The thermooxidative stability and thermomechanical properties of advanced composites which use high performance resin matrices such as polyimides and high strength carbon fibers may be improved by sizing the carbon fibers with uncapped or capped linear polyamideimides.
The uncapped linear polyamideimides useful as carbon fiber sizings generally contain repeating units having the general formula:
Wherein
R₂= a trivalent organic radical and generally benzenetriyl;
R₃= a divalent organic radical; and
n= an integer sufficiently large to provide a strong, tough coating.
Useful capped, linear polyamideimide oligomers may be formed by including end caps with an unsaturated functionality (Y) containing a residue selected from the group consisting of:
wherein
R₁= lower alkyl, lower alkoxy, aryl, aryloxy, substituted alkyl, substituted aryl, halogen, or mixtures thereof;
j= 0, 1, or 2;
i= 1 or 2;
G= -CH₂-, -O-, -S-, -SO₂, -SO-, -CO-, -CHR-, or -CR₂-;
T= methallyl or allyl;
Me= methyl; and
R= hydrogen, lower alkyl, or phenyl.
Prepregs and composites having carbon fibers sized with such polyamideimides are also described.
使用聚
酰亚胺等高性能
树脂基材和高强度碳纤维的高级复合材料的热氧化稳定性和热机械性能,可通过使用无封口或有封口的线性聚酰胺
酰亚胺对碳纤维进行定型来改善。
用作碳纤维定型剂的无封端线性聚酰胺
酰亚胺一般含有通式如下的重复单元:
其中
R₂= 三价有机基,一般为苯三基;
R₃= 二价有机基;以及
n= 足够大的整数,以提供强韧的涂层。
有用的封端线性聚酰胺
酰亚胺低聚物可通过加入具有不饱和官能团(Y)的端盖来形成,该官能团含有选自由以下组成的组的残基:
其中
R₁= 低级烷基、低级烷氧基、芳基、芳氧基、取代烷基、取代芳基、卤素或它们的混合物;
j= 0、1 或 2;
i= 1 或 2;
G= -CH₂-、-O-、-S-、-SO₂、-SO-、-CO-、-CHR- 或 -CR₂-;
T= 甲基烯丙基或烯丙基;
Me=甲基;以及
R= 氢、低级烷基或苯基。
此外,还介绍了使用此类聚酰胺
酰亚胺制成的碳纤维预浸料和复合材料。