微合金碳氮化物在铁素体中沉淀析出的PTT曲线的理论计算

根据经典形核长大动力学理论,分析解决了包括相变化学自由能、界面能、形核沉淀方式等一系列相关参量的理论计算或理论处理问题,由此提出了微合金钢中微合金碳氮化物在铁素体基体中沉淀析出的PTT曲线(沉淀量-温度-时间曲线)的相对定量理论计算方法.     

PTT弹性纤维性能研究

系统对比分析了PTT、PA、PTT/PET、PTT/PBT以及高收缩PET 5种纤维的定伸长反复拉伸回弹性、卷曲性及沸水收缩性。实验表明,PTT纤维具有优良的弹性回复率,PTT/PET、PTT/PBT纤维的卷曲性和沸水收缩性更为优异。     

PTT/PBT共混体系及可纺性探究

研究了PTT/PBT共混体系的相容性和结晶性能,并对体系的可纺性作了初步探究。结果表明:PTT/PBT共混体系在无定形区具有较好的相容性,但在晶区是晶相分离的。在冷结晶过程中,当PBT含量超过20%时,将促进体系的结晶性能;而在熔融结晶过程中,第二组分的加入抑制了体系的结晶性能,当配比为50/50时,结晶速率相对最低。另外,PTT/PBT共混体系表现出了良好的可纺性,共混纤维的断裂伸长率随着拉伸倍数和体系中PBT含量的增大而减小,强度增大,但稍差于纯组分纤维;当PTT含量达到50%后,共混纤维表现出了明显优于纯PBT纤维的回弹性,而当PTT含量达到70%时,共混纤维的回弹性能已接近纯PTT纤维。     

Differential scanning calorimetric and free volume study of reactive compatibilization by EPM‐g‐MA of poly(trimethylene terephthalate)/EPDM blends

Differential scanning calorimetry (DSC) and positron annihilation lifetime measurements have been carried out to study the effect of the compatibilizer maleic anhydride grafted ethylene propylene copolymer (EPM‐g‐MA) in poly trimethylene terephthalate and ethylene propylene diene monomer (PTT/EPDM) immiscible blends. The DSC results for the blends of 50/50 and 30/70 compositions show two clear glass transition temperatures, indicating that the blends are two‐phase systems. With the addition of compatibilizer, the separation between the two glass transitions decreased, suggesting an increased interaction between the blend components with compatibilizer. At 5 wt % of compatibilizer, the separation between the T_gs reduced in both 50/50 and 30/70 blends. The positron results for the blends without compatibilizer showed an increase in relative fractional free volume, as the EPDM content in the blend is increased. This suggests the coalescence of free volume of EPDM with the free volumes of PTT due to phase separation. However, the effect of compatibilizer in the blends was clearly seen with the observed minimum in free volume parameters at 5% of the compatibilizer, further suggesting that this percent of compatibilizer seems to be the optimum value for these blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 740–747, 2006     

玻璃纤维增强PTT复合材料热性能和动态力学性能

通过熔融共混挤出制备加入不同玻纤（GF）和硅烷偶联剂的玻纤增强聚对苯二甲酸丙二醇酯（PTT）复合材料,并用扫描电镜（SEM）观察了玻纤与PTT树眙基体的界面黏结形态,用示差扫描量热仪（DSC）和动态热机械分析仪（DMA）研究了玻纤增强PTT复合材料的热性能和动态力学性能。实验结果表明：随着玻璃纤维的加入,复合材料的结晶能力增强,储能模量增加;偶联剂的加入,玻璃纤维的结品成核作用增强,材料力学性能增加,内耗峰向高温移动。     

生物法PDO合成PTT结构与性能的研究

采用生物法1,3-丙二醇(PDO)直接酯化缩聚合成聚对苯二甲酸丙二醇酯(PTT),通过IR、1H NMR、DSC 和TG方法对其进行了表征,并与化学法PDO合成的PTT进行比较。结果表明,生物法PDO合成的产物是PTT;生物法PDO合成的PTT比同一纯度的化学法PDO合成的PTT色泽好、粘度大、摩尔质量高,且随PDO纯度提高,PTT粘度、摩尔质量增大;生物法PDO合成的PTT熔点与化学法PDO合成的PTT相差不大,熔融峰比化学法PDO合成的PTT 尖锐,熔融热大,结晶度高;不同PDO合成的PTT树脂热失重相差不大,表明PDO不同对PTT热分解行为影响不大。     

PRECIPITATING KINETICS OF V(C, N) IN FERRITE OF V–N MICROALLOYING STEEL

V--N微合金钢的C含量(质量分数)在0.05%---0.30%范围内变化时, V(C, N)在铁素体中析出开始时间随温度降低单调增加. 实验得到的开始析出点是在750 ℃时的10 s左右, 含C量不同的4种钢得到的形核率--温度 (NrT)曲线 和析出--温度--时间 (PTT) 曲线单调变化的趋势相同. 热力学与动力学计算得到的不同C含量钢中的V(C, N)形核驱动力非常接近, 其NrT和PTT曲线随C含量无明显变化. 实验与计算均证实, 实验钢的C含量在0.05%---0.30%范围内变化时, V(C, N)在铁素体中的析出动力学无明显差异.     

Photoactive Hybrid AuNR‐Pt@Ag2S Core–Satellite Nanostructures for Near‐Infrared Quantitive Cell Imaging

The quantitative detection of microRNA (miR) and multimode‐imaging‐induced photothermal therapy in vivo have become the focus of much attention. Platinum (Pt) decorated gold nanorods (AuNR‐Pt) and Ag₂S core–satellite (AuNR‐Pt@Ag₂S) multifunctional nanostructures are fabricated to quantify intracellular miRs (miR‐21), near‐infrared fluorescence cell quantitative imaging, and tumor ablation in vivo. When combined with miR‐21, the nanoassembly displays significant fluorescence intensity in the second window of the near‐infrared region (1000–1700 nm) after 808 nm excitation. The Ag₂S fluorescence intensity has a good linear relationship with the amount of intracellular miR in the range of 0.054–20.45 amol ng_RNA ^?1 and a limit of detection of 0.0082 amol ng_RNA ^?1. The nanoassembly is also used to develop multimodal bioimaging, including near‐infrared, X‐ray computed tomographic, and photoacoustic imaging in HeLa‐tumor‐bearing mice. Moreover, the tumors are completely eliminated by the high photothermal capacity of the AuNR‐Pt@Ag₂S assembly. This nanoassembly provides a multifunctional nanoplatform for the ultrasensitive detection of miRs and tumor diagnosis and therapy in vivo.     

Three-dimensional orientation change during thermally induced structural change of oriented poly(trimethylene terephthalate) films using polarized FTIR–ATR spectroscopy

The three-dimensional orientation change during thermally induced structural change was monitored in a ‘real-time’ mode with polarized FTIR–ATR spectroscopy using a double-edged parallelogram crystal in a temperature-controlled ATR set-up. Upon cold-crystallization of stretched PTT sample, the growth of crystalline phase along the stretching direction was much faster than those along the perpendicular directions. The cold-crystallization of melt-quenched amorphous PTT was found to produce crystallites of no orientation, as expected. The formation of crystalline phase along three orthogonal directions was followed by changes of three attenuation indices of 1358 cm⁻¹ band which is associated with the wagging vibration motion of CH₂ groups in crystalline phase. The orientation of CH₂ groups in amorphous phase estimated from three attenuation indices of 1385 cm⁻¹ band along three directions was very small even for the cold-crystallized, anisotropic PTT sample. This work appears to be the first successful observation in a ‘real-time’ mode on the dynamic change of three-dimensional orientation of polymeric materials using temperature-controlled polarized FTIR–ATR spectroscopy.     

Depolymerization of poly(trimethylene terephthalate) in supercritical methanol

The depolymerization of poly(trimethylene terephthalate) (PTT) in supercritical methanol was carried out with a batch‐type autoclave reactor at temperatures ranging from 280 to 340°C, at pressures ranging from 2.0 to 14.0 MPa, and for reaction time of up to 60 min. PTT quantitatively decomposed into dimethyl terephthalate (DMT) and 1,3‐propaniol (PDO) under the designed conditions. The yields of DMT and PDO greatly increased as the temperature rose. The yields of the monomers markedly increased as the pressure increased to 10.0 MPa, and they leveled off at higher pressures. The final yield of DMT at 320°C and 10.0 MPa reached 98.2%, which was much closer to the extent of the complete reaction. A kinetic model was used to describe the depolymerization reaction, and it fit the experimental data well. The dependence of the forward rate constant on the reaction temperature was correlated with an Arrhenius plot, which gave an activation energy of 56.8 kJ/mol. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2363–2368, 2004