阻燃聚丙烯/三聚氰胺聚磷酸盐/磷酸三苯酯复合材料的制备及性能研究

利用熔融共混法制备了阻燃聚丙烯(PP)/三聚氰胺聚磷酸盐(MPOP)/磷酸三苯酯(TPP)复合材料,并探讨了MPOP含量和MPOP/TPP质量比对其力学性能、热稳定性和燃烧性能的影响。结果表明,单独添加MPOP时,随着MPOP添加量的增加,复合材料的拉伸性能降低,冲击性能、热稳定性和阻燃性能提高;MPOP与TPP复配后,固定MPOP/TPP总含量为30份时,随TPP含量的增加,复合材料的断裂伸长率和缺口冲击强度呈增大趋势,拉伸强度呈减小趋势,热稳定性下降,阻燃性能先提高后下降,当MPOP/TPP质量比20/10进行复配时阻燃性能最佳。     

MPOP/APP复合阻燃剂对PP燃烧行为的影响

通过熔融共混法制备了聚丙烯/三聚氰胺聚磷酸盐(PP/MPOP)和聚丙烯/三聚氰胺聚磷酸盐/聚磷酸铵(PP/MPOP/APP)阻燃复合材料,探讨了阻燃剂MPOP的添加量以及MPOP、APP的配比对复合材料燃烧行为的影响。结果表明:PP/MPOP复合材料的热稳定性和阻燃性能随MPOP添加量的增加而提高,且均在MPOP添加量为30份时达到最大值。同PP/MPOP(100/30)相比,当复合阻燃剂MPOP/APP的添加量为30份、且配比为15/15时,复合材料PP/MPOP/APP的热稳定性下降。但在所有试样中,该阻燃PP复合材料具有最低的最大分解速率以及最高的成炭率;其极限氧指数(LOI)为23.6%,较PP/MPOP(100/30)和纯PP分别提高了22.3%和32.6%;并且PP/MPOP/APP(100/15/15)的平均热释放速率、总释热量、有效燃烧热均达到最低值,因此该复合材料具有最佳的阻燃性能。     

一种膨胀阻燃PP体系及其阻燃性能研究

研究了膨胀型阻燃剂三聚氰胺聚磷酸盐(MPP)和季戊四醇(PER)对PP阻燃性能的影响。采用垂直燃烧测试仪、锥形量热仪和扫描电子显微镜进行了PP/MPP/PER复合材料的阻燃性能、残碳形貌分析。结果表明,MPP与PER的质量比为3∶2时,阻燃剂总质量分数为25%就能达到UL94V-0等级,阻燃效果最好。     

羟基锡酸锌/MPP-PER协同阻燃聚丙烯的性能研究

将三聚氰胺磷酸盐(MPP)、季戊四醇(PER)用于聚丙烯(PP)阻燃改性，研究了羟基锡酸锌(ZHS)对PP抑烟效果的影响。采用极限氧指数(LOI)、UL-94燃烧等级测试、烟密度、锥量测试分析了阻燃PP复合材料的阻燃性能。结果表明，MPP-PER复配能起到较好的阻燃协同作用，能有效提升聚丙烯复合材料的阻燃性能；ZHS的加入能显著降低聚丙烯复合材料的产烟量。当MPP-PER阻燃剂添加量为26%,ZHS的添加量为3%时，LOI达25.1%,UL-94通过V-2级(1.6 mm),燃烧最大比光密度(Ds_max)相比于纯PP降低了23.7%。     

UF/MPOP与PEA/MPOP对木材燃烧性能的影响

分别以脲醛树脂(UF)和纯丙乳液(PEA)树脂为基料,三聚氰胺聚磷酸盐(MPOP)、三聚氰胺(MEL)、季戊四醇(PER)为膨胀阻燃体系,制备了膨胀型阻燃涂料。通过热重分析仪对制备的MPOP热稳定性及阻燃机理进行了表征,利用锥形量热仪、极限氧指数测试仪对涂料阻燃性能进行分析。结果表明,与PEA/MPOP相比,UF/MPOP对木材具有更好的阻燃性能,热稳定性和抑烟性能,极限氧指数提高了9.4 %,热释放速率、总热释放量、烟气释放速率降低,在木材表面形成的炭层更加完整。     

含磷三嗪环聚合物阻燃聚丙烯材料的制备及性能

利用自制的三嗪环低聚物(PMPT)及复合阻燃剂制备阻燃聚丙烯材料,研究复合阻燃剂APP/PER/PMPT用量对阻燃PP力学性能、热分解性能的影响,并初步推测阻燃剂PMPT的阻燃机理.结果表明:加入复合阻燃剂使阻燃PP的力学性能有所下降.TG曲线显示:复合阻燃剂使阻燃PP的热分解速率减小,热稳定性增加.复合阻燃剂APP/PER/PMPT使PP的氧指数(LOI)增加62%.APP/PER/PMPTF复合阻燃剂主要在凝聚相起到阻燃作用.     

三聚氰胺聚磷酸盐/硼酚醛协效体系阻燃PA66/GF复合材料的研究

采用氮磷型阻燃剂三聚氰胺聚磷酸盐(MPP)与硼改性酚醛树脂(BPF)组成的复合阻燃体系对玻纤(GF)增强尼龙66( PA66)复合材料进行阻燃,获得了阻燃性能优异、力学性能良好的增强复合材料,研究了协效阻燃剂BPF/MPP配比、BPF/MPP用量及GF用量对阻燃复合材料阻燃性能的影响,采用微型燃烧量热和质量保持率分析方法研究了阻燃复合材料的燃烧及成炭行为,对复合阻燃剂的协效机理进行了讨论.结果表明,当BPF在BPF/MPP中的质量分数为15％时,添加25％ BPF/MPP复合阻燃剂可使20％ GF增强PA66复合材料达到V-0( 1.6 mm)阻燃级别,极限氧指数增加至25.3％,拉伸强度、弯曲强度、缺口冲击强度分别为116 MPa,132 MPa,7.1 kJ/m2.该复合材料可满足高性能无卤阻燃的使用要求.     

TPP/EG在软质聚氨酯泡沫中协同阻燃作用的研究

采用磷酸三苯酯(TPP)和可膨胀石墨(EG)进行复配,通过一步法发泡工艺制备了具有阻燃性能的软质聚氨酯泡沫(FPUF)。通过极限氧指数(LOI)、垂直燃烧和烟密度测试对FPUF的阻燃性能进行研究,探索了TPP与EG之间的协同阻燃作用。结果表明:TPP与EG之间存在一定的协同增强FPUF的阻燃性能。当TPP/EG配比为1/3、复配型阻燃剂用量为30份时,阻燃FPUF的LOI值达到25%。同时,复配型阻燃剂添加到FPUF中还能降低有焰燃烧时间,并起到一定的抑烟作用。     

ALPi/MPP/FeCo-MOF协效阻燃PBT/PP复合材料的研究

制备了一种双金属协效阻燃剂(FeCo-MOF),研究了二乙基次膦酸铝(ALPi)/三聚氰胺聚磷酸盐(MPP)/FeCo-MOF协效阻燃聚对苯二甲酸丁二醇酯/聚丙烯(PBT/PP)复合材料的性能。结果表明：当ALPi/MPP/FeCo-MOF的质量比为13.00∶6.50∶0.60时,阻燃PBT/PP复合材料的极限氧指数为32%,UL-94垂直燃烧阻燃等级为V-0级,800℃时残炭率达8.97%。     

无卤阻燃ABS/TPU复合材料阻燃性能的研究

采用了微胶囊红磷(MRP)、氢氧化镁(MH)、聚硅氧烷组成复合阻燃剂,对丙烯腈-丁二烯-苯乙烯(ABS)/热塑性聚氨酯(TPU)合金进行改性,获得了环保型阻燃ABS/TPU复合材料。对该复合材料进行了阻燃性能、热稳定性测试和炭层形貌分析。结果表明,当复合阻燃剂MRP/MH质量比为1/1且添加量为16份时,复合材料的极限氧指数(LOI)为25.7%,垂直燃烧性能通过FV-0级;TPU结构中因含氧,有利于MRP/MH阻燃体系阻燃;添加6份聚硅氧烷,复合材料垂直燃烧级别达到FV-0级,聚硅氧烷燃烧过程中通过改变炭层形貌,提高阻燃性。     

Polymorphism of LiGa5O8 and of LiGa5O8-MgGa2O4Solid Solutions

High-temperature X-ray diffraction and differential thermal analyses showed that LiGa₅O₈ exists in two polymorphs related by the first-order transition at 1138°±3°C of the low-temperature simple-cubic form, space group (probably) O⁷, to the high-temperature spinel (fcc) form, space group O _h ⁷. The transition is rapid, and the high-temperature form in pure LiGa₅O₈ could not be quenched to room temperature under the conditions used. However, the high-temperature polymorph can be quenched under equilibrium conditions when 40 mol% or more MgGa₂O₄ is present. The subsolidus equilibrium relations in the system MgGa₂O₄-LiGa₅O₈ are discussed.     

Magnetoresistance of CuxCo1-xFe2O4 Ferrites

Magnetoresistance measurements (Δ/R) were carried out on Cu _x Co_{1- x} Fe₂O₄ samples with x =1, 0.75, 0.50, 0.25 and cobalt ferrite in the range of magnetic intensity (H) from 1.0 to 4.5 kG. Linear plots were obtained between log (Δ/R) and log H for all compositions except that of cobalt ferrite. The values of n at x =0.5 do not agree with the results of some authors. The discrepancy may be attributed to the value of magnetic field intensity at which such measurements were carried out. The similarity of features of n and μ_D with composition leads us to believe that the magnetoresistance may arise from the scattering of conduction electrons by localized electrons involving the s-d exchange interaction.     

Sintering of Si3N4-Y2O3-Al2O3

Sintering kinetics of the system Si₃N4-Y2O₃-Al₂O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si₃N₄ were studied with additions of 4 to 17 wt% Y₂O₃ and 4 wt% A1₂O₃. Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si₃N₄ and glass or β '-Si₃N₄, α '-Si₃N₄, and glass. The compositions and amounts of the residual glassy phases are estimated.     

Expansive properties of the mixture C4ASH12 − 2CS III. Effects of temperature and restraint

The effects of temperature and restraint upon the hydration and the expansion of $\text{C}{}_4\text{A}\text{S}\text{H}{}_{12}\text{? 2}\text{C}\text{S}$ mixture compacts in different contact solutions have been investigated. Temperatures above 20°C do apparently hinder the formation of an impervious felt-like layer of ettringite around the $\text{C}{}_4\text{A}\text{S}\text{H}{}_{12}$ particles, thus greatly reducing the retarding effect of the lime. An uniaxial restraint of 1 Kg/cm² is enough to reduce sensibly the expansions which remain however high (about 100%). The results can be satisfactorily interpreted by the reaction and expansion mechanism hypothesized in our previous papers.     

Raman Study of Glasses of Ba2TiSi2O8 and Ba2TiGe2O8

Raman spectra are reported for fresnoite (Ba₂Ti(Si,Ge)₂O₈ glasses, and comparison is made between the Raman spectra of the corresponding crystalline powders and glasses of Ba₂TiSi₂O₈ and Ba₂TiGe₂O₈. The Ba₂TiGe₂O₈ glass spectra show correspondence with the Ba₂TiGe₂O₈ crystalline Raman spectra; the v _s(Ge–O–Ge) mode occurs at 518 cm⁻¹ in the glass and at 521 cm⁻¹ in the crystalline material. Five-fold coordinated titanium is the majority species present in the Ba₂TiGe₂O₈ glass as revealed by a strong band at 824 cm⁻¹ in the I glass spectrum. The Ba₂TiSi₂O₈ glass spectra are similar to the Ba₂TiSi₂O₈ crystalline spectrum; the strongest band is found at 836 cm⁻¹ in the I glass spectrum. Through comparison with the previous Raman data of other titania silicate glasses, we conclude that the Ba₂TiSi₂O₈ glass has a structure similar to the crystalline phase.     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Effects of metal-support interactions on the hydrogenation of CO over PdSiO2 and PdLa2O3

A study of CO hydrogenation over $\text{Pd}\text{SiO}{}_2$ and $\text{Pd}\text{La}{}_2\text{O}{}_3$ has been carried out for the purpose of identifying the effects of Pd dispersion, Pd morphology, and support composition on the catalytic activity of supported Pd. The specific activity of each catalyst for methanol and methane synthesis was determined from microreactor studies carried out at a fixed set of reaction conditions. Palladium dispersion was measured by H₂O₂ titration, and the morphology of the Pd crystallites, as expressed by the distribution of Pd(100) and Pd(111) planes, was determined from in situ infrared spectra of adsorbed CO. The crystallite morphology of the $\text{Pd}\text{SiO}{}_2$ catalysts is the same, independent of Pd weight loading: 90% of the surface is comprised of Pd(100) planes and 10% of the surface is comprised of Pd(111) planes. By contrast, the crystallite morphology of the $\text{Pd}\text{La}{}_2\text{O}{}_3$ catalysts changes with Pd loading. Primarily Pd(100) planes are exposed at low-weight loadings while Pd(111) planes are exposed at high-weight loadings. The Pd dispersion has little effect on the methanol turnover frequency over both $\text{Pd}\text{SiO}{}_2$ and $\text{Pd}\text{La}{}_2\text{O}{}_3$, for dispersions between 10 and 20%. On the other hand, the methane turnover frequency is independent of Pd dispersion over $\text{Pd}\text{SiO}{}_2$, but increases with decreasing dispersion over $\text{Pd}\text{La}{}_2\text{O}{}_3$. It is further observed that the Pd morphology influences the specific activity of $\text{Pd}\text{La}{}_2\text{O}{}_3$ for methanol synthesis: Pd(100) is nearly threefold more active than Pd(111). For a fixed morphology, the specific methanol synthesis activity of $\text{Pd}\text{La}{}_2\text{O}{}_3$ is a factor of 7.5 greater than that of $\text{Pd}\text{SiO}{}_2$.     

In situ laser raman spectroscopy of the sulfiding of Moγ-Al2O3 catalysts

Raman spectra of sulfided $\text{Mo}\text{γ-}\text{Al}{}_2\text{O}{}_3$ catalysts were obtained using in situ techniques for two sulfiding methods. For samples sulfided by 10% $\text{H}{}_2\text{S}\text{H}{}_2$ at 400 °C, MoS₂ structures were observed. A stepwise sulfiding using 10% $\text{H}{}_2\text{S}\text{H}{}_2$, with spectra recorded at 150, 250, and 350 °C, resulted in observation of molybdenum oxysulfide, reduced molybdate, and surface “MoS₂” phases. Reexposure of these samples to air led to radical modification of the oxysulfide structures as well as transformation of some sulfide phases. A model incorporating terminal and bridging MoS bonding and anion vacancies is proposed. This model is based on the conversion of isolated and aggregated molybdate and MoO₃ species to oxysulfide and reduced molybdenum phases. Conversion of reduced molybdenum phases to sulfides is observed to be slow.     

Wet Milling of Fe/Al/Al2O3 and Fe2O3/Al/Al2O3 Powder Mixtures

Wet milling of Al₂O₃-aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al₂O₃ and Fe₂O₃/Al/Al₂O₃ powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe₂O₃/Al/Al₂O₃ powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al₂O₃ powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8.