国外动态

耐热聚酯PCT最近由Ge公司和Eastman公司联合开发,已使第三类型热塑性聚酯-聚环已撑二甲基对苯二酸盐(PCT)商业化。该材料的性能集中了PBT和PET两类结晶型聚酯的优点,它有PBT的强度和机械轫性,并且耐热性优于PET,是目     

新型耐高温聚酯PCT

PCT(聚对苯二甲酸1,4环己二甲醇酯)是一种新型耐高温聚酯,具有优异的韧性,很低的吸湿性,很好的加工成型性和耐化学性能。概述了PCT的制备、性能和应用。     

PET-PCT共聚酯的制备及其热性能研究

由直接酯化法制备了不同1,4-环己烷二甲醇(CHDM)含量的聚对苯二甲酸乙二醇酯-聚对苯二甲酸-1,4-环己烷二甲醇酯(PET-PCT)共聚酯;利用核磁共振表征了合成产物的实际组成及序列结构;采用差示扫描量热和热失重分析研究了共聚酯的结晶特性和热稳定性。结果表明:合成的共聚酯为无规嵌段聚合物,PCT的实际组成均高于投料比,各链段的序列长度与其含量成正比。随着CHDM含量的增加,共聚酯的玻璃化转变温度升高,退火后的试样在低温处和高温处出现了两个熔点,且熔点和焓值随PCT含量的增加而降低。合成产物热稳定性优良,起始分解温度均大于400℃,最大分解温度大于435℃。用Friedman法对热分解动力学的分析,进一步证明共聚酯的热稳定性优良。     

国外动态

LED电视用高性能聚酯化合物美国苏威特种聚合物推出一类新的高性能聚酯化合物商品,与LED电视所采用的材料相比,可提供更高的热稳定性和光稳定性,和一般的室内/外照明应用一样,它们基于广泛使用的聚酯树脂如PCT和LCP。     

我国PBT树脂市场发展趋势分析

<正>聚酯是由多元醇和多元羧酸聚合而成的一类聚合物的总称,一般可分为不饱和聚酯和饱和聚酯。目前已大规模生产的工程塑料级饱和聚酯主要包括聚对苯二甲酸二甲丁二醇酯(PBT)、聚对苯二甲酸丙二醇酯(PTT)、聚对苯二甲酸乙二醇酯(PET)、聚甲苯二甲酸环己烷二甲醇酯(PCT)及共聚聚酯等品种。PBT是由对苯二甲酸(PTA)或对苯二甲酸酯(DMT)与1,4-丁二醇(BDO)聚合而成的饱和聚酯     

全面了解热塑性聚酯

提起热塑性聚酯，很多人可能会想到PET、PBT和PETG，而往往对PCT、PCTG、PCTA和PTT缺乏足够的了解。随着技术的成熟，热塑性聚酯的应用需求也逐步增长，全面了解其性能．应用领域和供应情况可以帮助加工商更好地利用这类材料。[编者按]     

纯聚酯粉末涂料的发展概况

本文介绍了国内外纯聚酯粉末涂料的发展情况,纯聚酯粉末涂料的制备方法及其特点。重点探讨了羟基及羧基两种类型的聚酯所采用的固化剂及其固化体系,并指出了今后纯聚酯粉末涂料发展的趋势。     

含氟聚酯的制备及其应用研究进展

含氟聚酯具有优异的疏水性、耐溶剂性和热稳定性等性能,能够延长聚酯产品的使用寿命、拓宽其应用领域.本文介绍了含氟聚酯的主要合成方法、总结了含氟聚酯的主要特性,就氟化改性聚酯研究现状及其应用前景进行了展望.     

奥美凯扩大医用预着色工程塑料产品线

正奥美凯扩大其用于医疗领域的预着色工程塑料ColorRx~?产品系列的供应,新增PC/ABS合金料和PC/聚酯合金料两种产品。其中,ColorR x~?PA-2000RX、PC/ABS合金料、ColorR x?PCT1000FRRX、PC/聚酯合金料已通过第三方测试,符合ISO 10993生物相容性标准,且经UL阻燃等级测试确定为自熄性材料,材料点燃后会自行熄灭。与标准PC/聚酯合金料相比,该PC/聚酯合金料具有更高的耐化学性。奥美凯改性工程塑料为生物相容性和耐化学性提     

中国不饱和聚酯工业进展

综述了最近中国不饱和聚酯(UPR)及其原料的生产、供应、消费和产能扩充情况。介绍了不饱和聚酯技术发展动态,其中包括利用可再生资源及废弃物为原料制备新型不饱和聚酯或其复合材料,以及在提高不饱和聚酯阻燃性、耐腐蚀性,降低收缩率等方面的研究进展及其增强材料的应用进展。     

A novel potential cationic polymeric gene vector containing hydroxy groups and all grades of amino groups

A novel potential cationic polymeric gene vector, PCT, was synthesized by copolymerizing 3‐chloro‐1,2‐epoxypropane (CEP) and tetraethylene pentamine (TEPA). The protonizable nitrogen content of PCT is 17.7 mmol/g at 1 : 1 of CEP to TEPA, lower than 23.3 mmol/g of polyethylenimine (PEI) but higher than 7.8 mmol/g of polylysine, which indicates PCT is a candidate of polycation with high‐content but discrete charge after protonation. PCT has many hydrophilic quaternized amino and hydroxy groups contributing to hydrophilicity. Acid base titration showed that PCT was protonated in both pH 7.4–11 and pH 5.0–7.4 and had “proton sponge effect.” In aqueous solution, PCT complexed with weak anionic polymer, poly(acrylic acid) (PAA), into nanoparticles. Fourier transform infrared spectroscopy proved the formation of complex. Particle size is first increased and then decreased as increasing mass ratio θ of PCT to PAA from 0.1 to 1.7, as shown by dynamic light scattering. At θ values of more than 1.7 or less than 0.2, complex particles with mean diameter less than 200 nm were obtained. At θ of 0.5, the UV‐Vis absorbance of complex solution at first day was obviously higher than that at 7 day, while at θ of 1.7, two absorbance curves at these two time points had slightly smaller change, indicating that small complex particles were more stable than large ones because of electrostatic repulsion. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Ferroelectric and structural instability of (Pb,Ca)TiO3 thin films prepared in an oxygen atmosphere and deposited on LSCO thin films which act as a buffer layer

Structural, microstructural and ferroelectric properties of Pb_0.90Ca_0.10TiO₃ (PCT10) thin films deposited using La_0.50Sr_0.50CoO₃ (LSCO) thin films which serve only as a buffer layer were compared with properties of the thin films grown using a platinum-coated silicon substrate. LSCO and PCT10 thin films were grown using the chemical solution deposition method and heat-treated in an oxygen atmosphere at 700 °C and 650 °C in a tube oven, respectively. X-ray diffraction (XRD) and Raman spectroscopy results showed that PCT10 thin films deposited directly on a platinum-coated silicon substrate exhibit a strong tetragonal character while thin films with the LSCO buffer layer displayed a smaller tetragonal character. Surface morphology observations by atomic force microscopy (AFM) revealed that PCT10 thin films with a LSCO buffer layer had a smoother surface and smaller grain size compared with thin films grown on a platinum-coated silicon substrate. Additionally, the capacitance versus voltage curves and hysteresis loop measurement indicated that the degree of polarization decreased for PCT10 thin films on a LSCO buffer layer compared with PCT10 thin films deposited directly on a platinum-coated silicon substrate. This phenomenon can be described as the smaller shift off-center of Ti atoms along the c-direction 〈001〉 inside the TiO₆ octahedron unit due to the reduction of lattice parameters. Remnant polarization (P_r) values are about 30 μC/cm² and 12 μC/cm² for PCT10/Pt and PCT10/LSCO thin films, respectively. Results showed that the LSCO buffer layer strongly influenced the structural, microstructural and ferroelectric properties of PCT10 thin films.     

腰果酚醛胺固化环氧树脂泡沫塑料性能研究

以双酚A型环氧树脂(EP)为基体树脂、自制的腰果酚醛胺(PCT)为固化剂、正戊烷(N-PT)为发泡剂、吐温-80和二甲基硅油为稳泡剂室温发泡制备新型环氧树脂泡沫塑料。研究了PCT用量对发泡时间和泡沫性能的影响,通过扫描电子显微镜和热失重分析对泡沫塑料的微观形貌和热性能进行了表征。结果表明,随着PCT用量增加,发泡时间逐渐缩短;环氧树脂泡沫塑料的密度、压缩强度、吸水率和热导率均随PCT用量的增加呈现先减小后增大趋势;当PCT加入量为30 %(相对于纯EP)时,发泡时间降至5 min;泡沫塑料的综合性能较佳,密度为0.0467 g/cm^3、压缩强度为276 kPa、吸水率为2.9 %、热导率为0.037 W/m·K,此时泡孔大小均匀,不良泡孔少;泡沫初始失重温度为248.4 ℃,最大失重速率温度为362.3 ℃,耐热性最佳。     

Electrical and Pyroelectric Properties of Highly (001)-Oriented (Pb0.76Ca0.24)TiO3 Thin Films Grown by a Sol–Gel Process

Highly (001)-oriented (Pb_0.76Ca_0.24)TiO₃ (PCT) thin films were grown on Pt/Ti/SiO₂/Si substrates using a sol–gel process. The PCT film with a highly (001) orientation showed well-saturated hysteresis loops at an applied field of 800 kV/cm, with remanent polarization ( P _r) and coercive electric field ( E _c) values of 23.6 μC/cm² and 225 kV/cm, respectively. At 100 kHz, the dielectric constant and dielectric loss values of these films were 117 and 0.010, respectively. The leakage-current density of the PCT film was 6.15 × 10⁻⁸A/cm² at 5 V. The pyroelectric coefficient ( p ) of the PCT film was measured using a dynamic technique. At room temperature, the p values and figures-of-merit ( F _D) of the PCT film were 185 μC/m²K and 1.79 × 10⁻⁵ Pa^−0.5, respectively.     

Fluidization of extremely large and widely sized coal particles as well as its application in an advanced chain grate boiler

A pyrolysis combustion technology (PCT) was developed for high-efficiency and environment-friendly chain grate boilers (CGBs). The realization of the PCT in a CGB requires that extremely large and widely sized coal particles should be first pyrolyzed in a semi-fluidized state before being transported into the combustion chamber of the boiler. This article was devoted first to investigating the fluidization of 0-40 mm coal particles in order to demonstrate the technical feasibility of the PCT. In succession, through mixing 0-10 mm and 10-20 mm coal particles in different proportions, multiple pseudo binary mixtures were prepared and then fluidized to clarify the effect of particle size distribution. With raw steam coal used as the feedstock, the superficial gas velocity of about 2.0 m/s may be suitable for stable operation of the fluidized-bed pyrolyzer in the CGB with the PCT. In the fluidization of widely sized coal particles, approximately half of the coal mass is segregated into the bottom section of the bed, though about 15% of 10-20 mm large particles are broken into 0-10 mm small particles because of particle attrition. The experimental results illustrate that an advanced CGB with the PCT has a high adaptability for various coals with different size distributions.     

PCT高性能聚酯工程塑料

综述了以环己烷二甲醇与对苯二甲酸二甲酯合成PCT(聚对苯二甲酸环己烷二甲醇酯)树脂及其本体树脂PCT的加工技术(包括GFRPCT、共混等),对PCT树脂的物理、机械性能及其典型应用也作了介绍。     

Evaluation of two different scrap tires as hydrocarbon source by pyrolysis

The main objective of the present study is to investigate the effect of the polymer types in scrap tires on the pyrolysis products. Two different types of scrap tires (passenger car tire, PCT and truck tire, TT) have been pyrolyzed in a fixed bed reactor at the temperatures of 550, 650 and 800 °C under N₂ atmosphere. Pyrolysis products (gas, oil and carbon black) obtained from PCT and TT were investigated comparatively. The gaseous products were analyzed by GC–TCD. The psychical and chemical properties of pyrolytic oils were characterized by means of GC–FID, GC–MS, ¹H NMR. In addition, boiling point distributions of hydrocarbons in pyrolytic oils were determined by using simulated distillation curves in comparison with commercial diesel fuel. The production of activated carbon from pyrolytic carbon blacks (CBp) was also carried out. The composition of gaseous products from pyrolysis of PCT and TT were similar and they contained mainly hydrocarbons (C₁–C₄). Pyrolytic oils were found lighter than diesel but heavier than naphtha. The physical properties of pyrolytic oils from PCT and TT were similar at the same temperature. However, the composition of aromatic and sulphur content from pyrolysis of PCT was higher than that of TT. Furthermore, TT derived pyrolytic carbon black was found more suitable for the production of activated carbon due to its low ash content.     

Predictive Ability of Procalcitonin for Acute Kidney Injury: A Narrative Review Focusing on the Interference of Infection

Acute kidney injury (AKI) is a common yet complicated clinical entity with high morbidity and mortality. An essential strategy to improve AKI patients’ prognoses is finding optimal biomarkers to identify AKI in a timely manner. Procalcitonin (PCT), a well-recognized biomarker for diagnosing infection and guiding antibiotics therapy, has been proposed to predict AKI development and recovery in many clinical settings. The current review provides comprehensive and updated information from relevant studies to evaluate PCT’s AKI-predictive ability and the influence of infection on this predictive ability. PCT has demonstrated optimal predictive ability for AKI in various populations irrespective of infection. However, the predictive ability seems to be blunted by infection since infection and inflammation have a more potent influence than AKI on PCT elevation. We furthermore explain the complicated association between elevated PCT levels and AKI in infection and inflammation situations and recommend directions for further investigations to clarify the essential issue. In conclusion, although conflicting data exist, serum PCT level is a potential biomarker for predicting AKI in many clinical settings regardless of infection. Nevertheless, further studies are warranted to clarify the association between PCT, infection, and AKI and to confirm the utilization of PCT for AKI prediction.     

Evaluation of poly(1,4-cyclohexylene dimethylene terephthalate) blends for improved processability

Poly(l,4-cyclohexylene dimethylene terephthalate) (PCT) exhibits superior heat deflection temperature when compared to conventional polyesters such as poly(butylene terephthalate) or poly(ethylene terephthalate). It is subject to degradation, however, at the processing temperatures normally employed to extrude or mold this material. Several approaches were taken to broaden the processing window of this material including: blending PCT with other crystalline and amorphous polymers to allow for lower processing temperatures, addition of conventional stabilizers, addition of crosslinking agents to maintain viscosity during processing and the addition of lubricants to improve processing. Key parameters included physical properties, rate of degradation, extruder torque measurements vs. time, and Differential Scanning Calorimetry (DSC) analysis (melting point and glass transition). All systems tested produced significant reduction of the intrinsic viscosity (molecular weight) for PCT during processing. The most successful approach was the blending of various polymers with PCT to lower extruder processing temperatures. Reductions in processing temperature may have resulted from improved heat transfer due to the presence of a lower melting polymer, reduction in melting point of the blend, or changes in the frictional characteristics of the PCT in the extruder. Transesterification may have played a role in compatibilizing some polyester mixtures. As expected, certain polymers had major'effects on the flow behavior of the blend. Tradeoffs were obtained in physical and thermal properties. A combined approach of polymer blending and the use of lubricants, stabilizers or crosslinking agent may hold the most promise for future development work. Thermal resistance under vapor phase soldering conditions was best for LCP/PCT blends and worst for PBT/PCT blends. Additional evaluations of the blend materials will include solvent resistance, processability, thermal resistance, dimensional stability, heat aging resistance, flammability, and specific end use tests.