PA6/SMA/N-PMI共混物的制备及其性能研究

采用熔融共混法制备了尼龙6/苯乙烯-马来酸酐共聚物/N-苯基马来酰亚胺共混物(PA6/SMA/N-PMI),并利用DSC、TGA及力学性能测试等手段研究了SMA用量对PA6/SMA/N-PMI共混物熔融结晶行为、热学性能以及力学性能的影响。结果表明,共混物的最大分解温度较纯PA6有较大提高;SMA用量的增加,共混物的结晶温度、结晶度以及熔融焓均先降低再升高;当SMA用量为5份时,共混物的弯曲强度、弯曲模量以及热变形温度均达到最大值,分别为113.8、3 053 MPa及61.3℃,较纯PA6分别提高了25.1%、28.0%及19.0%;拉伸强度在SMA用量为7.5份时达到最大值81.4 MPa,较纯PA6提高了17.1%。     

PA6/SMA/LGF复合材料的制备及其性能研究

采用熔融共混法制备了聚酰胺6/苯乙烯-马来酸酐共聚物/长玻璃纤维(PA6/SMA/LGF)复合材料,利用差示扫描量热法(DSC)、热重分析(TGA)、热变形温度及力学性能测试等手段研究了LGF含量对PA6/SMA/LGF复合材料熔融结晶行为、热性能及力学性能的影响。结果表明:随着LGF含量的增加,PA6/SMA/LGF复合材料的结晶温度、结晶度以及熔融焓均先升高再降低,而且复合材料的最大分解温度较纯PA6显著提高;另外,随着LGF含量的增加,PA6/SMA/LGF复合材料的热性能及力学性能均明显改善,其中当LGF含量为27%时,复合材料的热变形温度、弯曲强度、弯曲模量、拉伸强度和冲击强度分别增至206.0℃、227.8 MPa、7 335 MPa、180.6 MPa和18.7 kJ/m2。     

PA6/SMA共混物的热性能及力学性能

采用熔融共挤制备了尼龙6(PA6)/苯乙烯-马来酸酐共聚物(SMA)共混物,利用差示扫描量热法、热重分析、热变形温度测试及力学测试等手段研究了SMA含量对PA6/SMA共混物熔融结晶行为、热性能及力学性能的影响。结果表明,SMA的加入使共混物的熔融温度、结晶温度及结晶度降低;当SMA用量为5份时,共混物最大分解温度较纯PA6提高了33.5℃;共混物的弯曲强度和弯曲模量在SMA用量为2.5份时达到最大,分别为115.0、3 227 MPa,比纯PA6提高了26.4%、37.0%,拉伸强度在SMA用量为5份时达到最大87.5 MPa,比纯PA6提高了25.9%。     

PA6/NMA共混物的制备及其性能研究

以聚酰胺6(PA6)为基体、自制N-苯基马来酰亚胺-马来酸酐二元共聚物(NMA)为耐热改性剂,通过熔融共混法制备了PA6//NMA共混材料。并采用差示扫描量热法(DSC)、热重分析(TGA)、热变形温度及力学性能测试等手段研究了NMA用量对PA6/NMA共混物熔融结晶行为、热性能及力学性能的影响。结果表明:随着NMA用量的增加,PA6/NMA共混物的熔融温度、结晶温度、结晶度以及熔融焓均逐渐降低,而且共混物的最大分解温度较纯PA6显著提高;随着NMA用量的增加,PA6/NMA共混物的力学性能及热性能均明显改善,其中当NMA用量为10份时,共混物的弯曲强度、弯曲模量、拉伸强度及热变形温度分别增至113.8 MPa、3 146 MPa、80.4 MPa以及71.5℃,较纯PA6提高了25.1%、31.9%、15.7%和27.5%;另外,随着NMA用量的增加,共混物的熔体流动速率(MFR)大幅下降,其中当NMA用量增至10份时,共混物的MFR降至5.3 g/10min。     

NMA与纳米SiO2复配对PA6热性能及力学性能的影响

N-苯基马来酰亚胺与马来酸酐的共聚物(NMA)对尼龙(PA)6具有良好的耐热改性作用,纳米Si O2能够较好地改善PA6的力学性能。采用自制的NMA与纳米Si O2以不同质量配比复配,对PA6进行共混改性,利用差示扫描量热法、热重分析、热变形温度和力学性能等表征方法研究了不同复配比例对PA6热性能及力学性能的影响。结果表明,随着纳米Si O2含量增加,PA6/NMA/纳米Si O2复合材料的熔融温度、结晶温度、结晶度及熔融焓均呈现先上升后下降的趋势;当NMA与纳米Si O2的质量比为10∶0时,复合材料的热稳定性最好;当NMA与纳米Si O2的质量比为8∶2时,复合材料的弯曲强度、弯曲弹性模量、拉伸强度和热变形温度均达到最大值,分别为108.3,2 989,77.6 MPa以及68.4℃,较纯PA6分别提高了19.0%,25.3%,11.7%和19.2%。随着纳米Si O2含量的增加,复合材料的熔体流动速率呈现先增加后减小的趋势。     

PA 6/NMA/nano-OMMT复合材料的制备

采用自制耐热改性剂N-苯基马来酰亚胺-马来酸酐二元共聚物(NMA)与纳米有机蒙脱土(nanoOMMT)复配对聚酰胺(PA)6进行共混改性,研究了不同m(NMA)∶m(nano-OMMT)对PA 6熔融结晶行为、热性能及力学性能的影响。结果表明:nano-OMMT剥离分散在PA 6基体中;随着nano-OMMT含量增加,PA 6/NMA/nano-OMMT复合材料的熔融温度、结晶温度、结晶度及熔融焓均先升后降;m(NMA)∶m(nano-OMMT)为8∶2时,复合材料弯曲强度、弯曲模量、拉伸强度和负荷变形温度均达最大,分别为117.1,3 301,80.5 MPa及82.7℃,较不加nano-OMMT分别提高21.2%,25.0%,12.9%,27.8%。     

SMA用量对PA6/LiCl/SMA复合材料结构与性能的影响

采用熔融挤出的方法制备了聚酰胺6/氯化锂/苯乙烯接枝马来酸酐(PA6/LiCl/SMA)复合材料,研究了SMA用量对PA6/LiCl/SMA复合材料的结晶熔融行为及性能的影响。结果表明:SMA的加入会促进Li+与PA6中酰胺基团的络合作用,破坏PA6分子链间的氢键,另外SMA自身能与PA6分子链发生接枝反应,在双重作用下使复合材料的熔点降低到185.53℃。通过DSC和XRD发现:SMA的加入会促使PA6/LiCl/SMA复合材料的结晶形态由α晶型向γ晶型转变,并能有效提高复合材料的力学性能,当SMA用量为3 phr时,其拉伸强度比未添加SMA时提高了53.02%,冲击强度也有所提高,但复合材料的熔体流动速率会有所下降。     

环氧树脂E-44反应增容尼龙6/废印刷电路板非金属粉复合材料的力学性能和热变形温度研究

用环氧树脂E-44作为反应性的增容剂,采用熔融共混方法制备了尼龙6(PA6)/废印刷电路板非金属粉(N-PCB)复合材料。研究了E-44用量、挤出温度以及N-PCB粉末的粒径大小对PA6/N-PCB复合材料力学性能和热变形温度的影响。对复合材料抽提残留物的红外分析实验结果表明E-44与PA6/N-PCB复合材料中PA6以及N-PCB粉末表面发生了化学键合。添加1.25份E-44的PA6/N-PCB复合材料与纯PA6相比,其拉伸强度、拉伸模量、弯曲强度和弯曲模量最大增幅分别为29%、49%、73%和72%,热变形温度提高了42.8℃,但其韧性降低。与未加增容剂相比,其拉伸强度、弯曲强度和缺口冲击强度最大增幅分别为9%、8%和43%,热变形温度提高了9.3℃。     

尼龙-6/芳纶浆粕/马来酸酐接枝聚合物复合材料的结构与性能

利用双螺杆挤出机制备了尼龙6(PA6)/芳纶浆粕(PPTA-pulp)/马来酸酐接枝聚合物复合材料,研究了两种马来酸酐接枝物(POE-g-MAH、LLDPE-g-MAH)对复合材料的力学性能、断面形态以及结晶性能的影响。其中POE-g-MAH能明显的提高复合材料PA6/PPTA-pulp的冲击强度和断裂伸长率,POE-g-MAH含量为3%时,PA6/PPTA-pulp/POE-g-MAH的拉伸强度和弯曲强度达到实验范围内的最佳值,此时其断裂伸长率和冲击强度较未加马来酸酐接枝物体系,分别提高了57.9%和28.8%。3%马来酸酐接枝物的加入有效增强了PA6和PPTA-pulp间的界面结合力,对复合材料的结晶具有诱导作用,且并不会改变PA6的晶型。     

分子筛负载马来酸酐及改性PP的研究

通过物理吸附将马来酸酐(MAH)负载在分子筛上,经母料法熔融制备了PP/分子筛复合材料.采用DSC、POM和电子拉力机等方法对复合材料的结晶行为和力学性能进行研究.结果表明:分子筛对PP结晶起到异相成核作用,随分子筛用量增加,复合材料的结晶温度由纯PP的116.3℃提高到119.5℃,结晶热焓逐渐减小,熔融热焓逐渐增大,复合材料的拉伸强度、弯曲强度及弯曲模量有不同程度的提高.低MAH负载量的分子筛(质量分数3%)有助复合材料力学性能的进一步提高,复合材料的拉伸强度、弯曲强度、弯曲模量及冲击强度分别由纯PP的35.3 MPa、45.2 MPa、1.47 GPa及2.24 kJ/m2提高到37.6 MPa、53.5 MPa、1.85 GPa及3.01 kJ/m2.MAH具有诱导PP形成β晶的倾向,150℃附近的β晶熔融峰强度随MAH用量增加而提高.     

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.     

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.     

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.     

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.