Application 应用
ASTM D789-98标准提供了一个测量聚酰胺/尼龙铸造模粉粘度的标准方法。聚酰胺的分子量越大，也就意味着尼龙的分子链越长，其在所选用溶剂里的一定浓度下的粘度就越大。对于固体制模产品来讲，大的分子量比小的分子量具有更大的强度和韧度。因此，如果一种物质在一定浓度下的溶液具有特定的粘度，那么就可以通过测量粘度来预测制模材料中与之有关的其它性能例如韧度。
ASTM D 789-98provides an official, standardized procedure for testing polyamideor nylon molding powders. The higher the molecular weight of thepolyamide - that is, the longer the nylon molecules - the higherthe viscosity will be at a given concentration in the selectedsolvent. The larger molecules also contribute more significantly tostrength and toughness in the solid molded product compared to theshorter molecules. Therefore, if a material at a specifiedconcentration in solution gives a particular viscosity, then thatmaterial will most likely give molded products having correlatingproperties such as a related level of toughness.
RequiredEquipment仪器
在这个测量方法中我们建议采用BrookfieldLVT 度盘粘度计。样品用8盎司的圆形、宽口有螺纹的瓶子盛装，并放在BrookfieldTC-501D恒温水浴里。为了更快速地进行测量和减少实验误差，也可以采用Brookfield其它型号的粘度计，例如 LVDV-E, LVDV-I+ 和LVDV-II+粘度计。
TheBrookfield LVT Dial Reading Viscometer is thespecified instrument in this method. The sample is contained in an8 ounce round, wide-mouth screw-cap bottle immersed in a BrookfieldTC-501D Circulating Bath. Thistest can also be performed with other Brookfield Viscometers, suchas the LVDV-E, LVDV-I+ and LVDV-II+ in order to save time andminimize error.
TestMethod测量方法
先将粉末溶解在甲酸或M-甲酚里。样品的温度恒定在25±0.1℃。聚酰胺溶液的粘度与在一定转速下对应使用的转子号见下表：
The powder isdissolved in either formic acid or m-cresol. The sample temperatureis maintained at25±0.1℃. The expected viscosities of polyamide solutions and the corresponding spindles at the specified speeds are shown below:
Spindle # for Given Speed in rpm 各转速下的转子编号 |
BVs | 60 rpm | 30 rpm | 12 rpm |
9-100 | 1 | | |
100-200 | | 1 | |
200-500 | 2 | | 1 |
这里“BVs”是指溶液的"Brookfield粘
度(单位为cP或mPa·s)：
Factor at Given Speed in rpm 各转速下对应的因子 |
转子 | 12 rpm | 30 rpm | 60 rpm |
LV1 | 5 | 2 | 1 |
LV2 | 25 | 10 | 5 |
LV3 | 100 | 40 | 20 |
LV4 | 500 | 200 | 100 |
用从表盘上的扭矩读数乘以右表上相应
的因子，就是粘度值，单位为cP：
The torque reading fromthe dial is multiplied
by the appropriate factor from thefollowing
table to provide the viscosity reading incP:
Options可选测量方法
用Brookfield数显式粘度计可以直接读出粘度值，不需要读扭矩值和使用因子表来计算粘度值。
TheBrookfield Digital Viscometers mentioned above provide theviscosity reading in cP directly, so that the user does not need toread %Torque and use the factor tables.