Pub Date : 2019-09-09DOI: 10.1177/0262489319872329
S. Milovanović, D. Marković, J. Ivanovic
This study explores utilization of biodegradable and biocompatible polymers for controlled release of natural bioactive substance. For that purpose, poly(ε-caprolactone) (PCL) beads, cellulose acetate (CA) film, and poly lactic-co-glycolic acid (PLGA) flakes were impregnated with thymol by employing environmentally friendly process of supercritical carbon dioxide (scCO2) impregnation. At selected pressure and temperature, prolongation of operating time increased thymol loading. Pure scCO2 did not affect CA film with average pore diameter of approximately 3 µm, while it enabled change of PCL beads and PLGA flakes into foams with average pore diameter approximately 175 µm and 87 µm, respectively. Additionally to scCO2, thymol acted as a plasticizer increasing pore size of polymers up to three times. Kinetic of thymol release from selected samples was tested using phosphate buffer saline at 37°C and successfully described with Korsmeyer–Peppas, zero-order, first-order, and Higuchi models. The suggested method of PCL, CA, and PLGA supercritical impregnation led to development of porous, solvent free, added-value materials that release thymol in a controlled manner from 5 h to several days.
{"title":"Added-value porous materials for controlled thymol release obtained by supercritical CO2 impregnation process","authors":"S. Milovanović, D. Marković, J. Ivanovic","doi":"10.1177/0262489319872329","DOIUrl":"https://doi.org/10.1177/0262489319872329","url":null,"abstract":"This study explores utilization of biodegradable and biocompatible polymers for controlled release of natural bioactive substance. For that purpose, poly(ε-caprolactone) (PCL) beads, cellulose acetate (CA) film, and poly lactic-co-glycolic acid (PLGA) flakes were impregnated with thymol by employing environmentally friendly process of supercritical carbon dioxide (scCO2) impregnation. At selected pressure and temperature, prolongation of operating time increased thymol loading. Pure scCO2 did not affect CA film with average pore diameter of approximately 3 µm, while it enabled change of PCL beads and PLGA flakes into foams with average pore diameter approximately 175 µm and 87 µm, respectively. Additionally to scCO2, thymol acted as a plasticizer increasing pore size of polymers up to three times. Kinetic of thymol release from selected samples was tested using phosphate buffer saline at 37°C and successfully described with Korsmeyer–Peppas, zero-order, first-order, and Higuchi models. The suggested method of PCL, CA, and PLGA supercritical impregnation led to development of porous, solvent free, added-value materials that release thymol in a controlled manner from 5 h to several days.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"38 1","pages":"153 - 166"},"PeriodicalIF":1.6,"publicationDate":"2019-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489319872329","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46502546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polypropylene/carbon black (PP/CB) and PP/CB/multiwalled carbon nanotube (PP/CB/MWCNT) composites were fabricated by solid and foam injection molding, with the goal of enhancing the electrical conductivity of the composites while decreasing the cost of the final product. The foaming behavior and through-plane (T-P) electrical conductivity of the composites were characterized and analyzed. Cell growth increased the interconnection of the conductive fillers, changed the filler orientation, and enhanced the T-P electrical conductivity of the composites. Under appropriate processing conditions (200°C melt temperature, 70 cm3/s injection flow rate, and 5% void fraction), the T-P electrical conductivity of the foam PP/CB composites was 5 orders of magnitude higher than that of the solid composites (from 5.877 × 10−12 S/m to 1.010 × 10−7 S/m). Moreover, the T-P electrical conductivity values of the PP/CB and PP/CB/MWCNT were compared at the same conductive fillers content (15 wt%). The results showed that the T-P electrical conductivity of the PP/CB/MWCNT composites was far higher than that of the PP/CB composites by almost five orders of magnitude because the MWCNT acted as a bridge between CB particles, and a unique geometric shape was formed in the system. The T-P electrical conductivity of the foam PP/CB/MWCNT composites with 15 wt% carbon fillers was higher than that of the solid PP/CB composites with 20 wt% carbon fillers. This study reveals that the effect of foaming and the addition of hybrid fillers can improve the T-P electrical conductivity of plastic products, which is very important for the development of lightweight conductive plastics.
采用固体和泡沫注射成型的方法制备了聚丙烯/炭黑(PP/CB)和PP/CB/多壁碳纳米管(PP/CB/MWCNT)复合材料，以提高复合材料的导电性，同时降低最终产品的成本。表征和分析了复合材料的发泡性能和通过面电导率。细胞的生长增加了导电填料的互连性，改变了填料的取向，提高了复合材料的T-P电导率。在适当的工艺条件下(熔体温度200℃，注射流量70 cm3/s，孔隙率5%)，泡沫PP/CB复合材料的T-P电导率比固体复合材料高5个数量级(从5.877 × 10−12 s /m提高到1.010 × 10−7 s /m)。此外，在相同的导电填料含量(15 wt%)下，比较了PP/CB和PP/CB/MWCNT的T-P电导率值。结果表明，PP/CB/MWCNT复合材料的T-P电导率远高于PP/CB复合材料近5个数量级，这是因为MWCNT在CB颗粒之间起到了桥梁作用，并在体系中形成了独特的几何形状。掺碳量为15%的泡沫PP/CB/MWCNT复合材料的T-P电导率高于掺碳量为20%的固体PP/CB复合材料。研究表明，发泡效果和混合填料的加入可以提高塑料制品的T-P电导率，这对轻质导电塑料的发展具有重要意义。
{"title":"Injection-molded lightweight and high electrical conductivity composites with microcellular structure and hybrid fillers","authors":"Shenghui Tian, Binbin Dong, Yahao Guo, Can Zhao, Mengxia Zhang, Mengjun Xiao","doi":"10.1177/0262489319871747","DOIUrl":"https://doi.org/10.1177/0262489319871747","url":null,"abstract":"Polypropylene/carbon black (PP/CB) and PP/CB/multiwalled carbon nanotube (PP/CB/MWCNT) composites were fabricated by solid and foam injection molding, with the goal of enhancing the electrical conductivity of the composites while decreasing the cost of the final product. The foaming behavior and through-plane (T-P) electrical conductivity of the composites were characterized and analyzed. Cell growth increased the interconnection of the conductive fillers, changed the filler orientation, and enhanced the T-P electrical conductivity of the composites. Under appropriate processing conditions (200°C melt temperature, 70 cm3/s injection flow rate, and 5% void fraction), the T-P electrical conductivity of the foam PP/CB composites was 5 orders of magnitude higher than that of the solid composites (from 5.877 × 10−12 S/m to 1.010 × 10−7 S/m). Moreover, the T-P electrical conductivity values of the PP/CB and PP/CB/MWCNT were compared at the same conductive fillers content (15 wt%). The results showed that the T-P electrical conductivity of the PP/CB/MWCNT composites was far higher than that of the PP/CB composites by almost five orders of magnitude because the MWCNT acted as a bridge between CB particles, and a unique geometric shape was formed in the system. The T-P electrical conductivity of the foam PP/CB/MWCNT composites with 15 wt% carbon fillers was higher than that of the solid PP/CB composites with 20 wt% carbon fillers. This study reveals that the effect of foaming and the addition of hybrid fillers can improve the T-P electrical conductivity of plastic products, which is very important for the development of lightweight conductive plastics.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"34 3-4","pages":"131 - 152"},"PeriodicalIF":1.6,"publicationDate":"2019-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489319871747","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41301466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-08-29DOI: 10.1177/0262489319871741
Guiwei Dong, Guoqun Zhao, Junji Hou, Guilong Wang, Y. Mu
In this work, the effects of dynamic mold temperature control (DMTC) on melt pressure, cellular structure, and mechanical properties of microcellular injection molding (MIM)-molded parts are investigated experimentally. It is found that with the increase of the mold temperature, the duration of foaming pressure in the cooling stage increases. Meanwhile, the average cell diameter and cell diameter dispersion increases as well as the cell density decreases in MIM molded parts. The turning point of mold temperature after which the foaming pressure in the cooling stage and the cellular structure in MIM molded parts generate a significant change is around the glass transition temperature of the used plastic material. Under DMTC conditions, with the increase of mold temperature, the tensile strength, flexural strength, and impact strength of MIM molded specimens of single gate without weld line change a little, while the tensile strength, flexural strength of MIM molded specimens of double gates with weld line increase obviously. When the mold temperature increases to 120°C and over, the tensile strength, flexural strength of MIM molded specimens of double gates with weld line reach an equivalent level of specimens of single gate without weld line.
{"title":"Effects of dynamic mold temperature control on melt pressure, cellular structure, and mechanical properties of microcellular injection-molded parts: An experimental study","authors":"Guiwei Dong, Guoqun Zhao, Junji Hou, Guilong Wang, Y. Mu","doi":"10.1177/0262489319871741","DOIUrl":"https://doi.org/10.1177/0262489319871741","url":null,"abstract":"In this work, the effects of dynamic mold temperature control (DMTC) on melt pressure, cellular structure, and mechanical properties of microcellular injection molding (MIM)-molded parts are investigated experimentally. It is found that with the increase of the mold temperature, the duration of foaming pressure in the cooling stage increases. Meanwhile, the average cell diameter and cell diameter dispersion increases as well as the cell density decreases in MIM molded parts. The turning point of mold temperature after which the foaming pressure in the cooling stage and the cellular structure in MIM molded parts generate a significant change is around the glass transition temperature of the used plastic material. Under DMTC conditions, with the increase of mold temperature, the tensile strength, flexural strength, and impact strength of MIM molded specimens of single gate without weld line change a little, while the tensile strength, flexural strength of MIM molded specimens of double gates with weld line increase obviously. When the mold temperature increases to 120°C and over, the tensile strength, flexural strength of MIM molded specimens of double gates with weld line reach an equivalent level of specimens of single gate without weld line.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"38 1","pages":"111 - 130"},"PeriodicalIF":1.6,"publicationDate":"2019-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489319871741","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48885626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-06DOI: 10.1177/0262489319852335
Z. Qu, Jianguo Mi, Yang Jiao, Hongfu Zhou, Xiangdong Wang
In this article, a facile melt blending and solid batch foaming approach was proposed to prepare microcellular polystyrene/thermoplastic polyurethane (PS/TPU) blending foams with supercritical carbon dioxide (CO2). Compared with those of pure PS and pure TPU, an interesting phenomenon about the enhanced complex viscosity and storage modulus, as well as decreased loss factor of PS/TPU blends, was found. The solubility of CO2 in the PS/TPU blends was enhanced, owing to the CO2 solubilization effects of TPU. An interesting bimodal cell structure (BCS) was observed in the PS/TPU blending foams with the TPU content of 10, 15, and 20%. Consequently, a significant conclusion could be speculated that the generation of BCS in the PS/TPU blending system depended on not only the viscosity and morphology of the polymer blends but also the solubility and diffusivity of the CO2 as well as the type of cell nucleation. The thermal insulation property of PS foam was improved by the introduction of TPU.
{"title":"Microcellular morphology evolution of polystyrene/thermoplastic polyurethane blends in the presence of supercritical CO2","authors":"Z. Qu, Jianguo Mi, Yang Jiao, Hongfu Zhou, Xiangdong Wang","doi":"10.1177/0262489319852335","DOIUrl":"https://doi.org/10.1177/0262489319852335","url":null,"abstract":"In this article, a facile melt blending and solid batch foaming approach was proposed to prepare microcellular polystyrene/thermoplastic polyurethane (PS/TPU) blending foams with supercritical carbon dioxide (CO2). Compared with those of pure PS and pure TPU, an interesting phenomenon about the enhanced complex viscosity and storage modulus, as well as decreased loss factor of PS/TPU blends, was found. The solubility of CO2 in the PS/TPU blends was enhanced, owing to the CO2 solubilization effects of TPU. An interesting bimodal cell structure (BCS) was observed in the PS/TPU blending foams with the TPU content of 10, 15, and 20%. Consequently, a significant conclusion could be speculated that the generation of BCS in the PS/TPU blending system depended on not only the viscosity and morphology of the polymer blends but also the solubility and diffusivity of the CO2 as well as the type of cell nucleation. The thermal insulation property of PS foam was improved by the introduction of TPU.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"38 1","pages":"68 - 85"},"PeriodicalIF":1.6,"publicationDate":"2019-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489319852335","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47860593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To improve the cellular foam structure of common polypropylene (PP), acrylonitrile–butadiene–styrene terpolymer (ABS) and compatibilizer were used to blend with PP, and the foaming behavior of PP/ABS blends was investigated. The solid and foamed samples of the PP/ABS blend with different component were first fabricated by melt extrusion followed by conventional injection molding with or without a blowing agent. The mechanical properties, thermal features, and rheological characterizations of these samples were studied using the tensile test, dynamic mechanical analyzer, differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and torque rheometry. The results suggest that ABS is a suitable candidate to improve the foamability of PP. The effect of ABS and compatibilizer on the foamability of PP can be attributed to three possible mechanisms, that is, the weak interaction between phases that facilitates cell nucleation, the improved gas-melt viscosity that prevents the escape of gas, and the influence of crystallization behavior that helps to form a fine foaming structure.
{"title":"Effect of acrylonitrile–butadiene–styrene terpolymer on the foaming behavior of polypropylene","authors":"Xiaoyan Tan, Ying‐Guo Zhou, Jinghong Zhou, Binbin Dong, Chun-tai Liu, Bai‐Ping Xu","doi":"10.1177/0262489319852331","DOIUrl":"https://doi.org/10.1177/0262489319852331","url":null,"abstract":"To improve the cellular foam structure of common polypropylene (PP), acrylonitrile–butadiene–styrene terpolymer (ABS) and compatibilizer were used to blend with PP, and the foaming behavior of PP/ABS blends was investigated. The solid and foamed samples of the PP/ABS blend with different component were first fabricated by melt extrusion followed by conventional injection molding with or without a blowing agent. The mechanical properties, thermal features, and rheological characterizations of these samples were studied using the tensile test, dynamic mechanical analyzer, differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and torque rheometry. The results suggest that ABS is a suitable candidate to improve the foamability of PP. The effect of ABS and compatibilizer on the foamability of PP can be attributed to three possible mechanisms, that is, the weak interaction between phases that facilitates cell nucleation, the improved gas-melt viscosity that prevents the escape of gas, and the influence of crystallization behavior that helps to form a fine foaming structure.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"38 1","pages":"47 - 67"},"PeriodicalIF":1.6,"publicationDate":"2019-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489319852331","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46000944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-05-20DOI: 10.1177/0262489319846785
Yun Zhang, C. Xin, Zeming Wang, Waqas Mughal, Yadong He
Polypropylene (PP) foamed products have the advantages of heat and chemical resistance, but it is difficult to foam without modified PP. Traditionally, researchers have used chemical modification to increase the melt strength to improve the foaming properties of PP. In this article, we designed four kinds of screw combinations, and five regions are selected for sampling. The polytetrafluoroethylene (PTFE) and isotactic polypropylene (iPP) were blended by one-step fiber forming method, and then we tested the rheological properties and foaming properties. It is found that the rheological properties of the in situ microfiber composite are significantly improved than the iPP, and the crystallization temperature is also increased. The foaming experiment of the composite showed that the foaming performance of the composite with in situ microfiber morphology was significantly improved compared with the pure iPP performance, and the foaming temperature window of iPP was widened from 3°C to more than 6°C.
{"title":"The foaming performance evaluation of fibrillated polytetrafluoroethylene and isotactic polypropylene blends","authors":"Yun Zhang, C. Xin, Zeming Wang, Waqas Mughal, Yadong He","doi":"10.1177/0262489319846785","DOIUrl":"https://doi.org/10.1177/0262489319846785","url":null,"abstract":"Polypropylene (PP) foamed products have the advantages of heat and chemical resistance, but it is difficult to foam without modified PP. Traditionally, researchers have used chemical modification to increase the melt strength to improve the foaming properties of PP. In this article, we designed four kinds of screw combinations, and five regions are selected for sampling. The polytetrafluoroethylene (PTFE) and isotactic polypropylene (iPP) were blended by one-step fiber forming method, and then we tested the rheological properties and foaming properties. It is found that the rheological properties of the in situ microfiber composite are significantly improved than the iPP, and the crystallization temperature is also increased. The foaming experiment of the composite showed that the foaming performance of the composite with in situ microfiber morphology was significantly improved compared with the pure iPP performance, and the foaming temperature window of iPP was widened from 3°C to more than 6°C.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"38 1","pages":"107 - 86"},"PeriodicalIF":1.6,"publicationDate":"2019-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489319846785","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47664216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Developing a multiple functional wound dressing suitable for different stages of wound healing is important for patients with special wound such as burn or decubital ulcers. In this study, poly (vinyl alcohol) (PVA), dextran, and chitosan are integrated to produce ideal wound dressing where glutaraldehyde (GA) is used as the cross-linker. The result demonstrated that 6% PVA hydrogel with 0.25% chitosan was found to provide antimicrobial ability. The PVA/chitosan hydrogel combined with 4% dextran utilizing GA cross-linking also presents the high cell proliferation ability, which suggests that the hydrogel is potential as a wound dressing. In the following physical analyses, the addition of chitosan and dextran appeared to promote the thermostability, mechanical properties, water retention, and moisturizing ability in the PVA hydrogel. In conclusion, the PVA/chitosan/dextran hydrogel has promising potential such as high water content, antimicrobial property, and well cell proliferation, which can be applied to wound healing application.
{"title":"Evaluation of PVA/dextran/chitosan hydrogel for wound dressing","authors":"Shin-Ping Lin, Kai-Yin Lo, Tien-Ni Tseng, Jui-Ming Liu, Ting-Yu Shih, Kuan-Chen Cheng","doi":"10.1177/0262489319839211","DOIUrl":"https://doi.org/10.1177/0262489319839211","url":null,"abstract":"Developing a multiple functional wound dressing suitable for different stages of wound healing is important for patients with special wound such as burn or decubital ulcers. In this study, poly (vinyl alcohol) (PVA), dextran, and chitosan are integrated to produce ideal wound dressing where glutaraldehyde (GA) is used as the cross-linker. The result demonstrated that 6% PVA hydrogel with 0.25% chitosan was found to provide antimicrobial ability. The PVA/chitosan hydrogel combined with 4% dextran utilizing GA cross-linking also presents the high cell proliferation ability, which suggests that the hydrogel is potential as a wound dressing. In the following physical analyses, the addition of chitosan and dextran appeared to promote the thermostability, mechanical properties, water retention, and moisturizing ability in the PVA hydrogel. In conclusion, the PVA/chitosan/dextran hydrogel has promising potential such as high water content, antimicrobial property, and well cell proliferation, which can be applied to wound healing application.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"38 1","pages":"15 - 30"},"PeriodicalIF":1.6,"publicationDate":"2019-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489319839211","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44086947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-03-31DOI: 10.1177/0262489319839632
E. Cusson, A. Akbarzadeh, D. Therriault, D. Rodrigue
Uniform foams (UF) and density graded foams (DGF) were produced by using similar or different temperatures on both sides of a compression molding system. The samples were produced using linear low density polyethylene as the matrix and activated azodicarbonamide as the chemical blowing agent. Morphological properties of the produced samples were analyzed via scanning electron microscopy to relate them to their mechanical properties. In particular, flexural and impact properties are reported for samples produced under a range of temperatures (140–200°C) and blowing agent concentration (0.7–1.0 wt%). The experimental results showed that a significant difference can be obtained in flexural modulus (up to 17%) and impact strength (up to 48%) depending on the side the stress is applied on. In all cases, the DGF showed better mechanical responses than UF of similar relative density for the range of conditions tested.
{"title":"Density graded polyethylene foams: Effect of processing conditions on mechanical properties","authors":"E. Cusson, A. Akbarzadeh, D. Therriault, D. Rodrigue","doi":"10.1177/0262489319839632","DOIUrl":"https://doi.org/10.1177/0262489319839632","url":null,"abstract":"Uniform foams (UF) and density graded foams (DGF) were produced by using similar or different temperatures on both sides of a compression molding system. The samples were produced using linear low density polyethylene as the matrix and activated azodicarbonamide as the chemical blowing agent. Morphological properties of the produced samples were analyzed via scanning electron microscopy to relate them to their mechanical properties. In particular, flexural and impact properties are reported for samples produced under a range of temperatures (140–200°C) and blowing agent concentration (0.7–1.0 wt%). The experimental results showed that a significant difference can be obtained in flexural modulus (up to 17%) and impact strength (up to 48%) depending on the side the stress is applied on. In all cases, the DGF showed better mechanical responses than UF of similar relative density for the range of conditions tested.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"38 1","pages":"14 - 3"},"PeriodicalIF":1.6,"publicationDate":"2019-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489319839632","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42517509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1177/0262489319843645
Fan Junfu, L. Junsheng, Wang Bixuan, Zhong Xin, Huang Guo-xia, Yan Liujuan, Ren Xiane
The main purpose of this study was to investigate the effects on the molecular structure and the properties of soybean proteins isolate (SPI) after two modifications: (1) peracetic acid oxidative cleavage of its disulfide bonds and (2) the subsequent addition of covalently bonded glucose to the SPI containing the cleaved disulfide bonds. An appropriate amount of peracetic acid will be capable of enhancing the surface properties of SPI significantly; however, excessive oxidation can obtain undesirable results. When the concentration of peracetic acid was 0.4%, following by 35.5% of the disulfide bond cleavage, compared with those of natural SPI, the foaming capacity (FC), foaming stability (FS), emulsifying capacity (EC), and emulsifying stability (ES) of oxidized-SPI were increased by 82.0%, 65.8%, 58.5%, and 41.5%, respectively. The surface activity of oxidized-SPI could be promoted by glucose modification, and the FC, FS, EC, and ES of oxidized-SPI have further risen to 146.8%, 96.0%, 131.4%, and 40.3%, respectively, after the further glucose modification. Particle size measurements showed bimodality for the SPI that was modified with glucose with a portion of smaller sizes seen. Fluorescence spectroscopy and circular dichroism measurements demonstrate that extensibility increases; flexibility is enhanced; and glycosylation occurs more readily due to the oxidation of SPI. When grafted with glucose, these oxidized soybean protein products produce more ideal foaming and display better emulsification properties.
{"title":"The effect on the surface activity and the structure of SPI caused by cleavage of disulfide bonds and by subsequent glucose modification","authors":"Fan Junfu, L. Junsheng, Wang Bixuan, Zhong Xin, Huang Guo-xia, Yan Liujuan, Ren Xiane","doi":"10.1177/0262489319843645","DOIUrl":"https://doi.org/10.1177/0262489319843645","url":null,"abstract":"The main purpose of this study was to investigate the effects on the molecular structure and the properties of soybean proteins isolate (SPI) after two modifications: (1) peracetic acid oxidative cleavage of its disulfide bonds and (2) the subsequent addition of covalently bonded glucose to the SPI containing the cleaved disulfide bonds. An appropriate amount of peracetic acid will be capable of enhancing the surface properties of SPI significantly; however, excessive oxidation can obtain undesirable results. When the concentration of peracetic acid was 0.4%, following by 35.5% of the disulfide bond cleavage, compared with those of natural SPI, the foaming capacity (FC), foaming stability (FS), emulsifying capacity (EC), and emulsifying stability (ES) of oxidized-SPI were increased by 82.0%, 65.8%, 58.5%, and 41.5%, respectively. The surface activity of oxidized-SPI could be promoted by glucose modification, and the FC, FS, EC, and ES of oxidized-SPI have further risen to 146.8%, 96.0%, 131.4%, and 40.3%, respectively, after the further glucose modification. Particle size measurements showed bimodality for the SPI that was modified with glucose with a portion of smaller sizes seen. Fluorescence spectroscopy and circular dichroism measurements demonstrate that extensibility increases; flexibility is enhanced; and glycosylation occurs more readily due to the oxidation of SPI. When grafted with glucose, these oxidized soybean protein products produce more ideal foaming and display better emulsification properties.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"38 1","pages":"31 - 44"},"PeriodicalIF":1.6,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489319843645","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43593424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-09-04DOI: 10.1177/026248931803700101
H. Kharbas, Thomas Ellingham, L. Turng
Without modifying existing part and mold designs, the conventional microcellular injection molding (MIM) process can typically save about 5–10% material without encountering problems such as incomplete filling, excessive shrinkage, or deteriorating microstructure and mechanical properties. In this study core retraction was used in combination with the MIM process to produce thick polypropylene (PP) parts (up to 7.6 mm thick) with high density reductions of 30% and 55%. The cavity volume was modified by changing the retraction distance, which enabled control of density reductions. The lowest densities were achieved with this core retraction-aided microcellular injection molding (CR-MIM) process, the results of which could not have been achieved by the conventional MIM process alone. The effects of delay time in core retraction and weight reduction on the microstructure of the core and skin layers were investigated. It was shown that the CR-MIM process yielded better microstructure and tensile properties than the conventional MIM process. Use of core retraction also yielded more consistent densities and tensile properties throughout the length of the foamed parts.
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