Calcium carbonate-filled syndiotactic poly-(propylene) (CaCO 3 -filled s-PP) was prepared in a self-wiping, co-rotating twin-screw extruder. The effects of CaCO 3 of varying particle size (1.9, 2.8 and 10.5 m), content (0 -40 wt %), and type of surface modification (uncoated, stearic acidcoated, and paraffin-coated) on the crystallization and melting behavior, mechanical properties, and processability of CaCO 3 -filled s-PP were investigated. Non-isothermal crystallization studies indicate that CaCO 3 acts as a good nucleating agent for s-PP. The nucleating efficiency of CaCO 3 for s-PP was found to depend strongly on its purity, type of surface treatment, and average particle size. Tensile strength was found to decrease, while Young's modulus increased, with increasing CaCO 3 content. Both types of surface treatment on CaCO 3 particles reduced tensile strength and Young's modulus, but improved impact resistance. Scanning electron microscopy (SEM) observations of the fracture surfaces for selected CaCO 3 -filled s-PP samples revealed an improvement in CaCO 3 dispersion as a result of surface treatment. Finally, steady-state shear viscosity of CaCO 3 -filled s-PP was found to increase with increasing CaCO 3 content and decreasing particle size.

The present contribution reports, for the first time, the successful fabrication of α-chitin whisker-reinforced poly(vinyl alcohol) (PVA) nanocomposite nanofibres by electrospinning. The α-chitin whiskers were prepared from α-chitin flakes from shrimp shells by acid hydrolysis. The as-prepared chitin whiskers exhibited lengths in the range 231–969 nm and widths in the range 12–65 nm, with the average length and width being about 549 and 31 nm, respectively. Successful incorporation of the chitin whiskers within the as-spun PVA/chitin whisker nanocomposite nanofibres was verified by infrared spectroscopic and thermogravimetric methods. The incorporation of chitin whiskers within the as-spun nanocomposite fibre mats increased the Young’s modulus by about 4–8 times over that of the neat as-spun PVA fibre mat.

Recycled poly(ethylene terephthalate) from waste bottles (hereafter, rPET) was used as an reinforcing material for isotactic polypropylene (iPP) based on the concept of in situ microfibrillar-reinforced composites (iMFCs). Microfibers of rPET were successfully generated during melt-extrusion and subsequent drawing and preserved in the final injection-molded specimens. The effects of draw ratio, initial size of ground rPET flakes, and rPET content on morphological appearance of the extrudates and the as-formed rPET fibers and mechanical properties of the as-prepared iMFCs were investigated. The results showed that diameters of the asformed rPET fibers decreased with increasing draw ratio, and the initial size of ground rPET flakes did not affect the final diameters of the as-formed rPET fibers nor the mechanical properties of the as-prepared iMFCs. Flexural modulus, tensile modulus, and tensile strength of iPP/rPET iMFCs were improved by the presence of rPET microfibers and further improvement could be achieved by the addition of maleic anhydride-grafted iPP (PP-g-MA), which was used as the compatibilizer.

Electrospinning is a facile method for preparing nanocomposite materials in fiber form. Nanomaterials that have been incorporated within such fibers are usually inorganic in nature. Recently, nanocomposite nanofibers based on poly(vinyl alcohol) (PVA) as the matrix and nanocrystals of α-chitin (i.e. chitin whiskers; ca 31 nm in width and ca 549 nm in length on average) as the nanofiller have been successfully prepared. In the study reported here, the fibers were further investigated using X-ray diffraction (XRD) and dynamic mechanical analyses in comparison with the corresponding solvent-cast films. The average diameters of the PVA/chitin whiskers fibers ranged between 175 and 218 nm. Careful analysis of the wide-angle XRD patterns of the fiber mats and the films showed that PVA was partially crystalline, and the incorporation of the whiskers within the fibers was confirmed by peaks characteristic to α-chitin crystals. Dynamic mechanical analysis showed that the fiber mats were weaker than the films and that the relaxation temperatures associated with the glass transition (T g ) of the fiber mats were greater than those of the films. The addition and increasing the amount of the whiskers caused the crystallinity of PVA within the nanocomposite materials to decrease and T g to increase. The present study shows that the geometry of nanocomposite materials plays a major role in determining their properties.

This study examines the effect of poly(butylene adipate- co-terephthalate) (PBAT) content on the physical, morphological, and mechanical properties of poly(butylene succinate) (PBS)/PBAT foam. A compression molding technique was used to prepare the PBS/PBAT foam using the chemical blowing agent azodicarbonamide and the cross-linking agent dicumyl peroxide. The chemical structure and morphological properties of PBS/PBAT foam were examined via Fourier transform infrared and scanning electron microscopy techniques, respectively, whereas tensile and flexural properties were investigated using a universal testing machine. The results reveal that the incorporation of PBAT barely enhances the viscosity of the PBS/PBAT blend, producing only minor changes in the average cell size of PBS/PBAT foam. However, increasing the PBAT content contributes to a relatively significant improvement in the flexibility and toughness of PBS/PBAT foam, where a decrease in Young’s modulus and tensile strength of the PBS/PBAT foam is observed compared with those of the PBS foam. Similar behavior to the tensile results is noticed for the flexural properties of the neat and PBS/PBAT foams.