Biodegradable polymer blends based on polycaprolactone

Abstract

The new biodisintegrable and biodegradable polymer blends based on polycaprolactone(PCL) were developed. The PCL and the various styrene-based polymers including PS, MIPS, and SAN, were blended in order to obtain the useful biodegradable material with available physical properties. The blending of PCL with PS or MIPS caused the significant reduction in elongation at break when compared with that of PCL homopolymer. On the other hand the PCL/SAN blend showed the good elongational property which reflects the good toughness unlike PCL/PS and PCL/MIPS blends. This different behavior in the PCL/SAN blend is originated from the good compatibility between PCL and SAN, as confirmed by the intermediate single $T^g$ between the $T^g$ values of the two homopolymers. All of mechanical properties of the PCL/SAN blend including tensile modulus, tensile strength and elongation at break were varied linearly with the blend composition as found in the miscible polymer blend generally. The tensile modulus and the tensile strength were increased monotonically with the SAN content, while the elongation at break was decreased. The biodegradability of PCL/SAN blend was investigated by using composting method. The blend samples containing more than 50wt% PCL are continually biodegraded during the composting period, while the biodegradation of blend sample containing 25wt% PCL is nearly negligible even after composting for 3 months. Unlike the PCL homopolymer which is completely biodegradable, the PCL/SAN blend samples are significantly affected by the blocking of non-degradable SAN component during the biodegradation. It can be the origin of slow and negligible biodegradation of the CL25 sample containing 25wt% PCL. However, the CL75 sample with continuous PCL phase and the CL50 sample with co-continuous structure showed the good biodegradability in spite of the presence of SAN component due to their morphological characteristics. Moreover, the CL50 with the higher amorphous fracti...