Reactive Compatibilization of PA6/PPE Blends
|摘要:||SG(styrene-g-glycidyl methacrylate)共聚物在PA6/PPE聚摻系統中，可在熔融狀態下與PA6反應形成SG-g-PA6共聚物，可有效增容PA6/PPE聚摻合物。SG共聚物中最適當的GMA(glycidyl methacrylate)含量是5wt%，太高的GMA含量對增容的效果並不見得有利。
SMA與PA6會反應形成in situ SMA-g-PA6共聚物，停留在PA6與PPE的相界面，成為真正的相容劑。而增容後的PA6/PPE聚摻合物，其PPE的Tg明顯的下降，顯示有未反應的SMA溶入PPE相中。在PA6/PPE = 30/70的聚摻合系統中，少量的PA6在未增容情況下與PPE互呈共連續相，但增容的系統卻趨向PA6為連續相的相形態。
SMA共聚物中所含MA的多寡是此反應型相容劑增容效果的重要影響因素。若SMA中的MAr 的含量過高(SMA 14, 14wt%MA)則會出現過度接枝（excessive grafted）情況，增容效果變差。另一方面，若SMA中MA的含量太低，雖然可以避免過度接枝的情形，在界所形成的SMA-g-PA6共聚物數量不足，無法達到增容的效果。在PA6/PPE/SMA的反應型增容聚摻研究中，含有80%MA的SMA共聚物，其增容效果應屬最佳。
市售的4官能基的環氧樹脂單體（TGDDM）可有效地提昇PA6/PPE聚摻合物的相容性，我們相信此種含環氧基的偶合劑可同時與PA6與PPE反應，形成PA6-co-TGDDM-co-PPE混合共聚物，由於共聚物含有PA6及PPE的鏈段，將落於PA6與PPE的相界面，作為PA6/PPE的真正相容劑。In situ PA6-co-TGADDM-co-PPE會使PA6的結晶度下降，並且使原本共連續相的形態轉變成PA6為連續相的形態。
Incompatible polymer blends between polyamide-6(PA6) and poly(2,6-dimethy-1,4-phenylene ether)(PPE) have been compatibilized in situ by the styrene-glycidyl methacylate (SG) reactive copolymers. The epoxy functional groups in SG copolymers can react with PA6 amine and carboxylic endtroups at to form various SG-g-PA6 copolymers. About 5 WT% GMA is the optimum content in SG copolymer tht produces the best compatibilization of the blends. The in situ-formed SMA-g-PA6 copolymer tends to reside at the interface to function as an effective compatibilizer of PA6/PPE blends. Substantial decrease of the glass transition temperature of PPE after compatibilization indicates that certain fraction of SMA is dissolved in PPE phase. PA6 is in a co-continuous strcture with PPE after comp9atibilization indicates that certain fraction of SMA is dissolved in PPE phase. PA6 is in a co-continuous structure with PPE in this PPE-rich uncompatibilized blend (PA6/PPE = 30/70) but tends to shift into continuous matrix after SMA compatibilization. Blending sequence is an important factor to the compatibility of PA6/PPE blends. The order of relative compatibility of that the PA/PPE = 70/30 blend compatibilized by SMA8(8wt%MA) is C Method > B Method > A Method. Reactive group concentration in SMA is an important factor in designing an optimized compatibilization system. Too high of MA concentration in SMA may produce the excessively grafted comb-like copolymers and too low MA concentration tends to produce less number of the desirable SMA-g-PA6 copolymers, that loses the expected role as an effective compatibilizer. SMA8 (0%MA) is probably the best compromise in the blending system. Fraction of this PMPI coupler is able to rect with both PA6 and PPE simultaneously at the interface to form the desired PA6-co-PMPI-co-PPE mixed copolymer. Significant mechanical property improvement can be achieved by the addition of a samll amount of PMPI coupler in PA6/PPE blends. The commercially available tetra-functional epoxy monomer (TGDDM) has demonstrated to be a highly efficient reactive compatibilizer for the imcompatible PA6/PPE blends. This exoxy coupler is able to react with both PA6 and PPE simultaneously to form the desirable PA6-co-TGDDM-co-PPE mixed copolymer. This mixed copolymer contains both PA6 and PPE segments and tends to anchor along the interface to function as an effective compatibilizer by reducing interfacal tension and enhancing the interfacial adhesion. The presence of the mixed copolymer tends to transform the cocontinuous structure into PPE-dispersed morphology and to reduce the crystallinity of the PA6 in the PA6/PPE blends. PNE coupling agent that can be used to compatibilize incompatible PA6/PPE blend since both of the blends compoments possess the necessary functional groups. Scanning electron micrographs show that the domain size of the compatibilized PA6/PPE blends has been reducing drastically with the increase of the PNE content. Additionally, a significant improvement of mechanical properties can be achived after compatibilization.
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