EPT接枝共聚物的制备及其对PA6/EPT共混体系的增容作用

采用溶液接枝技术成功制备了可反应性相容剂——EPT接枝共聚物(EPT-g-ITA和EPT-g-MAH),红外光谱分析证明ITA、MAH已经成功接枝在EPT主链上。实验研究了引发剂和单体用量对接枝共聚物接枝率和凝胶含量的影响,当EPT/ITA/BPO=100/20/4时,接枝率达到3.16%,凝胶含量为8.8%;当EPT/MAH/BPO=100/8/0.64时,接枝率达到3.58%,凝胶含量为6%。通过双螺杆挤出机将EPT接枝共聚物引入PA6/EPT共混体系,当EPT-g-MAH/PA6含量为15%时,PA6/EPT/EPT-g-MAH共混物的缺口冲击强度比纯PA6提高了20倍。通过对EPT接枝共聚物的接枝率、凝胶含量以及PA6合金的缺口冲击强度等实验数据的分析可知,接枝在EPT主链上的MAH支链较短,接枝点较多;接枝在EPT主链上的ITA支链较长,接枝点较少。     

PA6/TPU共混物的力学性能研究

采用电子万能试验机和冲击试验机研究了PA6/TPU共混物的拉伸性能、弯曲性能和冲击性能等力学性能,探讨了不同配比共混物的组成与力学性能的关系.结果表明,随着共混物中热塑性聚氨酯(TPU)用量的增加,共混物的冲击强度有明显地提高,但其拉伸强度和弯曲强度均稍有降低.     

MAH-g-SBS对SBS/PA6共混体系力学性能的影响

采用马来酸酐(MAH)熔融接枝热塑性弹性体(SBS),然后再与PA6进行共混的改性方法。研究了MAH接枝SBS时引发剂过氧化二异丙苯(DCP)的用量为0.05%和0.1%时对PA6力学性能的影响,着重研究了SBS-g-MAH的加入对PA6低温冲击性能的影响。结果表明:当共混物中SBS-g-MAH含量为40%时,共混物的常温冲击强度提高了3.4倍,低温(-30℃)冲击强度提高了4倍,得到了韧性较高的PA6/SBS的共混材料。     

POE接枝GMA的制备及其增韧PA6的应用研究

熔融法制备聚烯烃热塑性弹性体(POE)接枝甲基丙烯酸缩水甘油酯(GMA),对其产物进行红外表征,证实了GMA已成功接枝到POE大分子链上。将接枝物用于聚酰胺-6(PA6)增韧改性,通过力学性能测试和SEM研究了弹性体含量及种类对共混物冲击强度和断面形态的影响。结果表明,POE与其接枝物共混作为弹性体增韧效果更好,当PA6、POE和POE-g-(GMA-co-St)质量比为80:6:14时,弹性体分散均匀且粒径细化为0.5~2μm,共混物缺口冲击强度提升至纯PA6的3倍。     

硫化剂用量对丙烯酸酯类/聚己内酰胺共混物力学性能的影响

用密炼机制备了不同丙烯酸酯橡胶(chlorine-ACM、epoxy-ACM和AEM)和热塑性聚酰胺(PA)塑料的动态硫化耐油热塑性弹性体,其中丙烯酸酯与聚酰胺质量比70:30。研究了硫化剂含量对二元共混物力学性能的影响。结果表明,当3号硫化剂为2.5 phr时,活性氯型ACM/PA6力学性能最好。     

PA6/TPU共混物耐磨耗性的研究

采用TIMKEN型摩擦磨损试验机测试了聚酰胺6(PA6)/热塑性聚氨酯(TPU)共混物的磨耗性能,讨论了聚氨酯的种类、用量及试验机转速与PA6/TPU共混物磨耗量的关系。研究结果表明,PA6/TPU1共混物的磨耗量小于PA6/TPU2共混物磨耗量;随着共混物中TPU用量的增大,共混物的磨耗量明显降低,可由0.8 mg降至0.2 mg;随试验机转速的提高,磨耗量增大。     

石蜡油对动态硫化EPDM/PP热塑性弹性体力学性能的影响

通过双螺杆挤出机制备了动态硫化三元乙丙橡胶(EPDM)/聚丙烯(PP)热塑性弹性体。运用抽提法测试了该EPDM/PP弹性体的凝胶含量,并采用万能试验机等对其力学性能进行测试,研究了软化剂石蜡油的添加量对动态硫化EPDM/PP热塑性弹性体力学性能的影响。结果表明:当石蜡油添加量为20%时,EPDM/PP共混物的凝胶含量最大;当石蜡油添加量为25%时,EPDM/PP共混物的拉伸强度和断裂伸长率均达到最大值。此外,石蜡油的引入不仅能降低EPDM/PP热塑性弹性体的硬度和压缩永久变形,还能提高材料的耐热氧老化性能,其适宜添加量为20%~25%。     

两种弹性体接枝物对PA6/Mg(OH)2复合材料性能的影响

将Mg(OH)2、弹性体接枝物、抗氧剂与尼龙6(PA6)共混制得阻燃PA6/Mg(OH)2复合材料,探讨了两种弹性体接枝物对PA6/Mg(OH)2复合材料力学性能和阻燃性能的影响。结果表明,加入弹性体接枝物A比加入钛酸酯偶联剂可以明显提高PA6/Mg(OH)2复合材料的阻燃性能和某些力学性能。Mg(OH)2用量为20%时,加入弹性体接枝物A的复合材料的极限氧指数可达到38.4%;缺口冲击强度和断裂伸长率比加入钛酸酯偶联剂时分别提高了64.6%和172.4%。     

EPDM接枝共聚物对MXD6/PA6/EPDM共混物性能的影响

以马来酸酐接枝三元乙丙橡胶（EPDM-g-MAH）为反应性增容剂,通过熔融共混制得聚间苯二甲胺己二酸/聚酰胺6/三元乙丙橡胶（MXD6/PA6/EPDM）共混物。采用Molau实验研究了共混物的相容性,利用哈克转矩流变仪、差示扫描量热仪、偏光显微镜和热重分析仪等研究了MXD6/PA6/EPDM共混物的流变性能、熔融行为、结晶行为以及耐热性能。结果表明,由于EPDM-g-MAH的引入,共混物的平衡扭矩增大,PA6相与EPDM相界面黏附力明显提高;EPDM-g-MAH的引入导致共混物的球晶形貌规整性变差,成核密度下降,结晶速率减慢;随着EPDM含量的增加,共混物的玻璃化转变温度（Tg）和熔融温度（Tm）均呈下降趋势;EPDM-g-MAH的引入提高了共混物的热稳定性。     

PA6/PP/SEBS-g-MAH共混物的相容性研究

采用马来酸酐接枝(氢化苯乙烯/丁二烯/苯乙烯)共聚物(SEBS-g-MAH)作为增容剂,研究了增容剂用量对尼龙6/聚丙烯(PA6/PP)共混体系相态结构、力学性能的影响,以及在相同增容剂用量下不同PA6、PP配比对体系相形态的影响。结果表明,SEBS-g-MAH中的酸酐基团能与PA6末端的氨基发生化学反应,在PA6和PP的内表面形成PA6-SEBS接枝共聚物,明显改善了两相的界面相容性,并使共混物的力学性能得到显著提高。共混物冲击断面形貌的分析表明,共混物发生了明显的脆韧转变。     

Thermophysical performances of (La1/6Nd1/6Yb1/6Y1/6Sm1/6Lu1/6)2Ce2O7 high-entropy ceramics for thermal barrier coating applications

In this study, a novel high-entropy oxide of (La_1/6Nd_1/6Yb_1/6Y_1/6Sm_1/6Lu_1/6)₂Ce₂O₇was prepared using a sol–gel and high-temperature sintering technology. Additionally, its lattice structure, micro-morphology, elemental composition, and thermophysical and mechanical properties were evaluated. The results revealed that the obtained oxide powder has a typical fluorite-type lattice with particle sizes in the range of～30–100 nm. The bulk sample has a dense microstructure and uniform elemental distribution. Owing to its low lattice order, the thermal expansion coefficient of (La_1/6Nd_1/6Yb_1/6Y_1/6Sm_1/6Lu_1/6)₂Ce₂O₇ is greater than that of Sm₂Ce₂O₇, which also exhibits excellent lattice stability up to 1200 °C. Further, owing to phonon scattering due to lattice distortion, oxygen vacancy, and cation substitution, the thermal conductivity of (La_1/6Nd_1/6Yb_1/6Y_1/6Sm_1/6Lu_1/6)₂Ce₂O₇ is lower than that of Sm₂Ce₂O₇, while its mechanical performance is inferior to that of 7YSZ.     

Crystallization and phase evolution in novel (Gd1/6Tb1/6Dy1/6Tm1/6Yb1/6Lu1/6)2Si2O7 environmental barrier coating

Design of multiple rare-earth (RE) principal elements is a practical strategy to optimize key property of RE disilicate environmental barrier coating (EBC). However, multi-RE component in the feedstocks may also introduce critical fabrication problems due to the different evaporating and crystallizing behaviors of the EBC containing various RE composition. We herein report the preparation of a novel multi-RE disilicate (Gd_1/6Tb_1/6Dy_1/6Tm_1/6Yb_1/6Lu_1/6)₂Si₂O₇ EBC by atmospheric plasma spraying (APS). The crystallization behavior of the as-deposited coating annealed at 1100°C–1300°C with different durations (5 and 20 h) in air and argon atmospheres were investigated through comprehensive characterization techniques. RE disilicate, RE mono-silicate, and RE apatite were detected in the as-sprayed coatings, and mono-silicate and apatite transform to RE₂Si₂O₇ with the increment of temperature and extension of annealing duration. Furthermore, the contribution of multiple RE to the formation of apatite phase is discussed. The results provide a fundamental understanding and may guide the controllable preparation of multi-RE disilicate EBC via APS method.     

Thermal and mechanical behavior of polyamide 6/polyamide 6I/6T blends

The thermal and mechanical properties of blends, obtained by mixing polyamide 6 (PA6) and an amorphous aromatic copolyamide G21 (ISO nomenclature PA 6I/6T), were investigated by differential scanning calorimetry, dynamic mechanical analysis, and mechanical tensile tests. Quenched blends show a single glass transition temperature; the T_g-composition trend was interpreted by means of the Gordon–Taylor equation. The half-time of crystal-lization decreases by increasing the G21 content and this indicates a depression of the overall crystallization rate. A small decrease in the equilibrium melting temperature of PA6 in the blends was observed; this finding suggests that the interaction parameter in PA6/G21 blends is probably very small. The dynamic mechanical analysis of crystallized blends suggests the presence of a homogeneous amorphous phase even if the crystallization of PA6 occurred. The tensile mechanical properties reveal that G21 acts as stiffener of PA6. The collected experimental data suggest that PA6 and G21 are miscible in the composition range investigated. © 1996 John Wiley & Sons, Inc.     

Solid-state nuclear magnetic resonance of the PA6/PC,PA6/PPO,and PA6/PC/PPO blends

The effect of mixing time is very important to plasticization and/or occurrence of chemical reaction between polyamide 6/poly(propylene oxide), polyamide 6/polycarbonate, and polyamide 6/polycarbonate/poly(propylene oxide) blends. The systems were investigated through solid-state carbon-13 cross-polarization magic angle spinning with variable contact time in the NMR experiment. In the systems, polycarbonate can prevent the antiplasticization effect already observed in the polyamide 6/poly(propylene oxide) blend. Therefore, it was verified that the addition of polycarbonate in the polyamide 6/poly(propylene oxide) system causes a hardening of the blend. This fact can be attributed to the restriction of the mobility of the NH group, probably influenced by the type of interaction that occurs in the polyamide 6/polycarbonate/poly(propylene oxide), due to the effect of poly(propylene oxide), which can be act as an interfacial agent promoting a better interaction between polyamide 6 and polycarbonate. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 129–133, 1998     

Polymorphic behavior of nylon 6/saponite and nylon 6/montmorillonite nanocomposites

X‐ray diffraction methods and DSC thermal analysis have been used to investigate the structural change of nylon 6/clay nanocomposites. Nylon 6/clay has prepared by the intercalation of ε‐caprolactam and then exfoliaton of the layered saponite or montmorillonite by subsequent polymerization. Both X‐ray diffraction data and DSC results indicate the presence of polymorphism in nylon 6 and in nylon 6/clay nanocomposites. This polymorphic behavior is dependent on the cooling rate of nylon 6/clay nanocomposites from melt and the content of saponite or montmorillonite in nylon 6/clay nanocomposites. The quenching from the melt induces the crystallization into the γ crystalline form. The addition of clay increases the crystallization rate of the α crystalline form at lower saponite content and promotes the heterophase nucleation of γ crystalline form at higher saponite or montmorillonite content. The effect of thermal treatment on the crystalline structure of nylon 6/clay nanocomposites in the range between Tg and Tm is also discussed.     

PA6/MXD6/黏土复合材料的流变行为研究

采用毛细管流变仪研究了聚己二酰间苯二甲胺(MXD6)及黏土的引入对聚酰胺6(PA6)流变性能的影响。结果表明:PA6、PA6/黏土、PA6/MXD6和PA6/MXD6/黏土复合材料均为假塑性流体;在220~240℃之间,PA6及其复合材料的非牛顿指数为0.50~0.85。另外,加入黏土使得PA6和PA6/MXD6的黏度上升,非牛顿指数和黏流活化能下降;而加入MXD6则使得PA6、PA6/黏土的黏度下降,非牛顿指数和黏流活化能上升。     

PA6/PA6-g-MAH/云母复合材料的增韧研究

分别以乙烯-乙酸乙烯共聚物(EVA)、乙烯-1-辛烯共聚物(POE)、苯乙烯-丁二烯-苯乙烯共聚物(SBS)为增韧剂,研究了它们对聚酰胺6(PA6)/聚酰胺6接枝马来酸酐(PA6-g-MAH)/云母复合材料力学性能的影响。结果表明:以EVA为增韧剂所得复合材料的力学性能优于以POE或SBS为增韧剂所得复合材料;复合材料的冲击强度随EVA用量的增大而上升,当EVA用量为10%时,其冲击强度达到19.01 kJ/m2,较未经增韧改性的复合材料提高了5.29 kJ/m2;但复合材料的拉伸强度和弯曲模量均随增韧剂用量的增大而降低。     

PA66、PA6改性MXD6共混物的定性定量分析

通过对进口样品MXD6/尼龙6(PA6)及MXD6/尼龙66(PA66)合金的分析,确立了合金中MXD6的定性、定量分析方法。     

Iminiumsalze in quantitativen Gas/Festköper- und Festkörper/Festkörper-Reaktionen

Iminium Salts in Quantitative Gas/Solid and Solid/Solid Reactions Iminium salts that are highly susceptible to hydrolysis are quantitatively prepared and reacted in the solid state without solvents or liquid phases. Atomic force microscopy AFM helps in elucidating the mechanism of these still unusual gas-solid and solid-solid syntheses by recording surface topographies of reacting crystals of L-histidine (10) and triphenylverdazyl (15) . Various imines add gaseous HCl or HBr to form stable iminium halides (1, 3, 4, 5, 11) even if frozen liquids of very weak heterocyclic bases are treated at low temperatures. Another way for quantitative yields of iminium salt hydrates (6) starts with solid primary ammonium halides and gaseous acetone. o-Phenylenediamines (7) give quantitatively 1,5-benzodiazepines (9) by solid state cyclization of bis-iminium salt intermediates (8) . Crystalline nitroxyls (12) and triphenylverdazyl (15) undergo stoichiometric one-electron transfer with gaseous NO₂ or XeF₂ to give nitrosonium (14) and azonium salts (17) . The solid state chlorination of tetramethylthiuramdisulfide (18) or dimethylthiocarbamoylchloride (20) yields phosgene dimethyliminiumchloride (Viehe salt 21 ) in quantitative yield. Solid Viehe salt is quantitatively treated with gaseous Cl₂ to give the trichloride 19 and solid SbCl₅ or PCl₅ to produce the hexachloroantimoniates (22) , -phosphates (23) . Solid brenzcatechol (24) , mercaptobenzimidazole (27) , p-nitroaniline (30) , N-methylbenzothiazolone-2-hydrazone (34) and acetophenone (41) are treated with 21 to give the corresponding chloroiminium salts (25, 28, 31, 35, 43) . p-Toluenesulfonamide (37) and 22 give the chloroiminium salt 38 . These quantitative solid-solid reactions are most easily run in ball mills with cooling device. The “waste-free” techniques achieve exclusion of moisture in an elegant way. The preparative use of the versatile products with nucleophiles is indicated. The three-step solid-state mechanisms are discussed.