PVC阻燃抑烟的研究进展

介绍了聚氯乙烯(PVC)的热降解机理及燃烧特性。综述了PVC阻燃抑烟剂(如阻燃增塑剂、金属化合物、含硼阻燃剂、微胶囊红磷和无机填料等)的研究,特别提及了一些过渡金属(如Mo、Cu与Fe的化合物)在PVC抑烟中的明显作用。比较了各种阻燃抑烟方法的优缺点。采用阻燃剂和抑烟剂复合对PVC协同阻燃抑烟是未来的研究方向。     

锡酸锌对软质聚氯乙烯的阻燃和抑烟作用

采用氧指数法、热重分析及烟密度测试法就锡酸锌对软质PVC的阻燃抑烟行为进行了研究。发现锡酸锌不仅是软质PVC的良好阻燃剂，更是一种性能优异的抑烟剂，添加15份时，最大烟密度只是空白试样的32．5％，氧指数为30．8，有可能代替三氧化二锑用于软质PVC的阻燃和抑烟。     

SnO2和SiO2用于PVC的阻燃消烟及协同作用

研究了二氧化锡和二氧化硅对软PVC阻燃消烟性的影响。通过对极限氧指数、剩炭率、烟密度的测定和DTATG曲线的分析证明,添加8g二氧化锡/二氧化硅复合阻燃剂的PVC的氧指数和剩炭率比未添加的分别增高5.5个单位和4.1%,烟密度降低16.4%,降解活化能分别降低38kJ/mol和23.1kJ/mol,从而证明二氧化锡/二氧化硅复合阻燃剂对于PVC是一种很好的阻燃消烟剂,二氧化锡和二氧化硅有很好的协同作用。同时证明这种复合阻燃剂能代替三氧化二锑,使产品的成本进一步降低。     

ZnO与Al(OH)3在阻燃软PVC中的协同阻燃消烟作用

研究了ZnO和Al(OH)3复合阻燃剂对软PVC的协同阻燃消烟作用.通过热分析的方法研究了阻燃处理后的软PVC从室温到800℃的热降解过程,用Kissinger方程给出了热降解反应的活化能,通过剩炭率的测定以及用电子扫描显微镜(SEM)对燃烧后所生成炭层的观察探讨了协同体系阻燃抑烟的机理.结果表明经阻燃处理的样品具有较高的极限氧指数(LOI)、剩炭率较低的烟密度等级(SDR)和最大烟密度(MSD),与未处理的样品相比具有较好的阻燃和消烟性能.加入适量的ZnO与Al(OH)3复合使用可明显地提高软PVC的LOI和剩炭率,降低材料的SDR和MSD.ZnO的加入可改变PVC的热降解过程,使起始降解温度降低并且使反应的活化能增大,可能属于固相Lewis酸催化机理.     

纳米CaCO3对阻燃型软质聚氯乙烯的增韧增强作用

通过氧指数(LOI)、剩炭率、烟密度等级(SDR)、冲击强度、拉伸强度和断裂伸长率等参数的测定,研究了氢氧化物和金属配合物复合阻燃体系对软质PVC阻燃、消烟性能和力学性能的影响;通过冲击强度、拉伸强度、断裂伸长率以及材料流变性能的测定对比研究了纳米级CaCO3和微米级CaCO3对阻燃型软质PVC的力学性能和加工性能的影响。结果表明:氢氧化物和金属配合物复合阻燃体系在提高软质PVC阻燃、消烟性能的同时会恶化材料的力学性能;纳米CaCO3能明显提高阻燃型软质PVC的冲击强度、拉伸强度和断裂伸长率,对材料具有明显的增韧、增强作用,同时对材料的流变性能及阻燃、消烟性能影响不大。     

新型无卤阻燃填料在PVC中的应用

研究了新型无卤阻燃填料有其在PVC中的应用，为含氯高分子材料的阻燃研究提供了新方法、新途径。     

Effect of mechanochemical degradation on gelation and mechanical properties of PVC

The effect of vibromilling or jet milling on gelation and mechanical properties of poly(vinyl chloride) (PVC) was studied through SEM, FTIR, DSC, and mechanical properties tests. The experimental results show that the size of the grain and apparent density of PVC are decreased. The grains become much more loosely aggregated and the crystallinity of PVC is decreased during milling. The extensional fracture of degraded PVC is obviously different from that of undegraded PVC, the tensile strength and degree of gelation of degraded PVC are increased as compared with undegraded PVC. The mechanical properties of PVC are improved quite a lot after blending it with a small amount of mechanochemically degraded PVC. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2273–2281, 1997     

The preparation of core‐shell CaCO3 particles and its effect on mechanical property of PVC composites

In this study, a novel mechanochemical route to prepare core‐shell structured particles was introduced. XPS, TEM, and dissolving experimental results indicate the formation of [(inorganic particle)/(elastomer)] core‐shell structured particles, and several kinds of calcium carbonate (nano‐CaCO₃) particles with various interfaces were obtained. The mechanical properties and morphological results indicate that the surface treatment of nano‐CaCO₃ particles and the existence of outer elastic layer will strengthen the interfacial interaction between nano‐CaCO₃ particles and PVC matrix, which results in improvement of mechanical properties of PVC/CaCO₃ composites. The theoretical calculations of the interfacial interaction and DMA results confirm these especially when the surface of nano‐CaCO₃ particles was treated by MMA and coated in succession by ACR through vibro‐milling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1084–1091, 2006     

载铜蒙脱土对聚氯乙烯材料阻燃性能的研究

通过离子交换反应将铜离子负载在无机层状蒙脱土上,采用十六烷基三甲基溴化铵对载铜蒙脱土进行有机改性,并将其作为阻燃剂添加到软质聚氯乙烯(PVC)材料中。利用X射线衍射对PVC/有机改性载铜蒙脱土的结构进行表征。结果表明,PVC分子链插层进入有机改性载铜蒙脱土层间形成插层型结构,且蒙脱土的层间距达到3.69 nm。热重分析、极限氧指数、垂直燃烧和烟密度测试结果表明,有机改性载铜蒙脱土有效改善了PVC的热稳定性,大幅提高了其阻燃性能。载铜蒙脱土的用量仅为PVC用量的3 %时,垂直燃烧即可达到V0级。     

系列羟基锡酸盐对半硬质PVC的阻燃消烟作用

研究了系列羟基锡酸盐阻燃剂对半硬质PVC的阻燃消烟作用。通过对样品燃烧后剩炭含量及扫描电镜(SEM)分析,探讨了锡酸盐体系阻燃抑烟的机理。结果表明:经阻燃处理的样品具有较高的极限氧指数(LOI)和剩炭率,较低的烟密度等级(SDR)和最大烟密度(MSD),与未处理的样品相比具有较好的阻燃和消烟性能。由于阻燃剂的添加量较少,对材料力学性能影响不大。     

SnO2与氢氧化物复合阻燃剂对软PVC的阻燃消烟作用

研究了SnO2和无机氢氧化物阻燃剂对软PVC的阻燃消烟作用。通过热分析的方法研究了阻燃处理后的软PVC从室温到800℃的热降解过程,通过剩炭率的测定以及用电子扫描显微镜(SEM)对燃烧后所生成炭层的观察探讨了不同体系的阻燃抑烟的机理。结果表明:经SnO2和氢氧化物复合阻燃处理的样品具有较高的极限氧指数(LOI)和剩炭率,烟密度等级(SDR)和最大烟密度(MSD)明显降低,与未处理的样品相比具有较好的阻燃和消烟性能。SnO2的加入可改变PVC的热降解过程,使起始降解温度降低,SnO2可能是在凝聚相和气相同时起作用,但主要是在凝聚相起Lewis酸催化作用。     

氧化锌和氢氧化物对软聚氯乙烯阻燃性能的影响

引言 软质PVC制品中由于大量增塑剂的加入,大大提高了其可燃性,燃烧时还会产生大量有毒烟雾,因此对PVC制品的阻燃抑烟问题亟待解决.无机氢氧化物优点众多,在阻燃高分子材料中应用广泛,但阻燃效率低,常与其他阻燃剂复配使用.硼酸锌、锡酸锌、磷酸锌、氧化锌等可直接或与其他阻燃剂复合应用于PVC的阻燃消烟[1-3].     

锡酸锌包覆碳酸钙对聚氯乙烯的阻燃消烟作用

用氧指数、剩炭率、烟密度等方法测试了锡酸锌包覆碳酸钙对PVC的阻燃作用,同时采用热分析、扫描电镜的方法研究了锡酸锌包覆碳酸钙的阻燃机理。实验表明在锡酸锌含量相同的情况下,锡酸锌包覆碳酸钙对PVC的阻燃和消烟性能优于锡酸锌;在添加量为10份时,锡酸锌包覆碳酸钙阻燃PVC样品和三氧化二锑阻燃PVC样品具有相同的氧指数,但当添加量为20份时,前者的氧指数比后者的高3%,前者的烟密度等级比后者低约10%。     

Effect of hydrotalcite on the thermal stability,mechanical properties,rheology and flame retardance of poly(vinyl chloride)

Compounds of poly(vinyl chloride) (PVC) and hydrotalcite were prepared via melt blending, and the thermal stability, mechanical properties, rheology and flame retardance were studied. Transmission electron microscopy showed that the hydrotalcite achieved an optimal dispersion in PVC compounds when surface‐treated with titanate coupling agent. The Congo Red test and thermogravimetric analysis demonstrated that the thermal stability of PVC was improved significantly only in the presence of a complex of the hydrotalcite and the organotin stabilizer. Such a significantly positive thermal stabilizing effect was attributable to the stabilizing mechanisms that the electrostatic interaction generated between the electron cloud of chlorine atoms in PVC chain and the positive lay charge of hydrotalcite, which resulted in a decrease in electronic cloud density of chlorine atoms. This weakened the activity of chloride atoms, and restricted the initiation of the dehydrochlorination. A surface treatment for the hydrotalcite with the titanate coupling agent could reduce deterioration of the mechanical and rheological properties of the PVC at low concentration of hydrotalcite. The hydrotalcite also enabled useful application of PVC as a flame retardant as well as a smoke retarder in the light of a LOI value of more than 28.7 and UL 94 V‐0 grade at a PVC/hydrotalcite weight ratio of 70/30. Copyright © 2004 Society of Chemical Industry     

低熔点硫酸盐对软质PVC的阻燃与消烟性能研究

制得的硫酸盐混合物熔点低，在适当温度下熔融时，能有效地保护PVC降解过程中形成的剩磷，从而能提高剩碳率，提高阻燃与消烟性能。氧指数、烟密度、DTA、TG、SEM等证明了低熔点的硫酸盐是一种优良的填料性的、具有阻燃与消烟性的阻燃消烟剂，具有很好的消烟性，当添加量达40份时，烟密度能下降45％。研究表明其对力学性能的影响比其它填料小。     

PVC／纳米水滑石复合材料抑烟性研究

用烟密度测量仪初步研究了润滑剂、分散剂等加工助剂对聚氯乙烯(PVC)燃烧发烟的影响；研究了水滑石(LDHs)不同粉体含量及其在PVC中的分散状况对抑烟效果的影响；同时研究了采取不同的燃烧测试方法对PVC燃烧发烟量及LDHs对PVC抑烟效率的影响。结果表明：润滑剂等可燃性加工助剂可使PVC燃烧时显著发烟；LDHs对PVC的抑烟效果并不随着LDHs含量的增加而增大；较好分散的LDHs对PVC具有较好的抑烟效果；采用不同的燃烧测试方法，PVC燃烧的发烟量及LDHs对PVC抑烟效果具有显著差别。     

Effects of ammonium polyphosphate and triphenyl phosphate on the flame retardancy,thermal, and mechanical properties of glass fiber–reinforced PLA/PC composites

The purpose of this study is to increase of the flammability properties of the glass fiber (GF)–reinforced poly (lactic acid)/polycarbonate (PLA/PC) composites. Ammonium polyphosphate (APP) and triphenyl phosphate (TPP) were used as flame retardants that are including the organic phosphor to increase flame retardancy of GF‐reinforced composites. APP, TPP, and APP‐TPP mixture flame retardant including composites were prepared by using extrusion and injection molding methods. The properties of the composites were determined by the tensile test, limiting oxygen index (LOI), differential scanning calorimetry (DSC), and heat release rate (HRR) test. The minimum T_g value was observed for the TPP including PLA/PC composites in DSC analysis. The highest tensile strength was observed in GF‐reinforced PLA/PC composites. In the LOI test, GF including composite was burned with the lowest concentration of oxygen, and burning time was the longest of this composite. However, the shortest burning time was obtained by using the mixture flame retardant system. The flame retardancy properties of GF‐reinforced PLA/PC composite was improved by using mixture flame retardant. When analyzed the results of HRR, time to ignition (TTI), and mass loss rate together, the best value was obtained for the composite including APP.     

A multi-element flame retardant for rail transit to improve the flame retardant performance of epoxy resin while reducing smoke density

A P/N/Si structure flame retardant DTBD was successfully synthesized by 3,5-diaminobenzoic acid, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), triphenylsilanol, and benzaldehyde. The chemical structure of DTBD was analyzed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectra, which showed that DTBD was successfully synthesized. By analyzing the curing behavior, the addition of DTBD promoted the curing of epoxy resin (EP). According to the limited oxygen index (LOI) and UL-94 vertical combustion tests, it can be shown that the introduction of DTBD makes the epoxy resin have good self-extinguishing properties. Py-GC/MS analysis showed that the phosphorus free radicals and ammonia generated in the gas phase of DTBD could quench and dilute by capturing reactive free radicals and refractory gases. DTBD could improve the tensile and flexural properties of epoxy resin. According to the European flame retardant standard EN45545-2, the Ds of EP-15 and EP-20 obtained HL1 grade. With the increase in DTBD content, the VOF₄ of modified EP also gradually decreased, and both EP-15 and EP-20 obtained HL2 grade.     

Effect of wood sawdust content on rheological and structural changes,and thermo‐mechanical properties of PVC/sawdust composites

The use of untreated sawdust as a filler in poly(vinyl chloride) (PVC) was examined—the effects of sawdust content on structural and thermal changes, and rheological and mechanical properties being of main interest. The results revealed that the torque and die entrance pressure drop values during mixing were independent of sawdust particles up to 23.1 wt%. The extrudate swell monotonically decreased up to 33.3 wt% sawdust content. Smooth wood‐like texture with controllable size of the extrudate could be obtained at a sawdust content greater than 33.3 wt%. Tensile, impact, flexural and hardness properties of the PVC/sawdust composites considerably decreased with up to 16.7 wt% sawdust content before leveling off for higher sawdust loadings. The composites having sawdust higher than 16.7 wt% showed a benefit of cost savings. The decreases in the mechanical properties of PVC with sawdust are explained in association with the presence of moisture, interfacial defects between fibre and polymer, and fibre dispersions in the PVC matrix. Thermal degradations of PVC in PVC/sawdust composites were evidenced by a decrease in decomposition temperature and an increase in polyene sequences, which were caused by Cl cleavage due to strong hydrogen bonds of fibre–PVC molecules. The maximum of tanδ transition and the glass transition temperature were found to improve with sawdust content as a result of re‐formation of hydrogen bonds between the macromolecules of the fibre and the polymer. The overall results in this work suggest that the properties of PVC/sawdust composites were strongly influenced by sawdust content up to 16.7 wt%. Beyond this value the effect of sawdust content on the properties was comparatively small. Copyright © 2003 Society of Chemical Industry     

Effects of layered double hydroxides on the thermal and flame retardant properties of intumescent flame retardant high density polyethylene composites

In this study, two layered double hydroxides (LDHs), ZnAl-LDH, and MgAl-LDH, were combined with intumescent flame retardant (IFR) consisting of ammonium polyphosphate and tris (2-hydroxyethyl) isocyanurate to prepare flame retardant high density polyethylene composites. The thermal and flame retardant properties of these composites were investigated by thermogravimetric analysis, limiting oxygen index measurement, and cone calorimetry, while the morphology and chemical structure of the char residue were analyzed by scanning electron microscopy, Fourier transfer infrared spectroscopy, and laser Raman spectroscopy. The results showed that the peak heat release rate (PHRR) of both HD/IFR/Zn-LDH and HD/IFR/Mg-LDH composites was 52.0% and 12.0% lower than that of HD and HD/IFR, respectively, suggesting that there was no difference in the reduction of PHRR between the two LDHs. The use of LDHs resulted in the formation of compact char residue with a high graphitic degree, but no significant increase in tensile strength.