纳米SiO2对PP/MPP/PEPA膨胀阻燃体系的协同作用

以纳米SiO,为阻燃协效剂,采用多聚磷酸蜜胺(MPP)和茏状季戊四醇磷酸酯(PEPA)复配阻燃剂,制备具有良好阻燃性能的无卤阻燃聚丙烯(PP).研究纳米SiO2用量对PP阻燃性能和协效作用的影响.结果表明:添加少量的纳米SiO2可提高PP的阻燃性能;当纳米SiO2添加量为1%时,阻燃PP的氧指数达28.5%.TGA和FTIR分析及SEM和体式显微镜观测结果表明:添加少量的纳米SiO2可促进体系成炭,稳定炭层,从而提高材料的阻燃性能.     

纳米SiO2与RDP协同阻燃PC/ABS的研究

采用间苯二酚双（二苯基磷酸酯）（RDP）及其与纳米SiO2复配制备双酚A聚碳酸酯/丙烯腈-丁二烯-苯乙烯（PC/ABS）阻燃材料,测定了阻燃PC/ABS的极限氧指数、UL94V阻燃性能及热稳定性,采用扫描电子显微镜(SEM)观察了阻燃PC/ABS于600 ℃热分解残余物的形态,采用锥形量热仪测定了阻燃PC/ABS的释热速率峰值（p-HRR）、释热速率平均值（av-HRR）、总释热量（THR）、平均有效燃烧热（av-EHC）和平均质量损失速度（av-MLR）。结果表明,纳米SiO2与RDP添加量分别为5 %和9 %时,PC/ABS的阻燃性能达UL94V-0级,极限氧指数为29.0 %,且阻燃PC/ABS的p-HRR、av-HRR、THR、av-EHC以及av-MLR分别下降了16.12 %、58.82 %、40.83 %、17.91 %和36.90 %,同时也证明了纳米SiO2与RDP具有非常好的协同阻燃效应。     

纳米Mg(OH)2阻燃PP的性能研究

以微胶囊红磷(MRP)、有机化蒙脱土(OMMT)、SiO2和TiO2等为协效剂,制备了无卤阻燃型PP/纳米Mg(OH):复合材料,并与PP/微米Mg(OH)2复合材料进行比较.氧指数(LOI)测试表明:纳米Mg(OH)2的阻燃效果优于微米Mg(OH)2,OMMT的协效作用最佳.力学性能测试表明:纳米Mg(OH)2阻燃体系的力学性能明显优于微米Mg(OH)2阻燃体系.熔体指数(MI)测试结果表明:随Mg(OH)2含量增加,复合材料的加工性能变差,但纳米Mg(OH)2阻燃体系的加工性能优于微米Mg(OH)2阻燃体系.     

无卤阻燃PC/ABS合金的研究

研究了四苯基间苯二酚基二磷酸酷(RDP)和氢氧化铝复配阻燃体系对PC/ABS合金性能的影响;并以马来酸酐接枝丙烯腈-苯乙烯-丁二烯共聚物(ABS-g-MAH)为相容剂,考察了ABS-g-MAH的用量对合金性能的影响.结果表明,复配阻燃体系可显著提高PC/ABS合金的阻燃性能,当RDP为14份、Al(OH)3为6份时,氧指数可达到32%;相容剂的加人能够明显提高合金的力学性能,最佳用量为6%,但使体系的黏度增加,熔体质量流动速率降低.     

白炭黑改性膨胀阻燃剂对PP/POE燃烧及力学性能的影响

采用白炭(黑SiO2)作为协效阻燃剂,与膨胀阻燃(剂IFR)复配阻燃聚丙烯/乙烯-辛烯共聚物(PP/POE)复合材料,观察其用量对复合体系燃烧及力学性能的影响。结果表明:当SiO2/IFR/PP/POE为1/9/3.3/20时,体系的阻燃效果较好,垂直燃烧实验达到了UL 94 V-0级,拉伸强度提高很大,冲击强度略微降低,体系的综合性能最佳。     

芳基磷酸酯/膨胀型阻燃剂协同阻燃PP的制备及性能研究

以间苯二酚双(二苯基)磷酸酯(RDP)为阻燃协效剂,与三聚氰胺焦磷酸盐(MPP)和季戊四醇(PER)组成的膨胀型阻燃剂(IFR)复配,制备了具有良好阻燃性能的无卤阻燃聚丙烯(PP)。研究了RDP的用量对PP/IFR体系阻燃性能和力学性能的影响,并通过热重分析(TGA)和动态热机械分析(DMA)等手段对阻燃材料进行了表征。结果表明:RDP与IFR具有明显的协同阻燃作用。当RDP质量分数为5.0%时,阻燃PP的氧指数(LOI)从28.5%提高至30.5%,UL-94由V-1级提升至V-0级;此外,体系的缺口冲击强度也有较大幅度提高。     

铁酸镍在膨胀阻燃聚乳酸复合材料中的作用

利用水热法制备了铁酸镍(NiFe_2O_4)纳米粒子,基于生物可降解材料聚乳酸(PLA)的易燃性,将NiFe_2O_4纳米粒子作为协效剂与膨胀型阻燃剂(IFR)复配,应用于PLA的阻燃改性。结果表明,所有的PLA复合材料均达到UL-94 V-0级别,LOI显著提高至39%以上;NiFe_2O_4纳米粒子有助于PLA膨胀阻燃体系形成更为膨胀和相对致密的炭层,明显提高炭渣中有序化炭的含量,有效提高PLA膨胀阻燃体系的初始降解温度,并显著提高其成炭量。因此,NiFe_2O_4纳米粒子在PLA膨胀阻燃体系中具有良好的协效作用,能够显著提高PLA膨胀阻燃体系的热稳定性和阻燃性能。     

磷-氮-溴/POE协效阻燃体系在聚丙烯薄膜中的应用研究

考察了磷-氮-溴阻燃体系与聚烯烃弹性体(POE)对聚丙烯(PP)的协效阻燃作用,通过对PP薄膜阻燃和力学等性能的研究,分析了POE与磷-氮-溴阻燃体系的协效作用机理。结果表明:将POE与磷-氮-溴阻燃体系按1:1的比例复配,所得复合阻燃剂能取得良好的协同阻燃效果,其中当协效阻燃剂的添加量为9%时,PP薄膜的阻燃等级达到UL 94VTM-0级,且具备优异的综合性能。     

BDP阻燃PC/ABS及其纳米复合材料的阻燃性和热降解动力学

采用双螺杆挤出机挤出造粒制备了苯基双酚A二磷酸酯(BDP)阻燃的聚碳酸酯(PC)/丙烯腈-丁二烯-苯乙烯(ABS)、PC/ABS有机蒙脱土(OMMT)和PC/ABS有机改性纳米二氧化(SiO2)3种复合材料,采用热重分析探讨了PC/ABS/BDP , PC /ABS/BDP/OMMTPC/ABS/BDP/SiO2复合材料的热降解动力学行为,以此分析其阻燃性能与热降解行为的关系。结果表明,加入纳米材料后,在质量损失8%以前,PC/ABS/BDP/OMMT和PC/ABS/BDP/SiO2纳米复合材料的活化能均低于PC/ABS/BDP的活化能,但质量损失8%以后,PC/ABS/BDP/OMMT和PC/ABS/BDP/SiO2复合材料的活化能均高于阻燃PC/ABS。在质量损失5%-75%范围内,PC/ABS/BDP/OMMT和PC/ABS/BDP/SiO2平均活化能分别为139.39KJ/mol和144.17KJ/mol,均高于PC/ABS/BDP的平均活化能(104.87 kJ /mol),说明添加纳米材料后,由于BDP与OMMT或SiO2的协同阻燃作用,降低了材料的热降解速率,增大了材料的热稳定性,这与氧指数测试、UL94V阻燃性能及热重分析得出的结沦一致。     

NE/OMMT纳米复合物与RDP复配阻燃ABS的制备与性能

采用酚醛环氧树脂/有机蒙脱土(NE/OMMT)纳米复合物与间苯二酚双(二苯磷酸酯)(RDP)复配作为阻燃剂,制备了阻燃ABS;研究了OMMT用量对ABS阻燃性能及力学性能的影响;并通过TGA、XRD、TEM对材料进行了表征。结果表明:NE/OMMT纳米复合物与RDP对ABS具有很好的协同阻燃作用,当OMMT、NE和RDP用量分别为0.5%、6.0%和9.0%时,阻燃ABS氧指数高达39.0%,且力学性能优良;OMMT的添加提高了阻燃ABS的热稳定性;OMMT经NE插层后,层间距明显增大,与ABS熔融共混后可产生部分剥离。     

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.     

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.     

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.     

Participation of lewis base on vinyl chloride polymerization with Al(C2H5)3CCl4 catalyst system

The polymerization of vinyl chloride has been investigated using an $\text{Al}\text{(}\text{C}{}_2\text{H}{}_5\text{)}{}_3\text{CCl}{}_4$ catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed.     

Synthesis and Characterization of Ti0.33Ta0.33Nb0.33C and Ti0.33Ta0.33Nb0.33CxN1-x Whiskers

Ta_0.33Ti_0.33Nb_0.33C and Ta_0.33Ti_0.33Nb_0.33C _x N_{1− x} whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N₂. The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO₂, Ta₂O₅, Nb₂O₅, C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl₂( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature.