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In the recent few years, fused filament fabrication technique have seen extensively used to produce complex‐geometry objects. However, the relatively restricted range of 3D printable biocomposites decelerated its adoption in the biomedical sector as a conventional manufacturing technique. In this method, the introduction of biofillers with unique properties to produce high performance composites as printing feedstocks are increasingly recommended. The interest in using eco‐friendly fillers from waste as reinforcing agents for producing lightweight and low‐cost poly(lactic acid) (PLA) composites is recently increased. In this work, a series of PLA biocomposites filled with calcined seashell (CSh) particles have been prepared by melt mixing technique using a twin‐screw extruder, and characterized by different morphological, thermal, and mechanical methods. The visco‐elastic parameters have been determined for these biocomposites to optimize their processing conditions. The morphological analysis revealed a homogenous dispersion of CSh fillers within the biopolymeric matrix, which was responsible for the enhancement of the various mechanical properties. Where, by adding 10 wt% of treated CSh, the tensile modulus and strength were significantly increased from 183.8 ± 4.7 MPa and 29.81 ± 1.8 MPa to 241.9 ± 63 MPa and 49.06 ± 8.87 MPa, respectively, compared to the virgin PLA. In addition, respected to PLA matrix, the compressive moduli of the printed specimens of PLA/5CSh and PLA/10CSh biocomposite filaments exhibited improvements of 5% and 14%, respectively. Moreover, the thermal analysis showed a marked improvement in the thermal stability of the elaborated biocomposites, where the degradation temperature (Td50) have been upgraded by 4°C for the biocomposite containing 10 wt% of CSh bio‐filler. These outstanding properties of PLA/CSh composites make them very suitable for 3D printing applications in the biomedical field. [ABSTRACT FROM AUTHOR]

Implanting scaffolds designed for the regeneration or the replacement of bone tissue damaged by diseases and injuries requires specially designed biomaterials that promote cell adhesion. However, the biodegradation rate of these scaffolds based on a single material is uniform. Fourdimensional printing appears to be a promising method to control this aspect by changing the shape and/or the intrinsic properties of 3D-printed objects under the influence of external stimuli. Two main classes of biomaterials and biocomposites based on biopolyesters, namely poly(lactic acid) (PLA) and poly(caprolactone) (PCL), were used in this study. Each of them was mixed with the inorganic filler hydroxyapatite (HA), which is a component of natural bone. The biocomposites and biomaterials were prepared using the melt extrusion process and then shaped using a 3D printer. Three-dimensional specimens showed a decrease in elongation at break and breaking strain due to variations of crystallinity. The crystallinity of irradiated samples increased slightly with irradiation and a new crystalline phase was observed in the case of the PLA. Four-dimensional printing of biomaterials using electron radiation shows great promise for bone tissue engineering based on biocomposite scaffolds and other medical applications. [ABSTRACT FROM AUTHOR]

This study aimed at assessing and optimizing the influence of printing speed and extrusion temperature in a fused filament fabrication (FFF) process on the tensile properties of a polylactide/layered silicate nanocomposite. Mathematical models using Doehlert designs were formulated to examine factor and interaction effects. The models were corroborated by measurements using capillary rheology, tomographic images, and crystallinity analyses to find physical explanations for the differences in tensile properties. The tensile properties were a non‐monotonic function of printing speed, which may be due to various deposition defects that influence the porosity of composite tensile specimens. This study provides new insights into FFF process optimization regarding rheological behavior and mesostructure of nanocomposite by highlighting new modes of deposition defects that originate from process parameter settings and materials. The results contribute to the properties mastery of FFF‐processed materials. [ABSTRACT FROM AUTHOR]

ABSTRACT The fundamental rheological properties of a wide molar mass Mw range of poly(butylene succinate)s (PBSs) are investigated. For entangled samples and a reference temperature of 140°C, the shear viscosity is described by the Carreau-Yasuda model. The plateau modulus is estimated at 1.5 × 105 Pa, the average activation energy of PBS melt is [ABSTRACT FROM AUTHOR]

ABSTRACT The synthesis of poly(butylene succinate) (PBS) of Mw ranging from 4000 to 180,000 g mol−1 is realized with molar ratios [COOH]0/[OH]0 of 1 and 0.98, and varying amounts of titanium (IV) tetrabutoxide (TBT) catalyst. Polycondensation kinetics are followed by chemical titration of carboxylic groups, and the kinetic rate constants of self-catalyzed and external-catalyzed reactions are calculated. The synthesis of PBS with high molar mass follows the classical Flory theory. The effect of molar mass on PBS thermal properties is also studied. A faster crystallization rate and a higher temperature of crystallization are observed, for very high molar masses. This behavior could be due to a memory effect of the polymer. Complex melting behavior of PBS is induced by a continuous reorganization of the crystalline phase, as observed by MTDSC. DSC measurements also reveal that the crystallinity-and so the amorphous phase-is limited to about 35% when the molar mass Mn is higher than 40,000 g mol−1. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40639. [ABSTRACT FROM AUTHOR]

Polypropylene clay fibres loaded with different alkylammonium-modified montmorillonite were prepared using a melt spinning technique and relationships between the structure and properties of the nanopolypropylene fibres are discussed. Experiments carried out using transmission electron microscopy showed that the chemical structure of the organic modifier and the interlayer spacing of the clay induced different dispersions of the clay, thus improving accessibility of the nano fibre. It is known that nanoclays are effective and efficient sorbents for dyes. Therefore, the dyeing behaviour of the nano polypropylene fibres with two distinct acid dyes and a disperse dye was studied and the build-up of dyes, measured as colour yield, reported. The best results were obtained when the clay was well dispersed in nanopolypropylene fibres; that is, when maleated polypropylene was added as a compatibiliser and when disperse dye was used. Good wash fastness was then obtained. [ABSTRACT FROM AUTHOR]

Two procedures for incorporating low levels of poly(dimethylsiloxane) (PDMS) in polyurethane (PU) have been studied. The bulk synthesis of poly(siloxane-urethane) was performed in two steps: the first involves the formation of a prepolymer between isophorone diisocyanate (IPDI) and poly(tetramethylene oxide) (PTMO). In the second step 1,4-butanediol (BD) was added as the chain extender. A kinetic study followed by infrared spectroscopy showed the higher reactivity of PDMS compared to PTMO. Thus, two procedures for incorporating PDMS are described, depending on whether the poly(dimethylsiloxane) was introduced in the first or in the second step. Films were made from these formulations, and we studied their morphology. The products obtained from each procedure were characterized by size-exclusion chromatography (SEC), differential scanning calorimetry (DSC), dynamic thermomechanical analysis (DMTA) and uniaxial tensile testing, and showed significant differences. These poly(siloxane-urethane) polymers are intended to be used as hydrophobic coated formulations on polyester fabrics in a further study. [ABSTRACT FROM AUTHOR]

Presents a study which examined the flame behavior of cotton coated with polyurethane containing microencapsulated flame retardant agent. Information on the microencapsulation of ammonium phosphates to create fire retardant textiles; Experimental work; Results and discussion.

Crude rapeseed cake was employed as the starting material for the preparation of protein-based bioplastic films through a wet process. A simple exposure of the agricultural waste to formic acid realized at 40 °C for 15 min could afford a slurry ready for producing robust bioplastic films by casting without another plasticizer addition. After determining the optimal process conditions, all films and membranes were successively characterized by DSC and FT-IR spectroscopy. They were also tested for their water absorption capacity, tensile strength, and elongation at break performance. The respective surface morphology and elementary composition of the products were determined by FE-SEM/EDX. Some attempts to improve their intrinsic properties were performed by loading graphene oxide inside the biopolymer three-dimensional matrix. [ABSTRACT FROM AUTHOR]