• Food Engineering Progress
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• v.23 no.2
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• pp.118-124
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• 2019

This study aims to investigate the physical properties of extruded psyllium husk upon the addition of emulsifiers. Three different emulsifiers-glycerol monostearate (GMS), polyglycerol ester (PGE), and sugar ester (SE)-were added to the mixture of psyllium husk and rice powder before extrusion. Extrusion was performed using a twin-screw extruder at 140℃ die temperature, 200 rpm screw speed, and 16% feed moisture content. The physical properties of psyllium husk extrudates including expansion ratio, specific length, piece density, texture profile, color properties, water soluble index, and water absorption index were evaluated. It was observed that the expansion ratio was the highest while the specific length and piece density were the lowest in the control which had no emulsifiers. Texture profile analysis showed that the apparent elastic modulus and breaking strength were highest in the extrudate with a PGE of 0.1%. The adhesiveness was found to be lowest in the extrudates with an SE of 0.1% and GMS of 0.5%. Lightness value was highest in the extrudate with a PGE of 0.1%. Color difference, water soluble index, and water absorption index were highest in the control. The results reveal that some physical properties of extruded psyllium husk were improved with the addition of emulsifiers. This finding provides useful information for the development of psyllium snacks with good physical characteristics.

• The Korean Journal of Rheology
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• v.11 no.1
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• pp.50-56
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• 1999

Melt blends of polyamide 6 (PA 6) with polyester elastomer (PEL) were prepared in a corotating twin screw extruder using two types of coupling agent(CA), viz. diglycidyl ether of bisphenol A (DGEBA) and 1,4-phenylene bis(2-oxazoline) (PBO). Notched impact strength of PA 6 as well as PA 6/PEL blends increased with the addition of coupling agent, especially with DGEBA and the maximum impact toughening of the blend was obtained with 0.6%(by mol) DGEBA, where a minimum domain size was observed from SEM. Melt viscosities of the untreated blends were higher than those of base resins at low frequencies. Viscosities of base resins as well as blends increased with the addition of CA, and the effect was much more pronounced with DGEBA, especially for PA 6 and PA 6-rich blends.

• Polymer(Korea)
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• v.32 no.2
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• pp.178-182
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• 2008

Cellulose diacetate (CDA) and calcium carbonate ($CaCO_3$) biodegradable composites were prepared by melt mixing in a twin screw extruder and their physical properties were examined. In the melt processing, triacetine and epoxidized soybean oil were added to the composites as a plasticizer and lubricant, respectively. The optimal conditions for the preparation of the biodegradable composites were determined. Acetic acids ($CH_3COOH$) were made by pyrolysis acetyl group ($-OC (O)CH_3$) of CDA and TA in melt processing. Increasing the amount of $CaCO_3$ in the composites resulted in further enhancement of the $CH_3COOH$ absorption effects. The tensile strength and elongation were decreased, and Young's modulus and $T_g$ value increased with increasing amount of $CaCO_3$.

• Composites Research
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• v.30 no.2
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• pp.145-148
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• 2017

Wood powders were surface-modified by plasma-treating propylene to make them compatible with PP matrix in WPC(wood powder composite). The plasma treatment of propylene resulted in the deposition of an ultrathin hydrophobic film which had the chemical structure similar to that of polypropylene. Wood powder and polypropylene were mixed to pellets by twin screw extruder and then 50 wt% wood powder/PP composites were produced by an injection machine. Tensile strength and flexural strength were improved by 7.59% and 12.43% at the maximum respectively. SEM (Scanning Electron Microscopy) observation on the fracture surface revealed that the treatment improved the interfacial bonding and the mechanical properties of the composites.

• Elastomers and Composites
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• v.43 no.4
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• pp.241-252
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• 2008

ZnAl-LDH(layered double hydroxide) modified with oleic acid(SO-ZnAl LDH) was synthesized and added to the flame retardant ABS compounds containing brominated epoxy resin(BER) and antimony trioxide(${Sb_2}{O_3}$). Flame retardant ABS compounds were manufactured by using a twin-screw co-rotating extruder and subsequently injection molded into several specimen for flame retardancy and mechanical properties. The XRD patterns of ABS nanocomposites showed no peaks. The thermal stability of ABS nanocomposites was enhanced by the addition of SO-ZnAl LDH as shown in TGA results. However, these nanocomposites showed no rating in the UL 94 vertical test at 1.6 mm thickness. Only ABS nanocomposites with additional BER more than 1.5 wt% showed UL 94 V0 rating. Notched Izod impact strength, tensile modulus, and elongation at break of flame retardant ABS nanocomposites increased with the proportion of So-ZnAl LDH whereas their melt index decreased.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.22 no.3
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• pp.85-93
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• 2016

Flower-like zinc oxide (FZnO) was successfully synthesized via a sonochemical process. The chemical structure, morphology, and antimicrobial properties of as- prepared FZnO were investigated. Additionally, pure LDPE and five different LDPE/FZnO composite films were prepared with different FZnO content by using a twin screw extruder. According to the FTIR and SEM analyses, there exists weak interfacial interaction between LDPE and FZnO. Compared with pure LDPE, the LDPE/FZnO composite films showed UV barrier and enhanced antimicrobial activity against Escherichia coli (E. coli) as a Gram-negative micro-organism and Staphylococcus aureus (S. aureus) as a Gram-positive micro-organism. To enhance the interfacial interaction and good dispersion of FZnO into the LDPE matrix, and resultantly to such as UV barrier and antimicrobial properties of LDPE/FZnO composite films as the packaging materials, further efforts are required.

• Polymer(Korea)
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• v.29 no.3
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• pp.248-252
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• 2005

PP/MMT nanocomposites having a various compositions were prepared by melt blending with a twin screw extruder. In this study, maleic anhydride-grafted PP (MAH-g-PP) was used as a compatibilizer in order to assist the exfoliation or hen in the pp matrix. from the results or x-ray diffraction (XRD) and transmission electron microscope (TEM) measurements for the nanocomposites, we confirmed that MMT was exfoliated. PPM nanocomposites have shown good flame retardancy by synergistic effect between MMT and flame retardant. The mechanical and thermal properties of the nanocomposites showed significant enhancement compared with those of neat PP, The excellent flame retardancy of the PP/MMT nanocomposites, UL94 V-0 value, was successfully obtained with reduced amount of the flame retardant.

• Polymer(Korea)
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• v.26 no.3
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• pp.335-343
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• 2002

Blend resin (PET/PETG 70/30 blend) of poly (ethylene terephthalate) (PET) and poly (ethylene terephthalate glycol) (PETG) of weight percent 70/30 was prepared by a twin-screw extruder. Undrawn films of the blend and pure PETG were made by melt-press in hot press. Drawn films were made by capillary rheometer. Crystallinity, shrinkage, thermal, dynamic mechanical, and mechanical properties of these blends and PETG drawn films were investigated by wide angle X-ray diffractometer, dry oven, DSC thermal analyzer, and tensile tester. The crystallinity and density of these films increased with increasing draw ratio and draw rate but decreased with increasing draw temperature. The crystallinity and density of the blend films were higher than those of PETG films. The tensile strength and tensile modulus of these drawn alms increased with increasing draw ratio and draw rate but decreased with increasing draw temperature. The tensile strength and tensile modulus of blend films were higher than those of PETG films. Shrinkage of PETG md blend films decreased with draw ratio and draw rate. Shrinkage of undrawn blend film was 600% higher than that of pure PET film.

• Polymer(Korea)
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• v.38 no.3
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• pp.272-277
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• 2014

We studied in-line monitoring the dispersion of highly energetic material simulant by a twin screw extruder having a high temperature ultrasonic system. The simulant suspension system consisted of ethylene vinyl acetate and Dechlorane plus 25 as binder and filler, respectively. With increasing filling fraction, the ultrasonic velocity was not changed but the attenuation linearly decreased. It was possible to estimate the solid fraction of well dispersed suspension system by measuring ultrasonic attenuation. The ultrasonic attenuation of samples filled over 60 v% approached straight line with increasing filling fraction when the samples was extruded repeatedly. It was due to the enhanced dispersion of solid particles in the suspension system. It was believed that the degree of dispersion and filling fraction could be obtained by combination of on-line measurement like ultrasonic attenuation and off-line analysis like TGA and SEM with image analyzer.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.10
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• pp.1742-1747
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• 2004

Effects of raw material composition, feed moisture and process temperature on chemical, physical and sensory properties of extrudates produced by a single-screw extruder from the mixtures of rice flour, isolated soy protein and file fish were evaluated through response surface methodology (RSM). Nitrogen solubility index (NSI), integrity index (II), rehydration ratio (RR), density, and the external appearance were measured as indices of physicochemical and sensory properties of extrudates. RR was negatively correlated with density (R=-0.742, p<0.0l). Increased amounts of rice flour in feed mixtures resulted in increased RR. The extrudate prepared from the mixtures of ISP, rice flour and file fish showed the highest sensory score at which extrusion temperature was 13$0^{\circ}C$ or above.