低密度聚乙烯泡沫片材挤出成型技术的改进

阐述了物理高发泡LDPE片材的挤出成型,采用丁烷作为发泡剂时提高泡体质量所采用的工艺、配方和设备的生产技术改进     

聚碳酸酯厚壁制品的注射成型

通过分析聚碳酸酯的工艺特性,针对特定的厚壁注塑制品,在材料的选择上要考虑熔体流动速率、含水量等;在设备的选择上要考虑螺杆形式、压缩比、长径比等方面;在模具的设计上要考虑采用的浇口形式、大小、脱模斜度、排气、模具预热及冷却等;在注塑工艺上可通过调整料筒温度、注射压力、速度、模温等来设置合理的工艺参数。通过以上一些措施,可以使特定的厚壁制品达到要求。     

PP／LDPE共混物熔体流动特性的研究

将两种熔融流动指数（ＭＦＩ）相差大的聚丙烯（ＰＰ）分别与一低密度聚乙烯（ＬＤＰＥ）进行共混，用熔体流动速率仪测定其流动特性。发现ＭＦＩ值高的ＰＰ，当共混比ＰＰ／ＬＤＰＥ为５０／５０时，其熔体流动速率（ＭＦＲ）为最大，本文对此作了初步的分析和讨论。     

单螺杆混沌挤出过程周期性行为数值模拟

建立了混沌单螺杆挤出机计量段物理和数学模型。定义了更合理的边界条件,采用Carreau本构方程,采用有限体积方法对聚合物熔体在螺槽内流动的周期性效应进行了数值模拟分析。得到了不同位置的速度分布细节以及流体示踪粒子的行为轨迹。发现螺槽内速度分布表现出周期性和对称性的变化,揭示了同宿点及椭圆点存在及位置不变性,为进一步分析流体质点在相空间的动力学行为奠定了基础。     

NR/SBR混炼胶挤出流动中自然收敛角的计算

考察了ＮＲ／ＳＢＲ共混胎面胶在毛细管挤出流动中的末端效应、基于以前的工作［１］提出了粘弹性流体自然收敛半角方程，并估算了试样在挤出条件下的人口自然收敛角（２α０）。结果表明，２α０值随着温度的升高而有所增大．随着剪切速率的增加而减小。     

陶瓷部件挤出成型工艺

本文以蜂窝陶瓷生产工艺为例，讨论了陶瓷部件挤出成型过程中，塑性泥料的制备、成型、干燥和烧成等工艺技术和装备问题。     

等通道转角挤出制备自增强等规聚丙烯的结构与性能研究

采用等通道转角挤出方法对等规聚丙烯进行自增强挤出,研究和分析挤出工艺条件与材料结构、性能之间的关系。利用广角X-射线衍射、差示扫描量热分析等手段对材料结构进行表征。结果表明:经过等通道转角挤出后等规聚丙烯的结晶度提高、晶粒细化、熔点提高,形成明显的取向结构,经过3次等通道转角挤出,等规聚丙烯的拉伸强度由挤出前的17.13MPa提高到59.38MPa。     

Flaking and extrusion as mechanical treatments for enzyme-assisted aqueous extraction of oil from soybeans

Flaking and extruding dehulled soybeans were evaluated as a means of enhancing oil extraction efficiency during enzyme-assisted aqueous processing of soybeans. Cellulase, protease, and their combination were evaluated for effectiveness in achieving high oil extraction recovery from extruded flakes. Aqueous extraction of extruded full-fat soy flakes gave 68% recovery of the total available oil without using enzymes. A 0.5% wt/wt protease treatment after flaking and extruding dehulled soybeans increased oil extraction recovery to 88% of the total available oil. Flaking and extruding enhanced protease hydrolysis of proteins freeing more oil. Treating extruded flakes with cellulase, however, did not enhance oil extraction either alone or in combination with protease. Discrepancies in oil extraction recoveries were encountered when merely considering crude free fat because some oil became bound to denatured protein during extrusion and/or sample drying. Bound fat was unavailable for determination by using the hexane extraction method, but was accounted for by using the acid hydrolysis method for total oil determination. Oil extraction recovery from extruded soybean flakes was affected by oil determination methods, which was not the case for unextruded full-fat soy flour.     

UHMWPE瓷机滤板的研制

通过对超高分子量聚乙烯(UHMWPE)特性的分析，指出用其制作瓷机滤板的可能性，并针对UHMWPE的成型加工性能及瓷机滤板的结构特点，确定了压制、烧结成型的工艺方案，阐述了瓷机滤板压制、烧结成型工艺务件，压缩模具结构，模具工作过程，以及成型过程中使用的加热与冷却装置及加热与冷却油路设计，介绍了压制、烧结成型工艺要点和UHMWPE瓷机滤板的应用情况。     

Effect of ultrasound on the morphology and properties of polypropylene/inorganic filler composites

The effects of ultrasonic irradiation on the rheology, structure, and properties of PP/inorganic filler composites were studied. Scanning electron microscopy showed that ultrasound increased the orientation degrees of acicular fillers to the flow direction. WAXD indicated that ultrasound vibration induced sheet fillers orient with its surface perpendicular to the direction of the ultrasound vibration. The orderly rearrangements of fillers in the polymer melt induced by ultrasound vibration can reduce the steric hindrances in the flow field and increase the flowability of the PP/inorganic filler composites. The effect of ultrasound on reducing the apparent viscosities is very prominent, especially at lower shear rate. Ultrasound has an even more marked effect on reducing the apparent viscosities of composites containing fillers of larger size. With ultrasound vibration, the mechanical properties of the composites are also improved because of the orientation and uniform dispersion of fillers in the matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1553–1560, 2005