气相法乙烯－1－丁烯共聚产物结构性能的研究

Studies on Seed Deterioration and Ultrastructure of Lychee and Longan during Desiccation

研究了乙烯－丁烯气相共聚产物结构性质．ＤＳＣ，１３ＣＮＭＲ及密度测定结果表明，共聚物熔点，结晶度，密度随共聚单体１丁烯含量增加而降低，共聚物分子链中丁烯链节摩尔数则随共聚单体丁烯含量增加而增加．当共聚单体１丁烯体积含量为１７％～３８％时，共聚物熔点１２１８～１１７０℃，结晶度３４９％～２２９％，密度０９３８７～０９１３５，共聚物分子链中丁烯链节摩尔含量为１３％～６８％．乙－丁气相共聚物用沸己烷抽提后，其熔点和结晶度升高了，但分子链中丁烯链节减少了，乙烯链节增加了．共聚产物的沸己烷可溶物分子量小，结晶度低，分子链中丁烯链节数大。

chool of Life Sciences,Zhongshan University,Guangzhou 510275 Fu Jiarui Abstract Lychee seeds had 100% germination percentage (GP) when harvested at maturity.Longan seeds had 80% germinability and their GP reached 100% within 2 days.After 2 days of drying (32℃,30%￣40%RH),the germinability of lychee and longan seeds began to decline.At 6 days of drying,their moisture content (MC) was still above 25%,but GP decreased to less than 40%.Lychee and longan seeds lost viability at about 8 days of drying,while their MC being up to 18%. Ultrastructure studies indicated that,during the rapid deterioration of lychee and longan seeds,subcellular structure in their embryonic cells changed markedly,including plasmolysis and vacuolation,then nucleus membranes appeared abnormal,and no organelles could be recognized in the inviable seeds.The change of OD 280 of their leachates was well consistant with ultrastructure observation.The bound water content,measured by Nuclear Magnetic Resonance Spectrometer(NMRS),was very high in their embryonic axes.During drying,free water lost rapidly,then bound water content declined.It was proposed that subcellular structure of lychee and longan seeds was damaged at relatively high moisture content,which was possibly related with their recalcitrance.