扩链剂ADR对PLA/Nano-ZnO/CCA纳米复合抗菌材料的影响

将环氧系扩链剂ADR添加到聚乳酸(PLA)/Nano-ZnO/叶绿素铜酸(CCA)纳米复合抗菌材料中,研究了ADR添加量对复合材料抗菌性能和力学性能的影响。结果表明,在ADR质量分数为0%~1.0%范围内,随ADR含量的增多,复合材料对大肠杆菌的抗菌性能略有减弱,其缺口冲击强度有较大幅度的增加,弯曲强度、拉伸强度略有增加,断裂伸长率先增大后减小,ADR质量分数小于1.0%时仍属强抗菌材料。当ADR质量分数为1.0%时复合材料的综合性能较好,其抗菌率为99.4%,拉伸强度、断裂伸长率、缺口冲击强度、弯曲强度分别比PLA/Nano-ZnO/CCA复合材料提高了4.6%,11.6倍、71.4%,4.8%。     

CCA对PLA/S–AMB/TBC纳米复合抗菌材料性能的影响

用自制抗菌母料S1–AMB[含nano-Zn O和叶绿素酮酸(CCA)]和S2–AMB(只含nano-Zn O)分别与聚乳酸(PLA),柠檬酸三丁酯(TBC)热机械共混制得PLA/S1–AMB/TBC和PLA/S2–AMB/TBC纳米复合抗菌材料。对比研究了不同nano-Zn O含量的两类复合材料对大肠杆菌抗菌性能和力学性能的影响。结果表明,CCA的加入使PLA/S1–AMB/TBC复合材料的抗菌性能和断裂伸长率大幅度提高;当nano-Zn O/CCA质量比为18/6,nanoZn O质量分数为1.2%时,复合材料的抗菌率达到99.5%,为强抗菌材料;和PLA/S2–AMB/TBC相比,其断裂伸长率提高17.8倍,是纯PLA的16.4倍;缺口冲击强度、弯曲强度和拉伸强度保留率分别为76.0%,85.8%,92.0%;不加CCA时,PLA/S2–AMB/TBC的抗菌率仅为4.2%,不具备抗菌性能。     

抗菌母料中Nano-ZnO/CCA配比对PLA/AMB/TBC纳米复合材料性能的影响

以聚乳酸(PLA)为基体树脂,nano-ZnO和叶绿素酮酸(CCA)为复合抗菌剂,通过溶液共混制得抗菌母料(AMB),用PLA与AMB、柠檬酸三丁酯(TBC)热机械共混制得PLA/AMB/TBC纳米复合材料。研究了母料中nano-ZnO/CCA质量配比对纳米复合材料抗菌性能和力学性能的影响。结果表明,少量CCA的加入使纳米复合材料对大肠杆菌的抗菌性能大幅度提高;当纳米复合材料中TBC和nano-ZnO质量分数分别为10%和0.9%,AMB中nano-ZnO/CCA质量配比为18/8时,纳米复合材料的抗菌性能最好,其抗菌率达到99.6%,断裂伸长率是纯PLA的2.17倍,拉伸强度、弯曲强度和冲击强度保留率分别为75%,65%,70%。     

PETG/纳米氧化锌/叶绿素铜酸纳米复合抗菌材料的制备与性能

以国内试产的聚对苯二甲酸乙二醇1,4环己烷二甲醇酯（PETG）为基体,以叶绿素铜酸（CCA）及纳米氧化锌（nano-ZnO）作为复合抗菌剂,采用熔融复合工艺制备了PETG/nano-ZnO/CCA纳米复合抗菌材料,考查了nano-ZnO/CCA 质量配比对PETG抗菌性能和力学性能的影响。结果表明,当复合材料中nano-ZnO中的含量为1 %（质量分数,下同）、CCA的含量为0.5 %时,复合材料对大肠杆菌的抗菌性能最佳,达到99.9 %。     

ABS复合材料结构与力学性能研究

以苯乙烯-马来酸酐共聚物(SMA)为相容剂,在丙烯腈-丁二烯-苯乙烯共聚物(ABS)基体中分别添加乙烯-辛烯共聚物弹性体(POE)、热塑性聚氨酯弹性体(TPU)以及ABS高胶粉(ABSHR),制备了ABS复合材料。并运用动态力学分析(DMA)和扫描电镜(SEM)分析等手段,研究了该ABS复合材料力学性能的变化规律。结果表明:与纯ABS相比,POE与ABS的相容性稍差,相容剂SMA的增容效果不理想,ABS/SMA/POE复合材料的力学性能明显降低,其冲击强度降幅最大,达到56.5%;ABS/SMA/ABSHR复合材料各组分的相容性则相对较好,橡胶相分布均匀且粒子尺寸较小,材料的冲击性能明显改善,其冲击强度较纯ABS提高了34.4%。     

相容剂对玻纤增强ABS力学性能及外观的影响

以丙烯腈-丁二烯-苯乙烯共聚物(ABS)为基体,加入玻纤(GF)制备高性能ABS/GF复合材料,研究了自制的丙烯酸酯聚合物对该复合材料的力学性能及外观的影响。结果表明,该相容剂的加入,使得玻纤增强ABS复合材料的拉伸强度、弯曲强度及缺口冲击强度等性能明显提高,同时,还能明显减少浮纤,提高复合材料的光泽度。扫描电子显微镜(SEM)照片显示,该相容剂与玻纤的相容性良好,并趋向于分布在材料表面。     

ABS/Nano-ATH复合材料性能研究

采用熔融共混法制备出了丙烯腈-丁二烯-苯乙烯共聚物(ABS)/纳米氢氧化铝(nano-ATH)复合材料,研究了nano-ATH的用量对复合材料力学性能和阻燃性能的影响,并利用扫描电镜分析了nano-ATH在ABS基体中的分散情况。结果表明:随着nano-ATH用量的增加,ABS/nano-ATH复合材料的冲击强度和拉伸强度均是先升后降,分别在nano-ATH含量为10%和5%时达到最大值;nano-ATH的加入可以提高ABS复合材料的阻燃性能和弯曲模量,但随其用量的增加,nano-ATH在ABS基体中的分散性逐渐变差。     

纳米锡酸锌/ABS/PVO复合材料阻燃性能研究

采用熔融共混法制备了纳米锡酸锌/丙烯腈-丁二烯-苯乙烯共聚物(ABS)/聚氯乙烯(PVC)复合材料。并对复合材料的冲击强度、阻燃性能进行了测试。结果表明,纳米锡酸锌不但可以提高复合材料的缺口冲击强度,还可以改善复合材料的抑烟阻燃性能。特别是当纳米锡酸锌添加量为6份时,复合材料的阻燃抑烟性能最佳。与未添加纳米填料时相比,纳米锡酸锌/ABS/PVC复合材料的缺口冲击强度达到69．93 kJ/m~2,提高幅度达49．71%。扫描电镜(SEM)分析表明,当纳米锡酸锌在6份时,其在复合材料中呈纳米级分散,且与塑料基体结合良好。     

废旧丁腈橡胶粉和空心玻璃微珠改性丙烯腈-丁二烯-苯乙烯共聚物复合材料的研究

采用废旧丁腈橡胶粉(WNBR)和硅烷偶联剂改性的空心玻璃微珠(HGB)对丙烯腈-丁二烯-苯乙烯共聚物(ABS)改性,分别研究WNBR和改性HGB用量对WNBR/ABS和改性HGB/WNBR/ABS复合材料结构和性能的影响。结果表明:在WNBR/ABS复合材料中,WNBR用量较小时,WNBR粒子与ABS基体相容性较差,界面结合力较弱;WNBR用量为20份时,WNBR和ABS相容性较好,断面较平整光滑。WNBR可以降低复合材料的拉伸强度和弯曲强度,提高冲击强度。在改性HGB/WNBR/ABS复合材料中,改性HGB呈单分散状,没有团聚,分布比较均匀。改性HGB在用量低于5份时可以同时提高改性HGB/WNBR/ABS复合材料的拉伸强度、弯曲强度和冲击强度,用量为5份时复合材料的综合物理性能最佳。     

ABS回料/SB/DMMT复合材料的结构与性能

制备了苯乙烯-丁二烯塑料(SB)/双改性蒙脱土(DMMT)杂化物,并以其增韧增强丙烯腈-丁二烯-苯乙烯塑料(ABS)回料,研究了ABS回料/SB/DMMT复合材料的结构与性能。结果表明,随着SB/DMMT(70/30)杂化物用量的增加,复合材料的缺口冲击强度、拉伸强度和弯曲强度呈先增加后降低的趋势,在杂化物用量为10份时达到最大值,其力学性能和热稳定性明显高于ABS回料。透射电子显微镜和X射线衍射仪的测试结果显示,ABS回料/SB/DMMT复合材料属于插层结构与剥离结构共存的纳米复合材料。     

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.