Comparison Table and Application Analysis of High Density Polyethylene (HDPE) Grades and Melt Index (MI)
Table and application analysisOverview of HDPE materials
High Density Polyethylene (HDPE), as an important thermoplastic, occupies an important position in industrial production due to its excellent mechanical properties, chemical stability, and processability. The physical and chemical properties of HDPE are closely related to its molecular structure, and the melt index (MI), as a key indicator for measuring material flowability, directly affects the processing performance of the material and the quality performance of the final product.
The melt index refers to the mass of polymer melt flowing out through a specific diameter and length capillary tube under standard testing conditions within 10 minutes, measured in g/10 min. This indicator reflects the flowability of polymers in a molten state, with higher values indicating better flowability. In practical applications, different processing techniques have different requirements for the melt index of materials. Therefore, establishing a comprehensive grade melt index comparison system is of great significance for material selection and process optimization.
Analysis of Characteristics of HDPE Wire Drawing Grades
Wire drawing HDPE is mainly used in the production of various woven bags, ropes and other products. These applications require materials with moderate melt index and good tensile strength. From the data, the melt index of drawn HDPE is generally concentrated in the range of 0.6-1.0g/10min, which can ensure good flowability during processing and sufficient mechanical strength of the finished product.
As a typical representative of brushed HDPE, the 5000s grade has a melt index of 0.9g/10min, which has been verified through long-term practice and can effectively balance processing performance and product strength. Similarly, grades such as E308, 8010, and EE52009 also remain within this range, demonstrating the industry's consensus on this performance indicator. It is worth noting that the melt index range of 5410AA grade is slightly wider (0.9-1g/10min), which provides flexibility for parameter adjustment under specific process conditions.
Performance characteristics of HDPE injection molding grades
The injection molding process requires high material flowability, so the melt index of injection molded HDPE is significantly higher than that of brushed products. From the comparison table, it can be seen that the melt index of this type of brand is generally between 5-20g/10min, which can meet the filling requirements of complex molds.
2908 grade is used as the basic injection grade HDPE, with a melt index of 8g/10min, suitable for general injection molded products. The melting point of 2911 and 2911FS grades reaches 20g/10min, making them particularly suitable for producing thin-walled products or injection molded parts with complex structures. It is worth noting that the melt index of 5306J grade is 6.3g/10min, and that of 8008 grade is 8g/10min. These intermediate grades provide more choices for different injection molding processes. The melt index of 5218AA grade is 18g/10min, which is particularly suitable for injection molding applications that require rapid prototyping.
The hollow blow molding process of HDPE hollow grades is mainly used to produce various containers. This type of application requires high melt strength of the material, so the melt index of hollow HDPE is generally low. The data shows that the melt index of most hollow grades is between 0.05-0.7g/10min, and this low fluidity ensures good stability of the billet during the blow molding process.
The melt index of grades 541B and 4261A is only 0.05g/10min, making them particularly suitable for producing large hollow containers. The melt index of 5502AA and 5502FA grades is 0.2g/10min, making them ideal choices for medium-sized container production. It is worth noting that the melt index of HM6255 brand under 21.6kg testing conditions is 2.2g/10min, which is a special testing condition that is closer to the high-pressure working conditions in actual production. The melt index range of 6145 and 6147 grades is relatively wide (12-21 g/10 min and 7-14 g/10 min, respectively), and these high melt index hollow materials may be used for special hollow forming processes.
HDPE film grades application analysis
HDPE film grades require extremely low melt index to ensure the strength and uniformity of the film. From the data, the melt index of these grades is generally below 0.1g/10min, with some grades even as low as 0.04g/10min.
The melt index of 6098 grade is 0.08g/10min, which is a typical thin film grade HDPE. The melt index range of 7000F grade is 0.035-0.055g/10min, showing extremely high molecular weight and suitable for producing high-strength films. The melting point of TR144 grade is 0.16-0.22g/10min, slightly higher than typical film materials, and may be used for specific types of film products. The melt indices of HM9450F and HM9450F1 grades under 5kg testing conditions are 0.28g/10min and 0.22g/10min, respectively, which are closer to actual processing conditions.
Detailed explanation of special purpose HDPE grades
In addition to the conventional categories mentioned above, HDPE also includes multiple special purpose categories such as cable materials, pipe specific materials, cross-linked polyethylene, etc. Each type of product has its own unique melt finger requirements.
The melt index of cable materials such as 5300E and QHJ-01 grades is 0.8g/10min, which can ensure the extrusion molding of the insulation layer and sufficient electrical performance. Among the specialized materials for pipes, the melt index of 6360M grade is 0.22-0.3g/min, which is suitable for the production of pressure pipelines; The melt index of the 6380M grade is lower (0.13g/10min) and may be used for higher demand pipeline applications. The melt index of cross-linked polyethylene (PEX) such as P300X grade is extremely low (0.03-0.04g/10min), which is a special requirement of the cross-linking process.
In practical engineering applications, the selection of HDPE grades requires comprehensive consideration of multiple factors. Although the melt index is a key parameter, it still needs to be comprehensively evaluated in conjunction with the material's density, molecular weight distribution, additive system, and other characteristics.
For injection molding processes, it is common to choose grades with melt index within the range of 5-20g/10min, depending on the product wall thickness and structural complexity. Hollow blow molding should use grades with melt index below 1g/10min to ensure the stability of the billet. Thin film extrusion requires melting of ultra-high molecular weight materials with a melt index of less than 0.1g/10min. Pipeline applications should select specialized materials with melt fingers between 0.1-0.5g/10min based on pressure levels.
In addition, there may be differences in the melt index data of the same brand under different testing conditions, such as the test results under 5kg and 21.6kg load conditions. When referring to these data, engineering personnel should pay attention to the uniformity of testing conditions and conduct actual process validation if necessary.
