聚碳酸酯/聚萘二甲酸乙二醇酯复合物拉伸应变硬化的形成

为提高聚碳酸酯(PC)的力学性能,用不同比例的聚萘二甲酸乙二醇酯(PEN)与其共混,并选用乙烯-丙烯酸甲酯-甲基丙烯酸缩水甘油酯无规三元共聚物(E-MA-GMA)作为增容剂组成不同的PC/PEN共混体系。文中对不同PC/PEN复合物的拉伸应力应变行为进行研究,结果表明,与单纯的PC材料相比,加入PEN能够提高其力学性能,尤其当PEN的质量占比为25%时,其力学性能提高最为明显。同时,其力学性能与组分的相容性密切相关,增容剂的加入能够促进应变硬化的发生,从而促使PC/PEN复合物的断裂强度及断裂伸长率均显著增大。截面形貌、热分析及动态力学分析等研究的结果表明,其力学性能提高可以归因于PC/PEN复合物在拉伸中伴随其应变硬化过程而形成的稳定纤维结构。     

Optimizing process parameters for joint strength efficiency improvement in friction stir welding of polycarbonate sheets

The present work addresses optimization of these friction stir welding process variables to maximize joint strength efficiency of welded polycarbonate sheets by using particle swarm optimization algorithm over response surface method based regression model. Initially, parametric influence on weld quality characteristics namely weld bead profile, bead geometry with associated microstructure along with micro-hardness deviation through the weld centerline and stress-strain behavior of the weld have been studied in detail as per full factorial design of experiments by using three different tool pin profiles such as cylindrical, square and triangular. The center point experiment i. e. tool rotational speed of 1800 min⁻¹ and welding speed of 20 mm/min, and square tool pin profile were found to be the optimum combination with a maximum joint strength efficiency of 60.06 %. The regression model of weld ultimate tensile strength was developed by using response surface methodology which was found to be significant. Therefore, this model was further used for parametric optimization by using both response surface methodology and intelligent particle swarm optimization approaches. A slight improvement in joint strength efficiency with better optimization capability was found by using particle swarm optimization technique as compared to response surface methodology.     

Mechanical properties of miscible polycarbonate-copolyester blends

Miscible blends of polycarbonate and the copolyester based on 1,4-cyclohexane-dimethanol and a mixture of terephthalic and isophthalic acids were melt processed into film and injection moulded into test bars. Wholly amorphous specimens of each type were mechanically tested directly after fabrication and after a variety of annealing conditions. As processed blends exhibited nearly additive responses versus blend composition for modulus, strength, elongation at failure, and notched lzod impact strength. Various annealing protocols caused maxima to appear in plots of modulus versus composition. Similar responses were observed for blend density, and good correlations were noted between density and modulus as both composition andhistory were varied. Sub-T_g annealing of injection moulded specimens was demonstrated to involve simultaneous relaxations of volume and molecular orientation. The individual effects of this combined process were separated by sequential super-T_g (or T_m) and sub-T_g annealing steps.     

芳香聚碳酸酯合成工艺进展

本文介绍了聚碳酸酯的 3种合成工艺 ,即界面缩聚法、非光气法、氧化羰基化法。界面缩聚法工艺易于生成较高分子量聚合物 ,产品适于作片材 ,界面聚合聚碳酸酯在某些终端应用上具有一定优势 ,较长一段时期内不会退出市场 ;非光气法产品纯度较高、光学性能好、透明度高 ,适合光学应用 ,但高温下稳定性相对较低 ,不适用于注模 ;氧化羰基化法具有前两种方法没有的优点 ,是一种安全高效的绿色工艺 ,原料来源广泛、廉价 ,三废少、产品质量高 ,在 2 1世纪必将有大的发展前途。     

（PE—HD／PE—LD）—g—GMA增容PC／PE—UHMW共混物的冲击性能与断面形态

采用反应挤出方法，制备了缺口冲击性能良好的(PE-HD／PE-LD)-g-GMA(甲基丙烯酸缩水甘油脂)增容PC／PE-UHMW共混物。当增容剂(PE-HD／PE-LD)-g-GMA用量为6份时，共混物的冲击强度达到最大值66kJ／m^2，比未增容PC／PE-UHMW提高了28．5kJ／m^2。冲击断面的SEM分析表明，增容剂的加入产生了反应性的增容效果，提高了两相之间的界面粘结力，促进了相的分散，对基体的剪切屈服形变有利，冲击性能得以改善。     

Aggregation of lead phthalocyanine in blends with polycarbonate

The blends of a nonlinear optical dye with polycarbonate are described and comparisons are made with solutions of the dye in chloroform. Absorption spectra of blends with up to 1 wt % lead tetracumylphenoxy phthalocyanine showed the dye to be primarily in the monomer form. The monomer absorption spectrum and the measured extinction coefficient replicated those in chloroform solution. As the dye concentration increased to 20 wt %, the monomer intensity decreased and new spectral features characteristic of the dimer appeared. The spectra were resolved into contributions of monomer and dimer, and the concentration effect was analyzed according to the monomer/dimer equilibrium. Much higher monomer concentrations were achieved in polycarbonate blends compared to chloroform solutions. It was concluded that when the blends were quenched from the melt, the equilibrium established at the melt temperature was preserved in the solid state glass. Quenching the blend from different melt temperatures confirmed this interpretation. Extrapolation of the temperature dependent equilibrium constant to 25°C yielded a value close to that reported for chloroform solution at 25°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 104: 464–469, 2007     

Preparation and characterization of biodegradable foams from calcium carbonate reinforced poly(propylene carbonate) composites

Biodegradable foams were successfully prepared from calcium carbonate reinforced poly(propylene carbonate) (PPC/CaCO₃) composites using chemical foaming agents. The incorporation of inexpensive CaCO₃ into PPC provided a practical way to produce completely biodegradable and cost‐competitive composite foams with densities ranging from 0.05 to 0.93 g/cm³. The effects of foaming temperature, foaming time and CaCO₃ content on the fraction void, cell structure and compression property of the composite foams were investigated. We found that the fraction void was strongly dependent on the foaming conditions. Morphological examination of PPC/CaCO₃ composite foams revealed that the average cell size increased with increasing both the foaming temperature and the foaming time, whereas the cell density decreased with these increases. Nevertheless, the CaCO₃ content showed opposite changing tendency for the average cell size and the cell density because of the heterogeneous nucleation. Finally the introduction of CaCO₃ enhanced the compressive strength of the composite foams dramatically, which was associated with well‐developed cell morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5240–5247, 2006     

Modification of polycarbonate membrane by polyethylene glycol for CO2/CH4 separation

In this study, permeation of carbon dioxide (CO₂) and methane (CH₄) through the polycarbonate/polyethylene glycol (PC/PEG) blend membrane was investigated. The effect of PEG content (0–5 wt%) on the permeability and selectivity was studied. Permeability measurements were carried out at pressures of 1–7 bar and at room temperature. The membranes were characterized by Fourier transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR), X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and density measurement. The results revealed that the PC/PEG blends are miscible/partially miscible without considerable micro-phase separation. The effect of PEG content and gas pressure on the diffusion and solubility of coefficients were also investigated and analyzed. It was concluded that the most influential parameter for the permeation is the diffusion coefficient of the gases. The permeability and selectivity decrease as the operating pressure and PEG content are increased. Furthermore, the results showed that the addition of 5 wt% of PEG into PC increases the CO₂/CH₄ selectivity from 26.6 ± 0.99 to 40.9 ± 2.14 (more than 53%) at 1 bar.     

聚碳酸酯注射成型制品力学性能的Taguchi分析

采用Taguchi分析方法考察了注射成型工艺参数对聚碳酸酯(PC)力学性能的影响。结果表明,注射成型工艺参数对PC的拉伸强度影响较大,对弯曲强度和冲击强度影响较小;方差分析结果表明,模具温度对拉伸强度的影响最大,注射压力和冷却时间次之,熔体温度的影响最小;模具温度降低,熔体冷却固化层厚度增加,取向程度增大,拉伸强度增加;同时结果表明Taguchi分析方法可以准确地对优选出的成型工艺制备的PC试样的拉伸强度进行预测,其预测值与测量值的偏差仅为0.75%。     

二氧化碳与环氧化物交替共聚催化剂的最新研究

自1969年科学家Inoue用ZnEt2/H2O的混合物作催化剂由CO2与环氧化物合成聚碳酸酯以来,科学家们在催化剂体系的设计方面进行了大量研究.在此基础上,本文就最近几年CO2与环氧化物交替共聚的催化剂体系进行了详细的叙述和概括.