Carbon fiber versus glass fiber reinforcements: A novel, true comparison in thermoplastics

Abstract

Carbon fiber and glass fiber are two dominating reinforcements for polymer composites. Fiber-reinforced thermoplastics are widely used in many applications. It has a higher growth rate than thermoset composites due to ease in processing and recyclability. Glass fiber has been on the market for 80 years and carbon fiber over 50 years. There are hundreds, if not thousands, of research paper to compare the performance of the two fibers and hybrid. All the studies are from commercially available products. In all those cases, these two fibers are non-comparable. They have different fiber diameter, size and sizing content, chop length and chopping process. Taiwan Glass Industries, Corp. has cordially provided two experimental chopped strands that match the characteristics of chopped carbon fibers. The first one is for nylon reinforcement and the second one is for polypropylene. Now the glass fiber and carbon fiber have the same fiber diameter (7 microns), same size and sizing content (1%), and same chop length (6 mm). Most importantly, they are produced in identical way (off-line chop). The only difference between two fibers is silane on glass surface. This is the first of this kind of study. It gives a true comparison of two fibers with identical characteristics. As expected, fiber diameter has the biggest influence in mechanical properties among all fiber characteristics. For nylon, the difference between 7 micron and 10 micron glass fiber is small in tensile and flexural strength. It has bigger difference in impact strength. For polypropylene reinforcement, the fiber diameter of standard polypropylene dispersion (PP) glass fiber is 13 microns; almost double that of carbon fiber. Seven-micron PP glass actually outperforms PP carbon fiber in composite strengths.