INFLUENCE OF DRYING CONDITIONS ON THE RHEOLOGICAL PROPERTIES OF PRUNES

Rheological properties of rehydrated prunes were obtained applying compression-relaxation tests by using a Texture Analyzer TAXT2i. A mathematical development was adopted to determine the stress and area, along the deformation. Experimental data of stress versus time was fitted by using three different rheological models: generalized Maxwell, Normand & Peleg and Maxwell. Results showed that generalized Maxwell model can be used to describe the viscoelastic behavior of the samples. The rheological parameters obtained indicated that prunes exhibited elastic behavior more pronounced at low moisture content and drying air temperature. At high moisture content and temperature the sample became a more viscous and less rigid.     

干燥工艺条件对氨基模塑料性能的影响

简要介绍了氨基模塑料的生产工艺过程及生产中主要的工艺参数,研究了干燥工艺条件对氨基模塑料性能的影响.结果表明,干燥温度为90℃,干燥时间为2.5 h,物料层厚度为25 mm,空气排出量为30 m3/h时,所得到的氨基模塑料的固化时间为45 s,流动性为145 mm,符合厂家的使用要求.     

活化工艺对活性炭纤维性能的影响

探讨了粘胶纤维前处理和活化条件（如活化温度、活化时间、活化剂浓度）对活化收率、ＡＣＦ比表面积、苯酚吸附量的影响。结果表明，活化收率随活化温度、活化时间和活化剂水的浓度的增加而降低，ＡＣＦ比表面积和苯酚吸附量则随之而增大，经过磷酸和氯化锌前处理，可以明显提高粘胶纤维活化收率，增加ＡＣＦ比表面积和苯酚吸附量。     

INFLUENCE OF DRYING CONDITIONS ON THE FRAGILITY OF CORN KERNELS

ABSTRACT

A dynamic rcsring dnim war built to study the effects of air temperature, moisture content and grain shape on fragility of the air dried kernels. For drying rares under 0.05 kglkg min. the fragility of kernels could br described empirically as a function of the three experimental parameters.     

INFLUENCE OF DRYING CONDITIONS ON THE FRAGILITY OF CORN KERNELS

A dynamic rcsring dnim war built to study the effects of air temperature, moisture content and grain shape on fragility of the air dried kernels. For drying rares under 0.05 kglkg min. the fragility of kernels could br described empirically as a function of the three experimental parameters.     

增容剂对HDPE／AS合金流变和力学性能的影响

研究了增容剂氯化聚乙烯接枝（丙烯腈／苯乙烯）共聚物对ＨＤＰＥ／ＡＳ共混体系加工流变性能和力学性能的影响。增容剂使共混体系的塑化时间减少,且随着增容剂用量的增加,共混体系的平衡扭矩和拉伸强度增大,而断裂伸长率在ＨＤＰＥ／ＡＳ／ＰＥ－Ｃ－ｇ－ＡＳ＝８０／２０／４时出现极大值;螺杆转速的增加使共混体系的平衡扭矩增大。     

几种聚乙烯毛细管流变性能的研究

采用高压毛细管流变仪研究了聚乙烯(PE)在225℃和250℃下的流变行为.结果表明,PE的粘度随着剪切速率的增加而降低,相同结构PE的粘度随熔体流动速率(MFR)的增加而降低;在同一温度和剪切速率下,当MFR相当时茂金属线性低密度聚乙烯(PE-MLLD)的粘度最大、线性低密度聚乙烯(PE-LLD)次之、低密度聚乙烯(P...     

合成条件对聚苯胺成纤性能的影响

以苯胺为单体、过硫酸铵为氧化剂、在盐酸水溶液中化学法合成聚苯胺 ,研究的重点是确立一个能够适合纺丝要求的合成参数体系。合成的聚苯胺重均相对分子质量达 2 9× 10 4。以不同条件下合成的聚苯胺为原料湿法纺制了聚苯胺导电纤维。     

THE INFLUENCE OF CONSTANT AND VARIABLE CONDITIONS ON THE DRYING KINETICS OF APPLES

Abstract

The purpose of this work was to examine the influence of constant and variable temperatures or velocities on apples' drying kinetics. The step changes of temperature influenced forcefully on apples1 temperature in all situations. The drying curves -6f apples showed the influence of air's temperature as well velocity on the water content. The largest difference between the apple drying curves and absolute value of drying rate are obtained after introducing step changes or rectangle impulses of air's temperature or velocity at the beginning of the process.     

THE INFLUENCE OF CONSTANT AND VARIABLE CONDITIONS ON THE DRYING KINETICS OF APPLES

The purpose of this work was to examine the influence of constant and variable temperatures or velocities on apples' drying kinetics. The step changes of temperature influenced forcefully on apples1 temperature in all situations. The drying curves -6f apples showed the influence of air's temperature as well velocity on the water content. The largest difference between the apple drying curves and absolute value of drying rate are obtained after introducing step changes or rectangle impulses of air's temperature or velocity at the beginning of the process.     

PP/LDPE/EPDM三元共混物流变性能的研究

本文研究了硫化剂体系、炭黑、滑石粉对ＰＰ／ＬＤＰＥ／ＨＤＰＥ三元共混物流变性能的影响。结果表明,过氧化二异丙苯（ＤＣＰ）和硫磺（Ｓ）的配比对共混物熔体中粘度有明显影响。当ＤＣＰ／Ｓ为０８／０３时,共混物的熔体粘度相对较低;当ＤＣＰ／Ｓ为０３／０３时,粘度相对较高。炭黑和滑石粉配合使用比单独使用时更不利于共混物熔体的流动。     

共混工艺条件对EPDM/PP热塑性弹性体力学性能的影响

本文探讨了开炼机和单螺杆挤出机两种简单的共混设备制备的 EPDM/PP热塑性弹性体( TPES)性能差别 ,实验结果表明 ,单螺杆挤出机制备的 TPES具备更好的力学性能 ,170℃制备的 TPES的拉伸强度和 10 0 %定伸应力优于 190℃制备的 TPES,而断裂伸长率则相反     

模拟植物细胞悬浮培养体系和其两相培养体系流变特性研究

用颗粒状琼脂代替植物细胞从实验上系统研究了模拟植物细胞悬浮培养体系的流变特性。进而根据实验结果得出了模拟植物细胞悬浮培养体系的流动特性指数、稠度系数和表观粘度随植物细胞浓度的变化规律。并初步探索了加入有机溶剂后形成的模拟植物细胞两相培养体系流变特性     

EFFECT OF DEFORMATION SEQUENCE ON RHEOLOGICAL BEHAVIOUR AND MECHANICAL DEGRADATION OF POLYMER SOLUTIONS

The flow behaviour of polymer solutions of non-hydrolyzed polyacrylamide and Xanthan was investigated in two rectangular and similar plexiglas models containing 3 cylindrical enlargements of the same dimensions. These three enlargements were located successively at the mid point of the first model length, whereas they were equally spaced along the second one. Only non-hydrolyzed polyacrylamide polymer solutions have shown viscoelastic behaviour in these plexiglas models. However, the behaviour of these polymer solutions in the first model was different from that in the second one.

The multipass mechanical degradation of the non-hydrolyzed polyacrylamide polymer solutions was studied extensively in the two plexiglas models. It was shown that, at high flow rates, the multipass mechanical degradation was stronger in the second model than in the first one. The mechanical degradation in model 1 converges with that in model 2 as the flow rate decreases.

The difference in flow behaviour and mechanical degradation of the same polymer solutions in the used plexiglas models was ascribed to the different times allowed for polymer solutions to relax prior to extension in the tested flow fields.     

玻璃钢复合材料受热状态物性参数变化研究

玻璃钢复合材料主要成分为玻璃纤维和树脂,其制品在受热状态下会发生复杂的物理化学变化,相应的物性参数也随之会有较大变化,进而影响材料结构内部的温度分布;对其受热状态下的变化过程进行研究,给出相应的物性参数变化模型;制备玻璃钢试样进行风洞条件下的烧蚀试验,测量试样背面温升,与应用物性参数变化模型进行的仿真计算结果较为吻合,表明模型构建符合工程实际.     

木钠添加剂对水煤浆流变行为的影响研究

研究了木质素磺酸钠(简称木钠)对水煤浆流变行为的影响,包括木钠的浓度和分子量、浆体温度、p H值及木钠与NDF在预剪切条件下的流变性能.结果表明:木钠的添加量超过煤重的0 .8%时,煤浆表观黏度随添加剂的增加而增加.不同分子量的木钠对煤浆的流动性会有不同的影响.分子量在1 0 0 0 0～5 0 0 0 0级分对流变性较为有利.煤浆的温度低于60℃时,煤浆的黏度会不断减少;超过60℃时,黏度会有增加.煤浆溶液在弱酸和弱碱条件下,p H值为9时可使黏度较低.木钠在上述不同的条件下均有较为理想的假塑性.在预剪切实验中,随着预剪切时间的增加煤浆黏度会不断增加.     

THE INFLUENCE OF STORAGE/TRANSPORTATION CONDITIONS ON DRYING STRESSES AND THE PRONG TEST

From the time lumber is removed from the kiln to the time the remanufacturer uses it, it can be exposed to many different humidities With exposure to severe humidities, cupping in the final product can occur. This paper considers if humidity conditions during storage and transportation can significantly influence drying stresses and prong lest response. To determine the influence of exposure to different humidities, dried lumber was slowly equilibrated to 7,5% moisture content. It was than cut into blocks. The blocks were exposed to various humidity scenarios lo simulate actual storage and transportation conditions. Stress levels, moisture content and prong response were recorded. The analysis showed that stress level and prong response were strongly influenced by exposure to different humidities. The analysis also indicated that returning lumber to 7.5% equilibrium moisture content did not return the stress level or prong response to the original values. These combined results confirm that the prong test cannot be used as an indicator of how well the lumber has been dried or conditioned after it has been stored and transported. This makes seller/buyer disagreements difficult to resolve.     

THE INFLUENCE OF STORAGE/TRANSPORTATION CONDITIONS ON DRYING STRESSES AND THE PRONG TEST

ABSTRACT

From the time lumber is removed from the kiln to the time the remanufacturer uses it, it can be exposed to many different humidities With exposure to severe humidities, cupping in the final product can occur. This paper considers if humidity conditions during storage and transportation can significantly influence drying stresses and prong lest response. To determine the influence of exposure to different humidities, dried lumber was slowly equilibrated to 7,5% moisture content. It was than cut into blocks. The blocks were exposed to various humidity scenarios lo simulate actual storage and transportation conditions. Stress levels, moisture content and prong response were recorded. The analysis showed that stress level and prong response were strongly influenced by exposure to different humidities. The analysis also indicated that returning lumber to 7.5% equilibrium moisture content did not return the stress level or prong response to the original values. These combined results confirm that the prong test cannot be used as an indicator of how well the lumber has been dried or conditioned after it has been stored and transported. This makes seller/buyer disagreements difficult to resolve.     

糊料流变性对挤压成型的影响

通过糊料在压型嘴直筒区的流变性研究，论述了压型中麻面的产生原因，针对这些原因，提出了一些具体措施。     

INFLUENCE OF EXTRUSION COATING CONDITIONS ON STRUCTURE AND TENSILE PROPERTIES OF POLYETHYLENES

It is well known that the properties of a final polymer product are determined not only by the polymer characteristics but also, via process-related structural changes, by the processing technique and by processing conditions such as cooling rate and machine speed. In this study, the influence of the extrusion coating process on the structure and properties of LDPE-, LLDPE-, and m-LLDPE-grades was evaluated. Process variables such as the melt temperature, the draw ratio, the length of the air gap between the die exit, and the laminating nip and the machine speed were studied. The primary interest was in the influence of the process parameters on the degree of orientation and its corresponding impact on the tensile and barrier properties (water vapor transmission rate) of the polymer films. The degree of orientation of the films, assessed by shrinkage measurements, was found to be directly related to the elongational strain rate imposed on the films during the drawing stage of the coating process. Furthermore, the strain at break of the films in the machine direction correlated well with the shrinkage of the films, that is, the strain at break was strongly related to the imposed elongational strain rate. The relation is naturally also dependent on the polymer grade used and on how its rheological properties are affected by the process temperature. The melt temperature had a distinct influence on the water vapor transmission rate through the polymer films. This is discussed in terms of the orientation of the specimens.