Can HDPE Be Injection Molded

HDPE is a highly crystalline, non-polar thermoplastic resin. The appearance of the original state HDPE is milky white, in the micro-thin cross-section of a certain degree of translucent. Tasteless, odorless, non-toxic columnar or flat round particles of this color, hardness, tensile strength, creep, abrasion resistance, chemical stability is good.

Physical and chemical properties

HDPE’s high crystallinity leads to its high density, tensile strength, high twisting temperature, viscosity and chemical stability.

HDPE is more resistant to permeation than PE-LD. HDPE has lower impact strength. the properties of PH-HD are mainly controlled by density and molecular weight distribution. HDPE suitable for injection molding has a narrow molecular weight distribution. For the density of 0.91~ 0.925g/cm3, we call it type I HDPE; for the density of 0.926~ 0.94g/cm3, we call it type II HDPE; for the density of 0.94~ 0.965g/cm3, we call it type III HDPE.

The material has good flow characteristics, with MFRs ranging from 0.1 to 28. The higher the molecular weight, the worse the flow characteristics of LDPE, but it has better impact strength.

LDPE is semi-crystalline and has a high shrinkage after molding, between 1.5% and 4%.

HDPE is susceptible to environmental stress cracking. Cracking can be mitigated by using materials with very low flow characteristics to reduce internal stresses. HDPE dissolves easily in hydrocarbon solvents when the temperature is above 60 C, but its resistance to dissolution is somewhat better than that of LDPE.