A phase field model for dynamic simulations of reactive blending of polymers

A facile way to generate compatibilized blends of immiscible polymers is through reactive blending of end-functionalized homopolymers. The reaction may be reversible or irreversible depending on the end-groups and is...

Sericin cocoon bio-compatibilizer for reactive blending of thermoplastic cassava starch

Cassava starch was blended with glycerol to prepare thermoplastic starch (TPS). Thermoplastic starch was premixed with sericin (TPSS) by solution mixing and then melt-blended with polyethylene grafted maleic anhydride (PEMAH). The effect of sericin on the mechanical properties, morphology, thermal properties, rheology, and reaction mechanism was investigated. The tensile strength and elongation at break of the TPSS10/PEMAH blend were improved to 12.2 MPa and 100.4%, respectively. The TPS/PEMAH morphology presented polyethylene grafted maleic anhydride particles (2 μm) dispersed in the thermoplastic starch matrix, which decreased in size to approximately 200 nm when 5% sericin was used. The melting temperature of polyethylene grafted maleic anhydride (121 °C) decreased to 111 °C because of the small crystal size of the polyethylene grafted maleic anhydride phase. The viscosity of TPS/PEMAH increased with increasing sericin content because of the chain extension. Fourier-transform infrared spectroscopy confirmed the reaction between the amino groups of sericin and the maleic anhydride groups of polyethylene grafted maleic anhydride. This reaction reduced the interfacial tension between thermoplastic starch and polyethylene grafted maleic anhydride, which improved the compatibility, mechanical properties, and morphology of the blend.

Corn starch reactive blending with latex from natural rubber using Na+ ions augmented carboxymethyl cellulose as a crosslinking agent

A mixture of corn starch and glycerol plasticizer (CSG) was blended with latex natural rubber (LNR) and carboxymethyl cellulose (CMC). The addition of 10 phr of CMC improved the Young’s modulus (6.7 MPa), tensile strength (8 MPa), and elongation at break (80%) of the CSG/LNR blend. The morphology of the CSG/LNR/CMC blends showed a uniform distribution of LNR particles (1–3 µm) in the CSG matrix. The addition of CMC enhanced the swelling ability and water droplet contact angle of the blends owing to the swelling properties, interfacial crosslinking, and amphiphilic structure of CMC. Fourier transform infrared spectroscopy confirmed the reaction between the C=C bond of LNR and the carboxyl groups (–COO−) of CMC, in which the Na+ ions in CMC acted as a catalyst. Notably, the mechanical properties of the CSG/LNR/CMC blend were improved owing to the miscibility of CSG/CMC and the CMC/LNR interfacial reaction. The CSG/LNR/CMC biodegradable polymer with high mechanical properties and interfacial tension can be used for packaging, agriculture, and medical applications.

High fire-safety phosphorus-containing polyethylene terephthalate with well-balanced comprehensive performances by reactive blending with liquid crystalline copolyester

With increased public awareness of fire-safety, flame retardant materials have been widely used and developed. Among them, a polyester called CPET, synthesized by the copolymerization of polyethylene terephthalate and 2-carboxyethyl (phenyl) phosphinic acid, has a good fire-safety and has been employed in the manufacture of synthetic fibers. However, the fabricated fiber made of CPET simultaneously possessing good flame retardancy and mechanical properties is a dilemma. Herein, we resolve this problem through the reactive blending of CPET with a type of thermotropic liquid crystal copolyester (PPDT) and subsequently solid-state polymerization (SSP). Thus, the fire-safety of the CPET/PPDTSSP blend improves greatly. The peak heat release rate, total heat release, and total smoke release decrease by 31.2%, 16.3%, and 11.0%, respectively, compared with those of CPET. Meanwhile, the CPET/PPDTSSP shows better crystallization and mechanical properties than CPET. The strength at yield and Young’s modulus of CPET/PPDTSSP increase by 20.0% and 15.8%, respectively. This blend shows great potential in the fabrication of fire-safety fibers with high strength.

Sericin cocoon bio-compatibilizer for reactive blending of thermoplastic cassava starch

Cassava starch was blended with glycerol to prepare thermoplastic starch (TPS). TPS was premixed with sericin (TPSS) by solution mixing and then melt-blended with polyethylene grafted maleic anhydride (PEMAH). The effect of sericin on the mechanical properties, morphology, thermal properties, rheology, and reaction mechanism was investigated. The tensile strength and elongation at break of the TPSS10/PEMAH blend were improved to 12.2 MPa and 100.4%, respectively. The TPS/PEMAH morphology presented PEMAH particles (2 µm) dispersed in the TPS matrix, which decreased in size to approximately 200 nm when 5% sericin was used. The melting temperature of PEMAH (121°C) decreased to 111°C because of the small crystal size of the PEMAH phase. The viscosity of TPS/PEMAH increased with increasing sericin content because of the chain extension. Fourier-transform infrared spectroscopy (FTIR) confirmed the reaction between the amino groups of sericin and the maleic anhydride groups of PEMAH. This reaction reduced the interfacial tension between TPS and PEMAH, which improved the compatibility, mechanical properties, and morphology of the blend.

Morphology, Thermo-Mechanical Properties and Biodegradibility of PCL/PLA Blends Reactively Compatibilized by Different Organic Peroxides

Reactive blending is a promising approach for the sustainable development of bio-based polymer blends and composites, which currently is gaining more and more attention. In this paper, biodegradable blends based on poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) were prepared via reactive blending performed in an internal mixer. The PCL and PLA content varied in a ratio of 70/30 and 55/45. Reactive modification of PCL/PLA via liquid organic peroxides (OP) including 0.5 wt.% of tert-butyl cumyl peroxide (BU), 2,5-dimethyl-2,5-di-(tert-butylperoxy)-hexane (HX), and tert-butyl peroxybenzoate (PB) is reported. The materials were characterized by rotational rheometer, atomic force microscopy (AFM), thermogravimetry (TGA), differential scanning calorimetry (DSC), tensile tests and biodegradability tests. It was found that the application of peroxides improves the miscibility between PCL and PLA resulted in enhanced mechanical properties and more uniform morphology. Moreover, it was observed that the biodegradation rate of PCL/PLA blends reactively compatibilized was lower comparing to unmodified samples and strongly dependent on the blend ratio and peroxide structure. The presented results confirmed that reactive blending supported by organic peroxide is a promising approach for tailoring novel biodegradable polymeric systems with controllable biodegradation rates.

Reaction Mechanism and Mechanical Property Improvement of Poly(Lactic Acid) Reactive Blending with Epoxy Resin

Polylactic acid (PLA) was melt-blended with epoxy resin to study the effects of the reaction on the mechanical and thermal properties of the PLA. The addition of 0.5% (wt/wt) epoxy to PLA increased the maximum tensile strength of PLA (57.5 MPa) to 67 MPa, whereas the 20% epoxy improved the elongation at break to 12%, due to crosslinking caused by the epoxy reaction. The morphology of the PLA/epoxy blends showed epoxy nanoparticle dispersion in the PLA matrix that presented a smooth fracture surface with a high epoxy content. The glass transition temperature of PLA decreased with an increasing epoxy content owing to the partial miscibility between PLA and the epoxy resin. The Vicat softening temperature of the PLA was 59 °C and increased to 64.6 °C for 0.5% epoxy. NMR confirmed the reaction between the -COOH groups of PLA and the epoxy groups of the epoxy resin. This reaction, and partial miscibility of the PLA/epoxy blend, improved the interfacial crosslinking, morphology, thermal properties, and mechanical properties of the blends.

Corn Starch Reactive Blending with Latex from Natural Rubber in Presence of Na+ Ions of Carboxymethyl Cellulose as a Catalyst

Corn starch (CS) was blended with glycerol, latex natural rubber (LNR), and carboxymethyl cellulose (CMC). The addition of 10 phr of CMC improved the Young’s modulus (6.7 MPa), tensile strength (8 MPa), and elongation at break (80%) of the CSG/LNR blend. The morphology of the CSG/LNR/CMC blends showed a uniform distribution of LNR particles (1–3 µm) in the CSG matrix. The addition of CMC enhanced the swelling ability and water droplet contact angle of the blends owing to the swelling properties, interfacial crosslinking, and amphiphilic structure of CMC. Fourier transform infrared spectroscopy confirmed the reaction between the C=C bond of LNR and the carboxyl groups (–COO-) of CMC, in which Na+ ions in CMC acted as a catalyst. Notably, the mechanical properties of the CSG/LNR/CMC blend were improved owing to the miscibility of CSG/CMC and the CMC/LNR interfacial reaction.