The kinetics of α and β transcrystallization in fibre-reinforced polypropylene

Transcrystallization in nanofiber bundle/isotactic polypropylene composites: effect of matrix molecular weight

“…Besides, the transcrystalline layer is not symmetrically developed around the nanofiber bundle. As reported, the shape of transcrystalline layer was dependent on the fiber surface topography, e.g., a helical defect along kevlar fiber resulted in a helix transcrystallization, while a parallel growing transcrystalline front on high-modulus carbon fiber led to a much more uniform transcrystallinity [6]. Therefore, for our case, it can be easily understood that the nonuniform transcrystalline layer has resulted from the disordered arrangement of nanofiber in bundle (see Fig.…”

“…According to Hoffman's theory, these essential parameters relate to the crystalline forms of polymers [6,34]. From literatures [6], the essential parameters in Eq. (1) and (2) can be obtained; b 0 is 0.626 nm, T 0 m is 458 K, Δh f is 196 MJ m −3 , and T inf is 231.2°C for α form iPP.…”

“…The nuclei are so dense that they hinder the lateral extension of crystal and force them to grow in one direction, which results in a transcrystalline layer finally. Many kinds of semicrystalline polymers can form transcrystallinity surrounding fiber, e.g., isotactic polypropylene (iPP) [1,[6][7][8], polyethylene (PE) [9,10], polylactide acid [4,5], and so on. Among them, iPP is the most popular one.…”

“…More interestingly, when provided with suitable conditions, iPP is capable to crystallize into different polymorphic (viz., α, β, γ, and smectic) forms. Many kinds of fibers, e.g., carbon fibers [11], modified glass fibers [2,6], kevlar fibers [3,6], and iPP fibers [12][13][14][15], can easily induce transcrystallization of iPP, and α [1-3, 6-8, 11], β [6,[12][13][14][15], or even γ [1,16,17] form transcrystallinity can be developed if crystallization conditions are elaborately manipulated. Nevertheless, α form iPP transcrystallinity is the most common one while the others are rarely observed.…”

Structural, mechanical and thermal studies of double‐molded isotactic polypropylene nanocomposites with multiwalled carbon nanotubes

“…Therefore, iPP is generally modified with nanoscaled clay and fibers. [13][14][15][16] Recently, CNTs are also used as special nanofiller to prepare iPP/CNTs composites, providing a new avenue of fabricating high performance iPP engineering plastics. [17][18][19][20] The structure of CNTs can be single walled (SWCNTs) or multiwalled (MWCNTs) of which the latter is simply composed of concentric single-walled nanotubes having more rigid structure than the former one.…”