聚乙烯相结构与性能的关系

将均聚低分子量高密度聚乙烯(HDPE)组分和共聚高分子量线型低密度聚乙烯(LLDPE)组分按不同比例熔融共混,制备了双峰聚乙烯,对其进行了力学性能、流变、DSC测试,以表征共混物中的均聚HDPE组分与共聚LLDPE组分的溶混性。采用SEM观察了不同比例的熔融共混物试样的冲击断面,当高分子量组分LLDPE在共混物中的含量小于50%(w)时,共混试样中会观察到椭圆状的分散相,从而直观地看到共混物中存在较大尺度的相分离结构。这种由于两种组分黏度差异大造成的相分离对HDPE/LLDPE共混物的力学性能有一定的影响。     

非茂单活性中心-BCG复合催化剂用于制备双峰高密度聚乙烯

用负载化的非茂单活性中心催化剂和工业上聚乙烯气相法BCG催化剂复合,在单釜中进行了双峰高密度聚乙烯(双峰HDPE)的合成实验。通过考察氢气分压、聚合温度、聚合时间、乙烯压力、共聚单体等对乙烯聚合性能的影响,研究了双峰HDPE的相对分子质量及其分布、熔体流动指数和密度的变化规律,获得了双峰HDPE制备的有效调控方法。实验结果表明,此复合催化体系可在单反应器中制备出高相对分子质量部分高支化度和低相对分子质量部分低支化度的理想双峰HDPE。     

UCC的Unipol工艺又有新突破

<正> 美国UCC用于生产聚烯烃的Unipol工艺已有20年的历史.据报道,该公司目前不但可用该气相工艺生产HDPE、LLDPE、VLDPE及PP,而且能用一个反应器分别生产乙烯与丙烯、丁烯、己烯、4-甲基成烯-1、辛烯等其他单体共聚的新型聚烯烃,其中包括称为柔性聚合物(flexomer)的很低模数的聚烯烃.据称,到1990年开发的新产品可能有模数为69MPa到6MPa的聚烯烃以及乙丙橡胶等.UCC最近开发的高效催化剂可以廉价地使乙烯与高含量的共聚单体和二烯共     

高密度聚乙烯/低密度聚乙烯共混物氧化诱导时间研究

采用熔融共混方法对高密度聚乙烯(HDPE)/低密度聚乙烯(LDPE)共混物的耐热性进行研究。将不同含量抗氧剂的LDPE与HDPE按一定质量比,在双螺杆挤出机上共混挤出,利用DSC研究了同种/不同种聚乙烯共混物及不同配比对氧化诱导时间(OIT)的影响及二元聚乙烯共混物的熔融行为。实验结果表明,LDPE与HDPE共混后因两种共混组分不均匀、导致OIT偏低;HDPE与HDPE共混时因相容性好、混合较均匀,OIT与抗氧剂含量成正比。以不同温度下测得的OIT为基础,建立温度与寿命相关的Arrhenius方程,可快速推算聚乙烯共混物料的寿命。     

高密度聚乙烯共混增加薄膜韧性的研究

为提高高密度聚乙烯(HDPE)薄膜的韧性,尝试加入其它高分子材料与HDPE进行共混改性,先制成专用料,然后吹塑成薄膜进行表征分析。先通过拉伸实验测试得出LLDPE、PP共混改性HDPE效果较好;通过落标冲击强度和雾度确定改性韧性的最佳比例,最后经红外光谱(IR)研究薄膜的内部结构。结果表明,在最优配方(30%LLDPE+HDPE+10%PP)下,最优配方生产薄膜的抗冲击强度提高22%,雾度下降20%,薄膜韧性显著增加。     

丁烯-1的国内外市场及其应用兼论燕化公司恢复MTBE建设的可行性

前言由于燕化公司30万 t/a 乙烯改扩建工程聚乙烯项目的技术路线由拟用 UCC 公司气相法聚合生产全密度聚乙烯技术转为国产化的淤浆法生产 HDPE 的技术,共聚单体丁烯-1的使用量相应由原来近1万 t/a 减少到1500t/a(最大量)左右,因此原可行性研究报     

采用新型催化剂可从单一反应器生产双峰HDPE

据“Chemical Engineering,2004,111(12)：15”报道,Univation技术公司开发并已工业化生产的．Prodigy BMC 100型催化剂,可用于从一个单一的反应器生产有双峰相对分子质量分布的高密度聚乙烯(HDPE)薄膜级树脂。采用新催化剂也可用于生产管材级HDPE树脂,其树脂性能可与多反应器生产的最优等级树脂相媲美。该工艺投资比多反应器系统节约40％,对于300kt／a的生产装置,可节约3500万美元。截至此前,至少用2台串联的淤浆反应器才能生产出双峰HDPE。     

新型浆液催化剂在高密度聚乙烯生产中的应用

介绍了新型钛系浆液催化剂的特点、配制及加入系统。考察了该浆液催化剂在高密度聚乙烯 (HDPE)生产装置上的应用情况。使用浆液催化剂生产HDPE反应静电控制稳定 ,催化剂活性调整方便 ,成本低 ,反应器中聚合物细粉少 ,产品性能优良     

丙烯为主单体的烯烃共聚合金的研究

根据冷模研究结果,设计了一套研究半连续烯烃气相聚合的反应器,其温度、压力控制及反应速率的测定完全能够达到催化剂性能评价和动力学研究的要求。通过试验发现,在烯烃共聚合金工艺气相聚合中,反应速率分为反应控制和扩散控制两个阶段,其中反应控制阶段的撤热是气相聚合反应器设计的关键。     

调整工艺参数延长聚丙烯抗冲共聚单元运行周期

分析了气相反应器结块的原因和影响抗冲共聚单元长周期运行影响因素,据此对相关参数作了适当的调整.经过调整,共聚单元运行周期延长为53 d,产品质量没有变化.     

高密度聚乙烯和石油树脂共混物的热性能

通过熔融共混法制备了一系列高密度聚乙烯(HDPE)与石油树脂(P-100)的共混物。用示差扫描量热法表征HDPE/P-100共混物的热性能。表征结果显示,随HDPE含量的降低,HDPE/P-100共混物中HDPE的熔点向低温方向移动,过冷度减小,HDPE/P-100共混物中HDPE的结晶度比纯HDPE的结晶度大,表明P-100对HDPE的结晶具有一定的促进作用。通过Jeziorny改进的Avrami方程分析表明,P-100有效促进了HDPE晶核的形成。广角X射线衍射表征结果显示,P-100的加入使HDPE衍射峰半峰宽减小,表观厚度增大,同样说明P-100对HDPE结晶具有促进作用。扫描电子显微镜表征结果显示,HDPE/P-100共混物中HDPE和P-100形成双连续的网络结构,且网络尺寸随HDPE含量的增加而减小,结晶度随HDPE含量的降低而增大。     

Influence of Asphaltenes on the Rheological Properties of Blended Paving Asphalts

Abstract

Some of the refineries in India produce asphalt by blending propane deasphalting (PDA) pitch and heavy extract. This investigation reports the rheological and chemical characterization of various blends made with PDA pitch and heavy extract. The main objective is to develop an understanding on the influence of asphaltene change on the changes in the rheological properties under all aged conditions. Three blend proportions were manufactured using three different crude sources, and all the blends were subjected to short- and long-term aging. All the blends were tested for steady shear, creep and recovery, and stress relaxation properties. A chemical composition analysis of all the blended asphalt samples was carried out under all three aging conditions. It was seen that the proportion of PDA pitch considerably controls the rheological properties and that the kinetics of short-term aging are completely different when compared to long-term aging for blended asphalt.     

聚乙烯／聚己内酰胺共混物力学性能的研究

采用双螺杆挤出机将聚己内酰胺与马来酸接枝聚乙烯进行熔融共混，对共混物的冲击性能、拉伸性能、热变形、吸水率进行测定，发现共混物两相间具有较好的相容性，共混物的缺口部击强度提高了６倍，吸水率降低了５０％。     

Properties of gasoline-ethanol-methanol ternary fuel blend compared with ethanol-gasoline and methanol-gasoline fuel blends

Two binary sets of gasoline-methanol (GM) and gasoline-ethanol (GE) blends along with two other ternary sets of gasoline-methanol-ethanol (GME) blends were formulated comprising single and dual alcohol. ASTM-D86 distillation, vapor pressure, and octane number were measured. Also, distillation curves were constructed for each blend and the influence of azeotrope formation was discussed. The obtained results reveal that distillation curves of gasoline blends, comprising from 5 to 15 vol% methanol, display a more significant decrease in distillation temperature than gasoline-ethanol blends. Also, more decrease in distillation temperature is observed by increasing the rate of blended alcohol. At equal rates of blended alcohol, the distillation curve of ternary fuel (GE5M5) is positioned in between distillation curves of binary fuel blends GM10 and GE10. More acceptable vapor pressure is achieved in ternary GEM fuels containing 7.5–15.0 vol% of dual alcohol, the same rate in GM blends increases vapor-lock tendency. At equal alcohol content, GEM blends give a higher octane number than GE one.     

用结晶分级仪快速表征聚烯烃树脂的分子链结构

用结晶分级仪快速分析了不同聚烯烃树脂的结晶分布曲线特点及与分子链结构的关系。结晶分级法不仅可 用于聚烯烃树脂分子链结构的表征,还可用于对聚烯烃共混物的分析鉴别。该分析方法简便、快速,是表征聚烯烃结 构的有效手段。     

Low-temperature Properties of Biodiesel： Rheological Behavior and Crystallization Morphology

A soybean oil derived biodiesel was prepared and blended with a conventional No. 0 petrodiesel. The pour points (PP) and the cold filter plugging points (CFPP) of biodiesel blends were evaluated on a low-temperature flow tester. Dynamic viscosities of the blends at different temperatures and different shear rates were measured on a rotary rheometer. The crystal morphologies of biodiesel blends at low temperatures were analyzed using a polarizing microscope. The results indicated that blended fuels demonstrated slight decrease in PPs and CFPPs as compared with those of neat soybean oil derived biodiesel and pure petrodiesel. Below the temperatures of PPs or CFPPs, the dynamic viscosity of biodiesel blends dramatically increased with a decreasing temperature, but decreased with an increasing shear rate, so that biodiesel blends exhibited non-Newtonian behavior. At temperatures higher than PPs or CFPPs, a linear relationship appeared between the dynamic viscosity and shear rate and biodiesel blends became Newtonian fluids. At low temperatures, wax crystals of biodiesel blends grew and agglomerated rapidly. Loss of fluidity for biodiesel blends at low temperatures could therefore be attributed on one hand to the sharp increase of viscosity and on the other hand to the rapid growth and agglomeration of wax crystals.     

Cold flow properties and crystal morphologies of biodiesel blends

A soybean biodiesel was prepared and blended with a conventional China’s No. 0 petrodiesel. The pour points (PP) and cold filter plugging points (CFPP) of the biodiesel blends were evaluated on a low-temperature flow tester. Dynamic viscosities of the blends at different temperatures and different shear rates were measured on a rotatory rheometer. The crystal morphologies of the biodiesel blends at low temperatures were analyzed using a polarizing microscope. The results indicate that the blended fuels provided a slight decrease in PPs and CFPPs as compared with those of neat soybean biodiesel and pure petrodiesel. Below the temperatures of PPs or CFPPs, the dynamic viscosity of the biodiesel blends increased dramatically with decreasing temperature, but decreased with increasing shear rate, the biodiesel blends exhibiting non-Newtonian behavior. At temperatures higher than PPs or CFPPs, linear relationships appeared between dynamic viscosity and shear rate and the biodiesel blends became Newtonians. At low temperatures, wax crystals of the biodiesel blends grew and agglomerated rapidly. The loss of fluidity at low temperatures for the biodiesel blends can therefore be attributed, on the one hand, to the sharp increase of viscosity and, on the other hand, to the rapid growth and agglomeration of wax crystals.     

Effect of cyclohexanol on phase stability and volatility behavior of hydrous ethanol-gasoline blends

Biofuels can contribute to reducing greenhouse gas emissions and bridging the gap between production and consumption. Ethanol is a renewable source of energy. It can reduce oil dependence and also can be appropriately used in gasoline as a blend. The high cost of dry ethanol has turned the researcher's attention to the more economic hydrous ethanol. However many works were focused on its impact on the engine performance and the exhaust emissions; few works were interested in the phase stability of those blends. This work aims to study the impact of blending cyclohexanol (CH) into hydrous ethanol-gasoline blends as a stabilizing agent. Four dual-alcohol (E5-3CH, E10-3CH, E15-3CH, and E20-3CH) blends were investigated besides their single hydrous ethanol (E0, E5, E10, E15, and E20) blends. The tests involved; water tolerance, distillation curve, and vapor pressure. Vapor lock protection potential, the area under the distillation curve (AUDC), and the area due to azeotrope formation (ADAF) were calculated. The obtained results show that cyclohexanol significantly increases the water tolerance of hydrous ethanol-gasoline blends. The blends of E5 and E10 which were separated at 30 °C converted into miscible and clear samples when they were blended with 3 vol% of cyclohexanol. These samples can also tolerate additional water. For E20, the addition of 3 vol% of cyclohexanol increased the water tolerance by about six times. Also, it was found that cyclohexanol does not have any negative effect on the volatility properties of the fuel blends. It was found that blending CH into the hydrous ethanol blends causes a significant increase in the AUDC and consequently, the area due to azeotrope formation (ADAF) decrease.     

生物喷气燃料的组成与基本性质研究

通过对不同原料来源的生物喷气燃料的烃类组成分析,分析原料对产品的影响,同时与石油基喷气燃料比较,研究生物喷气燃料组成与石油基喷气燃料的差别,进一步与石油基喷气燃料调合,分析烃类组成和理化性能,比较生物喷气燃料与石油基喷气燃料性能。数据表明,生物喷气燃料的性能完全符合ASTM D7566附录2的要求,调合后的喷气燃料完全符和GB6537对3号喷气燃料的要求。     

Study on Producing Marine Fuel Oil by Blending

In this paper, Fushun shale oil (FSO) was used as basis oil, which was blended with Anshan heavy oil (AHO) and Liaoyang heavy oil (LHO), respectively. Their physico-chemical properties were gained comprehensive analyses. Additionally, the contents of Na, K, Ca, Ni, V, and Zn of blended oils were determined by the Inductively Coupled Plasma Atomic Emission Spectrometry (ICP), and blended oils were divided into four groups and analyzed by column chromatography. The experimental results showed that there was optimal proportion between shale oil and heavy oil by blending. Its physico-chemical properties reached the standard of corporation, which further showed that the blending method was a feasible way to produce marine fuel oil.