可见光引发剂研究进展

光固化技术的应用非常广泛，常用于光固化涂料、油墨、牙科固化、胶粘剂以及 3D打印材料等领域。与紫外光固化相比，可见光固化具备辐射安全、固化深度高、设备价格低廉等优势。作为光固化体系的重要组成部分，光引发剂的研究一直备受关注。本文对近 2~3 a可见光引发剂的研究进展进行了综述，主要从 TPO类、萘酰亚胺类、蒽醌类、咔唑类、硅酮类、肟酯类、共轭染料类、光生酸剂类和金属配合物类光引发剂 9个方面进行了综述，并对可见光引发剂的发展方向做了简单的概述。     

改性剂用量对紫炭黑填充天然橡胶/顺丁橡胶并用胶性能的影响

研究改性剂（间苯二酚/六次亚甲基四胺共混物）用量对紫炭黑填充天然橡胶/顺丁橡胶并用胶性能的影响。结果表明：随着改性剂用量增大，胶料的硬度和定伸应力提高，拉伸强度、撕裂强度先下降后提高，阿克隆磨耗量先增大后减小；当改性剂/紫炭黑用量比为4%时，胶料的物理性能较好。添加改性剂可提高紫炭黑对胶料的补强作用，并在一定程度上改善胶料的热稳定性。     

不同折流板结构螺旋折流板换热器传热性能的比较(英文)

Numerical simulations were performed on flow and heat transfer performances of heat exchangers having six helical baffles of different baffle shapes and assembly configurations, i.e., two trisection baffle schemes, two quadrant baffle schemes, and two continuous helical baffle schemes. The temperature contour or the pressure contour and velocity contour plots with superimposed velocity vectors on meridian, transverse and unfolded concentric hexagonal slices are presented to obtain a full angular view. For the six helix baffled heat exchangers, the different patterns of the single vortex secondary flow and the shortcut leakage flow were depicted as wel as the heat transfer properties were compared. The results show that the optimum scheme among the six configurations is a circumferential overlap trisection helix baffled heat exchanger with a baffle incline angle of 20° (20°TCO) scheme with an anti-shortcut baffle structure, which exhibits the second highest pressure dropΔpo, the highest overal heat transfer coefficient K, shel-side heat transfer coefficient ho and shel-side average comprehensive index ho/Δpo.     

Heat propagation in thermally conductive polymers of PA6 and hexagonal boron nitride

Thermally conductive polymers offer new possibilities for the heat dissipation in electric and electronic components, for example, by a three‐dimensional shaping of the heat sinks. To face safety regulations, improved fire performance of those components is required. In contrast to unfilled polymers, those materials exhibit an entirely different thermal behavior. To investigate the flammability, a phosphorus flame retardant was incorporated into thermally conductive composites of polyamide 6 and hexagonal boron nitride. The flame retardant decreased the thermal conductivity only slightly. However, the burning behavior changed significantly, due to a different heat propagation, which was investigated using a thermographic camera. An optimum content of hexagonal boron nitride for a sufficient thermal conductivity and fire performance was found between 20 and 30 vol%. The improvement of the fire performance was due to a faster heat release out of the pyrolysis zone and an earlier decomposition of the flame retardant. For higher contents of hexagonal boron nitride, the heat was spread faster within the part, promoting an earlier ignition and increasing the decomposition rate of the flame retardant.     

大口径光学元件装夹转运结构设计及分析

为了实现大口径光学元件的安全装夹、转运,通过光学元件开槽与不开槽两种装夹方式的分析,得出开槽夹紧转运方式将带来微裂纹、应力集中、成本高等缺陷,提出了利用摩擦力克服光学零件的重力和惯性力的低应力装夹转运方案。通过对光学元件低应力夹紧结构设计,并利用有限元分析方法,得到不开槽装夹方式下,光学元件的最大主应力为1.11 MPa,最大切应力为0.73 MPa,远低于光学元件破坏的强度极限,且受力均匀,无应力集中现象。     

化工过程分析与合成课程教学模式改革与实践

基于工程教育专业认证的核心要求和学生素质教育的目标,化工过程分析与合成课程进行了教学模式改革与相应教学内容的建设,通过多层次的教学环节设计,探索以学生为中心的课程教学方法和评价模式,引导学生从整体上把握化工过程,培养学生把握问题本质及分析和解决问题的综合能力,使学生掌握过程分析与合成的方法论。     

Lipase‐catalyzed synthesis of aliphatic poly(β‐thioether ester) with various methylene group contents: thermal properties,crystallization and degradation

A series of novel aliphatic poly(β‐thioether ester)s with various methylene group contents were prepared by direct lipase‐catalyzed polycondensation of the monomer with an acid‐labile β‐thiopropionate group. The polycondensation reaction using immobilized lipase B from Candida antarctica was carried out in diphenyl ether at 90 °C. Poly(β‐thioether ester)s with high molecular weights of 20 500–57 000 Da and narrow polydispersities in the range 1.40–1.48 were obtained. Thermogravimetric analysis, differential scanning calorimetry and wide‐angle X‐ray diffraction were used to investigate the thermal properties and crystal structures of these polyesters. All the poly(β‐thioether ester)s were semicrystalline polymers and thermally stable up to at least 200 °C. In vitro degradation studies showed that they can rapidly degrade under acidic conditions by the hydrolysis of the β‐thiopropionate groups, suggesting their potential as acid‐degradable polymeric materials. © 2019 Society of Chemical Industry