PP/MP/PDMS composites was investigated, and the improved water leaching of MP was observed. The TG and RTFTIR results illustrate the thermal stability of the PP/MP composites containing PDMS is improved. Moreover, the pyrolysis of the PP/MP/PDMS composites was studied by the Py–GC/MS method.     

Effect of Thermal Treatment on the Photocatalytic Activity in Visible Light of TiO<Subscript>2</Subscript>-W Flame Spray Synthesised Nanopowders

Effect of W doping as well as a thermal treatment on the structural and photocatalytic properties of TiO₂ produced by flame spray synthesis (FSS) were the subject of investigation. Structural properties were studied by means of X-ray diffraction (XRD), BET adsorption isotherm and transmission electron microscopy (TEM). The surface condition was investigated by X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC) and differential thermal and thermogravimetric analysis (DTA-TGA). The photocatalytic properties were studied by optical measurements and photodecomposition of methylene blue under visible irradiation. It was found that the photoactivity in the visible region was enhanced significantly by the W-doping as well as by additional thermal treatment of those nanopowders. The obtained TiO₂-W nanopowders exhibited higher performance under visible light than P25.     

MRP/MH/EG协同阻燃HDPE的性能研究

以微胶囊化红磷(MRP)、氢氧化镁(MH)及可膨胀石墨(EG)为阻燃剂,采用熔融挤出法制备了多组高密度聚乙烯(PE-HD)阻燃复合材料。采用氧指数测试、垂直燃烧测试、红外光谱分析、激光拉曼光谱分析、热重-差热分析、扫描电子显微镜分析及拉伸性能测试等方法对复合材料的阻燃性能、热稳定性、力学性能和断面的微观形貌进行了研究,并探讨了阻燃机理。结果表明,单独使用EG时阻燃效果差,但将EG与MRP、MH复配使用能有效改善材料的阻燃性能;当PE-HD/MH /MRP /EG = 100/35/15/5(质量份,下同)时,复合材料的氧指数为28.5 %,垂直燃烧达到UL 94 V-0级,而阻燃剂的加入对材料拉伸性能的影响并不是很大;SEM分析表明, EG与PE-HD基材有很好的相容性,而MRP或MH与PE-HD基材的相容性较差。     

Synergistic effects of hydroxy silicone oil on intumescent flame retardant polypropylene system

The effects of hydroxy silicone oil as a synergistic agent on the flame retardancy of intumescent flame retardant polypropylene composites (IFR-PP) were studied, and the IFR system mainly consisted of the ammonium polyphosphate (APP), melamine (MEL) and pentaerythritol (PER). The UL 94 rating, thermogravimetric analysis (TGA), cone calorimeter (CONE) and digital photograph were used to evaluate the synergistic effects of hydroxy silicone oil (HSO). It has been found that the PP composite containing only APP, MEL and PER does not show good flame retardancy at 30% additive level. The cone calorimeter results show that the heat release rate, mass loss rate, mass, total heat release, carbon monoxide and carbon dioxide of PP/APP/MEL/PER/HSO composites decrease in comparison with the PP/APP/MEL/PER composite. The digital photographs demonstrated that HSO could promote to form the homogenous and compact intumescent char layer. Thus, a suitable amount of HSO plays a synergistic effect in the flame retardancy.     

Preparation and characterization of phosphine oxide containing organosilica hybrid coatings by photopolymerization and sol–gel process

A series of UV-cured organic–inorganic hybrid coating materials containing up to 20 wt.% silica were prepared by sol–gel method from tetraethoxy silane (TEOS) which is used as the primary inorganic precursor, and diallylphenylphosphine oxide monomer (DAPPO), aliphatic urethane diacrylate resin (Ebecryl 210) are employed as the source of the organic components. In addition, methacryloxypropyltrimethoxy silane (MAPTMS) was used as both a secondary inorganic source and a silane-coupling agent to improve the compatibility of the organic and inorganic phases. The DAPPO content in all the coating formulations were from 0 to 20 wt.%. The physical and mechanical properties such as gel content, hardness, adhesion, gloss, contact angle as well as tensile strength were measured. These measurements revealed that all the properties of the hybrid coatings improved effectively, in case of adding the sol–gel precursor and DAPPO monomer content in the hybrid systems. The photo-calorimetric-DSC studies showed that the double bond conversion of the hybrid coatings was faster than the coating materials without silica. The thermal stabilities of the UV-cured hybrid materials were investigated by thermogravimetric analysis. The results showed that the addition of sol–gel precursor and DAPPO into the organic network also improves the thermal-oxidative stability of the hybrid coating materials. The surface morphology was also characterized by scanning electron microscopy (SEM). SEM studies indicated that inorganic particles were dispersed homogenously throughout the organic matrix.     

阻燃性PET/GF复合材料的研制

对阻燃性PET/GF复合材料进行了研究。发现适当表面处理的玻纤可以有效地增强增韧PET ;选择合适的增容剂可达到减少阻燃剂用量的目的 ,6至 7份的溴 -锑阻燃剂即可使PET/GF复合材料的氧指数达 2 7;DSC分析表明玻纤、阻燃剂粒子、滑石粉均起到了成核剂的作用。     

Ethylene vinyl acetate/layered silicate nanocomposites prepared by a surfactant-free method: Enhanced flame retardant and mechanical properties

Exfoliated EVA/layered silicate nanocomposites were prepared by a masterbatch process using polymer-modified layered silicate instead of small molecule surfactant-modified clays. The nanocomposites exhibited improved mechanical properties and flame retardancy. Microscale flammability test showed that the heat release capacity (HRC) and total heat release (THR) were reduced by 21-24% and 16%, respectively. Radiant gasification studies revealed that the exfoliated EVA nanocomposites exhibited better improvements in flame retardant properties of EVA than did the corresponding intercalated nanocomposites. The peak mass loss rate of the exfoliated EVA nanocomposite containing about 5 wt% clay was reduced by 80% and the mass loss rate plot was spread over a much longer period of time. The mechanical and flammability tests revealed that the observed improvements in all the desirable properties were due to the presence of both the incorporated polymeric surfactant and the nanoclay.     

An approach to develop high-Tg epoxy resins for halogen-free copper clad laminates

A series of advanced epoxy resins (2) were prepared by the nucleophilic addition of cresol novolac epoxy (CNE) with a benzoxazine monomer (1), which is prepared by a one-pot procedure using 2-hydroxybenzaldehyde, 4-aminophenol and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) as starting materials. The nucleophilic addition was monitored by epoxy equivalent weight titration and NMR analysis. Based on this approach, the overall number of functionality of the resulting epoxy resins was retained because a curable benzoxazine linkage was also incorporated after the nucleophilic addition. As a result, high-Tg thermosets qualified for the UL-94 V-0 rating can be achieved after curing. When an UL-94 V-0 rating was achieved, Tg as high as 245 °C (DMA data) was obtained for 4,4′-diaminediphenyl sulfone (DDS)-cured systems. The corresponding phosphorus content for the UL-94 V-0 rating was as low as 0.61 wt%. The flame-retardant nature of oxazine linkage and nitrogen-phosphorus synergistic effect might be responsible for the low phosphorus content required for flame retardancy.     

气相色谱-火焰光度法测定苯中微量环丁砜和噻吩

建立了气相色谱-火焰光度法测定苯中微量环丁砜和噻吩的方法,对色谱条件进行了优化,定量方法采用外标法。该方法的加标回收率为114%～136%;相对标准偏差（RSD）不大于7%。测定苯样品中微量环丁砜和噻吩具有灵敏度高、重现性好和可靠性高等优点。     

四风道煤粉燃烧器常见问题分析及解决措施

介绍了水泥回转窑用四风道煤粉燃烧器的结构及其原理,以及四风道煤粉燃烧器在水泥厂实际使用过程中常见的一些问题,并针对这些问题提出了解决或改进的方法和措施。