Enhanced properties of poly(lactic acid) with silica nanoparticles

In this paper, silicone‐coated intumescent flame retardants was prepared by an efficient and simple approach, aiming at enhancing the flame‐retardant efficiency and smoke suppression properties. The surface of expandable graphite (EG) was treated prior to the coverage of nonflammable silicone. The resultant silicone‐modified EG hybrid (SEG) was combined with ammonium polyphosphate (APP) and applied as a flame‐retardant and smoke‐suppressant for ultrahigh molecular weight polyethylene (UHMWPE). Compared with UHMWPE/APP/EG (with 15 wt% APP/EG), UHMWPE/APP/SEG (with 15 wt% APP/SEG) gives decrement by 18.5% in the peaks of the heat release rate, 6.33% in total heat release and 13.6% in total smoke release, whereas increment by 23% in tensile strength and 12.1% in elongation at break, respectively. It is suggested that the introduction of silicone on the surface of EG can improve the interfacial compatibility between EG and UHMWPE. Moreover, it can lead to forming more char residue and reducing the release of smoke particulates during combustion process of the composites.

Section: Resultsmentioning

confidence: 96%

Hugely enhanced flame retardancy and smoke suppression properties of UHMWPE composites with silicone‐coated expandable graphite

Wang

Cao

Luo

et al. 2019

“…In recent years, the growing global “white pollution” problem has progressively increased the interest in the development and utilization of more environmentally friendly polymeric materials . In such a context, poly(lactic acid) (PLA) is undoubtedly 1 of the most promising candidates; it is not only biodegradable but is also obtained from sugar beets or corn straws etc . Being environmentally friendly and biodegradable, it has attracted considerable attention for applications in packaging, coating, and biomedical engineering .…”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization of layered double hydroxide‐poly(methylmethacrylate) graft copolymers via activators regenerated by electron transfer for atom transfer radical polymerization and its effect on the performance of poly(lactic acid)

Geng

Zhen

Song

et al. 2018

Layered double hydroxide‐poly(methylmethacrylate) (LDH‐PMMA) graft copolymers were prepared via activators regenerated by electron transfer for atom transfer radical polymerization. The results showed that the hydrophobicity of LDH‐PMMA was improved by the incorporation of hydrophilic groups. Moreover, poly(lactic acid) (PLA)/LDH‐PMMA nanocomposites were prepared by melt blending to enhance the performances of PLA. The crystallization and mechanical properties of the PLA/LDH‐PMMA nanocomposites were studied by differential scanning calorimetry, tensile testing, and polarized optical microscopy, respectively. Results of mechanical testing showed that the tensile strength, elongation at break, and impact strength of PLA/LDH‐PMMA nanocomposites were increased by 5.64%, 37.95%, and 49.70%, respectively, compared with PLA. The differential scanning calorimetry results indicated that LDH‐PMMA eliminated the cold crystallization of PLA matrix and improved the crystallinity of PLA by 37.26%. The polarized optical microscopy of PLA/LDH‐PMMA nanocomposites demonstrated that LDH‐PMMA increased the crystallization rate of PLA. It was also found that the rheological behaviors of the PLA nanocomposites were significantly enhanced. Based on these results, a new choice for modified LDHs was provided and used as a nucleating agent to improve the properties of PLA.

“…Various kinds of fillers such as organo‐modified montmorillonite (OMMT), carbon nanotubes (CNTs), calcium carbonate, silica, and carbon fullerenes are used to enhance the thermomechanical properties of PLA. Although, OMMTs and carbon nanotubes worked well with PLA, the formers need special organic treatments to get exfoliated, while the latters are expensive and are detrimental to the environment.…”

Section: Introductionmentioning

confidence: 99%

Poly(lactic acid)/(styrene‐ethylene‐butylene‐styrene)‐g‐maleic anhydride copolymer/sepiolite nanocomposites: Investigation of thermo‐mechanical and morphological properties

Nehra

Maiti

Jacob

2017

In this study, sepiolite nanoclay is used as reinforcing agent for poly(lactic acid) (PLA)/(styreneethylene-butylene-styrene)-g-maleic anhydride copolymer (SEBS-g-MA) 90/10 (w/w) blend.Effects of sepiolite on thermal behavior, morphology, and thermomechanical properties of PLA/SEBS-g-MA blend were investigated. Differential scanning calorimetry results showed 7% improvement in crystallinity at 0.5 wt% of sepiolite. The nanocomposite exhibited approximately 36% increase in the tensile modulus and 17% increase in toughness as compared with the blend matrix at 0.5 and 2.5 wt% of sepiolite respectively. Field emission scanning electron microscopy and transmission electron microscopy images exhibited sepiolite-induced morphological changes and dispersion of sepiolite in both PLA and SEBS-g-MA phases. Dynamic mechanical analysis and wide angle X-ray diffraction present evidences in support of the reinforcing nature of sepiolite and phase interaction between the filler and the matrix. This study confirms that sepiolite can improve tensile modulus and toughness of PLA/SEBS-g-MA blend. Biobased polymers have received a great deal of attention because they minimize the use of petrochemical resources and are superior in eco-friendliness. 1 The poly(lactic acid) (PLA) is a biodegradable polyester with high tensile strength and modulus. However, because of its brittleness, low thermal stability, and tensile toughness, neat PLA is limited in applications. Properly modified PLA can be used in many applications like food packaging, textile, electronics, surgical sutures, drug delivery systems, and transport and building. [2][3][4][5] Techniques such as plasticization, copolymerization, and blending are used to deal with the drawbacks of PLA. Blending is a feasible option compared with other techniques because of its cost effectiveness and minimum trade-off in properties. Blending with a thermoplastic elastomer like SEBS can be an effective way to toughen PLA. The SEBS is widely used in commercial applications such as sealants, footwear, coatings, 6 automotive parts, adhesives, temperature sensors, 7 and wire insulation. Sangeetha et al 8 reported that impact strength was higher in PLA/SEBS-g-MA blends than that in PLA/SEBS, which may be due to the interaction between maleic anhydride groups in SEBS-g-MA and carbonyl groups of PLA. SEBS-g-MA copolymer is used to toughen many polymers such as polypropylene (PP), 9 high density polyethylene, 10 nylon-6, 11 nylon-6,6 12 and PLA. 8,[13][14][15] reported that SEBS-g-MA is an effective impact modifier for PP/PLA blends. However, tensile modulus and strength decreased.Various kinds of fillers such as organo-modified montmorillonite (OMMT), [16][17][18][19] carbon nanotubes (CNTs), 20-22 calcium carbonate, [23][24][25] silica, 26-28 and carbon fullerenes 29,30 are used to enhance the thermomechanical properties of PLA. Although, OMMTs and carbon nanotubes worked well with PLA, the formers need special organic treatments to get exfoliated, while the latters are expensive and are detrimen...