高密度聚乙烯与其他聚烯烃共混物高取向薄膜结晶结构的电子显微学研究

本文用透射电子显微镜方法研究了高密度聚乙烯(HDPE)与其它聚烯烃[包括线性低密度聚乙烯(LLDPE)、低密度聚乙烯(LDPE)、等规聚丙烯(iPP)、聚丁烯-1(PB-1)等]共混物高取向薄膜的结晶结构,其中聚烯烃组分含量为10%。在共混物熔体拉伸薄膜中,HDPE以高取向的片晶形式存在,片晶的生长方向垂直于拉伸方向。共混物中LLDPE、LDPE与HDPE形成共晶。与HDPE不相容的iPP、PB-1在共混体系中未观察到明显的相区存在。聚烯烃组分的加入,不仅影响HDPE的片晶尺寸,同时影响结构的对称性,即由纯HDPE的非对称“近单晶”结构变为对称的纤维结构。     

凝胶渗透色谱法测定HDPE的分子量及分子量分布

采用示差折光及粘度双检测器凝胶色谱系统,利用普适校正原理,不需要Mark常数K、a值,直接测定了高密度聚乙烯(HDPE)的分子量及分子量分布;优化选择了色谱柱组合、样品浓度、柱温等色谱条件并给出分子量分布曲线。     

大庆HDPE装置超负荷生产的探讨

大庆ＨＤＰＥ装置原设计生产能力１４万ｔ／ａ，“八五”期间，乙烯装置生产能力由３０万ｔ／ａ。为了平衡乙烯总量，ＨＤＰＥ装置在没有大的改造的条件下，进行了超负荷生产的探讨。实践证明，超负荷生产是成功的。     

PP／GF／HDPE复合物的结晶行为和性能研究

用差示扫描量热(DSC)法研究PP/GF/HDPE复合物熔融试样的冷却过程,同时采用偏光显微镜技术观察复合物的形态结构。试验表明PP/GF/HDPE复合物的结晶峰温度升高8～9℃,结晶起始斜率变大,球晶几何尺寸明显减小,复合物中的玻璃纤维(GF)起到异相成核作用,高密度聚乙烯(HDPE)对聚丙烯(PP)有增塑作用并对异相成核具有协同效应。     

自增强HDPE的断裂行为分析和力学性能预测

研究发现自增强ＨＤＰＥ的断裂行为不同于普通的ＨＤＰＥ，它的断裂强度σｕ小于屈服强度σｓ表现出脆性破坏特征，采用断裂分子理论分析了自增强ＨＤＰＥ抗破断能力提高的内在原因，认为ＨＤＰＥ自增强后，断裂活化能的改变和活化体积的减小，从而抑制了原子键的热激活，是提高抗破断能力的主要原因之一，据自增强ＨＤＰＥ的结构特征，提出了自增强高分子材料的力学性能估算方法。     

Biodiesel compatibility with carbon steel and HDPE parts

Compatibility of the new environmentally-friendly alternative of diesel engine fuels, biodiesel, with storage and engine part materials, is still an open issue. In this work, the interaction between three fuels (petroleum diesel and two types of biodiesel — soybean and sunflower) and two materials (carbon steel and high density polyethylene) used in storage and automotive tanks, is analyzed in detail. A wide set of characterization techniques was used to evaluate the changes in both solid and fluid materials, as weight change measurement, optical, scanning electron and atomic force (AFM) microscopies, Raman and FTIR spectroscopies, and differential scanning calorimetry. The AFM technique allowed detecting surface roughness and morphology changes in the metallic material following the trends in the weight losses. In the case of polymeric material, weight gain by fluid absorption occurred, being detected by the spectroscopic techniques. The biodiesel fuels underwent some ageing however this phenomenon did not affect the interaction between the biodiesel fuels and the substrates. The petrodiesel, which did not age, caused more significant degradation of the substrates.     

振动注射对PP/HDPE共混物性能及晶型的影响

采用熔融共混法制备了聚丙烯(PP)/高密度聚乙烯(HDPE)共混物,研究了成型温度、振动频率、振动压力对共混物力学性能、结晶形态的影响。结果表明:高温下低频率振动,共混物的力学性能随振动压力的提高呈明显的上升趋势;WAXD测试结果表明:在一定振动条件下,共混物会有少量的次稳定晶型γ晶的生成。     

Effect of packaging materials and storage time on changes of colour,phenolic content,chlorogenic acid and antioxidant activity in arabica green coffee beans (Coffea arabica L. cv. Catimor)

The conditions and storage time of green coffee beans are very important for the commercial quality of coffee. This includes factors such as light, humidity and temperature in the warehouse and also the packaging material used. The aim of this study was to evaluate the effects of type of packaging materials namely high density polyethylene (HDPE) bag and jute sack on moisture content, colour, phenolic contents, chlorogenic acids content and antioxidant activity of Arabica green coffee bean during 15 months of storage. The results show that HDPE bag can preserve the moisture content, colour and chlorogenic acid in green coffee beans (GCB) better than a jute sack during storage. No significant difference of phenolics content in green coffee beans was observed during 4 months of storage in both types of packaging. During initial 10 months of storage the antioxidant activity of GCB stored in HDPE showed higher values than that of GCB stored in jute sack. However, after 1 year of storage, the phenolics content and antioxidant activity in GCB in a jute sack were higher than in HDPE bag. The fluctuation of moisture content could lead to stress condition of green coffee bean and contributing to forming of bioactive compounds. This finding was observed and need further investigation.     

填埋场高密度聚乙烯膜缺陷渗漏试验及计算模型研究

因施工等原因造成土工膜渗漏十分常见,但渗漏量的计算是工程建设和运营面临的重大难题。本研究通过室内试验,测试了不同高密度聚乙烯(HDPE)膜厚度(w=0.5、1.0mm)、缺陷孔径(φ=3、5、10 mm)和膜上不同压力水头(h=0.3、0.5、0.65、0.8 m)时的缺陷渗漏量,并建立数学模型进行拟合。结果表明:相对于膜厚度而言,膜缺陷大小和压力水头高度对渗漏量的影响更大;渗漏量可表达为膜缺陷大小和水头高度的幂函数,但不同工况下的系数有别,因此实际工程应通过试验方式确定。     

HDPE／PA—6防渗合金的研制及应用

本文介绍了阻隔容器用HDPE/PA-6防渗合金的工艺技术,包括配方选择、相容剂的选择及最佳工艺条件的确定。将制成的改性粒料吹塑成小型中空容器,并进行了二甲苯、汽油防渗试验。