In situ reinforced polypropylene fiber

Development of In Situ Reinforced Polypropylene Fibers for Use in Formable Woven Preforms... 

Ch Tselios, D. Bikiaris, P. Savidis, C. Panayiotou, A. Larena, Glass-fiber reinforcement of in situ compatibilized polypropylene/polyethylene blends. Journal of Materials Science 34 (2) (1999) 385-394. 

In situ polymerization to prepare immiscible blends was pioneered by Watkins and McCarthy [108], stimulating other researchers to apply this methodology to prepare novel polymer blends [109-112], fiber-reinforced composite materials[39], and electrically conducting composites [66, 67, 113-116]. Polymer blends produced in this manner include polystyrene/poly(vinyl chloride) [117, 118], polysty-rene/PET [119], nanometer-dispersed polypropylene/polystyrene interpenetrating networks [120], polypropylene/polystyrene [121] and polyethylene/polystyrene [122]. The resultant polymer blend may have a unique morphology compared to the traditionally prepared counterpart (if it is feasible to prepare such a blend via conventional procedures) and therefore demands a thorough investigation. 

It should be noted that there is not simply an addition of thermotropic LCPs into fiber-reinforced plastics to get in situ hybrid composites. Bafna et al. used glass fibers to decrease the anisotropy of LCP fibril-reinforced polyetherimide [136]. He et al. improved the processability and mechanical performances of glass fiber-reinforced polypropylene by the addition of LCPs [159]. However, these two works did not actively and purposely generate a reinforced composite with the reinforcements having their diameters at two orders of magnitude. The key point for in situ hybrid composites is the formation of LCP fibrils in the material system. As a combination of in situ composite and hybrid fiber reinforcing, the fabrication of in situ hybrid composites utilizes fabrication... 

In Chapter 3, mechanical properties of glass fiber-reinforced polypropylene are improved by addition of a coupling agent. Likewise, the in situ generation of modified polypropylene by grafting acrylic acid onto the polymer backbone in the Nichols and Kheradi investigation yields enhanced tensile strength compared with unfilled polypropylene and uncoupled composite (Fig. 10.2). 

Fibers comprised of polypropylene matrix reinforced with 50 wt.% VB fibrils were processed up to a fiber draw ratio of 220. The reinforcement was developed in situ using a dual extrusion fiber spinning process. The dual extrusion process not only allowed the processing of polymers with widely different melting temperatures but also allowed continuous streams of the TLCP to be introduced into the PP and maintained in the drawn extrudate. The tensile properties of the fibers increased with... 

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