polymerguru

Today's KNOWLEDGE Share Historically, early injection molding machines would essentially be pressure controlled. Many good parts have been made under such process control. So, it is not all bad ! However, note that when molding an end-gated fairly long part, a constant pressure fill translates into an ever decreasing melt front velocity, as the pressure drop builds up. This in turns corresponds to a decreasing average temperature of the melt front along the flow. Such a decreasing T will create an increasingly strong degree of molecular orientation when moving away from the gate. The part, especially when using semi-crystalline grades, will have a strong gradient of mechanical properties along the flow which could be as serious as showing good ductility near the gate and severe brittleness far from the gate. source:Vito leo #injectionmolding #polymers

Today's KNOWLEDGE Share Understanding the Differences Between PEKK, and PEEK Materials: PEKK and PEEK are both in the Polyaryletherketone family of ultra-high performance polymers.  Unlike PEEK, PEKK is a copolymer with a slower and highly tunable crystallization rate making it the preferred choice for additive manufacturing. PEKK can be printed directly in either the amorphous or semi-crystalline state, or printed amorphous and crystalline in a secondary process, offering the ultimate combination in performance and processing flexibility.     CHEMICAL COMPOSITION AND STRUCTURE PEKK (Polyetherketoneketone): Structure: PEKK consists of ether (O) and ketone (C=O) linkages,with two ketone groups in the repeating unit. This structure provides high thermal stability and chemical resistance, making PEKK ideal for demanding environments. PEAK (Polyetherketone): Often confused with PEKK, PEAK is a general term referring to various types of polyetherketones. It includes polym...