Toughening of Poly(butylene terephthalate) by Core-Shell Polymer Containing Glycidyl Methacrylate Units.

Surface modification effects of core–shell rubber particles on the toughening of poly(butylene terephthalate)

“…The physical properties of filler‐loaded polymer blends are strongly affected by the filler dispersion and filler–matrix interface properties. The CSR surface used in this study was not sufficiently compatible with the PBT matrix, with the anticipated agglomeration of the CSR fillers in the low‐viscosity PBT melt 9. By changing the grafting ratios of GMA around the PMMA shell, however, we could control the filler dispersion and aggregate size in the PBT blends because hydroxyl (OH) and/or carboxyl (COOH) moieties on the PBT chain ends could react with the epoxide moiety in g GMA during melt compounding.…”

“…The grafting ratios of GMA were controlled from 0 to 4 wt % of the PMMA shell. In the resulting CSR fillers, about 70% of g GMAs were chemically active by the titration method:9 the epoxy group in the CSR was cleaved with an excess of HCl, and then the remaining HCl was back‐titrated with KOH (0.1 N ). The resulting values corresponded to 0.2, 0.4, 0.7, and 0.85 wt % in the fillers, respectively.…”

“…Semicrystalline poly(butylene terephthalate) (PBT) is one of the most prevalent engineering plastics used in the automotive and construction industries. Because its properties include notch sensitivity, brittleness, and low wear resistance, PBT is often blended with rubbery fillers as an efficient way to improve its physical properties 1–9. The main factors affecting the properties of rubber‐modified semicrystalline polymer blends are as follows: (1) rubbery content and size, (2) rubber properties, (3) crystalline structure and morphologies of the blends, (4) dispersed interparticle spacing (τ), and (5) the rubber–polymer interface.…”

“…However, because of their incompatibility with polymer matrices, CSR fillers tend to aggregate with each other, especially in low‐viscosity matrices. This agglomeration can be minimized by the use of a chemical reaction that directly links the matrix chains around the fillers during blending9–11 or by the loading of a tertiary polymer that is physically compatible with both components 12–14…”

“…Wu15 explained the BDT behavior in rubber‐toughened polyamide 66 with a stress‐field theory; under an applied load, it is related to the overlap of the stress field around the neighbor fillers, and the subsequent stress relaxation is induced by rubber cavities. The parameter τ has been considered one of the most influential factors in toughening and contributes to significant increases in the toughness of many semicrystalline polymers 9, 16–19. For high‐density polyethylene (HDPE) blends containing either CaCO 3 or rubber fillers, Bartczak et al17, 18 found that the toughness of these HDPE blends was dramatically improved below a critical value of interparticle spacing (τ c ) of 0.6 μm, regardless of which filler was used.…”