谈生态农业体系建设

生态农业体系建设是人类文明进步对农业发展提出的最高要求和发展目标。文章简述了生态农业的含义、生态农业体系的特点、要求，生态农业体系建设的思路和方法。     

环氧化SBS胶粘剂的研制

研究了环氧化SBS橡胶胶粘剂的合成及应用。试验结果表明环氧化SBS胶粘剂在粘接极性材料时的性能要优于SBS胶粘剂。     

羧基丁腈橡胶的制备及在耐温环氧胶中的应用

采用接枝的方法在丁腈-40分子链中接入羧基,获得了高门尼黏度的羧基丁腈橡胶,并用其对环氧树脂进行改性,从而制备出耐高温环氧树脂结构胶。通过加入促进剂可将固化温度从180℃降至120℃。     

DSC分析在聚酯生产中的应用

通过聚酯产品的DSC测试谱图信息,剖析不同情况下聚酯切片及瓶胚的特性,提出了利用DSC测试进行聚酯切片的异物分析、切片来源判断、结晶性能评价、用户投诉样品剖析以及新产品开发时工艺调整的建议,进一步说明DSC测试在聚酯生产、品质控制工作中的重要作用。     

原位生成SiO_2改性硼硅酚醛树脂的合成与性能研究

在合成酚醛树脂的过程中引入有机硅预聚物和硼酸,制得硼硅酚醛树脂,并在此基础上加入正硅酸乙酯,原位水解生成SiO 2,进一步改性了硼硅酚醛树脂。分别考查了有机硅预聚物、硼酸和正硅酸乙酯加入量对改性酚醛树脂粘接强度的影响。通过IR考查了改性树脂的结构,硼氧键和硅氧键成功地引入到酚醛树脂中。还通过DSC和不同条件下粘接强度的测试考查了改性树脂的固化性能,确定了其固化工艺。空气气氛中的热重分析则表明改性酚醛树脂初始分解温度为475℃,1 000℃残炭率为21%,耐热性明显优于普通酚醛树脂。     

Study on the influence of three-grid assembly thermal deformation on breakdown times and an ion extraction process

In order to study the influence of three-grid assembly thermal deformation caused by heat accumulation on breakdown times and an ion extraction process,a hot gap test and a breakdown time test are carried out to obtain thermal deformation of the grids when the thruster is in 5 k W operation mode.Meanwhile,the fluid simulation method and particle-in-cell-Monte Carlo collision(PICMCC) method are adopted to simulate the ion extraction process according to the previous test results.The numerical calculation results are verified by the ion thruster performance test.The results show that after about 1.2 h operation,the hot gap between the screen grid and the accelerator grid reduce to 0.25–0.3 mm,while the hot gap between the accelerator grid and the decelerator grid increase from 1 mm to about 1.4 mm when the grids reach thermal equilibrium,and the hot gap is almost unchanged.In addition,the breakdown times experiment shows that 0.26 mm is the minimal safe hot gap for the grid assembly as the breakdown times improves significantly when the gap is smaller than this value.Fluid simulation results show that the plasma density of the screen grid is in the range 6?×10~(17)–6?×?10~(18) m~(13) and displays a parabolic characteristic,while the electron temperature gradually increases along the axial direction.The PIC-MCC results show that the current falling of an ion beam through a single aperture is significant.Meanwhile,the intercepted current of the accelerator grid and the decelerator grid both increase with the change in the hot gap.The ion beam current has optimal perveance status without thermal deformation,and the intercepted current of the accelerator grid and the decelerator grid are 3.65 m A and 6.26 m A,respectively.Furthermore,under the effect of thermal deformation,the ion beam current has over-perveance status,and the intercepted current of the accelerator grid and the decelerator grid are 10.46 m A and 18.24 m A,respectively.Performance test results indicate that the breakdown times increase obviously.The intercepted current of the accelerator grid and the decelerator grid increases to 13 m A and 16.5 m A,respectively,due to the change in the hot gap after 1.5 h operation.The numerical calculation results are well consistent with performance test results,and the error comes mainly from the test uncertainty of the hot gap.     

Study of the key factors affecting the triple grid lifetime of the LIPS-300 ion thruster

In order to ascertain the key factors affecting the lifetime of the triple grids in the LIPS-300 ion thruster,the thermal deformation,upstream ion density and component lifetime of the grids are simulated with finite element analysis,fluid simulation and charged-particle tracing simulation methods on the basis of a 1500 h short lifetime test.The key factor affecting the lifetime of the triple grids in the LIPS-300 ion thruster is obtained and analyzed through the test results.The results show that ion sputtering erosion of the grids in 5 kW operation mode is greater than in the case of 3 kW.In 5 kW mode,the decelerator grid shows the most serious corrosion,the accelerator grid shows moderate corrosion,and the screen grid shows the least amount of corrosion.With the serious corrosion of the grids in 5 kW operation mode,the intercept current of the acceleration and deceleration grids increases substantially.Meanwhile,the cold gap between the accelerator grid and the screen grid decreases from 1 mm to 0.7 mm,while the cold gap between the accelerator grid and the decelerator grid increases from 1 mm to 1.25 mm after 1500 h of thruster operation.At equilibrium temperature with 5 k W power,the finite element method(FEM)simulation results show that the hot gap between the screen grid and the accelerator grid reduces to 0.2 mm.Accordingly,the hot gap between the accelerator grid and the decelerator grid increases to 1.5 mm.According to the fluid method,the plasma density simulated in most regions of the discharge chamber is 1?×?10~(18)-8?×?10~(18)m~(-3).The upstream plasma density of the screen grid is in the range 6?×?10~(17)-6?×?10~(18)m~(-3)and displays a parabolic characteristic.The charged particle tracing simulation method results show that the ion beam current without the thermal deformation of triple grids has optimal perveance status.The ion sputtering rates of the accelerator grid hole and the decelerator hole are 5.5?×?10~(-14)kg s~(-1)and 4.28?×?10~(-14)kg s~(-1),respectively,while after the thermal deformation of the triple grids,the ion beam current has over-perveance status.The ion sputtering rates of the accelerator grid hole and the decelerator hole are 1.41?×?10~(-13)kg s~(-1)and 4.1?×?10~(-13)kg s~(-1),respectively.The anode current is a key factor for the triple grid lifetime in situations where the structural strength of the grids does not change with temperature variation.The average sputtering rates of the accelerator grid and the decelerator grid,which were measured during the 1500 h lifetime test in5 k W operating conditions,are 2.2?×?10~(-13)kg s~(-1)and 7.3?×?10~(-13)kg s~(-1),respectively.These results are in accordance with the simulation,and the error comes mainly from the calculation distribution of the upstream plasma density of the grids.     

双氰胺与噁唑烷酮环氧树脂体系固化动力学

采用非等温DSC法对双氰胺固化剂与噁唑烷酮环氧树脂和双酚A环氧树脂混合树脂体系固化动力学进行了研究,随着升温速率的增大,固化反应放热量急剧增加,而且固化体系的放热峰向高温方向移动。采用T-β外推法,得到了混合固化体系的特征温度,Ti为156℃,Tp为178℃,Tf为210℃,为实践中的固化工艺提供了重要依据。采用Kissinger、Crane和Arrhenius方程,计算了固化反应的表观活化能为130.86k J/mol、反应级数为0.9443和固化反应速率常数,确定了固化反应的动力学方程。     

有机硅密封胶粘附性能的改善

研究了交联剂、催化剂、填料等对单组分有机硅密封胶性能的影响。     

聚氨酯改性环氧树脂光学结构胶的研制

采用自制的端异氰酸基聚醚型聚氨酯预聚体对环氧树脂进行改性,对其添加量对改性树脂的性能的影响进行了考察,并与A-12胶黏剂的性能做了综合对比。结果表明环氧树脂增韧改性后对多种材料都具有良好的粘接性能,其中冲击强度由未改性时的12．1kJ／m^2提高到24．4kJ／m^2,剥离强度由1．4kN／m提高到3．4kN／m,断裂伸长率由5．2％提高到14．8％;其耐高低温交变性能好,-60～100℃循环5次玻璃未炸裂,并具有优异的耐介质性能。