Blending Alkatuff LLDPE, Alkamax Metallocene MLLDPE and Alkathene LDPE
Although the previous blog post (Grade Selection Of Polymer Grades For Film Extrusion) explored the differing film properties of polymer grades and how they can be combined to create the best possible results, some are better than others. This post will explore the compatibility of Alkatuff LLDPE, Alkamax Metallocene MLLDPE and Alkathene LDPE in greater detail to help with grade selection for film extrusion.
Alkatuff LLDPE, Alkamax mLLDPE and Alkathene LDPE are normally compatible. Linear-rich blends or LDPE- rich blends are widely used in film applications. Blends containing 40 – 60% LDPE are not so common.
The addition of LDPE to LLDPE or mLLDPE improves several properties, including processing and optical properties.
Such linear rich blends have rheological properties intermediate between those of the two polymers and their processing performance is modified sufficiently to improve the film processing with little loss in the desirable mechanical properties.
In particular, a small addition of LDPE to LLDPE makes the LLDPE less sensitive to disturbances and significantly decreases the tendency for bubble instability.
The blending of a small amount of LDPE into LLDPE also gives a considerable improvement to the gloss and haze of the film.
As would be expected, the properties of the linear-rich blends are modified slightly away from those of LLDPE or mLLDPE towards those of LDPE but generally, this is not a serious disadvantage. At the other end of the scale, small amounts of Alkatuff LLDPE or Alkamax mLLDPE (less than 40%) blended into Alkathene LDPE improve processability, with enhanced tensile properties, stiffness, puncture resistance and heat sealability which may allow the benefits of downgauging.
These are only some of the polymer grades that can be blended optimally and the next blog post will look into the blending of HDPE with LLDPE, Alkamax Metallocene MLLDPE and LDPE in more detail.