Sennur Alay Aksoy

Cellulose–PEG grafts from cotton waste in thermo-regulating textiles

This study focused on the production of heat storage materials from cotton wastes by incorporating a phase-change material and determination of their thermo-regulating properties. Polyethylene glycol (PEG) was grafted onto a cellulosic cotton backbone to give solid–solid phase change properties. The change in the surface morphology of the fibers was studied by scanning electron microscopy. Chemical characterization of the fibers was carried out using Fourier-transform infrared radiation spectroscopy. Thermal analysis of the modified fibers was performed by differential scanning calorimetry, and the thermal regulating properties of the PEG-grafted fibers were investigated using a thermal history system comprising insulated boxes, temperature sensors and a data-logger. Static thermal insulation measurements were also carried out on the fibers. The PEG-grafted cellulose fibers were shown to absorb up to 33.8 J/g heat at 33.0℃, releasing 31.5 J/g heat at 29.4℃, during the phase transitions. Thermal history results showed that temperature of the box containing PEG1000-incorporated fiber differed by 1–1.5 ± 0.1℃ from the temperature of the box containing untreated cotton fibers over 23–25 minutes. Based on these results it is concluded that PEG-grafted cellulose has sufficiently high energy storage properties to be employed as a thermo-regulating material.

Encapsulation of phase change materials by complex coacervation to improve thermal performances and flame retardant properties of the cotton fabrics

This paper reports a study on the thermal stability and flame-retardant properties of microencapsulated phase change materials (PCMs) with clay nano-particles (Clay-NPs) doped gelatin/sodium alginate shell. The novel microcapsules were fabricated by the technique of complex coacervation using gelatin and sodium alginate as the shell and PCM n-eicosane as the core. Their flame retardant property as well as their practicable thermal performances when incorporated into woven cotton fabrics by pad-dry-cure were investigated. Thermal storage/release properties of the prepared microcapsules were analyzed using DSC instrument. Thermal gravimetry (TG) analysis was performed to measure the thermal stability and surface morphology of the microcapsules was observed by means of optical microscopy and SEM. The DSC results indicated that the latent heat storage capacity of prepared microcapsules changed in range of 97-114 J/g. The microcapsules had spherical shape with particle sizes between 1.37 μm and 1.6 μm. The PCM microcapsules (PCMMs) and nano-composite PCM microcapsules (NCPCMMs) with clay-NPs doped gelatin/sodium alginate shell were found to have good potential for developing thermal comfort in textiles. Comparing with conventional PCMMs, NCPCMMs have significantly better thermal stability. Nano-composite structure of the NCPCMMs, in which clay-NPs doped in the polymeric shell structure, attributed to increase the shell thermal stability. Improved flame retardant properties of the cotton fabrics treated with NCPCMs were declared as a result of flame retardant tests. Thermo-regulating properties of the fabrics were proved by thermal history (THistory) measurement results from releasing heat from microcapsules.

Synthesis of poly(methyl methacrylate-co-acrylic acid)/n-eicosane microcapsules for thermal comfort in textiles

Homogeneous distribution by adsorption is one of the key issues for application of microencapsulated materials to textiles. This study focused on production and characterization of poly(methyl methacrylate-co-acrylic acid)/n-eicosane microencapsulated phase change materials (MEPCMs) as textile thermal comfort additives with a functional outer surface. For this reason, methyl methacrylate was copolymerized with acrylic acid at three different ratios. The chemical structure, thermal energy storage properties, and thermal stability of microcapsules were investigated by FT-IR spectroscopy, differential scanning calorimetry, and thermogravimetric analysis techniques, respectively. Microcapsules were found to have a thermal energy storage capacity of 50.9–90.9 J/g in the 31.74–36.30℃ temperature interval and they release between −88.4 and −40.2 J/g in the 33.88–35.59℃ temperature interval. Using a scanning electron microscope and a particle size instrument, the spherical morphology and particle size distribution of were determined for the microcapsules produced. The average particle sizes were 22.53 µm, 21.87 µm, and 11.73 µm for microcapsules with increasing amount of acrylic acid content. The microcapsules were thermally stable up to at least 120℃.

Preparation and textile application of poly(methyl methacrylate-co-methacrylic acid)/n-octadecane and n-eicosane microcapsules

In this study, a series of microencapsulated phase change materials with poly(methyl methacrylate-co-methacrylic acid) P(MMA-co-MAA) shell and n-octadecane or n-eicosane core were synthesized by emulsion polymerization method. The aim was to produce microencapsulated n-alkanes having functional groups on their outer surface, so that functional groups would help increasing physical interactions between microcapsules and fiber surface. Therefore, methyl methacrylate (MMA), ethylene glycoldimethacrylate (EGDM), and methacrylic acid (MAA) were copolymerized in oil phase of n-alkane. FT-IR results proved the successful synthesis of P(MMA-co-MAA) shell of microencapsulated n-alkanes. The DSC results indicated that the microencapsulated n-alkanes have considerable latent heat storage capacity in a range of 58–145 J/g. The average melting and freezing temperatures of the microencapsulated n-alkanes were measured as 27 and 26 °C for n-octadecane and 36 and 35 °C for n-eicosane, respectively. The microcapsules were of spherical and compact shape with particle sizes between 15 and 32 μm. The microcapsules on the cotton fabric applied by pad-dry-cure method were found highly durable and they showed sufficient stability upon several washings and rub fastness. Thermo-regulating properties of the fabrics were declared as a result of thermal history measurements.

İnorganik Madde İlave Edilerek Geliştirilmiş Termal Stabiliteye Sahip Isı Depolama Özellikli Mikrokapsül Üretimi ve Karakterizasyonu

Faz degistiren maddeler (FDMler) belirli faz degistirme sicakliklarinda ortamdaki isi enerjisini sogurmak ve yaymak suretiyle isi regulasyonu saglayan maddelerdir. Faz degistiren madde olarak ozellikle mikrokapsullenmis parafinlerin tekstilde kullanimi dikkat cekmektedir. Bu calismada komplekskoaservasyon metodu ile mikrokapsullenmis parafin uretimi gerceklestirilmistir. Calismada amac isi depolama ozellikli bu mikrokapsullerin termal stabilitesinin arttirilmasidir. Bu amac dogrultusunda inorganik materyal olan Al2O3 (aluminyum oksit) mikrokapsullerin duvar yapisina ilave edilmistir. Mikrokapsulun duvar yapisini olusturmak icin jelatin, sodyum alginat ve Arap zamki polimerleri kullanilmistir. Mikrokapsullerinentalpi ve faz degisim sicakliklari gibi isil ozellikleri DSC (diferansiyel taramali kalorimetre), termal kararliliklari ise TGA (termal gravimetrik analiz) cihazi ile analiz edilmistir. Mikrokapsullerinkimyasal yapilari FT-IR spektroskopisi ile analiz edilirken morfolojileri optik mikroskop ve SEM (elektron taramali mikroskop) ile karakterize edilmistir.

Development of PEO nanofibers having novel morphologies via distance positioning apparatus

In this study, PEO nanofibers with novel architectures were developed via newly designed distance positioning apparatus in order to feed polymer solution in a different way. The surface morphology and alignment of nanofibers were observed using a scanning electron microscope (SEM). SEM micrographs revealed that different morphologies could be obtained by changing feeding position. For the first time in the nanofibers literature; nanofibers were simultaneously collected on three different positions (collector plate, X-axis, and Y-axis) and surface morphology of these nanofibers was found to be different which is promising in terms of their potential regarding utilization of same nanofibrous mat for functional applications.

Nano Çinko Oksit Takviyeli Jelatin/Arap Zamkı ve Kitosan/Arap Zamkından Üretilen ve N-Oktadekan İçeren Mikrokapsüllerin Karakterizasyonu ve Tekstil Uygulaması

Bu calismada, kompleks koaservasyon metodu ile cekirdek madde olarak n-oktadekan parafin iceren jelatin/arap zamki/nano cinko oksit ve kitosan/arap zamki/nano cinko oksit duvarli mikrokapsuller uretilmistir. Calismada amac nano cinko oksit ilave ederek mikrokapsullerin duvar yapisinin fonksiyonellestirilmesidir. Bu amac icin mikrokapsul duvar yapisini olusturmak icin kullanilan polimer yapiya nano cinko oksit partikuller ilave edilmistir. Uretilen mikrokapsullerin isi depolama/yayma sicaklik ve kapasiteleri diferansiyel taramali kalorimetre (DSC), morfolojileri optik mikroskop ve taramali elektron mikroskop (SEM), kimyasal yapilari Fourier Transform Infrared (FT-IR) spektroskopisi ile incelenmistir. Mikrokapsullerin elementel bilesimleri SEM-EDX analizi ile arastirilmistir. Analiz sonuclarina gore kuresel morfolojili, parafin cekirdek iceren, isil enerji depolama/yayma ozellikli mikrokapsullerin basariyla uretildigi belirlenmistir. Mikrokapsul yapisindaki nano cinko oksit varligindan kaynaklanan antibakteriyel aktivite kantitatif antibakteriyel test metodu ile arastirilmistir. Test sonucuna gore mikrokapsullerin yapilarina ilave edilen nano cinko oksitten dolayi antibakteriyel aktivite gosterdikleri tespit edilmistir. Calismada uretilen mikrokapsuller emdirme metodu ile pamuklu kumasa uygulanmis ve kumas yapisinda mikrokapsul varligi SEM analizi ile teyit edilmistir. Kumaslarin sicaklik duzenleme ozelligi T-history testi ile tespit edilmistir.

Microencapsulation of Three-Component Thermochromic System for Reversible Color Change and Thermal Energy Storage

In this study, poly(methyl methacrylate)/thermochromic system (PMMA/TS) and poly(methyl methacrylate-comethacrylic acid)/thermochromic system (P(MMA-co-MA)/TS) microcapsules were prepared by using emulsion polymerization method. The thermochromic system was consisting of crystal violet lactone (CVL) as a leuco dye, bisphenol-A (BPA) as a color developer, and 1-tetradecanol (TD) as a solvent. Microcapsules with different ratio of core/shell were synthesized to examine the effect of core/shell ratio on the properties of microcapsules. Phase transition temperatures and enthalpies, morphology, and particle size distributions of the microcapsules were analyzed using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and particle size analyzer instruments, respectively. FT-IR spectroscopy was used to prove the presence of the thermochromic system in the microcapsules. UV-Vis absorption bands of the thermochromic system (TS) and microencapsulated thermochromic system (MTS) at both below and above the melting temperature of the solvent were obtained by using a UV-Vis spectrophotometer. The visible color change depending on temperature was monitored for each microcapsule individually by using a digital camera. Spherical morphology and unimodal particle size distribution of the microcapsules were determined by means of SEM photographs and particle size distribution curve analysis. The mean particle sizes of the produced microcapsules varied in a range of 16.0-35.2 μm. The digital camera photographs and the UV-Vis absorbance curves proved that color changed between dark blue and light blue depending upon the temperature change. Meanwhile, the produced microcapsules were proven for an excellent heat storage capacity for thermal energy storage owing to phase changing of the tetradecanol solvent used in the thermochromic system. The melting enthalpy of the microcapsules ranged from 145.5 J/g to 193.4 J/g.

Enhancing the performance properties of ester-cross-linked cotton fabrics using Al2O3-NPs

In this research, use of aluminum oxide nano-particles (Al2O3-NPs) as a catalyst and co-catalyst in the wrinkle-resistant finishing of cotton fabric with 1,2,3,4-butanetetracarboxylic acid (BTCA), was investigated. For this, cotton fabrics were cross-linked with BTCA catalyzed by Al2O3-NPs or sodium hypophosphite (SHP) in the presence of Al2O3-NPs as the co-catalyst. Surface morphology and chemical composition of the treated fabrics beside the fabric properties, such as wrinkle resistance, flame retardancy, yellowing, and air permeability, were also evaluated. Scanning electron microscope and energy-dispersive X-ray microanalysis proved the presence of Al2O3-NPs on the fabric structure. The cross-linking of the fabrics with BTCA catalyzed by Al2O3-NPs or SHP was identified by Fourier transform infrared spectroscopy. The fabric test results indicated that the Al2O3-NPs co-catalyst could act as a multifunctional finishing material. The flame retardant property of the fabric, besides wrinkle resistance, was improved. It was also concluded that Al2O3-NPs could enhance the finishing performance and minimize the side effect of SHP.