Characteristics of Bio Thermoplastic Composite Pellets Based on Modified Cassava Starch and Glucomannan in Variations of Synthetic Polymers

Abstract

The research aims to determine the appropriate type and concentration of synthetic polymers in production of biothermoplastic composite pellets from modified cassava starch and glucomannan (BTC-MCS/GM). This research used a factorial randomized block design experiment. Factor 1: type of synthetic polymer consisting of PCL (polycaprolactone), PLA (poly lactic acid), PE (polyethylene), and PP (polypropylene) while factor 2: concentration of synthetic polymer with levels of 40, 50, 60% w/w, thus there are 12 treatment combinations grouped into 3 pellet making process times, so there are 36 experimental units. The data obtained were analyzed for diversity and continued with the Duncan test. Variables measured were tensile strength, elongation at break, Young’s modulus, density, water vapor transfer rate (WVTR), oxygen transfer rate (O₂TR), swelling, melting point/temperature (Tm), melt flow rate (MFR), crystallinity and time biodegradation, surface profile, and functional groups. The research results show that the type and concentration of synthetic polymer have a very significant effect on the average tensile strength, elongation at break, Young’s modulus, density, WVTR, O₂TR, swelling, Tm, MFR, crystallinity, and biodegradation time of BTC-MCS/GM pellets.  BTC-MCS/GM pellets that use PCL, PLA, PE, and PP almost all meet SNI 7818:2014 and international standards. However, the best is BTC-MCS/GM pellets using PLA (BTC-MCS/GM/PLA) with characteristics of tensile strength 23.56 MPa, elongation at break 7.18%, Young's modulus 1548.34 MPa, density 1.22 g/ml, WVTR 179.76 g/m².day, O₂TR 199.67 ml/m².day, swelling 120.58%, Tm 152.47^oC, MFR 0.62 g/10 minutes, crystallinity 0.62%, biodegradation time 11.67 days. The longitudinal surface profile of the BTC-MCS/GM/PLA pellets shows smooth spots that are evenly distributed on all surfaces, while the transverse surface profile shows the presence of small, regular wavy lumps. BTC-MCS/GM/PLA pellets contain OH alcohol functional groups at wave numbers of 2144.94, 2884.67, 3100.7, 3283.95, 3601.25 cm^-1, C=C (alkyne) at wave numbers of 1937.58 cm^-1, C=O at wave number of 1719.61cm^-1, C=C at wave number of 1663.68 cm^-1, C=C (aromatic rings) at wave number of 1553.73 cm^-1, C-O at wave number of 1052.21, 1112.97 and 1248 cm^-1, C-H at wave number of 707.91 and 923.94 cm^-1, (CH₂)n at wave number of 380.96 and 453.29 cm^-1. Thus, it has great potential to be used as raw material for ecofriendly bags.