Effect of Graphite Filler on the Physiochemical Properties of Graphite Reinforced Thermoset Rooflite – Unsaturated Polyester Resin Composites

Received: 24.01.24. Revised: 09.02.24. Accepted: 09.02.24. Available online: 29.02.24.The authors would like the thank the Principal, and Head of the department of Chemistry, Government Arts college, Udumalpet 642 126, for allowing us to conduct the experi-ments. We extend our thanks to Dr. R. Venckatesh, Depart-ment of Chemistry, Government Arts college, Udumalpet 642 126 for helping us in the IR spectral studies of the sam-ples. The Authors wish to thank DST FIST DST-FIST-2018 (SR/FST/COLLEGE-417/2018) (TPN-2011) laboratory of the department for providing assistance to this research.The crystallinity index of the studied composite materials increased due to the enhanced interaction between the resin matrix and graphite filler.Agglomeration due to higher concentration of graphite filler lowers the interfacial contact and affects the mechanical characteristics of the composites.The glass transition temperature increases with the addition of graphite.When the percentage of graphite in composites is raised, the limiting oxygen index revealed that the composites are self-extinguishing.The synthetic composites exhibit a consistent swelling behavior in response to different chemical environments.It is well known that many polymers are insulators with poor mechanical properties, which limit their use in fuel cell applications. Physicochemical properties of the polymers can be improved by adding conductive fillers. Carbon-based materials like graphite, which provides excellent mechanical strength and thermal conductivity to the polymer matrices, is of special interest because of its abundance, low cost and light weight when compared to other carbon allotropes. In the present work we describe the physicochemical properties of rooflite unsaturated polyester resin/graphite composites. Rooflite resin and three of its composites containing 1%, 3% and 5% of graphite by weight (C-2, C-3, and C-4, respectively) were synthesized and characterized by FTIR spectral data. XRD showed two peaks at 2 = 27.37°and 55.40° with d spacing value of 3.2559 nm and 1.6571 nm, respectively, indicating the change in degree of crystallinity of the composite. The calculated crystallinity for the resin is 7.3%, and for C-2, C-3 and C-4 its values are 12.1%, 14.3%, 17.1%, respectively, evidencing the interactions between the graphite and polymer matrix. The composites showed fractured surfaces and porous rough structure with randomly distributed vascularized cavities. Agglomeration occurs, when the concentration of graphite increases. The glass transition temperature for the pure resin is 65.9 °C and increases when the resin is filled with graphite. Thermogravimetric analysis (TGA) of the composites showed no marked difference between Tmax and Tfinal, and LOI values of C-3 and C-4 are above 21%, making them self-extinguishable materials that could be used for making bipolar plates. The chemical resistance investigation against water, NaCl, NaOH, acetic acid, and toluene showed more resistance to acid than alkali solutions. These rooflite resin/graphite composites could be further studied to explore the possibility of making bipolar plates, which are an essential component of fuel cells

A 45-year old man with recurrent syncope: an unusual presentation of coronary artery disease

A 45-year old normotensive, euglycaemic, non-smoker was referred from a peripheral hospital to the Cardiology unit of the University College Hospital, Nigeria for evaluation of recurrent exercise induced syncope. Initial 12-lead electrocardiogram (ECG), 24-hr ambulatory ECG, transthoracic echocardiogram and electroencephalogram (EEG) were normal. A repeat episode of syncope warranted further investigation. Immediate post syncope ECG showed deeply inverted symmetrical T waves in the anterior leads. He underwent coronary angiogram which revealed distal left main disease and 70-80% stenosis of the proximal Left Anterior Descending Artery (LAD). The Circumflex artery was non dominant with normal Right Coronary artery. He subsequently had Percutaneous Transluminal Coronary Angioplasty (PTCA) of the LAD. Post-revascularisation course has been satisfactory with no recurrence of syncope. In view of the rising trend of cardiac death in the country, there is the need for high index of suspicion in making diagnosis of coronary artery disease in patients with syncope.Pan African Medical Journal 2013; 14: 7

Randomized comparison of six versus twenty-four months clopidogrel therapy after balancing anti-intimal hyperplasia stent potency in all comer patients undergoing percutaneous coronary intervention. Results of the PRODIGY Trial 1M.ValgimigliG.CampoG.Percoco(PRODIGY Investigators)Randomized comparison of six versus twenty-four months clopidogrel therapy after balancing anti-intimal hyperplasia stent potency in all comer patients undergoing percutaneous coronary intervention. Results of the PRODIGY Trial2011European Society of Cardiology Scientific CongressParis

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A case of recurrent unstable angina – Insight from optical coherence tomography imaging

Intimal tear is a rare cause of ACS and is angiographically indistinguishable. OCT provides unprecendented insight to the mechanism of ACS with its near tissue level definition. This is a case of unstable angina with non-significant RCA lesion. OCT showed intimal tear/flaps with evidence of thrombi, thus clinching the diagnosis

Dual left anterior descending coronary artery with origin of short left anterior descending coronary artery from left main shaft - A rare coronary anomaly

Dual left anterior descending (LAD) coronary artery with separate origin of the short LAD from the left main (LM) coronary artery is very rare and not reported in the literature. A 49-year-old male was admitted with history of mid-sternal chest pain at rest. He underwent coronary angiography, which showed normal origin of the left and right coronary arteries. A LAD branch (short LAD) with an early take-off from the LM entered the proximal interventricular groove and gave rise to the septal branches. The LM then divided into the circumflex branch and the other LAD branch (long LAD), which ran on the left ventricular side of the interventricular groove and entered the groove distally. The major diagonals originated from the latter LAD

Zero contrast optical coherence tomography–guided percutaneous coronary intervention for in-stent restenosis of the saphenous vein graft using a non-contrast flush medium

Percutaneous coronary intervention (PCI) is often denied for individuals with coronary artery disease who are prone to develop contrast-induced acute kidney injury. We report a 73-year-old, stage 3 chronic kidney disease patient (CKD), who underwent coronary artery bypass surgery and saphenous vein graft (SVG) stenting in the past, presented with in-stent restenosis (ISR) of SVG stent. Zero contrast optical coherence tomography (OCT) guided–PCI was successfully performed using low molecular weight dextran-40 (LMWD-40) as the flush medium. Our report suggests the safety and feasibility of LMWD-40–based OCT-guided zero contrast PCI in ISR of SVG in a CKD patient, although further prospective studies are needed to evaluate this technique. Keywords: Zero contrast, Optical coherence tomography, Dextran-40, Chronic kidney disease, Percutaneous coronary intervention, Contrast induced-Acute kidney injur