Studies on the Mechanical Properties and Uv-Accelerated Weathering of Ldpe with Benzophenone and Carboxy Methylated Starch

Abstract

LDPE of MFI 2 g/10 min was blended with carboxy methylated starch (CMS) at various proportions of 5–30% (wt.%), photo-degradable additive – benzophenone (3%) and glycerol (3%) as compatibilizer using a twin screw extruder. Tubular blown film was extruded using blown film extruder. LDPE with CMS was processable into sheets (>250 microns) in the temperature range 150 to 230°C. It was observed that higher the CMS content, lower the processing temperature range. All the formulations made using CMS were easy for processing though the MFI was decreased as the CMS starch content increased. The sheets obtained were of golden-yellow color with snakeskin appearance. The sheets obtained were tested for various mechanical tests like tensile strength, elongation at break and tear strength in both machine direction and transverse direction. The mechanical properties like tensile strength and elongation at break were lowered. Tear strength was lowered. Also accelerated UV weathering and compost biodegradation tests were done on all the samples. Scanning Electron Microscope images were taken before and after UV weathering to determine the morphological changes on the samples. As the starch content increased, the photodegradation time also increased, but very less when compared to pure LDPE. The samples were highly photo/ biodegradable and hence will not pollute the environment.