Effect of Dendritic Copper Powder Addition to Polyamide 12 in Selective Laser Sintering

Günümüzde polimer malzemeler ev eşyalarından mühendislik uygulamalarına kadar geniş bir kullanım alanına sahiptir. Bu nedenle özelliklerinin geliştirilmesi önemlidir. Katkı maddeleri ilavesi, polimer malzemelerin özelliklerini artırabilmektedir. Katkı ilave tekniği ve bileşimleri imalat yöntemine göre değişebilmektedir. Yeni bir üretim yöntemi olup kızılötesi lazer ışını ile polimer tozlarının sinterlenmesine dayanan Seçici Lazer Sinterleme (SLS) toz yataklı eklemeli imalat metodunda da katkı maddelerinin kullanılması mümkündür. Bu metotta katkı kullanımı çok yaygın olmasa da en çok tercih edilen katkı maddeleri seramik esaslı inorganik malzemelerdir. Bununla birlikte, ince metalik parçacıklar da katkı maddesi olarak kullanılabilir. Bu çalışmada dendritik bakır tozu katkılı poliamid 12'nin SLS ile prosesi incelenmiştir. İki farklı katkı içeriğindeki toz karışımları proses parametreleri belirlemek amacıyla karakterize edilmiş ve artan enerji yoğunluğunun kullanılması gerektiği saptanmıştır. Beş farklı parametre kullanılarak üretilen numunelerin fiziksel ve mekanik testleri sonucu katkı ilavesiyle eğme özellikleri ve boyutsal hassasiyet düşerken, yüzey pürüzlülüğü değişmemiş ve depolama modülü iyileşme göstermiştir.Today, polymer materials have a wide range of usage areas that are from household goods to engineering applications. Therefore, improvements in their properties are essential. The addition of fillers can increase the properties of polymer materials. Filler addition techniques and compositions can vary with the manufacturing methods. It is also possible to use fillers in selective laser sintering (SLS) powder bed fusion additive manufacturing method, which is a new manufacturing method based on the sintering of polymer powders with an infrared laser beam. Although the use of fillers is not very common in this method, the most preferred fillers are ceramic based inorganic materials. However, fine metallic particles could also be used as fillers. This study investigates the processing of dendritic copper powder filled polyamide 12 by SLS method. Powder mixtures in two different filler contents were characterized to determine process parameters, and it was determined that increased energy density should be used. As a result of the physical and mechanical tests of the sintered samples produced using five different parameters, the bending properties and dimensional sensitivity decreased with the filler addition, while surface roughness did not change, and the storage modulus improved

Polyamide 12/E-glass Fabric Composite Production with Dip-coating

In this study PA12 was reinforced with E-glass woven fabric by dip-coating. PA12 powder and ethanol suspensions were prepared with ratios at 30, 40 and 50% of powder to obtain different fibre contents. Coated fabrics were laid-up and kept in oven at 60°C to evaporate ethanol. Then it was placed in a compression mould and pressed. Obtained laminates were subjected to tensile, bending and impact tests. Fractured surfaces were observed. It was found that mechanical properties were highest when 40% PA powder used in suspension with dip-coating with additional lamination. Fibre failure and fibre pull-out were observed on fractured surfaces

Polyamide 12/E-glass Fabric Composite Production with Dip-coating

In this study PA12 was reinforced with E-glass woven fabric by dip-coating. PA12 powder and ethanol suspensions were prepared with ratios at 30, 40 and 50% of powder to obtain different fibre contents. Coated fabrics were laid-up and kept in oven at 60°C to evaporate ethanol. Then it was placed in a compression mould and pressed. Obtained laminates were subjected to tensile, bending and impact tests. Fractured surfaces were observed. It was found that mechanical properties were highest when 40% PA powder used in suspension with dip-coating with additional lamination. Fibre failure and fibre pull-out were observed on fractured surfaces

Effects of Copper Fillers on Mechanical and Electrical Properties of Selective Laser Sintered PA 12-Cu Composites

Selective Laser Sintering (SLS) is a widely used additive manufacturing (AM) technique for creating 3D geometries by adding materials in layers. Although neat polymer is mainly used in powder forms for production, organic or inorganic fillers can be added to produce polymer composites by SLS method. In this study, Polyamide 12 (PA 12) matrix composite parts filled with two different copper particles, dendritic and spherical shaped, were produced, and their mechanical, structural and electrical properties were investigated. The present study outlined that by increasing incident energy densities during sample fabrication, changes in mechanical and electrical characteristics were examined. The findings were analysed in terms of filler type and energy input, which were discovered to have a slight change in the bending behaviour of SLS components. Furthermore, the impact strength was shown to increase constantly with increasing energy density. Furthermore, whereas the electrical conductivity of spherical Cufilled parts rose considerably, no significant change was seen in dendritic-shaped Cu-filled parts

Inkudostapedial Bağlantı Süreksizliklerinin Onarımında Kullanılan Cam İyonomer Çimentosunun Biyomedikal Özellikleri

In this study, the biomechanical properties of glass ionomer cement used for repair of incudostapedial joint bridge in ear in two different distances was investigated. A master block was used to locate the incus and stapes with a 91 degree angle constant. Two experimental groups were composed according to the distances between incus and stapes which were adjusted as 1.0 and 2.0 mm. The mixture of bone cement was applied to the gap between incus and stapes and adhere them together. Compression tests were performed to these joints. Strength value of group 1 were found significantly higher than group 2 (p=0.042). The fragility of bone cement used in 2 mm gap was 25,5% higher compared to 1 mm ga

Effects of copper fillers on mechanical and electrical properties of selective laser sintered PA 12-Cu composites

Selective Laser Sintering (SLS) is a widely used additive manufacturing (AM) technique for creating 3D geometries by adding materials in layers. Although neat polymer is mainly used in powder forms for production, organic or inorganic fillers can be added to produce polymer composites by SLS method. In this study, Polyamide 12 (PA 12) matrix composite parts filled with two different copper particles, dendritic and spherical shaped, were produced, and their mechanical, structural and electrical properties were investigated. The present study outlined that by increasing incident energy densities during sample fabrication, changes in mechanical and electrical characteristics were examined. The findings were analysed in terms of filler type and energy input, which were discovered to have a slight change in the bending behaviour of SLS components. Furthermore, the impact strength was shown to increase constantly with increasing energy density. Furthermore, whereas the electrical conductivity of spherical Cu-filled parts rose considerably, no significant change was seen in dendritic-shaped Cu-filled parts

The Effects of Local and Systemic Administration of Proline on Wound Healing in Rats

Purpose: Wound healing consists of a sequence of complex molecular and cellular events. Collagen is composed mainly of proline and hydroxyproline. Proline and hydroxyproline constitute 1/3 of the amino acids in collagen, which makes up approximately 30% of the proteins within the body. The hydroxylation of proline found in collagen determines the stability of the triple helical structure of collagen. In this study, we examined the effects of local and systemic administration of proline on wound healing. Materials and Methods: 24 female Sprague-Dawley rats were used in the study and divided into three groups. Group 1: The defect created in the backs of the subjects was left to secondary healing. Group 2: 200 µl proline per day was administered topically for 30 days on the defect in the backs of the subjects. Group 3: 200 µl per day was administered intraperitoneally for 30 days on the defect in the backs of the subjects. Results: On day 21, there was a statistically significant difference between the groups in terms of the mean re-epithelialization score. On days 7 and 14, there was a statistically significant difference between the groups in terms of the mean granulation score. On days 7, 14, and 21, there was a statistically significant difference between the groups in terms of the mean collagen accumulation score. On day 30, there was a statistically significant difference between Groups 1 and 3 in terms of the mean E-mode score on mechanical tensile test. Conclusion: Our study confirmed that proline has positive effects on wound healing. However, it revealed that systemic administration of proline is more effective than local administration of proline

Nutritional characteristic of children with inflammatory bowel disease in the nationwide inflammatory bowel disease registry from the Mediterranean region

© 2022, The Author(s), under exclusive licence to Springer Nature Limited.Background/objectives: We analyzed the nationwide pediatric inflammatory bowel disease (PIBD) registry (1998–2016), to evaluate the nutritional status at the time of diagnosis. Subjects/methods: Nine types of nutritional status by the combination of weight-for-length (2 years) and length/height-for-age with three categories (2 SD) were described. Malnutrition was defined by WHO criteria. Univariate and multivariate regression analysis was used to identify risk factors for malnutrition. Results: In total, 824 IBD patients (498 Ulcerative colitis (UC); 289 Crohn’s Disease (CD); 37 Indeterminate Colitis (IC); 412 male; the median age 12.5 years) were eligible. The prevalence of eutrophy, wasting/thinness, stunting, overweight, tall stature, concurrent wasting/thinness and stunting, tall stature with overweight, tall stature with wasting/thinness, and short stature with overweight were 67.4%, 14.9%, 6.6%, 3.1%, 3.2%, 3.3%, 1.1%, 0.4%, and 0.1%, respectively. The prevalence of malnutrition was 32.7%, indicating a higher prevalence in CD (p 10 years), prepubertal stage, severe disease activity, perianal involvement, and high C reactive protein level were independently associated with malnutrition in pediatric IBD. Conclusion: We showed the frequency of nutritional impairment in PIBD. The percentage of overweight subjects was lower than the other studies. The age of onset, disease activity, CRP level, perianal involvement, and pubertal stage were associated with a higher risk for developing malnutrition. Our results also confirmed that CD patients are particularly vulnerable to nutritional impairment. Clinical trial number: ClinicalTrials.gov Identifier: NCT04457518