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Vinylidene chloride - vinyl chloride suspension copolymerized resin Synthesis and Characterization

Author: YuanZhu
Tutor: HuangZhiMing；DanGuoRong
School: Zhejiang University
Course: Chemical processes
Keywords: VDC-VC suspension copolymerization Crystalline properties Processing performance
CLC: TQ325.12
Type: Master's thesis
Year: 2002
Downloads: 80
Quote: 4
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Abstract

Vinylidene chloride (VDC) - vinyl chloride (VC) the suspension copolymerization resin excellent barrier properties to oxygen, water vapor and other widely used in the packaging industry, domestic currently dependent on imports. Article suspended to the better performance of the synthesis processing VDC-VC copolymer resin as the goal, after the analysis of the sample at home and abroad, a clear resin structure parameters, the design of the process recipe and copolymerization was carried out to study the synthesis process - molecular structure - the relationship between the processing performance, processing performance optimization process recipe better VDC-VC suspension copolymer resins, which laid the foundation for the expansion of trials in the resins. Parsing abroad sample found: The resin having a number average molecular weight of 30000 to 42000, a weight average molecular weight of 85,000 to 100,000, a molecular weight distribution index of between 2.3 to 2.7; the intrinsic viscosity of the resin - in tetrahydrofuran (1%) solution at 25 ° C for 46 ~ 50ml / g. The domestic sample the the VC monomer unit quality content is higher than 11% the Dow and Wuyu sample of 8 to 10%, only 5% of samples Bilishi. Abroad sample weight average particle diameter is between 150 ~ 240μm, a narrow distribution, spherical shape. The degree of crystallinity of the resin Bilishi for up to 43.7%, and the remaining 33 to 37%. Rheological curve of the resin HAAKE maximum torque at 50 nm or less, the balance torque at about 5Nm. Wuyu resin contains 4.5 to 8.3% of acetyl tributyl citrate (ATBC) plasticizer. Reference to foreign resin performance, design process recipe and VDCNC suspension copolymerization the copolymerization of law: As the the VC feeding ratio increases, the final conversion rate decreased and the molecular weight of the resin. Before polymerization the ESO or ATBC on the conversion rate, molecular weight and distribution, particle size and distribution. For Variable stirring process, the initial rotational speed of 300r/min, the largest size, the widest distribution; average particle diameter of the resin with the composite dispersant K proportion increases, the particle size distribution is also increased substantially, resin particles spherical; water to oil ratio increases, the particle diameter becomes small, the distribution becomes narrower. The optimized polymerization process Formulations: VDC / VC 79/21 (weight ratio), the initiator issue of EHP (40% water emulsion) used in an amount of 6g/kg monomer the composite dispersing Homogeneous A, K of each 0.3g/kg single body, the water-oil ratio is 1.5 to 2, and the polymerization temperature at 31 to 55 ° C for continuous heating, predispersed stirring speed 350r/min, the polymerization speed of 300r/min. Small test VDC-VC copolymer prepared characterize studied synthesis process - molecular structure - the relationship between the resin properties, the results show: With the resin copolymerization composition of the of VC monomer unit content increases, the low temperature of the melting curve peak area increases, the decrease in the high-temperature peak area, until it disappears; while the low-temperature peak and the high-temperature peak temperatures are reduced, the degree of crystallinity of the resin is also reduced. The addition of processing aids, and the high-temperature peak and the low temperature peak temperature of the resin is also reduced. Flory's melting point decline theory predicts that the decline in the melting point of the copolymer with copolymer composition and processing aids the dosage changes tomb this law, the forecast is consistent with the experimental results. Resin HAAKE rheological curve maximum torque and balance torque is reduced with the resin the VC monomer unit content increased, Zhejiang University, a master's degree thesis with the molecular weight increases with the increase. Plus help DWh agent can experience the maximum torque of the resin and the balance torque and improve the processing performance. Processing aids ESO can increase the resin is thermally stable offerings.

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