三氧化二铝对环氧树脂固化动力学及 热降解动力学的影响

采用热分析法研究了高含量Al₂O₃填料对环氧树脂（E51）/二氨基二苯甲烷（DDM）体系的固化表观活化能、热降解动力学和性能的影响.非等温差式扫描量热法（DSC）固化动力学研究表明,加入Al₂O₃体系的反应活化能由51.49 kJ/mol降低至48.12 kJ/mol;用n级非等温动力学法分析获得了固化反应的动力学参数.利用热重分析研究了环氧固化物体系的热降解动力学,用FWO方法计算固化物降解活化能结果表明,Al₂O₃粉体对E51/DDM体系初始分解活化能影响不大,当降解率达到30%时,Al₂O₃粉体对E51/DDM体系分解有明显的抑制作用.热重红外联用测试结果表明,甲烷、羰基化合物、胺和双酚A是E51/DDM热分解过程中的主要产物,Al₂O₃粉体能提高E51/DDM体系的热稳定性.动态热机械研究表明,Al₂O₃的加入增大了环氧树脂固化产物的储能模量.DSC测试结果表明,Al₂O₃加入后,体系的玻璃化转变温度由114.16℃提高到121.51℃.     

电生H2O2协同电解絮凝法处理餐饮废水实验研究

采用电生H2O2协同电解絮凝法处理餐饮废水，研究了废水初始浓度、电解时间、电压、电极材料、pH等因素对降解餐饮废水的影响．结果表明，进水CODCr在1200mg／L以内、pH值为中性的餐饮废水，在10V电压、电磁搅拌、曝气条件下，电解15min后，COD去除率在80％以上．该法利用了铝阳极反应生成的絮凝剂Al(OH)3和阴极上电合成的H2O2对有机物的去除作用，同时阳极产生的H^ 与阴极产生的OH^-中和又促进了两极的反应，使有机物降解更彻底．     

Fabrication, in vitro Degradation and Cytotoxic Assay of Different Crystalline Phases Calcium Polyphosphate

Fabrication, in vitro degradation and cytotoxic assay of different crystalline phases calcium polyphosphate（CPP） were reported. The CPP ceramics were fabricated by crystallizing the amorptous frits, and sintered at 550℃ ,875℃, 1000℃ for 1 h to obtain the 7-CPP, β-CPP and α-CPP respectively. The efffects of the different crystalline phases on their weight loss and released PO4^3- were investigated during the degradation. And the surface change was observed by the SEM, The osteoblastic ROS17/2.8 cell line was used to estimate the cytotoxicity of CPP. The effects of CPP on cells ＇ proliferation were evaluated by using MTT assay. The experimental restdts showed that γ-CPP, β-CPP and α-CPP did not exert cytotoxic effect on the cells. In addition, the proliferation of the growth of ROS17/2.8 cells on β-CPP was optimal.     

OXPXP漂白中活化处理的机理和聚糖降解的机理

经活化处理后纸浆中木素含量降低，残余木素中的羰基和酚羟基增多，聚糖中的羰基也增多。木素大分子的降解和酚羟基的增多提高了木素的反应性能，因而有利于后续漂段木素的脱除和纸浆白度的提高。活化处理后聚糖中羰基的生成是导致铜乙二胺粘度降低的主要原因，也是导致后续漂段聚糖降解的主要原因之一。纸浆经漂白后结晶度增加，聚糖分子量降低，分子量分布半漂浆范围较窄，全漂浆则出现双峰。     

Population balance models for the thermal degradation of PMMA

A widely accepted view of the thermal degradation of polymers such as PMMA is that an initiation reaction produces radical fragments that undergo rapid depropagation and are also converted back to molecules by a termination reaction. This mechanism is applied to a population of linear molecules and radicals and the evolution of the population is modelled by appropriate discrete sets of ordinary differential equations. In particular, end-chain and random initiation reactions with first-order termination are analysed and compared with experimental data. We find on comparison with TG data for PMMA that the initiation reaction is important in dictating the qualitative behaviour of the overall rate of thermal degradation. Furthermore, the behaviour of degradation rate with initial degree of polymerisation is also investigated and interpreted within the framework of the model.     

Study of thermodegradation and thermostabilization of poly(lactide acid) using subsequent extrusion cycles

The thermomechanical degradation and thermostabilization of poly(lactic acid) (PLA) have been studied using subsequent extrusion cycles under different temperature profiles. Primary and secondary antioxidants were used to avoid degradation process during extrusion. Melt flow index (MFI), size exclusion chromatography (SEC), and infrared spectroscopy (FTIR) analysis were used to evaluate the degradation and stabilization of PLA. The MFI and SEC analysis show that the main thermodegradation mechanism of PLA is governed by scission reactions. FTIR analysis confirmed the SEC results and showed that the synergetic effect between primary and secondary antioxidant is a suitable way to thermostabilize the PLA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40023.     

Designing oligomeric ethylene terephtalate building blocks by chemical recycling of polyethylene terephtalate

The intelligent recycling of plastics waste is a major concern. Because of the widespread use of polyethylene terephtalate, considerable amounts of PET waste are generated that are ideally re‐introduced into the material cycle by generating second generation products without loss of materials performance. Chemical recycling methods are often expensive and entail environmentally hazardous by‐products. Established mechanical methods generally provide materials of reduced quality, leading to products of lower quality. These drawbacks can be avoided by the development of new recycling methods that provide materials of high quality in every step of the production cycle. In the present work, oligomeric ethylene terephthalate with defined degrees of polymerization and defined molecular weight is produced by melt‐mixing PET with different quantities of adipic acid as an alternative pathway of recycling PET with respect to conventional methods, offering ecofriendly and economical aspects. Additionally, block‐copolyesters of defined block length are designed from the oligomeric products. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39786.     

Construction,structure and photocatalysis of janus nanofiber modified by g-C3N4 nanosheets heterostructure photocatalysts

The construction of photocatalyst with gradient band structure is guided by the principle of band gap engineering. Rational structural design is advanced and applied to construct a new-typed peculiarly structural and functional carbon-based [TiO₂/C]//[Bi₂WO₆/C] Janus nanofiber modified by g-C₃N₄ nanosheets heterostructure photocatalyst (denoted as TB-JgHP). The flexible carbon-based [TiO₂/C]//[Bi₂WO₆/C] Janus nanofiber with one side responding to ultraviolet light and the other capturing visible light is fabricated by conjugate electrospinning, and then g-C₃N₄ nanosheets are uniformly grown in-situ on the surface of the Janus nanofibers by using gas-solid reaction via gasification of urea. The optimized TB-JgHP possesses remarkable hydrogen evolution efficiency (17.48 mmol h⁻¹ g⁻¹) and methylene blue degradation rate (99.2%) under simulated sunlight illumination for 100 min, demonstrating prominent dual-functional characteristics. The enhanced photocatalytic performance benefits from the unique Janus structure as well as the synergistic effects among the triple heterostructures of TiO₂ and Bi₂WO₆, g-C₃N₄ and TiO₂, g-C₃N₄ and Bi₂WO₆. The formation of gradient band structure among heterostructures is more conducive to the multi-step separation of photo-induced electron-hole pairs and more effective absorption of light. Further, flexible self-standing carbon-based photocatalysts not only have outstanding electron transport performance, but also are easy to separate from solution with preeminent recyclable stability. Based on a series of characterization techniques, it is further proved that TB-JgHP has higher carrier separation efficiency than the counterpart contrast samples. The formation mechanism of TB-JgHP is proposed, and the construction technique is established. The design philosophy and construction technique presented in this work pave a new avenue for research and development of other heterostructure photocatalysts.     

In vitro cellular response and hydrothermal aging of two-step sintered Nb2O5 doped ceria stabilized zirconia ceramics

Niobia (1 mol. %) doped Ceria Stabilized Zirconia (NbCSZ) powders were synthesized using a co-precipitation method. The synthesized powders were uniaxially compacted and sintered in air. The two-step sintering method was adopted to sinter the samples, and the sintering schedule was optimized based on density, grain size, the phase present, and the hardness of the sintered sample. It was observed that the two-step sintering method effectively suppressed the grain growth of NbCSZ samples and helped in achieving a finer grain size of 1.57 μm along with the hardness of 1195 HV10 and optimum fracture toughness value 6.20 MPa m^1/2. The Low-Temperature Degradation (LTD) behavior of the sintered samples was estimated through an accelerated hydrothermal aging test, which revealed that the samples are highly resistant to LTD and shown no phase change even after 150 h of study. Moreover, the cytocompatibility of the NbCSZ was tested by culturing MG63 cells on the samples for 7 days. The NbCSZ was found to be highly biocompatible as evident from cell viability and metabolic activity assay.