DOPOHM/丙烯酸树脂复合材料的制备及阻燃性能研究

采用9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物（DOPO）与甲基丙烯酸-β-羟乙酯（HEMA）反应合成了有机膦阻燃剂——2-甲基-3-(6-氧代-6H-二苯并[c,e][1,2]氧磷杂己环-6-基)丙酸-2-羟乙酯(DOPOHM),以DOPOHM对丙烯酸树脂进行阻燃,得到阻燃丙烯酸树脂复合材料（DOPOHM/AR）。利用TGA分析仪和极限氧指数（LOI）测定仪测定了复合材料的热稳定性和阻燃性能,用SEM、XPS和EDS研究了复合材料的阻燃机制;通过Horowitz-Metzger理论计算复合材料的分解活化能(Ea)。结果表明：DOPOHM/AR的分解活化能（Ea）随DOPOHM用量的增加而升高,DOPOHM对丙烯酸树脂热降解速率具有抑制作用,DOPOHM的热分解产物聚磷酸盐催化基体成炭,致密的炭层覆盖在材料表面构成热量和分解产物逸散的屏障;当DOPOHM用量占单体总质量的25%时,复合材料的LOI达到26,UL-94测试达V-0级。     

六苯氧基环三磷腈对聚碳酸酯的阻燃作用

通过极限氧指数测定(LOI)、垂直燃烧和锥型量热分析研究了六苯氧基环三磷腈(HPTCP)对聚碳酸酯(PC)的阻燃性影响。结果表明:HPTCP对PC具有良好的阻燃效果,当添加质量分数为10%时,阻燃PC的LOI就高达30.7%,阻燃等级达FV-0,与未阻燃PC相比,其最高热释放速率明显降低,质量损失变慢,点燃时间和完全燃烧所需时间延长。热失重和残余物分析结果表明,HPTCP主要是通过凝聚相机理产生阻燃作用,HPTCP热解形成的磷酸类化合物促进了PC成炭,形成的膨胀性炭层通过隔热、隔氧及阻止PC分解产物的挥发而产生阻燃作用。     

苯氧基磷腈的组成对其阻燃PC/ABS的影响

通过极限氧指数测定、垂直燃烧实验和锥形量热分析研究了苯氧基磷腈的组成对其阻燃PC/ABS的影响,并通过锥形量热实验的残炭分析研究了其作用机理。结果表明,苯氧基磷腈的组成对其阻燃PC/ABS有较大影响。随苯氧基磷腈中六苯氧基环三磷腈(HPTCP)含量的降低,其阻燃作用明显降低。残炭分析结果表明,苯氧基磷腈在燃烧过程中分解成磷酸、聚磷酸和偏磷酸等磷酸化合物,这些物质可有效地促进PC/ABS成炭,并形成膨胀性炭层,因而产生阻燃作用。苯氧基磷腈中x(HPTCP)降低,燃烧时形成的磷酸化合物较少,因而降低了其成炭和阻燃作用。     

溴化环氧树脂协同三氧化二锑阻燃PET的燃烧性能及阻燃机理研究

研究了溴化环氧树脂(BER)协同不同粒径的三氧化二锑（Sb2O3）阻燃PET的燃烧性能、垂直燃烧性能（UL94）、烟气释放、物理性能高和力学性能,研究了炭层的红外光谱和阻燃PET的裂解特性,分析了阻燃PET的阻燃机理。锥形量热分析表明,BER协同Sb2O3阻燃PET的燃烧性能显著减低,均可以达到UL94 V-0级,且Sb2O3粒径越小,阻燃效果越好,但溴-锑协同不能抑制烟毒的产生,平均CO生成量和材料释烟量显著上升。BER协同Sb2O3阻燃PET的熔体流动速率、维卡软化点、邵氏硬度、弯曲强度和弯曲模量提高,缺口冲击强度和断裂伸长率下降。红外和裂解色谱分析表明,阻燃PET与纯PET的燃烧残炭结构不完全相同,裂解产物的主要出峰保留时间也不相同,说明了BER协同Sb2O3不仅在气相发挥阻燃作用,在固相也同样发挥阻燃作用。     

有机磷/硼杂化小分子阻燃改性环氧树脂

从二苯基次膦酰氯和苯基磷酰二氯出发,分别合成了含单个苯硼酸基团和含两个苯硼酸基团的两种有机磷/硼杂化小分子（缩写为：DPC-1B和PDS-2B）。两种杂化小分子与环氧树脂有着良好的相容性并可参与环氧固化,在比较低的添加量下便有较高的机械强度和优异的阻燃性能,且保持环氧的透明度。DPC-1B和PDS-2B添加量为2%（质量）时,复合材料氧指数从25.7%分别提高到了31.8%和31.5%,热释放速率峰值分别降低了26.5%与21.8%,UL-94阻燃等级均达到了V-0级。改性环氧树脂燃烧后的残炭分析表明,炭层外部连续紧密,内部多蓬松,硼磷共同作用形成致密炭层,隔绝热质传递,从而达到阻燃效果。     

AlPi和PPBBA复配阻燃PET的燃烧性能

采用二乙基次膦酸铝(Al Pi)和聚丙烯酸五溴卞酯(PPBBA)复配,提高聚对苯二甲酸乙二酯(PET)的阻燃性能。测定了阻燃PET的极限氧指数(LOI)、垂直燃烧性能、热失重分析、动态流变性能,并采用扫描电子显微镜(SEM)观测了燃烧炭层的形貌。结果表明,Al Pi∶PPBBA分别以5∶5和10∶5复配,添加量分别为10%和15%时,LOI达到28.0%和33.3%,垂直燃烧测试均达到V–0级。复配阻燃体系的加入促进了PET的提前分解,阻燃剂主要在气相发挥阻燃作用,同时有利于成炭。当添加15%复配阻燃剂时,相比于纯PET,阻燃PET的最大分解速率降低21.2%,残炭率提高97.6%,提高了阻燃PET在高温下的热稳定性。在角频率为1 rad/s条件下,当添加10%和15%复配阻燃剂时,体系的复数黏度由39.4 Pa·s分别提高到296 Pa·s和1 970 Pa·s,具有较高的抗熔滴性能。烧结后的残留物高倍膨胀,炭层致密连续。     

聚氨酯泡沫塑料的阻燃及热解性能

采用热重分析仪、傅里叶变换红外光谱仪和扫描电子显微镜研究了氨基树脂型高分子膨胀阻燃剂（AIFR）阻燃软质聚氨酯泡沫塑料（FPUF）的阻燃、热解性能。结果表明,w（AIFR）为15％以上时,阻燃FPUF的垂直燃烧性能达到美国联邦航空局颁布的条例FAR25．853的要求。AIFR阻燃FPUF热解首先发生脱磷酸、酸催化FPUF脱水和重排交联炭化反应,使其热解中间产物热稳定性增加,热失重速率降低0．144％／s,剩炭率提高10．6％,AIFR主要以凝聚相成炭作用模式起阻燃作用。残炭扫描电子显微镜照片显示,AIFR阻燃FPUF的炭层致密,空洞少;残炭的韧性好．强度较高,可阻挡燃烧过程中的热量和气体的交换,达到阻燃目的。     

含磷阻燃PET母粒的制备及阻燃PET性能研究

根据聚对苯二甲酸乙二醇酯(PET)阻燃改性机理,采用高磷含量阻燃剂二乙基次磷酸锌(ZDP),利用熔融共混的方法,制备高磷含量的阻燃PET母粒。将磷质量分数为10. 0%的阻燃PET母粒与PET切片共混,制得不同磷含量的阻燃PET。采用核磁共振波谱仪、傅里叶变换光谱仪对阻燃剂的结构进行分析,并采用热重分析仪、氧指数仪、垂直燃烧仪和扫描电子显微镜对阻燃PET母粒及阻燃PET的性能进行表征。结果表明:当阻燃PET中磷质量分数为1. 0%时,阻燃PET的极限氧指数达到32. 4%,UL-94为V-1级; ZDP受热产生的次磷酸自由基可以捕获可燃的小分子自由基,有效提高PET的成炭性,阻燃PET的阻燃机理为凝聚态阻燃;当阻燃PET中磷质量分数达0. 5%时,燃烧后其表面可形成致密炭层,阻燃效果最明显,且无熔滴出现,500℃锻烧15 min后成炭率可达到17. 91%,阻燃剂可以有效提高PET阻燃性能。     

PET纤维及其织物的阻燃技术进展

概述了聚对苯二甲酸乙二醇酯(PET)纤维及其织物的阻燃技术,包括共缩聚阻燃PET纺丝、PET与阻燃剂共混纺丝及PET织物阻燃后处理等。其中,阻燃剂主要有磷系及磷-氮系阻燃剂,如:9,10-二氢-9-氧杂-10-磷杂蒽-10-氧化物(DOPO)衍生物、次膦酸(酯)及其聚合物、氧化膦聚合物、膦酸酯及螺环磷酸酯等。今后应积极开发生态和环境兼容的阻燃PET纤维新技术。     

线型酚醛与微胶囊红磷阻燃ABS的研究

采用线型酚醛(Novolac)与微胶囊红磷(MRP)复配阻燃,制备了无卤阻燃丙烯腈-丁二烯-苯乙烯(ABS)复合材料。研究了Novolac/MRP质量比和用量对阻燃ABS性能的影响。研究结果表明:Novolac/MRP的质量比为3/2,总量为15%(质量分数)时,可以制备极限氧指数(LOI)为26.7%,垂直燃烧(UL94)V-0级的无卤阻燃ABS;Novolac的酚羟基与MRP燃烧产生的聚磷酸在高温下发生的脱水成炭反应减缓了ABS的分解;SEM炭层形貌分析表明:Novolac/MRP复合阻燃ABS材料燃烧表面形成了平整、致密的炭层,该炭层能够有效地隔绝燃烧过程所产生的易燃气体及热量,起到较好的阻燃效果。     

Surface modification of ethylene copolymers moulded against different mould surfaces-1. Surface enrichment by functional groups

A polymer surface chemical composition can be changed by the influence of different environments. Results presented from this study show that the surface of the mould influences the outermost polymer surface by enriching it with specific functional groups. This was done by moulding random copolymers against polymer films with low and high surface energies. The values presented are interpreted in terms of differences in surface energy between the mould surface and the copolymer. The random copolymers used were poly(ethylene-co-vinylacetate) (EVA) and poly(ethylene-co-acrylic acid) (EAA), both with a different comonomer content. The copolymers were moulded in contact with mould surfaces made of polymer films which were perfluorinated ethylene propylene copolymer (FEP), poly(tetrafluoroethylene) (PTFE), and poly(ethylene terephthalate) (PET). The resultant surfaces were characterized by X-ray photoelectron spectroscopy (XPS or ESCA) and contact angle measurements The surface content of acrylic acid functional groups increased in the case of EAA copolymer moulded against PET, and decreased when moulded against FEP as compared to the bulk concentration. EVA copolymers were found to be enriched in acetate groups when moulded against FEP and deficient when moulded against PET. The contact angle measurements together with the XPS measurements showed significant differences between materials moulded in contact with low and high energy surfaces. A low molecular weight additive (an internal release agent), in an EVA copolymer, was found to be enriched at the moulded polymer surface when a PET film was used as mould surface. A material transfer was also found to occur from the solid polymer films to the moulded polymer surface.     

原位FTIR研究含磷阻燃PET的阻燃机理

采用原位傅里叶变换红外光谱并结合热分析等手段研究了含磷阻燃聚酯的热解过程。通过与未加阻燃剂聚酯的比较,得出阻燃剂分子抑含磷阻燃聚酯聚合物中肪肪族ＣＨ２基的氧化,捕获热产生的可燃物,促使聚酯成碳形成的惰性隔层,从而达到阻燃目的。     

Dehydrogenation and aromatization of methane in the absence of oxygen on Mo/HZSM-5 catalysts before and after NH4OH extraction

A phosphorus-modified electrolytic silver catalyst was prepared and used as catalyst in the oxidative dehydrogenation of glycoto glyoxal. The yield of glyoxal was observed as high as 82% at 98% conversion for the Ag-P catalyst, while 62% at 89% conversion for the pure electrolytic silver. The formation of the surface compounds between the phosphorus additives and the silver surface was demonstrated by means of XPS and SEM. It caused the decrease of the surface concentration of atomic oxygen species, and restrained the decomposition and total oxidation of adsorbed glycol to C₁ products.     

稀土元素对甲硫醇催化分解活性位点的调控作用

采用等体积浸渍法制备La、Ce改性的MCM-41催化剂,考察不同稀土金属元素对甲硫醇催化分解活性位点的调控作用。采用N_2吸附-脱附、XRD、XPS、H_2-TPR和NH_3/CO_2-TPD等对La、Ce改性催化剂进行物理化学性能测试,确定稀土元素La、Ce在催化剂中存在的形态和作用。研究表明,甲硫醇催化分解存在两步反应,低温条件下甲硫醇催化分解生成甲硫醚中间体,高温条件下甲硫醚进一步催化分解生成硫化氢和甲烷等小分子产物。对于10%Ce/MCM-41催化剂,表面活性氧是甲硫醇催化分解的低温活性中心,强酸性位点是甲硫醇催化分解的高温活性中心,二者在反应中起协同催化作用,而对于10%La/MCM-41催化剂,强酸性位点是甲硫醇催化分解的活性中心。     

Investigation of the thermal degradation of polyurea: The effect of ammonium polyphosphate and expandable graphite

Polyurea was compounded with ammonium polyphosphate and expandable graphite and the morphology was studied by atomic force microscopy. The thermal degradation of polyurea and polyurea compounded with the additives has been investigated using thermogravimetry coupled with Fourier Transform infrared spectroscopy and mass spectrometry. The study of the thermal degradation and the parameters affecting the thermal stability of PU is essential in order to effectively design flame retarded polyurea. In general, thermal decomposition of polyurea occurs in two steps assigned to the degradation of the hard segment and soft segment, respectively. Adding these additives accelerates the decomposition reaction of polyurea. However, it is clear that more char is formed. This char is thermally more stable than the carbonaceous structure obtained from neat PU. The intumescent shield traps the polymer fragments and limits the evolution of small flammable molecules that are able to feed the flame.     

Effects of aromatic groups in polymer chains on plasma surface modification

Three polyester films with different repeating units—poly(lactic acid) (PLA), poly(ethylene terephthalate) (PET), and poly(oxybenzoate‐co‐oxynaphthoate) (PBN)—were modified by plasma, and the way in which the chemical compositions of the polymer chains influenced the plasma modification was investigated with contact‐angle measurements and X‐ray photoelectron spectroscopy (XPS). There were large differences in the compensated rates of weight loss among the three polyester films when they were exposed to Ar and O₂ plasmas. The PLA film showed the highest rate for weight loss of the three films, and the PBN film showed the lowest rate. The PET and PBN film surfaces were modified to become more hydrophilic by either argon or oxygen plasma. However, the PLA film surface was not made more hydrophilic by the plasmas. XPS spectra showed that the PLA film surface was not modified in its chemical composition, but the PBN film surface was modified in its chemical composition to form C? O groups in the PBN polymer chains. The reason that the PLA film surface was not modified but the PBN film surface was modified was examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 96–103, 2003     

Surface modification of ethylene copolymers molded against different mold surfaces. Part 2. Changes at the outermost surface

The influence of the mold surface on the surface composition of thermoplastics has been investigated. Two different random copolymers, poly(ethylene-co-acrylic acid) (EAA) and poly(ethylene-co-vinyl acetate) (EVA), with varying comonomer contents were used. Specimens were prepared in molds coated with films of perfluorinated ethylene-propylene copolymer (FEP) and of poly(ethylene terephthalate) (PET). Samples were also molded against air and vacuum. Changes in the concentration and arrangement of the functional groups at the outermost surface were studied using X-ray photoelectron spectroscopy (XPS or ESCA), Fourier transform infra-red techniques (FTIR), and contact angle measurements. The concentration of functional groups at the outermost copolymer surface depended on the nature of the surface against which the random copolymers were molded. Results are interpreted in terms of differences in surface energy between the mold surface and the copolymer. The polar acrylic acid groups in EAA increased when molded against the polar PET mold surface and decreased when molded against nonpolar mold surfaces. Air exposure affected the EAA copolymer surface so that the nonpolar parts migrated to the outermost polymer surface, which resulted in a decreased content of acrylic acid groups. Acetate groups in EVA were found to be in excess at the surface when molded against both polar PET and nonpolar FEP. The signal of O 1s in the XPS spectra depended on the mold surface and the time in the XPS vacuum environment. This can be explained in terms of preferential arrangement of the acrylic acid and the vinyl acetate groups.     

Effect of grafting of acrylic acid onto PET film surfaces by UV irradiation on the adhesion of PSAs

To improve the peel strength between a pressure-sensitive adhesive (PSA) and its substrate, grafting of acrylic acid (AA) onto the surface of poly(ethylene terephthalate) (PET) film was carried out. After AA was coated onto the surface of PET films using a spin coater, the coated PET films were irradiated by UV. To investigate the surface chemistry and topography of the PET-g-AA films, the grafted surface of the PET films was characterized by FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning probe microscopy (SPM). From these investigations, the effects of grafting of AA at the surface of PET by UV irradiation were discussed. In addition, to determine the effect of grafting on the adhesion between PSA polymer and PET-g-AA films, peel strength was measured after the PSA/PET-g-AA system was cured at various temperatures. As the esterification between PSA polymer and PET-g-AA films occurred in the interfacial region, the peel strength of the PSA/PET-g-AA system generally increased with increasing curing temperature.     

Synthesis and characterization of copolyesters containing the phosphorus linking pendent groups

Poly(ethylene terephthalate)‐co‐poly(ethylene DDP)s [PET‐co‐poly(ethylene DDP)s], were synthesized by charging 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOP), itaconic acid, terephthalic acid, and ethylene glycol in one reactor to conduct the microaddition reaction (using H₂PtCl₆ as catalyst), esterification reaction, and polycondensation reaction. H₂PtCl₆ has demonstrated to be a highly efficient microaddition catalyst to improve the DDP conversion. The microaddition reaction of the phosphorus compound (DOP) with the itaconic acid can be proceeded at a significantly lower temperature (110°C) and results in higher conversion (> 98%). The use of the H₂PtCl₆ catalyst makes it possible to charge all the reactants in one reactor to produce high molecular weight phosphorus‐containing copolyesters without requiring the presynthesis of the DDP. These resulting copolyesters are identified by Fourier transform infrared spectroscopy, ¹H‐NMR, and differential scanning calorimetric analysis. Thermal characteristics, thermal stability, intrinsic viscosity, acid value, and rheological and mechanical properties of these copolyesters were also characterized. The presence of the bulky pendent phosphorus side groups in the copolyester tends to decrease the structural regularity and retards its crystallization. The formation of a protected char layer for the phosphorus‐containing copolyester raises the decomposition temperature of the copolyester under an oxygen atmosphere higher than that of PET. The limiting oxygen index values of all phosphorus‐containing copolyesters are all higher than 33. Higher phosphorus content results in decreasing crystallinity, lower melting temperature, lower decomposition temperature, as well as lower tensile strength, but increasing residual char after thermal degradation and higher limiting oxygen index value. The rheological behaviors of copolyesters remain similar to that of PET. The glass temperatures of copolyesters are all ∼ 77°C (76.8°–77.2°C). Incorporation of phosphorus moieties into its molecular chain has a significant effect on thermal and flame retardancy behavior. However, the crystal lattice of all copolyesters do not change with incorporation of the pendent phosphorus side group in the backbone of the copolyester. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 109–122, 1999     

Recovery of gold by electroless precipitation from acid solutions using polyaniline

The oxidation of the leucoemeraldine (LM) and emeraldine (EM) states of polyaniline (PAN) and the subsequent reprotonation and reduction of the nigraniline (NA) and pernigraniline (PNA) in acid gold solution were utilized for the spontaneous and sustained reduction of gold. The rate of Au reduction is strongly dependent on the intrinsic oxidation state of the polymer and the polymer surface area. The rate also increases with decreasing pH of the chloroauric solution to about pH ～ 1. X-ray photoelectron spectroscopic (XPS) results indicate that only elemental gold or Au(0) accumulates on the polymer surface. The N1s core-level spectra of the protonated and base form of EM films after Au reduction confirm that the intrinsic structure of the polymer remains intact. The process, however, is limited by the decreasing effective surface area of the polymer due to Au deposition. The results indicate that an LM film accumulated up to five times its own weight of Au (Au/monomer mole ratio > 2) before the recovery rate was significantly retarded.