CAVALLO D.

The complete understanding of polymers crystallization kinetic in real industrial processes is fundamental for designing materials towards specific applications. Hereby, we propose a method for fast cooling preparation of polymers by means of air and water sprays, which presents several enhancements with respect to previous similar devices. The...

Crystallization of isotactic polypropylene (iPP) at the interface with crystalline films of two commercially employed nucleating agents (sodium benzoate (NaBz) and sodium 2,2'-methylene bis-(4,6-di-tert-butylphenyl)phosphate (NA-11)) and with a glass fiber (GF) was investigated using a polarized optical microscope. The analysis of the light...

A fast and easy-to-implement technique able to investigate the complex chemical composition of polyethylene/polypropylene (PE/PP) blends derived from recycling is required. Thermal fractionation, in particular the Successive Self-nucleation and Annealing (SSA) method, proves to be suitable for this purpose. Therefore, a new tailor-made SSA...

The self-nucleation behavior of a polybutene-1/ethylene random copolymer, P(B1-ran-E), which undergoes a complex crystal-crystal transition behavior, has been studied in detail. Similar to PE random copolymers, this material shows a strong melt memory effect even above equilibrium melting point of PB-1 homopolymer. Different polymorphic forms...

The sorting stage of mechanical recycling of post-consumer polyolefins has severe challenges. Polypropylene (PP) is often contaminated with polyethylene (PE) and vice versa. To meet quality requirements, characterization of the recycled pellets is needed. To address this problem, fast characterization generating a statistical assessment of the...

Fused filament fabricated (FFF) parts generally show anisotropic mechanical properties. Moreover, the anisotropy in FFF-printed parts varies with polymeric materials, depending on their characteristic relaxation and/or crystallization behavior. To acquire in-depth understanding of the mechanical anisotropy induced by the FFF technique, long...

Crystallization kinetics under processing-relevant cooling conditions of polyethylene/isotactic-polypropylene (PE/PP) blends, with compositions similar to real recycled blends, was investigated through an in situ temperature monitoring technique. Continuous Cooling Curve (CCC) diagrams in a large crystallization temperature range were obtained...

Biomedical applications of polymers require precise control of the solid-state structure, which is of particular interest for biodegradable copolymers. In this work, we evaluated the influence of crystallization conditions on the comonomer exclusion/inclusion balance of biodegradable poly(butylene succinate-ran-butylene adipate) (PBSA)...

Rheological measurements were carried out to in-situ monitor the re-entanglement process of large amplitude oscillatory shear flow (LAOS) modified partially disentangled isotactic polypropylene (i-PP) melt. The characteristic entanglement recovery time (τent) was essentially longer than the average reptation time (τD) of fully entangled melt....

Broadening the range of materials available to 3D print accurately and reliably via extrusion-based printing techniques is key to diversifying into advanced applications. One leading aim is to achieve higher temperature resistance from material-extrusion (MatEx) printed parts, whilst maintaining strength. To this end, several feedstock...

Cross-nucleation between different crystal polymorphs is a particular, self-seed assisted type of heterogeneous nucleation, where a fast-growing polymorph nucleates at a pre-existing crystal surface of another polymorph. Here, we present a study on cross-nucleation between different crystalline phases of poly(butylene 2,6-naphthalate) (PBN),...

The crystal transition from Form II to Form I of isotactic polybutene-1 (PB-1) occurs spontaneously and irreversibly when the polymer is stored at room temperature. The transition kinetics is influenced not only by the thermal history, but also by spatial confinement. In this study, the crystal transition of infiltrated PB-1 within 400 nm...

The existence of a "memory"of the previous crystalline state, which survives melting and enhances recrystallization kinetics by a self-nucleation process, is well-known in polymer crystallization studies. Despite being extensively investigated, since the early days of polymer crystallization studies, a complete understanding of melt memory...

Ternary biodegradable polymer blends of poly(lactic acid) (PLA), poly(butylene succinate) (PBS), and poly(ε-caprolactone) (PCL) with the composition 45/10/45 wt% and exhibiting partial-wetting morphology were prepared. In this morphology, the minor phase is present as self-assembled droplets at the co-continuous interface of the other two major...

Three semicrystalline polyesters, poly(lactic acid), poly(caprolactone) and poly(butylene succinate) (PLA, PCL and PBS) were melt blended to prepare binary and ternary systems of selected compositions. In binary blends with a sea-island morphology, each of the polymers is either the major or dispersed phase in the various samples. Analogously,...

The crystallization of heterogeneously nucleated bulk polymers typically occurs in a single exothermic process, within a narrow temperature range, i.e., a single exothermic peak is detected by differential scanning calorimetry when the material is cooled from the melt. However, when a bulk semicrystalline polymer is subdivided or dispersed into...

The effect of confinement on the crystallization, crystal orientation, and polymorphic crystal transition of bulk and infiltrated polybutene-1 (PB-1) within anodic aluminum oxide (AAO) templates were studied. After cooling from the melt, PB-1 within AAO templates crystallized into tetragonal Form II directly. The nucleation process inside the...

Usually, the nature of surface-induced nucleation in polymer blends is not easily disclosed. A novel approach for studying surface-induced crystallization in blends of semicrystalline polymers is proposed here. It consists of detecting variations in the crystallization kinetics of the dispersed phase with changing the crystalline state of the...

This work presents the first investigation on the crystallization behavior of partially wet droplets in immiscible ternary blends. Poly(lactide), poly(ϵ-caprolactone), and poly(butylene succinate) (PLA, PCL, and PBS, respectively) were melt blended in a 10/45/45 weight ratio to produce a "partial wetting" morphology with droplets of the PLA...