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ÒÔÏÂÊÇÎÒдµÄÒ»¶ÎÎÄÕÂǰÑÔ£¬Àϰå˵¾ä×ÓÓë¾ä×ÓÖ®¼ä²»Á¬¹á£¬Âé·³¸÷λ´óÏÀ°ïæÈóÉ«ÈóÉ«£¬ÎÒÒ²Ö»ÓÐÒÔ½ð±ÒÀ´±í´ï¶Ô¸÷λµÄ¸ÐлÁË£¬Ð»Ð»ÁË¡£Âé·³ÁË¡£ Thermotropic liquid crystalline polymers (TLCPs) are macromolecular materials capable of forming anisotropic liquids either in solution or in the bulk state upon heating. This arises from the presence of rigid, rodlike, mesogenic molecules, either as part of the backbone or as side chains linked to a more flexible backbone. To reduce the melting point(Tm) of the intractable homopolymer, monomer must be introduced that disrupt the order or regularity of the backbone. Generally, processing temperature can be lowered by copolymerizing the rigid backbone moieties with controlled amounts of a moiety having flexible linkages. Polyurethanes constitute one of the most complete and versatile classes of polymeric materials known today. Polyurethanes are characterized by the presence of urethane linkage (NHCOO) formed typically through the reaction of a diisocyanate and a glycol. A unique feature of polyurethane is that a wide variety of structural changes could be brought about with different hydroxyl compounds and isocyanates, leading to a wide spectrum of properties in polyurethanes. Thermotropic liquid crystalline polyurethanes continue to draw attention primarily due to their good mechanical properties and ease of processing. Initial research on liquid crystalline polymers was mainly focused on main chain thermotropic polyesters and lyotropic polyamides. Even though polyurethanes (main chain and side chain) contribute to a broad spectrum of applications, liquid crystalline behavior in these materials is a recent development. |
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banban6322(½ð±Ò+1,VIP+0):2 9-7 16:58
banban6322(½ð±Ò+1,VIP+0):2 9-7 16:58
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banban6322(½ð±Ò+15,VIP+0):ллŶ 9-7 17:00
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Thermotropic liquid crystalline polymers (TLCPs) are macromolecular materials which can form anisotropic liquids either in solution or in the bulk state upon heating. This arises from the presence of rigid, rodlike, mesogenic molecules, either as part of the backbone or as side chains linked to a more flexible backbone. In order to reduce the melting point(Tm) of the intractable homopolymer, monomer should be introduced to disrupt the order or regularity of the backbone. Generally, the rigid backbone moieties can be copolymerized by controlling amounts of a moiety which has many flexible linkages, which can lowered the processing temperature. Polyurethanes characterized by the presence of urethane linkage (NHCOO) which are formed typically in the reaction of a diisocyanate and a glycol are one of the most complete and versatile classes of polymeric materials so far. A unique feature of polyurethane is that a wide variety of structural changes can be brought about with different hydroxyl compounds and isocyanates, thus lead to a wide spectrum of properties in polyurethanes. Thermotropic liquid crystalline polyurethanes has been draw great concern primarily due to their good mechanical properties and simplification in processing. Initial research on liquid crystalline polymers mainly focused on the main chain thermotropic polyesters and lyotropic polyamides. Even though polyurethanes (main chain and side chain) contribute to a broad spectrum of applications, liquid crystalline behavior in these materials is a recent development |
3Â¥2009-09-07 11:57:58
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banban6322(½ð±Ò+20,VIP+0):Ì«¸ÐлÁË£¬Ð»Ð» 9-7 17:01
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Thermotropic liquid crystalline polymers (TLCPs) are macromolecular materials which can form anisotropic liquids in solution or in the bulk state on heating. This results in the presence of rigid, rodlike, mesogenic molecules, either as part of the backbone or as side chains linked to a more flexible backbone. To reduce the melting point (Tm) of the intractable homopolymer, monomer must be introduced that disrupt the order or regularity of the backbone. Generally, processing temperature can be reduced by copolymerizing the rigid backbone moieties with controlled amounts of a moiety having flexible linkages. Polyurethane is the biggest family in polymeric materials known today. The urethane linkage (NHCOO) is the Basic features of Polyurethanes, which formed through the reaction of a diisocyanate and a glycol. Different hydroxyl compounds and isocyanates of variety Polyurethanes structure lead to a wide spectrum of properties. For good mechanical property and easy production, thermotropic liquid crystalline polyurethanes were concerned for a long time. Initial research on liquid crystalline polymers was mainly focused on main chain thermotropic polyesters and lyotropic polyamides. Since polyurethanes (main chain and side chain) contribute to wide applications, liquid crystalline behavior of these materials is developed recently. ºóÁ½¶ÎÐ޸Ľ϶à |

4Â¥2009-09-07 16:36:51














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