英语科技论文写作课件

1、英语科技论文写作,1,By,Fei Mingyue,Functional packaging materials: factors affecting the capacity and rate of water adsorption in desiccant composites,英语科技论文写作,2,1,2,3,4,Introduction,Experimental,Results and discussion,Conclusions,5,Acknowledgments,Content,英语科技论文写作,3,Plastic packaging materials form an impor

2、tant part of the economy and our everyday life. They fulfill numerous functions,such as making it possible to safely distribute products,protecting them from the environment, and informing the customer.,Introduction,However, the ever-increasing demands of consumers have resulted in new packaging sol

3、utions, including functional and smart packaging materials.The latter respond to changes in the environment, while the former fulfills some function that improves the performance of the packaging. The number of these materials is increasing rapidly,and they are already used in everyday life.,英语科技论文写

4、作,4,Introduction,The main functions targeted for functional packaging materials are humidity control,regulating ethylene content,exerting an antimicrobial effect,adsorbing odorous materials, or the oppositereleasing desirable aromas.Controlling the humidity of packaged wares is extremely important i

5、n several areas.,英语科技论文写作,5,For several hundred years, the quality of food has been preserved by drying it out, but moisture control has recently become very important in the pharmaceutical and electronic industries as well. Controlling moisture content is important in food packaging,while maintaini

6、ng dry conditions is usually a requirement of packaging for pharmaceuticals and electronics.,Introduction,So the desiccantcan be added to the packaged ware in a semipermeable satchet or incorporated into the packaging material.,英语科技论文写作,6,Introduction,As a consequence, the goal of our study was to c

7、arry out systematic experiments with desiccant composites prepared with a selected zeolite and to determine the effect of desiccant content and the properties of the matrix polymer on the rate and capacity of water adsorption. Three different polymers were selected for the study, and desiccant conte

8、nt was varied across a wide range from 0 to 50 vol.%.,英语科技论文写作,7,Polymers high density polyethylene polycarbonate polyvinyl chloride polymer Desiccant 5A-type zeolite The average particle size of the desiccant was 4.5 m, its density was 1.66 g/cm3, and its specific surface area was 533 g/m2.The theo

9、retical pore diameter of this zeolite was 4.3 .,Experimental,英语科技论文写作,8,Before composite preparation, the zeolite was dried at 300 C for 16 h in a vacuum. The components were homogenized in a Brabender (Duisburg, Germany) W50 EH internal mixer attached to a Haake(Thermo Scientific,Waltham, MA,USA) R

10、heocord EU 10 V driving unit at 190 C for 10 min,except for PC, for which the mixing was done at 240 C.,Experimental,英语科技论文写作,9,Experimental,One-millimeter-thick films were compression molded from the homogenized material at 190 or 240 C.The zeolite contents of the composites varied between 0 and 50

11、 vol.%. The water adsorptions of the zeolite and the composites were determined by measuring the weights of 20201 mm specimens under an atmosphere of 100%RH as a function of time.,英语科技论文写作,10,Results and discussion,Adsorption is relatively fast, and the desiccant adsorbs 23.8 % of its weight in wate

12、r.,英语科技论文写作,11,Results and discussion,We can see the much slower rate of adsorption mentioned above, and also that maximum adsorption is more or less proportional to the zeolite content of the composite.,英语科技论文写作,12,Results and discussion,3,Comparison of the results obtained for the three polymers s

13、hows that the adsorption capacity of the composite depends mainly on the amount of desiccant present and only slightly on the type of the polymer used as the matrix.,英语科技论文写作,13,Results and discussion,3,According to the figure, adsorption increases with zeolite content linearly for all three polymer

14、s, and it is completely independent of the type of polymer used as the matrix.,Fig.4 Effects of matrix type and zeolite content on the water adsorption capacities of desiccant composites.(squares HDPE,cirlcles PVC,triangles PC),英语科技论文写作,14,This study of zeolite desiccant composites prepared with three different matrices showed that the desiccant can adsorb a considerable amount of water in its free pores. The adsorption capacity of the composite depends linearly on the amount of desiccant present, but is independen