Mechanical and thermal characteristics of mulch film derived from linear low-density poly ethylene (LLDPE) with the addition of lignin or coconut coir powder.

Linear Low-Density Polyethylene (LLDPE) has good mechanical properties, translucent, flexible, waterproof, and easily processed into thin sheets. Therefore, LLDPE is suitable for mulch film production. However, besides having advantages, LLDPE-based mulch film has some disadvantages when applied in the field. LLDPE mulch is easily degraded due to sunlight ultraviolet (UV) radiation and is also difficult to decompose in the soil after it's used. The addition of lignin or coconut coir powder that has high lignin content was intended to improve LLDPE mulch properties regarding UV resistance properties and biodegradability. In this preliminary study, the mechanical and thermal properties ofLLDPE mulch by adding lignin and coconut coir powder with high lignin content were studied. The mulch was in form of a thin sheet plastic composite. LLDPE and lignin or coconut coir powder were compounded with rheomixer at a temperature of 120 °C, and a rotor speed of 80 rpm for 6 minutes. The proportion of lignin or coconut coir powder was 1%, 5%, and 9% of the total weight. Thereafter, the compound produced was hot-pressed into a thin sheet of plastic. The plastic sheet's mechanical properties were characterized using Universal Testing Machine and the thermal properties were analyzed using Differential Scanning Calorimeter. The addition of 9% coconut coir powder resulted in the highest modulus of elasticity and tensile strength values, which were 0.202 GPa and 16.91 MPa, respectively. Thermal analysis of LLDPE with the addition of lignin showed melting points that were close to LLDPE or lignin. The addition oflignin slightly changed the LLDPE melting point. The crystallization temperature (Tc) of LLl (lignin 1%), LLS (lignin 5%), and LL9 (lignin 9%) were not much different; 106.22°C, 106.22°C, and 105.66°C, respectively. The addition of 5% lignin or coir powder increases the crystallinity of LLDE film compared to the addition of 1% lignin or coir powder. However, the addition of9% lignin or 9% coir powder decreases the mulch film's crystallinity, due to higher lignin or coir powder content loading into LLDPE which prevents the crystallization of LLDPE. Based on thermogravimetry analysis, LLDPE+lignin 9% film is more thermally stable than LLDPE+coir 9% film. Moreover, the temperature processing of coir powder while blended with thermoplastic should be below 209°C to avoid thermal degradation of the coir powder. [ABSTRACT FROM AUTHOR]