微胶囊化红磷/酚醛环氧树脂阻燃ABS的研究

采用微胶囊化红磷(MRP)和酚醛环氧树脂(NE)复配阻燃剂,制备了无卤阻燃丙烯腈/丁二烯/苯乙烯共聚物(ABS).研究了MRP/NE质量比及用量对阻燃ABS性能的影响.结果表明,MRP/NE质量比为3:7、总量为20%(质量分数)时,可以制备氧指数(LOI)达24.0%、垂直燃烧级别达V-0的阻燃ABS;MRP/NE复配可以延缓ABS的分解并提高成炭率,残炭中保留了更多的ABS特征吸收峰;MRP/NE复配后,材料燃烧残炭的表面形成致密的炭层,内部有很多大的孔洞.     

丁腈橡胶增容无卤阻燃ABS

以丁腈橡胶(NBR)为增容增韧改性剂,采用微胶囊化红磷(MRP)和酚醛环氧树脂(NE)复配阻燃剂,制备具有良好阻燃性能的无卤阻燃ABS.研究丁腈橡胶(NBR)用量对ABS阻燃和冲击性能影响.结果表明:添加少量的NBR即可显著提高材料的冲击强度,但对阻燃性能损害不大;SEM形貌分析表明:NBR的加入提高了阻燃剂与基体的相容性;TGA和FRIT分析结果表明:NBR的加入没有改变材料热降解机理和产物的结构.     

新型无卤阻燃剂的制备及其阻燃ABS性能

制备新型的单分子磷-氮类膨胀型阻燃剂(TPA),采用微胶囊化红磷(MRP)与TPA复配阻燃剂,制备具有良好阻燃性能的无卤阻燃ABS.研究组分质量比和总用量对ABS阻燃性能的影响.结果表明:MRP/TPA质量比为1:1时,阻燃复配效果最好;总用量为20%时,材料的氧指数达24%,垂直燃烧迭V-0级.TGA结果表明:MRP/TPA的复配可以延缓ABS的分解并提高成炭率;由FTIR谱图看出,MRP/TPA复配后,残留物形成了更多交联结构.     

PP/MPP/PEPA的制备及其热降解性能研究

采用多聚磷酸蜜胺(MPP)和笼状季戊四醇磷酸酯(PEPA)复配阻燃剂,制备了具有良好阻燃性能的膨胀阻燃聚丙烯(PP),研究了各组分质量比对PP阻燃性和热降解性能的影响.结果表明:MPP与PEPA质量比为3:2时,阻燃复配效果最好;且添加阻燃剂质量分数为20%时,极限氧指数达到27%,UL达到Ⅴ-0级;热失重分析结果表明,MPP/PEPA可以延缓PP的分解;利用Kissinger法求取了材料的活化能,发现添加阻燃剂后,材料的活化能提高;残留物的红外光谱分析结果表明,MPP复配PEPA后,保留了更多的PP特征峰;体视显微镜和扫描电镜分析表明,添加阻燃剂后,材料形成了膨胀炭层,提高了 PP阻燃性能.     

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。     

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。     

高抗冲聚苯乙烯/微胶囊红磷/膨胀石墨阻燃材料的制备及性能研究

用熔融混合法制备了高抗冲聚苯乙烯(HIPS)/微胶囊红磷(MRP)/膨胀石墨(EG)无卤阻燃材料.用氧指数法、垂直燃烧及热重分析等方法研究了EG/MRP复配阻燃剂对高抗冲聚苯乙烯的阻燃作用,并对阻燃前后的HIPS复合阻燃材料进行了红外分析。结果表明,MRP和EG复配,可以使HIPS的氧指数提高到27%,垂直燃烧级别达到FV-0(1.5 mm);但是MRP与EG之间不存在协同阻燃效应;复配阻燃剂的作用机理为凝聚相阻燃机理,抗滴落剂的加入可以有效阻止材料燃烧时的滴落,提高材料的阻燃级别。     

EG与DBDPE/Sb2 O3复合阻燃ABS热失重行为研究

采用可膨胀石墨(EG)与十溴二苯乙烷(DBDPE)、三氧化二锑(Sb2O3)复合阻燃(丙烯腈/丁二烯/苯乙烯)共聚物(ABS),通过热重分析研究了阻燃ABS体系的热失重行为。结果表明,DBDPE/Sb2O3改变了ABS的热降解历程,以气相阻燃机理为主;EG对ABS的热降解历程影响不大,形成的炭层有利于阻燃,以凝聚相阻燃机理为主;两者复配可同时在气相和凝聚相起作用,使得ABS的峰值热失重速率均大幅下降,阻燃ABS的极限氧指数可达30%,EG与DBDPE/Sb2O3复合对ABS阻燃具有一定的协同阻燃效应。     

复配磷酸酯阻燃PC／ABS合金的研究

研究了复配磷酸酯阻燃剂对PC/ABS合金材料的性能的影响.探讨了复配磷酸酯阻燃剂阻燃PC/ABS合金材料的力学性能和阻燃性能,复配阻燃剂对PC/ABS合金的阻燃机理.结果表明:在PC/ABS合金(质量比为70/30)体系中,磷酸三苯酯(TPP)和四苯基[双酚-A]二磷酸酯(BDP)按质量比为3:2复配具有协同阻燃作用.加入18份复配阻燃剂后材料的氧指数提高了6个单位,阻燃性能达到了FV-0级,并保持了材料较好的力学性能.     

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.