界面层结构对填充聚丙烯力学性能及流变行为的影响

本文采用各类偶联剂处理填充改性聚丙烯的无机填料。实验结果表明,硅烷类 KH-550偶联剂在界面层形成刚性架的有机硅烷膜复盖层结构,使填充聚丙烯屈服强度明显提高,断裂面形貌为界面结合较好的脆性断裂。TSC,NDZ-201,OLT-671和 DL-411等酯类偶联剂在界面形成线型柔性链的单分子层结构,使填充聚丙烯冲击强度、断裂仲长率提高,加工流动性能明显改善。

本体聚合稀土异戊橡胶的加工性能

对2L釜合成的5个本体聚合稀土异戊橡胶(LnIR)胶样([η]=2.38～8.10 dL/g)的辊筒行为、挤出行为,硫化特性和硫化胶性能进行了研究。结果表明,LnIR具有明显的素炼降解行为,混炼辊筒温度不宜低于70℃,混炼行为与NR和溶液聚合钛系异戊橡胶(IR-10)相当,在110～130℃时,胶料的挤出性能可达良级;口型膨胀(B)位随温度和生胶[η]的增大而略有增加,在[η]相同时,B值与IR-10胶料相近。但小于NR胶料。硫化湿度为143℃时,LnIR硫化胶的性能除拉伸强度和扯断伸长率外,其他均对硫化时间不敏感,从综合性能考虑,硫化时间应为20～40min,LnIR硫化胶的拉伸强度和撕裂强度稍低于IR-10和NR硫化胶,而回弹性、低温性能、生热和抗湿滑性等均优于或相当于后两者。为获得良好综合性能的硫化胶。LnIR[η]应为4.0～6.0dL/g。

CHARACTERIZATION OF GAMMA-IRRADIATED CRYSTALLINE POLYMER .3. THERMAL-BEHAVIOR OF GAMMA-IRRADIATED POLYAMIDE-1010

Thermal behaviour of gamma-irradiated plain PA1010 and PA1010 containing different amounts of difunctional cross-linking agent BMI was investigated. In DSC endo- and exotherm, it was found that during irradiation, the presence of BMI markedly changes the melting and crystallisation characteristics of PA1010. A supposition that the network of BMI-containing specimens is rather loose in structure was proposed to explain the discrepancy in thermal behaviour between these two kinds of specimens. The supposition was further ascertained by the less brittleness in mechanical property of specimens containing BMI. Besides, the complexity of the thermal behaviour of gamma-irradiated PA1010 was discussed and attributed mainly to the increase in sigma-e, the fold surface free energy of chain fold crystals.

MOLECULAR-WEIGHT DEPENDENCE OF THE GLASS-TRANSITION OF CYCLIC POLYSTYRENE

The glass transition temperature (T(g)) of cyclic polystyrene was measured by differential scanning calorimetry. There was a marked difference in the glass transition behaviour between cyclic and linear polystyrene. In the low molecular weight region (M(n) < 5 x 10(3)), the T(g) of the cyclic polystyrene increased with decreasing M(n), contrary to that of linear polystyrene. With M(n) higher than 5 x 10(3), the T(g) of cyclic polystyrene increased with increasing M(n). The T(g) of cyclic and linear polystyrene approached the same constant value when the M(n) was high enough (M(n) > 10(5)). Combining the results of specific volume, it is believed that the variation of T(g) with molecular weight does not depend only on free volume effects but that configurational entropy is also an important factor.

异戊二烯均相聚合催化剂

分别用C_6H_5CH_2Cl,CH_2-CHSiCl_3,CH_ SiHCl_2,(CH_3)_2SiCl_2,(CH_3)_3CCl,CH_2—CHCH_2Cl,Cl_3SiCH_2CH_2SiCl_3代替非均相催化剂Nd(naph)_3-Al_2Et_3Cl-Al(i-Bu)_2H(简称Nd-Cl-Al)中的助催化剂后,除C_6H_5CH_2Cl,CH_2=CHSiCl_3,CH_SiHCl_2形成悬浊催化剂外,在Cl/Nd<8(mol比)时,其他氯化物均形成均相催化剂,并能催化异戊二烯均相聚合,得到顺式-1,4含量约95％,[η]约3 dL/g的聚合物。分别用(CH_3)_3CCl和(CH_3)_2SiCl_2代替Cl所组成的两催化剂,其催化活性接近,最佳Al/Nd和Cl/Nd值分别为40和2.5;异戊二烯浓度为10％—20％时,转化率不随其浓度的改变而变化。符合一级反应动力学特征。

CHARACTERIZATION OF GAMMA-RADIATION CROSS-LINKED CRYSTALLINE POLYMERS BY CRYSTALLIZATION TEMPERATURE

The effect of gamma-radlatlon on plain crystalline polymers and crystalline polymers containing different amounts of difunctional monomer both in vacuum and in air at room temperature has been investigated with DSC. It was found that the crystallization temperature T_c of crosslinked sample measured on DSC at a constant cooling rate decreases with increasing radiation dose. The difference between T_c before and after crosslinking (T_(c_0)-T_(c_R)) is linearly related to the radiation dose for plain polymer....

苯乙烯存在下的稀土催化丁二烯聚合

研究了在不同量St(St/Bd=0.02—0.50,mol比)的存在下,稀土催化剂对Bd溶液聚合的影响,Sdt/Bd=0.50时,Bd转化率大于76％,得到不含凝胶的聚丁二烯,其中顺式-1,4含量在95 ％左右,[η]=4—5 dL/g;在无链终止条件下使聚丁二烯和St热引发共聚,可得Bd和St的接枝(或嵌段)共聚物。用 IR、NMR、DSC 和透射电子显微镜等方法对聚合物进行了表征。

Identification of Porphyra lines (Rhodophyta) by AFLP DNA fingerprinting and molecular markers

Twenty-seven Porphyra lines from 5 classes, including lines widely used in China, wild lines, and lines introduced to China from abroad in recent years, were screened by means of amplified fragment length polymorphism (AFLP) with 24 primer pairs. From the generated AFLP products, 13 bands that showed stable and repeatable AFLP patterns amplified by primer pairs M-CGA/E-AA and M-CGA/E-TA were scored and used to develop the DNA fingerprints of the 27 Porphyra lines. Moreover, the DNA fingerprinting patterns were converted into computer language expressed with digitals 1 and 0, which represented the presence (numbered as 1) or absence (numbered as 0) of the corresponding band. On the basis of these results, computerized AFLP DNA fingerprints were constructed in which each of the 27 Porphyra lines has its unique AFLP,fingerprinting pattern and can be easily distinguished from others. Software called PGI-AFLP (Porphyra germplasm identification-AFLP) was designed for identification of the 27 Porphyra lines. In addition, 21 specific AFLP markers from 15 Porphyra lines were identified; 6 AFLP markers from 4 Porphyra lines were sequenced, and 2 of them were successfully converted into SCAR (sequence characterized amplification region) markers. The developed AFLP DNA fingerprinting and specific molecular markers provide useful ways for the identification, classification, and resource protection of the Porphyra lines.

A simple method for DNA extraction from sporophyte in the brown alga Laminaria japonica

A simple method was developed for extracting DNA from brown algae Laminaria japonica, which possess large amounts of acidic polysaccharides. Firstly, the sporophyte were washed by eliminating polysaccaride buffer to remove the polysaccharides and then ground in liquid nitrogen. Secondly, the powders were treated with lysing buffer. Thirdly, KAc was used to eliminate the remaining acidic polysaccharides. The extracted DNA was purified using a chloroform-isoamyl alcohol ( 24: 1 v/v), and precipitated in cold isopropanol. The yield was from 18.7 to 37.5 mu g g(-1) (wet weight) and the purity of total DNA was determined spectrophotometrically as the ratio of A(260)/A(280), which was about 1.7 - 1.9. The extracted DNA was of high quality and suitable for molecular analyses, such as PCR, restriction enzyme digestion. This method is a reproducible, simple, and rapid technique for routine DNA extraction from sporophyte in Laminaria japonica. Furthermore, the low cost of this method makes it attractive for large-scale studies.

Assessment of genetic diversities of selected Laminaria (Laminariales, Phaeophyta) gametophytes by inter-simple sequence repeat analysis

Inter-simple sequence repeat (ISSR) analysis was used to assess genetic diversity among 10 pairs of male and female Laminaria gametophytes. A total of 58 amplification loci was obtained from 10 selected ISSR primers, of which 34 revealed polymorphism among the gametophytes. Genetic distances were calculated with the Dice coefficient ranging from 0.006 to 0.223. A dendrogram based on the unweighted pair-group method arithmetic (UPGMA) average showed that most male and female gametophytes of the same species were clustered together and that 10 pairs of gametophytes were divided into four groups. This was generally consistent with the taxonomic categories. The main group consisted of six pairs of gametophytes, which were selected from Laminaria japonica Aresch. by intensive inbreeding through artificial hybridization. One specific marker was cloned, but was not converted successfully into a sequence characterized amplified region (SCAR) marker. Our results demonstrate the feasibility of applying ISSR markers to evaluate Laminaria germplasm diversities.

Identification of 27 Porphyra lines (Rhodophyta) by DNA fingerprinting and molecular markers

Twenty-seven Porphyra lines, including lines widely used in China, wild lines and lines introduced to China from abroad in recent years, were screened by random amplified polymorphic DNA (RAPD) technique with 120 operon primers. From the generated RAPD products, 11 bands that showed stable and repeatable RAPD patterns amplified by OPC-04, OPJ-18 and OPX-06, respectively were scored and used to develop the DNA fingerprints of the 27 Porphyra lines. Moreover, the DNA fingerprinting patterns were converted into computer language expressed with two digitals, 1 and 0, which represented the presence (numbered as 1) or absence (numbered as 0) of the corresponding band, respectively. Based on the above results, computerized DNA fingerprints were constructed in which each of the 27 Porphyra lines has its unique fingerprinting pattern and can be easily distinguished from others. Software named PGI (Porphyra germplasm identification) was designed for identification of the 27 Porphyra lines. In addition, seven specific RAPD markers from seven Porphyra lines were identified and two of them were successfully converted into SCAR (sequence characterized amplification region) markers. The developed DNA fingerprinting and specific molecular markers provide useful ways for the identification, classification and resource protection of the Porphyra lines.

An efficient method for DNA isolation from red algae

A simple, inexpensive and efficient method was developed for rapid isolation of total genomic DNA from 15 red algal species. It resulted in 0.1 mug high quality DNA from 1 mg fresh algal material, with an A(260)/A(280) ratio of 1.68 - 1.90. Using this rapidly isolated DNA, the 18S ribosomal RNA genes ( rDNA) and the nuclear ribosomal DNA of the internal transcribed spacer (ITS) regions were amplified. The tested DNA was suitable for restriction endonuclease digestion, genetic marker analysis and polymerase chain reaction (PCR) amplification, and may be valid for other genetic manipulation.

DNA fingerprinting of selected Laminaria (Phaeophyta) gametophytes by RAPD markers

Random amplified polymorphism DNA (RAPD) analysis was applied to germplasm characterization in 33 different selected Laminaria male and female gametophytes. The positional homology of the RAPD analysis using sequence characterized applied region (SCAR) method was successfully conducted. A total of 233 polymorphic loci were obtained from 18 selected primers after screening, of which 27 stable and clear bands were selected to construct a fingerprint map for discrimination of each gametophyte. Seven RAPD markers from five primers were finally determined by a computer program to construct the fingerprint map. Three specific markers closely related with gametophytes were obtained and were converted to gametophytic SCAR markers, the first SCAR marker report on Laminaria germplasm and applicable to cultivars identification. These results demonstrated the feasibility of applying RAPD markers to germplasm characterization in selected Laminaria gametophytes, and can provide a molecular basis for breeding new Laminaria strains. (C) 2004 Elsevier B.V. All rights reserved.