Effects of Screw Configurations on the Grafting of Maleic Anhydride II
Materials
Low-density polyethylene [LDPE; LD-100, melt flow index 5 2.0 g/10 min(1908C, 2.16 kg)] was supplied by ChinaSINOPEC Beijing Yanshan Chemical Co.(Beijing, China) Dicumyl peroxide, obtained from Shanghai Chemical Reagent Co. (China Pharmacy Group, Shanghai, China), was recrystallized twice from absolute alcohol before use. MA, xylene, and acetone were provided by Beijing Yili Fine Chemical Co., Ltd. (Beijing, China) Polycarbonate [PC; PC-110, melt flow index 5 10 g/10 min (3008C, 1.2 kg)] and acrylonitrile butadiene styrene [ABS; PA-747S, melt flow index 5 0.7 g/10 min (2008C, 5 kg)] were pur- chased from Chi Mei Corp. (Zhenjiang, China)
Screw configurations and barrel
In this study, four groups of extrusion experiments were performed in a laboratory modular Leistritz LSM 30.34 intermeshing, corotating twin screw extruder (Nuremberg, Germany). The screw diameter was 34 mm, the distance between the two screw axes was 30 mm, and the active barrel length was 870 mm (length/diameter 5 25.6). These four groups of extrusion processes were designated ExI, ExII, ExIII, and ExIV. These experiments were designed to evaluate the grafting degree (GD) of maleic anhydride grafted low-density polyethylene (LDPE-g-MA) during the reactive extrusion, the degree of fill along the screw channel, the RTD, and the mixing performance of the screw configurations. In each group of experiments, seven screw configurations were investigated. Their differences were only in the kneading block zone .The geometry parameters of the kneading blocks in the KB zone are listed in detail. The screw configura tions are named on the basis of the kneading block used in the KB zone. Screws KB30, KB60, KB90, KB120, and KB150 had kneading blocks with different staggering angles, whereas the kneading discs in screw configurations KB90-2 and KB90-4 were wider than the others. The barrel in ExI, ExIII, and ExIV comprised five modular barrel sections and three online sampling instruments. A clam-shell barrel was used in ExII, which allowed the quick quenching of the polymer melt along the screw channel. A solidi fied carcass was used to measure the degree of fill along the screw channel and the polymer melting endpoint.
The circular aperture in the barrel wall allowed the flow of the melt out of the extruder. Through the rotation of the valve, the circular aperture could be switched conveniently. In the process of online sampling, the valve was first turned on, and when enough material was collected, the valve was turned off, and then the collecting pot was pulled out. The sample was removed and quenched for subsequent analysis. Generally, it took 3–5s to sample about 3 g of the polymer melt; this depended on the flow rate and degree of fill.
Low-density polyethylene [LDPE; LD-100, melt flow index 5 2.0 g/10 min(1908C, 2.16 kg)] was supplied by ChinaSINOPEC Beijing Yanshan Chemical Co.(Beijing, China) Dicumyl peroxide, obtained from Shanghai Chemical Reagent Co. (China Pharmacy Group, Shanghai, China), was recrystallized twice from absolute alcohol before use. MA, xylene, and acetone were provided by Beijing Yili Fine Chemical Co., Ltd. (Beijing, China) Polycarbonate [PC; PC-110, melt flow index 5 10 g/10 min (3008C, 1.2 kg)] and acrylonitrile butadiene styrene [ABS; PA-747S, melt flow index 5 0.7 g/10 min (2008C, 5 kg)] were pur- chased from Chi Mei Corp. (Zhenjiang, China)
Screw configurations and barrel
In this study, four groups of extrusion experiments were performed in a laboratory modular Leistritz LSM 30.34 intermeshing, corotating twin screw extruder (Nuremberg, Germany). The screw diameter was 34 mm, the distance between the two screw axes was 30 mm, and the active barrel length was 870 mm (length/diameter 5 25.6). These four groups of extrusion processes were designated ExI, ExII, ExIII, and ExIV. These experiments were designed to evaluate the grafting degree (GD) of maleic anhydride grafted low-density polyethylene (LDPE-g-MA) during the reactive extrusion, the degree of fill along the screw channel, the RTD, and the mixing performance of the screw configurations. In each group of experiments, seven screw configurations were investigated. Their differences were only in the kneading block zone .The geometry parameters of the kneading blocks in the KB zone are listed in detail. The screw configura tions are named on the basis of the kneading block used in the KB zone. Screws KB30, KB60, KB90, KB120, and KB150 had kneading blocks with different staggering angles, whereas the kneading discs in screw configurations KB90-2 and KB90-4 were wider than the others. The barrel in ExI, ExIII, and ExIV comprised five modular barrel sections and three online sampling instruments. A clam-shell barrel was used in ExII, which allowed the quick quenching of the polymer melt along the screw channel. A solidi fied carcass was used to measure the degree of fill along the screw channel and the polymer melting endpoint.
The circular aperture in the barrel wall allowed the flow of the melt out of the extruder. Through the rotation of the valve, the circular aperture could be switched conveniently. In the process of online sampling, the valve was first turned on, and when enough material was collected, the valve was turned off, and then the collecting pot was pulled out. The sample was removed and quenched for subsequent analysis. Generally, it took 3–5s to sample about 3 g of the polymer melt; this depended on the flow rate and degree of fill.
