At present, the rubber toughening of plastics has become an attractive field of study in polymer science and technology because brittleness is known to be a drawback in many engineering plastics; it can cause premature failure during application. Among existing rubber materials, epoxidized natural rubber (ENR) has been widely used as an impact modifier or toughening agent in a large number of engineering plastics; in particular, it enhances the impact strength, which deteriorates with the incorporation of other additives, such as fillers and flame retardants. ENR is a modification product from natural rubber produced via an epoxidation reaction. ENR also has good chemical resistance. In this review, we aim to provide a concise current status in the field of ENR toughening agents for plastics with a brief discussion of their associated problems and potential applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42270.

A comparative study was performed on the use of esterified alkaline lignin (AAL) and esterified organosolv lignin (AOSL) as the interfacial modifying agent to improve the properties of polypropylene-chitosan composites. Chitosan was chemically modified through a reaction with the esterified lignin in an alcohol medium. The composites were prepared using an internal mixer and hot-pressed method. Both modified chitosan showed a different chemical structure upon modification with the esterified lignins as confirmed by Fourier transform infrared spectroscopy spectra. With a lower molecular weight, the AOSL attachment on the chitosan surface resulted in more efficiency in decreasing hydrophilic characters. Tensile tests showed the increased tensile strength by 32.15% and 26.43% for AOSL-modified composites and AAL-modified composites as compared with the unmodified composites. Overall, the AOSL was superior in improving the mechanical strength and thermal stability of the composites, while the AAL exhibited the most apparent enhancement in ductility and crystallization.

The effect of sodium dodecyl sulfate (SDS) on mechanical and thermal properties of chitosan-filled polypropylene (PP) composites was investigated. Mechanical and thermal properties of PP/chitosan composites were analyzed according to ASTM D 638-91, thermogravimetry analysis and differential scanning calorimetry, respectively. Results showed that the treated PP/chitosan composites had higher tensile strength and Young’s modulus when compared with untreated PP/chitosan composites, but lower in elongation at break in the same filler loading. Thermal analysis results showed that the thermal stability and degree of crystallinity of treated PP/chitosan composites were higher than untreated ones. Scanning electron microscopy and Fourier transform infrared studies revealed less detachment of filler from matrix on the tensile surface of treated PP/chitosan composites as an evidence of enhanced interfacial adhesion between filler and matrix due to the formation of covalent bonding between chitosan and SDS.