Melt-Processable Nanocomposites Grafting-From Platelet Surfaces by Vapor-Assisted Surface Polymerization

One issue accompanying the melt-processing polymer/clay nanocomposites is the reaggregation of silicate platelets, which induces decreases in advantages of nanocomposites. To address this issue, vapor-assisted surface polymerization (VASP) method was applied with an initiator-attached and copolymerizable surfactant moiety-bound A-C18/C6MMT to obtain the exfoliated and intercalated nanocomposites using methylmethacrylate and styrene as vinyl monomers, respectively. The melt processing of the nanocomposites was carried out by a melt-compression molding method at 200°C. From XRD measurements, the C18/C6MMT-based nanocomposites showed no change in d-spacing even after melt processing, indicating the maintenance of the exfoliation and intercalation states. This maintenance must result from polymer chains grafting from the silicate layer surfaces, thus clearly confirming the anchoring effect of the copolymerizable surfactant moiety units

Green polymer blends compatibilized with biomass derived-agents

The effect of soybean lecithin (SOLE) and acrylated epoxidized soybean oil (AESO) as biomass-based compatibilizer agents was studied for the purpose of enhancing the compatibility of environmentally friendly thermoplastic/elastomeric blend of poly (lactic acid) (PLA) and synthetic rubber (PI). PI was melt mixed 25:75 into PLA with and without compatibilizer agents by a twin-screw extruder. The content of compatibilizer agents was kept at 0.5 and 2%, rrespectively. The compatibility of SOLE and AESO was investigated with thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and tensile test. From the thermal degradation and morphologic analysis, it was observed that SOLE was more effective in improving compatibility of PLA/PI blend in comparison with AESO. The inclusion of 0.5% SOLE into the blend system led to increment in the thermal stability, approximately, 10°C. Furthermore, a reduction of the size of PI islands distributed homogenously in the PLA matrix with the help of SOLE was observed, indicating the enhancement of interfacial adhesion. In other words, partially compatibilization took place resulting in the minimization of the dispersed PI island size

Auto-Drawing and Functionalization by Vapor-Phase Assisted Polymerization on Solid Surface

Formation of two- and three-dimensional micro architectures with chemical functions was verified by photo-vapor phase assisted surface polymerization (VASP) of functional monomer vapors combined with an auto-drawing system manipulated by prescribed programs. The surface modification by the photo-VASP of styrene vapor progressed rapidly, and a fine lines-pattern of photo-mask was transcribed as the corresponding polymer accumulations on poly(methyl methacrylate) (PMMA) substrate surfaces. Substrate surface modified by photo-VASP of acrylic acid showed reversible changes in hydrophilic/hydrophobic properties according to repeating external chemical stimuli. The successive auto-drawing by photo-VASP of three kinds of monomer vapors was examined under spot illumination from a fine optical fiber on an X-Y stage manipulated by a prescribed program, resulting in the production of a pre-designed functional structure by successful accumulations of corresponding polymers on the substrate surface

Effect of Ultrasonic-Assisted Extraction on Phenolic Content of Avocado

This study evaluate the effect of ultrasonic application in the extraction process on total phenolic content (TPC) of Hass avocado (Persea americana Mill) pulp. In this study, the solid/ solvent ratio of 1/30 (wt/ vol) and extraction temperature of 40 degree Celsius gave higher TPC value. This ratio and temperature was applied in the ultrasonic-assisted extraction (UAE) of avocado pulp. This study then compared the TPC obtained from the avocado pulp extract without involving ultrasonic and the TPC obtained from the UAE. Results showed that the TPC value of avocado pulp was significantly higher in the UAE (235.77 mg GAE/ 100g dried sample) compared to the TPC in the non-UAE (166.32 mg GAE/ 100g dried sample). The increase in the TPC was between ∼31 % and ∼41 % when 5 to 20 min of ultra sonication applied in the extraction. Ultra sonication duration of 15 min gave the highest TPC where the value was significantly higher compared to the other duration

Simple Procedure for Polystyrene-based Nanocomposite Preparation by Vapor-Phase Assisted Surface Polymerization

Polystyrene (PSt)-based copolymer/montmorillonite (MMT) nanocomposites were prepared by an in-situ vapor-phase assisted surface polymerization (VASP) as a solventless method using an organically modified MMT and a free radical initiator. Simultaneous and consecutive VASP of styrene (St) and methyl methacrylate (MMA) on the pre-modified MMT induced the accumulation of poly(MMA-ran-St) and poly(MMA-block-St) on the MMT surface, resulting in effective intercalation and exfoliation of silicate layers. The homogeneously dispersed silicate platelets in the polymer matrices were confirmed by X-ray diffraction and transmission electron microscope analyses. An important contributor to this phenomenon must be the particular interaction between a small amount of MMA-units and silicate surfaces. This approach allows the nanocomposites with accompanying intercalation and exfoliation of silicate layers to be applied to a wide range of vaporizable monomers which in the absence of this technique would be otherwise difficult to individually prepare

Simple Manufacture of Surface-Modified Nanolignocellulose Fiber via Vapor-Phase-Assisted Surface Polymerization

This work tackles the disadvantages in the production of functionalized nanofibers from biomass and offers a new methodology to nanofiber-reinforced composite manufacturing. A vapor-phase-assisted surface polymerization (VASP) method has been used to develop surface-modified lignocellulosic nanofibers. Through the vaporized monomers during polymerization, the polymer chains can be introduced deep within oil palm mesocarp fibers (OPMFs) due to their unique porous structure. After OPMFs are modified with polymer chains, the simple Mortar grinder mill–ionic liquid (M-IL) method provides fibrillation from the macro- to nanoscale, retaining the grafted polymer chains. This approach for the functionalization of biomass could lead to the large-scale fabrication of surface-modified nanofibers for reinforced materials and promote innovative implementations of the renewable biomass resource

Enhanced polyphenol content and antioxidant capacity in the edible portion of avocado dried with superheated-steam

In order toevaluatethe effects of drying methods on assay, this present study investigated the effect of superheated-steam drying at three different temperatures (130°C, 150°C and 170°C), in comparison with freeze drying on phenolic and flavonoid contents as well as antioxidant capacities in avocado (Persea americanaMill) pulp. The results showed that superheated-steam dried (SHSD) avocado pulp gave significantly higher total phenolic and total flavonoid contents compared to its freeze dried (FD) counterpart. The IC50 values from the DPPH assay were significantly lower (higher antioxidant activity)in SHSD pulp at all the temperatures used (6.69 – 12.16 mg/ml) compared to FD (35.02 mg/ml). The ORAC values also showed significantly higher radical absorbing capacitywhen SHSD at 170°C (26.58 µmol TE/1g)compared to FD (15.18 µmol TE/1g).The results showed that the drying methods significantly increased antioxidant capacity of SHSD avocado pulp in comparison with the FD.Superheated-steam drying at 170°C is proposed as an appropriate drying technique and condition to preserve pulp in avocado

O-Alkylation of Dihydroxo(tetraarylporphyrinato)phosphorus(V) and Antimony(V) Complexes with Alkyl Halides

The O-alkylation of dihydroxo(tetraarylporphyrinato)phosphorus(V) complexes with several kinds of alkyl bromide in MeCN in the presence of K2CO3 and 18-crown-6 ether produced dialkoxo(tetraarylporphyrinato)phosphorus(V) complexes in-moderate-good yields. Similar O-alkylation was applied to dihydroxo(tetraarylporphyrinato)antimony(V) complexes. The O-alkylation proceeded by the occurrence of an SN2 attack of the alkoxide anion of the complexes at the carbon substituted with halides

A Useful Biomass Component for Simple Fabrication of the Honeycomb Poly(L-lactide) Film

This concept is the development of useful material based on biomass such as a poly(L--lactide)[PLLA] with new added-value to extend applications. PLLA, which is an attractive raw material produced from renewable resources, has received much attention for applications in bioabsorbable and biodegradable materials. However, PLLA is not utilized well for practical use. This paper has explored an additive compound, which is a biocompatible, to facilitate a regular patterned porous film from PLLA to provide a valuable material. The method we adopted was to form a regular pattern on polymer film containing a surfactant in order to help the amphiphilic polymer to migrate at the interface between the organic solvent and the water droplets as the water-assisted formation method. To give the regular patterned porous film, some compounds from biomass were used for the water-assisted formation method. As surfactants in PLLA solutions, the experimental results showed the effectiveness of soy-bean oil. The pore size and surface morphology on the film can be controlled through the moisture condition, the PLLA concentration, and the molecular weight of PLLA

Development of pseudo-surface modification method for graphene

In recent years, it cannot be denied that it is more difficult to imagine spending a day without the help of electronic devices in modern technologies. However, these devices consume power and generate intense heat, and caused low efficiency and performance. Therefore, thermally conductive polymer composites for electronic devices is generating a lot of interest in various fields. Recently, graphene has attracted enormous attention owing to its remarkable properties. It is flexible, lightweight, ultra-strong, and highly conductive in both electrically and thermally. However, due to high surface area, van der Waals and π- π interactions, graphene sheets tend to aggregate and cause dispersion problem in solvents, resulting limit applications. Herein, pseudo-surface modification is proposed, which is a non-covalent modification method, which can maximally preserve graphene’s natural structure and its inherent properties. In this study, this facile and cost-efficient way was used to prepare functionalized GO (fGO), which involving aromatic hydrocarbons in polymerization; 2-naphthalene thiol (2-NT) acted as chain transfer agent in radical polymerization with MMA, while 1-naphthalene methanol (1-NM) acted as aromatic agent in ring opening polymerization with ε-CL. SEC profiles and NMR spectra indicated the attachment of aromatic agent on polymer chains. Both fGO showed good dispersion in more solvents compared to GO. In term of thermal conductivity, 0.35wt% fGO-PCL showed 43% improvement compared to PCL with 1-NM. While, 5wt% fGO-PMMA showed 25% improvement compared to PMMA with 2-NT. In summary, proposed pseudo-surface modification able to synthesis fGO with better dispersion and thermal conductivity for applications in electronic devices