Plastics Industry and Engineering DCPD and PET Synthesis of Unsaturated Polyesters Liu Zhengping, Zhang Weimin, Dong Bingxiang (Department of Chemistry, Beijing Normal University, Beijing 100875, China). The synthesis of unsaturated polycondensation with dicyclopentadiene and polyethylene terephthalate waste was discussed. The method of ester resin: after alcoholysis of PET with glycol, maleic anhydride and DCPD are added, and the same amount of water as DCPD is added dropwise at 80-120 ° C, and other components are added after about 2.5 h of reaction. Esterification is carried out at elevated temperature until the reaction is complete. PET-timed, the content of DCPD affects the miscibility and curing process of unsaturated polyester with styrene. The unsaturated polyester resin synthesized by DCPD and PET is compared with the standard resin: good mechanical properties, good air-drying, environmental pollution, and good economic benefits. Polyethylene terephthalate (PET) is widely used in the production of polyester fibers, packaging containers, tapes and films. However, a large amount of waste is generated in the production process. For example, a medium-sized polyester fiber plant has more than one hundred tons of waste silk per year. If the polyester waste is subjected to alcoholysis instead of the unsaturated polyester portion, the glycol not only recovers the waste, but also can reduce the cost and performance of the unsaturated polyester resin (UPR), and has good economic and social benefits. . Zhelev et al. of Romania applied for the patent for synthetic UCR in rice in 1976, Rebeizf1, Castano, Vaidya, Xiang Fengqi, Wang Desheng 5 and Wang Yuantong and others used PET synthesis UPR. However, according to our experience, the preparation of UPR with PET has a common defect. The polyester has poor miscibility with styrene and is easy to stratify. In order to solve this problem, we used double cyclopentadiene (DCPD) modified UPR to explore the effect of DCPD content and process route on the properties of synthetic polyester. 1 Experimental part 1.1 Raw material maleic anhydride (MA): industrial grade, Tianjin Zhonghe Chemical Plant; transparent polyethylene terephthalate (PET): industrial grade, Yanshan resin plant; diethylene glycol (DEG): Industrial grade, Yanshan Petrochemical Company; Dicyclopentadiene (DCPD): Industrial grade, Anshan Chemical Plant No. 1; Ethylene glycol (EG): Industrial grade, Yanshan Petrochemical Company; Hydroquinone: Analytically pure, Beijing Beijiao Farm Chemical Plant; Styrene: Industrial Grade, Yanshan Petrochemical Company; Zinc Acetate: Analytical Pure, Beijing Organic Chemical Plant; Accelerator: 2% Cobalt Liquid Laboratory Self-made; Curing Agent: 50% methyl ethyl ketone peroxide (MEPO) ), industrial grade, Beijing 251 factory. 1.2 Instrument electronic automatic balance recorder: XQC-100 type, Beijing Automation Instrument Factory; Super constant temperature water tank: Shanghai Experimental Instrument Factory; Gel time measuring instrument: British import. 1.3 Determination of gel time and exothermic peak 0 g of cobalt solution was placed in a 25 C constant temperature water bath, and the gel time was measured by a gel time measuring instrument, and the exothermic peak temperature was simultaneously recorded by an electronic automatic balance recorder. 1.4 Performance test The air drying performance is characterized by curing speed (dry time and dry time), measured according to GB1728-79; the bending strength and tensile strength of the resin casting body are determined according to GB2570*81 and GB2568*81, respectively. The synthesis principle of 2UPR resin is carried out in three steps. First, the alcoholysis of PET is carried out under the action of hot glycol and catalyst. The PET is gradually degraded to form a lower molar mass of glycol and then the alcoholysis product. Addition reaction with maleic acid and DCPD, and finally alkyd by condensation reaction to form modified UPR. 3 Results and discussion 3.1 DCPD addition process route selection DCPD modified UPR synthesis method can be roughly divided into initial method, half Ester method, capping method and hydrolysis addition method. For the hydrolysis addition method, both the hydrolysis of maleic anhydride and the addition reaction of maleic acid and DCPD are both strong exothermic reactions. If maleic anhydride, DCPD and water are simultaneously put into the reactor for reaction, two strong exothermic reactions occur simultaneously, making the system temperature rise sharply difficult to control, and some DCPD may be decomposed into cyclopentadiene, and cyclopentane The diene can also be diene addition to maleic acid, consuming double bonds, resulting in a decrease in final resin activity. In order to solve this problem, we have adopted the method of first putting PET pellets, catalyst (zinc acetate) and diethylene glycol and part of ethylene glycol into a reactor equipped with a thermometer, a electric stirrer, a reflux condenser and a vent. In the heating, heating, high temperature reflux alcoholysis, when the PET is completely dissolved, continue to react for 1h. Cooling to 120C will be maleic acid*: Liu Zhengping, male, born in 1965, Ph.D., professor, has been engaged in polymer chemistry for many years. Work with physics majors, as well as environmentally friendly polymers and functional 19 polymer 1 and other research work has published the rest of the paper. PublishingHouse.Allrightsreserved.Anhydride and DCPD were added to the reactor. The same amount of water as DCPD was added dropwise at 80~120C for about 2.5h. Then the remaining ethylene glycol was added to gradually increase the temperature to carry out the polycondensation reaction. The maximum temperature was controlled at 210 * Within C, the column temperature does not exceed 103 * C. When the effluent reaches 2/3 of the theoretical effluent, the vacuum is forced to dilute a small amount of water, the acid value drops below 40 mg KOH / g, and the vacuum is stopped. Cool down to 180 to add hydroquinone, stir for 0.5h, continue to cool down to below 120 * C and styrene blending, blending temperature is controlled at 70 ~ 90 * C, and finally cooled, filtered, that is, the product. The effect of DCPD on the miscibility of polyester with styrene PET is a structurally symmetric linear polymer. The unsaturated polyester produced by it has a tendency to crystallize, has poor mutual solubility with styrene, and the resin is easy to mix in the pool. . End-blocking with DCPD destroys the symmetry of the molecular structure of the polyester and reduces the crystallization ability of the polyester. On the other hand, the structure of DCPD is similar to that of styrene. Both factors contribute to the miscibility of the PET-synthesized unsaturated polyester with styrene. The effect of DCPD on the mutual solubility of polyester and styrene is shown in Table 1. It can be seen from Table 1 that when the mole fraction of DCPD is more than 5.4%, the polyester can be completely miscible with styrene, solving the delamination problem. Table 1 Effect of DCPD on the miscibility of unsaturated polyester with styrene! A 4 appearance layer layer slightly mixed, transparent and soluble, the effect of transparent DCPD dosage on the curing of the resin is the effect of the amount of DCPD on the gel time and curing exotherm peak of the unsaturated polyester. It can be seen that when the mole fraction of DCPD is greater than 15%, the amount of DCPD has affected the gel time and exothermic peak of the resin. This is obviously due to the excessive amount of DCPD, which is decomposed into cyclopentadiene during the late heating process, while the impurities such as olefins in cyclopentadiene and DCPD can be combined with the unsaturated double bonds in the polyester molecular chain. As a result of the reaction, the unsaturated double bonds of the polyester are reduced, the activity is lowered, and the curing is slowed down. 5 and 191UPR performance comparison The performance of UP*5 and 191UPR is shown in Table 2~3. As can be seen from Table 2, UP*5 has many excellent properties compared with general-purpose UPR, such as mechanical properties and air drying. These excellent properties are related to the structure of the polyester. Under the experimental conditions, the introduction of DCPD adds the number of double bonds per unit molecular chain, so that the end groups of most polyester molecular chains contain double bonds, polymerize, and form a faster surface. The film prevents the UPR from being inhibited by oxygen. The introduction of DCPD adds the density of the rigid ring, which improves the physical properties of the polyester. The capping of the polyester by DCPD greatly reduces the carboxyl group and hydroxyl group of the terminal hydrophilic group, and the steric hindrance of the terminal group after introduction into DCPD is large, so that the ester group on the terminal group is protected; the performance of the benzene type UPR is better than the adjacent benzene type. The performance of UPR is excellent, so the polyester prepared using DCPD and PET has improved chemical stability. Dry time 1 dry time / h 1) UP-5 without paraffin, 191UPR plus paraffin. Table 3 Comparison of Mechanical Properties of UPR Castings Bending Strength / MPa Tensile Strength / MPa Barcol Hardness 匕 1) 5 5 Conclusions (1) A reasonable route for preparing unsaturated polyesters with DCPD and PET is: PET first in the reactor The same part of the diol is subjected to high-temperature alcoholysis, then maleic anhydride and DCPD are added to the reactor, and the same amount of water as DCPD is added dropwise at 80-120 ° C for reaction, so that the alcoholysis product is The dilution is beneficial to absorb the heat of maleic anhydride hydrolysis and the reaction of maleic acid and DCPD addition reaction; then the remaining glycol is added and the esterification is carried out until the reaction is complete. (2) The DCPD content directly affects the miscibility and curing properties of unsaturated polyesters with styrene. When the DCPD mole fraction is greater than 5.4%, the polyester is completely miscible with styrene, which solves the delamination problem; when the DCPD mole fraction is more than 15%, the curing process of the unsaturated polyester is affected. (Continued on page 12) becomes the active point 1 under the action of the initiator, a double bond of 3 points is hitting the Ashing skeleton vibration peak. In the infrared spectrum of PDLLA, there is a 2 996 cm CH3 stretching vibration peak, and there are no absorption peaks at two points, which proves that the lactide ring structure disappears and the conversion rate is high. 3 Conclusions In this experiment, the lactic acid was dimerized into DL-LA.SnCk.2 with a stepwise heating and stage decompression dehydration method. The catalytic vacuum was 0.66 kPa, and DL-LA was distilled off. The solvent was recrystallized three times with methanol as solvent. It can reach 126 yield of 21.7% DL-LA ring-opening polymerization. The effect of Sn(Oct) catalyst is better than that of SnCV2H2. Different molar masses of PDLLA can be synthesized by different processes. The weight average molar mass can reach more than 100,000. Emf Bed Canopy,Square Type Canopy,Emf Shielding Canopy,Emf Shield Canopy Shandong EMF New Material Technology Co., Ltd , https://www.earthingsilver.com