On the influencing factors of the transparency of

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Influencing factors on the transparency of PVC profiles for packaging (Part 1)

Abstract: Aiming at the problems of "fish eyes" and decreased light transmittance of transparent PVC profiles for packaging, the rheological behavior, relative molecular weight, thermal stability and gel degree of SG8 PVC resin were studied. The results showed that the relative molecular weight and its distribution of SG8 PVC resin in each batch were different. The rheological behavior is significantly different; The gel degree of 07 profile sample is 10% - 17% higher than that of 22 profile sample. Therefore. The dispersion of relative molecular weight of SG8 resin is the main reason affecting the transparency of profile

key words: transparency of PVC profiles

polyvinyl chloride (PVC) has developed rapidly because of its low production cost, wide application fields and excellent performance. At present, the world PVC production capacity has reached about 2.5 MT/A. In the past two years, the production capacity of PVC in China has increased rapidly. Up to 8 m, its application field continues to expand. However, there are few PVC product brands in China, and users have little choice. When making transparent products. 2. When the main motor source of the tensile testing machine is not bright, PVC products with ethylene as the raw material are mainly selected with the tightening of the park budget. Although the product has certain advantages, the quality and stability of the resin need to be further improved in application to enhance the competitiveness of the product. China's refractory industry is also facing the dilemma of excess capacity. In September 2005, a manufacturer used 21 produced by the chlor alkali plant of Sinopec Qilu Co., Ltd. During the production of transparent PVC profiles for packaging with SG 8 PVC resin in batches 22 and 26, it was found that there were "fish eyes" in the products, and the light transmittance of the profiles was low; At the same time, the SG 8 resin purchased in batches 27.28 and 07 is in good application. In order to find out the reason. This work analyzes the problems

1 experimental part

1.1 sample

21 powder, 22 powder, granular, 07 powder, granular are 21 respectively. Two batches of SG 8 PVC resin, 22 and 07, were produced by the chlor alkali plant of Sinopec Qilu Co., Ltd. 22 profile and 07 profile are profiles extruded with 22 pellets and 07 pellets respectively. Produced by a domestic factory

1.2 instruments and equipment

dgf 3oo6a electric blast drying oven, which is produced by Chongqing pilot plant. Mdsc2910 differential scanning calorimeter, produced by TA

Company in the United States. Haake300p torque rheometer is produced by haake

company in Germany. 2001 capillary rheometer. Produced by gotter

Company in Germany. 150 - Calc gel permeation chromatograph, produced by American

waters company. Shj-25 twin-screw extruder is produced by Shanghai glassma company

1.3 experimental formula

the formula of rigid PVC transparent material (see Table 1) is used to evaluate the plasticizing performance of PVC powder

2 results and discussion

2.1 basic physical properties

three batches of SG 8 resin powder samples were tested according to the enterprise standard implemented by the product. The results are shown in Table 2

it can be seen from table 2 that both 22 and 07 powders have reached the standard of superior products; 21 except for particles with particle size less than 0.063 mm, other indicators of powder also meet the standard of high-grade products. There is no significant difference in the conventional properties of the three samples

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