PVC coated glass fiber reinforced composite material production and investigation of the mechanical properties

Yüksek Lisans TeziKompozit malzemeler sahip oldukları yüksek özelliklerden dolayı çağımızın gözde malzemeleridir. Dünya çapında geniş uygulama alanı bulan bu malzemelerin, Türkiye'de de kullanımı giderek artmaktadır. Bu çalışmada termoset matrisli kompozitlere göre üzerinde daha az çalışılan termoplastik matrisli kompozit üretimi ve çekme mukavemeti üzerinde durulmuştur. Takviye olarak kullanılan cam elyaf üzerine termoplastik matris olarak kullanılan PVC kaplaması yapılmış, daha sonra bu malzeme uygun formatta hem dokuma hemde tek yönlü olarak preslenerek anizotropik yapıda kompozit levha üretilmiştir. Bu levha üzerinde uygun standartlara göre çekme deney numuneleri çıkarılarak her iki yöndeki (atkı-çözgü) çekme dayanımları karşılaştırılmıştır. Fiber olarak kullanılan cam elyafa göre oldukça düşük dayanıma sahip olan ancak kolay üretilmesi, çok geniş kullanım alanına sahip olması, elektrik ve ses izolasyonu sağlaması, geçirgenlik ve geri dönüşüm yeteneğine sahip termoplastik matris malzeme (PVC)'ye daha yüksek mekanik özellikler kazandırılması amaçlanmıştır.Composite materials are the favorite materials in our age because of their high properties. The use of these materials has wide application area in the world and usage has increasing in Turkey. In this study focuses on thermoplastic matrix composite production and tensile strength, which are less studied than thermoset matrix composites. On the glass fiber used as a reinforcement, PVC coating which is used as a thermoplastic matrix was made, then this material was pressed in a suitable format both in weaving and unidirectional to produce anisotropic composite sheet. Tensile test specimens were removed from this plate according to the appropriate standards and the tensile strengths on both direction (weft-warp) were compared. It is aimed to acquire higher mechanical properties to thermoplastic matrix material (PVC) which has very low strength but has easy production, wide usage area, electrical and sound insulation, transparency and recycling ability compared to glass fiber used as fiber

The effect of silicon dioxide and zinc borate on the flame retardancy, thermal and mechanical properties of jute/epoxy hybrid composite

With the increase in environmental pollution, studies on the use of sustainable resources are increasing day by day. For this purpose, the use of natural fiber-reinforced polymer composites is encouraged in many areas such as automotive, transportation, construction, and home textiles. However, they are flammable and therefore seriously threaten the safety of people and property. Various flame retardant additives have been used to improve the flame retardancy properties of these composites. In this study, silicon dioxide (SD) and zinc borate (ZB) microparticles in different weight percentages (3, 5, 7, and 10%) were reinforced to give flame retardant properties to jute-epoxy composites. In addition, composites containing both SD and ZB microparticles were produced and they were labeled as HB. Then, thermal conductivity, flammability, water absorption, and mechanical properties of these composites were investigated. The burning rate of the composites decreased as the amount of microparticle increased. 5ZB5SD, including %5 SD and %5 SD microparticles, showed 36.60% less burning rate than the neat jute-epoxy composite. 5ZB showed 10.84% higher tensile strength than the neat jute-epoxy. The impact strength of the specimens increased with the increase in the filling ratio, and 5ZB5SD showed approximately 2.50 times the impact strength of the jute-epoxy composite

Re-examining the characteristics of pediatric multiple sclerosis in the era of antibody-associated demyelinating syndromes.

Background: The discovery of anti-myelin oligodendrocyte glycoprotein (MOG)-IgG and anti-aquaporin 4 (AQP4)-IgG and the observation on certain patients previously diagnosed with multiple sclerosis (MS) actually have an antibody-mediated disease mandated re-evaluation of pediatric MS series. Aim: To describe the characteristics of recent pediatric MS cases by age groups and compare with the cohort established before 2015. Method: Data of pediatric MS patients diagnosed between 2015 and 2021 were collected from 44 pediatric neurology centers across Turkiye. Clinical and paraclinical features were compared between patients with dis-ease onset before 12 years (earlier onset) and >= 12 years (later onset) as well as between our current (2015-2021) and previous (< 2015) cohorts. Results: A total of 634 children (456 girls) were enrolled, 89 (14%) were of earlier onset. The earlier-onset group had lower female/male ratio, more frequent initial diagnosis of acute disseminated encephalomyelitis (ADEM), more frequent brainstem symptoms, longer interval between the first two attacks, less frequent spinal cord involvement on magnetic resonance imaging (MRI), and lower prevalence of cerebrospinal fluid (CSF)-restricted oligoclonal bands (OCBs). The earlier-onset group was less likely to respond to initial disease-modifying treatments. Compared to our previous cohort, the current series had fewer patients with onset < 12 years, initial presentation with ADEM-like features, brainstem or cerebellar symptoms, seizures, and spinal lesions on MRI. The female/male ratio, the frequency of sensorial symptoms, and CSF-restricted OCBs were higher than reported in our previous cohort. Conclusion: Pediatric MS starting before 12 years was less common than reported previously, likely due to exclusion of patients with antibody-mediated diseases. The results underline the importance of antibody testing and indicate pediatric MS may be a more homogeneous disorder and more similar to adult-onset MS than previously thought