Stratiform β crystals in ultrahigh molecular weight polyethylene and β-nucleating agent-nucleated isotactic polypropylene at micro-injection molding condition

Structure evolution and orientation mechanism of isotactic polypropylene during the two‐stage solid die drawing process

“…Thus, TD samples gain a more uniform orientation structure than SD samples at Section II, as shown in Figure with pictures for TD‐B 2 . However, for SD process, samples endure constant shear stress at skin layer close to the die forming typical skin–core structure with the core layer having sufficient time to relax under lower cooling rate while the skin layer being composed of high oriented structure owing to high shear stress and rapid solidifying rate, similar to microinjection process, thus forming an structure with high orientation skin layer and less orientation core layer at Section II, as shown in SD‐B 2 in Figure . Both of the two types of samples then experience the same cooling condition outside the die when drawn at the same speed.…”

Influence of Different Copolymer Based Compatibilizers on Performance of Pristine and Recycled PP/PE blends

“…This is probably because MB4 is mainly based on a PE resin. XRD diffractograms of all virgin samples exhibit the characteristic diffraction peaks of the α-phase of PP (2θ of 14.2 (110), 17.1 (040), 18.6 (130)), and also the characteristic crystalline peaks of orthorhombic crystals of LLDPE (2θ of 21.4 (110) and 23.7 (200)) [30,31]. It is clear from patterns evaluation that compatibilizers do not affect crystalline structure of constituents, as it was previously reported by other authors for polyethylene-polypropylene blends [1,15].…”

Structure evolution and orientation mechanism of long-chain-branched poly (lactic acid) in the process of solid die drawing

“…12. At Portion B, an obvious "sandwich" structure can be observed for both PLA and LCB-PLA, which showed the highly oriented fibrous morphology in the skin layer and relative low oriented structures in the core layer [17,18]. When samples went through the convergent die with a constant speed, the velocity was zero at the die wall, which was much slower than that at the center, and thus samples near the surface was stretched by the shear stress while the part of the sample near the center was compressed, resulting in oriented skin layer and isotropic core layer.…”