Finite Element Analysis of 2.5D Woven Composites,Part I: Microstructure and 3D Finite Element Model

A new parameterized finite element model, called the Full-cell model, has been established based on the practical microstructure of 2.5D angle-interlock woven composites. This model considering the surface layer structure can predict the mechanical properties and estimate the structural performance such as the fiber volume fraction and inclination angle. According to introducing a set of periodic boundary condition, a reasonable overall stress field and periodic deformation are obtained. Furthermore, the model investigates the relationships among the woven parameters and elastic moduli, and shows the structural variation along with the corresponding woven parameters. Comparing the results calculated by FEM with the experiments, the veracity of calculation and reasonability based on the Full-cell model are confirmed. In the meantime, the predicted results based on the Full-cell model are more closed to the test results compared to those based on the Inner-cell model.     

Pre-annealing induced oxide barrier to suppress the over-selenization of Mo contact

Molybdenum (Mo) is commonly used as the back contact material complying well with the formation of an ohmic contact for chalcogenide thin film solar cells. However, the easy formation of an over-thick MoSe₂ layer between the Cu₂ZnSn(S,Se)₄ absorber and Mo back contact significantly deteriorates the device performance. To overcome the degradation, the effects of thermal treatment on Mo layers have been investigated in this paper. It was found that pre-annealing Mo back contacts is effective to control the growth of interfacial MoSe₂ layer during selenization. Moreover, the thickness of MoSe₂ layer could be conveniently tailored by simply varying the pre-annealing temperature. The work provides direct proof that the appearance of a thin MoO₂ layer on the top of annealed Mo film indeed acts as a temporary barrier to block the over-selenization of Mo back contact.     

CMSs/PET微胶囊阻燃PET纤维制备与表征

将采用原位聚合法自制的核-壳型碳微球(CMSs)/聚对苯二甲酸乙二醇酯(PET)微胶囊(PCMSs)作为阻燃剂,采用熔融纺丝法制备阻燃PCMSs/PET功能纤维。通过扫描电镜、声速仪、强伸仪、极限氧指数仪等测试设备对添加不同质量分数的阻燃剂的阻燃功能纤维的结构及性能进行测试和表征。结果表明:当阻燃剂PCMSs的质量分数为0.6%时,PCMSs在PET纤维基体中的分散性和相容性良好,此时纤维表面较为光滑,同时具有优良的吸湿性能和阻燃性能,但其力学性能稍低于PCMSs质量分数为0.2%时的PCMSs/PET纤维。     

光氧化TiO_2/PEO/LDPE复合薄膜的生物降解性能

以聚氧乙烯(PEO)为亲水改性剂、纳米TiO_2颗粒作为光催化助氧剂,与低密度聚乙烯(LDPE)树脂复合制备了光氧化-生物降解TiO_2/PEO/LDPE纳米复合薄膜。通过密封堆肥和土壤微生物的降解实验,研究了该复合薄膜在空气中紫外光氧化降解后的生物降解性能。结果表明,TiO_2/PEO/LDPE复合薄膜在UVA340的紫外光照射600h后,发生了明显的降解,羰基指数增大,产生了大量羰基类的化合物,结构发生明显的破坏;光氧化后的薄膜碎片经过180d的堆肥或254d的土壤微生物降解后,其矿化率达到15.26%,薄膜表面长满了孢子及大量的菌丝,能够为微生物的生长提供所需的碳源。PEO的加入能提高纳米TiO_2在LDPE基体中的亲水性,从而提高其光催化氧化活性,使得LDPE薄膜的光氧化降解程度明显增大,有利于其后续的生物降解。