Retardant Polymer Research Articles

Bioinspired polyimide film with fire retardant and gas barrier properties by gravity‐induced deposition of montmorillonite

AbstractFlame retardants play a crucial role in improving the flame retardant properties of polymer materials. In recent years, environmental problems caused by flame retardants have attracted widespread attention. It is urgent to use green and effective methods to prepare flame retardant polymers. Bioinspired nanocomposites with layered structures seem to provide effective ideas, but in general, their hydrophilic raw materials limit their applications in certain fields. Here, we prepared biomimetic composites with a layered “brick‐and‐mortar” structure by gravity‐induced deposition using polyimide as the polymer matrix and montmorillonite (MMT) as the filler. The well‐arranged structures of the composite material could isolate oxygen and prevent combustible gases from escaping. The gas barrier performance has been greatly improved, in which the water vapor transmission rate and the oxygen transmission rate decreased by 99.18% and three orders of magnitude, respectively. The flame retardant performance has also been improved, and its limiting oxygen index can reach 67.9%. The polyimide matrix can be converted to water‐insoluble by thermal imidization of water‐soluble poly (amic acid) salt precursors, which endows the composites with low hygroscopicity. The coating containing MMT can protect against polyurethane (PU) foam from fire. During the conical calorimetric test, the coated sample self‐extinguished, and the peak heat release rate, total heat release, and total smoke production are significantly decreased by 53.39%, 40.69%, and 53.03%, respectively. Taking advantage of these properties, this work utilizes a facile method to prepare biomimetic composites with low moisture absorption, excellent gas barrier properties, and flame retardancy, which have great application potential.

Gel electrolyte with flame retardant polymer stabilizing lithium metal towards lithium-sulfur battery

Gel polymer electrolytes have the advantages of both solid and liquid electrolytes. Generally speaking, the liquid electrolyte is physically stored in the porous structure of polymer matrix which cannot block the reactions between the liquid electrolyte and the thermodynamically unstable lithium metal. At the same time, the stored liquid electrolyte still presents a safety hazard. This work designed and prepared a flame-retardant polymer Polyimide (PI) that can gelatinize the classic carbonate liquid electrolyte to form a flame-retardant gel polymer electrolyte, which greatly improved the safety of the battery. More importantly, there was CH/π interaction between the PI and the carbonate solvents which obviously reduced electrolyte consumption and side reactions with lithium metal. The proposed gel polymer electrolyte achieved a high lithium ion transference number of 0.727 and ensured remarkably stable lithium-sulfur batteries with SPAN cathodes.

FORMULATION AND EVALUATION OF FLOATING DRUG DELIVERY SYSTEM OF REPAGLINIDE

Objective: The present study’s is to develop floating drug delivery system of repaglinide. Methods: Moringa gum, Repaglinide, HPMC K100M, Sodium alginate, Calcium Carbonate, Sodium Citrate. The obtained formulation was evaluated for drug content, pH, in vitro gelling capacity, in vitro buoyancy studies, and in vitro dissolution studies. Results and Discussion: All the total F1-F12 formulations showed pH ranging from 5.1 to 7.9, floating lag time of F1-F12 ranging from 5 s to 12 s with total floating time greater than 12 h, viscosity of F1-F12 ranging from 619 to 3856 cp, drug content of F1-F12 ranging from 31.2% to 93.1%, and percent drug release of F1-F12 ranging from 78.9% to 93.9%. Dissolution studies showed that F12 formulation-containing drug (30 mg) and polymer (4000 mg) showed 93.9% drug release in 12 h which is said to be optimized. Thus, the best formulation (F12) was subjected for a 3-month period of stability studies found to be stable and reported no significant change. Conclusion: The study’s goal is to develop and evaluate floating in situ gel forming solution of repaglinide with moringa gum as rate retardant polymer.

Formulation and Evaluation of Floating Microspheres of Sitagliptin

Gastro retentive dosage forms have potential for use as controlled- release drug delivery systems. Gastro retentive floating drug delivery systems have a bulk density lower than that of gastric fluids and thus increase residence time of drug in stomach and provide controlled delivery of many drugs. The aim of the present study is formulation and characterization of floating microspheres using Sitagliptin as a model drug for the management of type-2 diabetes mellitus. Floating microspheres were prepared by oil-in-water emulsion solvent evaporation technique using ethyl cellulose and eudragit S-100 as release retarding polymers. The floating microspheres were evaluated for percentage yield (%), particle size, drug content, drug entrapment efficiency, in-vitro floating ability and in-vitro drug release studies. The surface morphology of prepared microspheres was characterized by scanning electron microscopy. The microspheres were found to be spherical in shape and porous in nature. Compatibility studies were performed by fourier transform infrared (FTIR) technique. The prepared microspheres showed prolonged drug release of 12 h and remain buoyant for more than 12 h. In-vitro release kinetics were studied in different release kinetics models like zero order, first order, higuchi and korsmeyer peppas model and the best fit model was found to be higuchi plot with release exponent n value less than 0.89. It was concluded that developed floating microspheres of Sitagliptin offers a suitable and practical approach for prolonged release of drug over an extended period of time and thus oral bioavailability, efficacy and patient compliance is improved.

Improvement of flame retardancy and thermal stability of highly loaded low density polyethylene/magnesium hydroxide composites

AbstractThis study aims to enhance the flame retardant efficiency and thermal stability of low density polyethylene (LDPE) by using halogen‐free inorganic additives. To prepare the highly loaded flame retardant polymer composites, LDPE melt mixes with magnesium hydroxide and magnesium carbonate at different weight ratios using a twin‐screw extruder. The composites are characterized by thermogravimetric analysis, crystallinity degree, tensile strength, morphological analysis, limiting oxygen index and UL‐94 vertical burning test. An optimum MH/MC weight ratio of 60/40 provides satisfactory composite properties with increased maximum thermal degradation temperature from 472.3 to 483.5°C, the highest LOI value of 32.5% and a UL‐94 V‐0 rating without melt dripping. The homogeneity of this composite is improved by using a polymeric compatibilizer, MAH‐g‐PE and an enhancement in tensile strength, elongation at break and elastic modulus values of 33.68%, 33.02% and 23.55%, respectively, are obtained. In order to create synergism between the flame retardant additives, 1, 3 and 5 wt% zinc borate is added to the composite system. The incorporation of 5 wt% ZB causes a significant delay in the thermal decomposition of MH with an improvement of 51.8°C in maximum degradation temperature. This composite also exhibits a satisfactory flame retardant grade with a UL‐94 V‐0 rating.

NANOSPONGE HEALING APPROACH FOR TREATMENT OF STREPTOCOCCAL GANGRENE

Objective: The envisaged research work aims to develop a nanosponge loaded gel for the treatment of Streptococcal gangrene. Methods: In the present study, permeability is enhanced by targeted drug release formulation of topical clindamycin phosphate nanosponges were prepared by emulsion solvent diffusion method using ethyl cellulose as release retardant polymer and PVA as surfactant or emulsifier. Nanosponges were prepared by emulsion solvent diffusion method by changing drug polymer ratio (1:0.05, 1:0.1, and 1:0.15) and process parameters were optimized using 32 full factorial central design. CP nanosponges were then incorporated into a hydrogel prepared using Carbopol 934. Results and Discussion: The drug loaded nanosponges were evaluated for physical appearance, drug content, entrapment efficiency, and particle size. Characterization of CP nanosponges was done by SEM for the formulation. In vitro release study indicated that the release of CP varied according to the concentration of matrix forming polymer. The best standardized formulation G5 and G6 were further evaluated for microbiological studies. Microbial studies were done using Staphylococcus aureus as the strain organism and the activity of the gel against the organism was evaluated by measuring the zone of inhibition. It was also found to be stable for 2 months during its stability studies. Conclusion: Thus, it was concluded that CP can be formulated as nanosponge hydrogel that can release the drug up to 24 h with increased permeability and targeted release. Therefore, clindamycin phosphate nanosponges prepared are promising drug delivery for topical application as being more useful than conventional formulation therapy.

Bio-inspired adenosine triphosphate-modified h-BN-based coral-like CuAl-LDH nanosheets as a functional green flame retardant to improve the fire safety of epoxy resins via catalyzing intumescent char formation

High flammability and fire toxicity are the biggest hindrances to further applications of epoxy resins (EP). In this work, we designed a novel “integrated” green intumescent flame retardant via bio-inspired adenosine triphosphate modification of h-BN-anchored coral-like CuAl-LDH nanosheets (mBN@LDH@PATP). Then, the mBN@LDH@PATP was used as a filler to improve the fire safety of EP. Specifically, the anisotropic heat transfer mode of h-BN can effectively promote the longitudinal barrier and lateral diffusion of heat. The coral-like CuAl-LDH can successfully promote the catalytic carbonization of pyrolytic volatiles and their adsorption. Furthermore, adenosine triphosphate (ATP) synergistically interacts with h-BN and CuAl-LDH to impart a high heat-stable intumescent char network to EP. As expected, mBN@LDH@PATP significantly improved the flame retardancy and smoke suppression of the EP nanocomposites. Compared with the control EP, the prepared mBN@LDH@PATP/EP showed a 43.3 %, 40.8 %, 36.5 % and 39.1 % decrease in PHRR, THR, PSPR and TSP, respectively. In addition, CO and CO2 yield were significantly reduced by 53.5 % and 57.5 %, while LOI (32.9 %) and UL-94 (V-0) were significantly improved. The enhanced fire safety of EP nanocomposites was confirmed by adequate characterization. This research offers a workable way to achieve efficient and environmentally friendly flame retardant polymers.

Flame Retardant Polymer Composite and Recent Inclusion of Magnesium Hydroxide Filler Material: A Bibliometric Analysis towards Further Study Scope

Fire accidents occur frequently and pose a great threat to high-rise buildings with flammable construction materials. Recently, researchers have been doing significant work on this topic to improve the flame retardancy of composites by adding inorganic metal hydroxide, such as magnesium hydroxide (MH), due to its higher thermal decomposition temperature and low toxicity. Research on flame retardant polymer composites with magnesium hydroxide is rapidly moving toward a more sustainable and safer future. This article provides a comprehensive review of the research trend along with the most cited publications. Most cited articles were chosen to observe the developments. The data collected from the Scopus database in the second week of March 2023 were also categorised to present country-wise improvement, the subject areas involved, and the author’s contribution to the topic. Some issues and challenges have also been highlighted from the analysis. By observing the research direction and highly cited articles, some of the further study scopes are also pointed out to develop fire-rated polymer composites for use as sustainable cladding materials for high-rise buildings.

Micro-crosslinking of phosphaphenanthrene/siloxane molecule initiate aggregation flame retardant and toughening enhancement effects on its polycarbonate composite

The precise construction of molecular functional systems is an important way to develop high-performance flame retardant polymer composites with excellent comprehensive mechanical properties. A micro-crosslinked macromolecule (PMD) with group aggregation features has been synthesized from vinyl monomers (MD) bearing phosphaphenanthrene and cyclotetrasiloxane groups. The micro-crosslinking polymerization of MD results in superior structural stability and charring capability. PMD not only endows the polycarbonate (PC) composite with excellent comprehensive flame retardant performance, but also maintains the flexural and tensile properties of the PC matrix, as well as an enhanced anti-impact performance. More importantly, when compared with congeneric low molecular weight contrast, PMD exhibits much higher efficiency in suppressing the combustibility of the PC composite. A toughening effect on the matrix was only observed in the PMD/PCs upon increasing the additive content that did not appear in MVCD/PCs, which fractured more easily. 5 %PMD/PC passed the UL94 V-0 rating with a LOI value of 36.3%, and achieved 31.4% higher impact strength, 46.4% lower pk-HRR, 26.7% longer time to pk-HRR, 57.1% lower FGI, 57.7% higher FPI, and 25.6% lower peak of CO production rate when compared with those of the initial sample. The toughening and flame retardant mechanisms of PMD were also revealed upon analyzing the resultant micro-/macro- morphology and chemical components of the char residue, thermal decomposition volatiles, and pyrolytic fragments. These provide a beneficial molecular-structure construction reference for developing high-performance polymer composites with excellent comprehensive performance in both of flame retardancy and mechanical properties.

Exploration, Development and Optimization of Eco-friendly Novel Dosage Form – Pastilles

Background: Now-a-day, there is the need to explore the concept of green chemistry in every field. Many existing conventional and novel drug delivery systems have problems related to green chemistry. To overcome the existing limitations of the different dosage forms, a newer untouched dosage form pastilles was explored. Objective: The present study aims to optimize the Glipizide (GPZ) matrix pastilles using waxy erodible polymers integrating the concept of quality by design (QbD) and green chemistry. Methods: The pastilles were formulated using the fabricated lab-scale pastillator. GPZ was used as a model drug. The concern related to the drug is low aqueous solubility and short variable half-life. The solubility of the drug was improved by formulating a complex between GPZ and chemically modified ß –cyclodextrin (β-CD) - hydroxypropyl-ß-cyclodextrin (HP- ß -CD). The complex was prepared using the kneading method. The complex was formulated incorporated different stoichiometric ratios of GPZ: complexing agent. Sustained-release pastille formulated using Gelucire 43/01 (GC 43/01) as release retardant polymer. The central composite design had been used to obtain an optimum batch, using the amount of GC 43/01 and temperature as independent variables, while drug release at 2h, 6h, and 10h was chosen as dependent variables. Design batches were evaluated for post-and preformulation parameters. An optimum formulation was evaluated for the influence of hydroalcoholic media on drug release. Results: The complex formulated using HP- ß –CD (1:1) shown better solubility (36.5mg/ml) and dissolution. The complex was incorporated in the pastilles with erodible polymer GC 43/01. The formulation was found robust with optimum pre and post formulation parameters. Optimized batch was chosen from the design space of central composite design. The drug release of the optimized formulation was found 29.13%, 57.29% and 85.70% at 2, 6 and 10 hrs respectively which was similar to the drug release of the marketed formulation. As the amount of alcohol increased from 5 to 40 %, the drug release also increased but did not show a dose dumping effect. It is just due to the altered solubility of GPZ in alcohol. Conclusion: The untouched formulation, Pastilles of GPZ were developed incorporating the waxy erodible polymer. Pastilles were capable to control drug release up to 12 h. The amount of GC 43/01 and temperature had a significant effect on the formulation of GPZ sustained-release pastille. The newer approach of formulating pastilles might apply to the industry as it is an eco-friendly, single-step process and uses fewer excipients.

Ultra-thin flame retardant polymer nanocomposite coating based on synergistic effect of graphene and glass sheets

It is still a high challenge to develop environmental-friendly and highly efficient flame retardant for application in thin polymer coating. Here, a graphene@glass sheets composite flame retardant is developed and prepared by a new in-situ liquid-phase exfoliation process. When the flame retardant is doped into polymer coating, it exhibits excellent flame retardancy for flammable plastic, wood and nonflammable steel. The limiting oxygen index (ca.32.3%) and UL-94 V-0 rating of a ultra-thin polymer coating (ca.65 um) can be obtained for fire protection of wood. The long fire-retardant time (55.0min) is also observed, which is far longer than that of the conventional polymer coating (1.0 min) for fire protection of steel. This work provides a new strategy for creating cost-effective thin flame retardant polymer coatings for various industrial applications.

Formulation and Evaluation of Sotalol Gastrorententive Tablets

The objective of this study was to formulate floating tablets (GRDDS) of Sotalol using direct compression method to increase its bioavailability and the gastric residence time of the dosage form. The Sotalol tablets were prepared by direct compression method. The tablets were prepared by using different types of polymers i.e.; Sodium CMC, Chitosan and Psyllium Husk which act as a release retardant polymer. Sodium bi carbonate (NaHCO3) was used as a gas degenerating agent and MCC (Micro crystalline cellulose) was used as a diluent. The prepared formulation were subjected to some evaluation parameters like hardness, friability, weight variation, drug content, buoyancy property, drug release study etc. In the FT-IR study it was revealed that there is no interaction between the drug and excipients. The formulation which containing Chitosan polymer and Sodium bicarbonate shows good drug release pattern with less floating lag time and good floating duration. The in vitro drug release pattern of Sotalol floating tablets was fitted to different kinetic models which showed the highest regression for Higuchi order kinetics. Thus, it can be concluded that the floating drug delivery system of Sotalol using the appropriate polymers in right amount may enhance the activity of the drug by prolonging the gastric residence time or reducing the floating lag time.

The influence on flame retardant epoxy composites by a bird's nest-like structure of Co-based isomers evolved from zeolitic imidazolate framework-67

The machining of metal-organic frameworks (MOFs) based templates into diverse layered double hydroxides (LDHs) is essential to maximize their advantages in flame retardant polymers. However, improving the thermal stability of LDHs has so far continued to be a great challenge. Herein, a MOFs sacrificial template has been developed to realize the controlled synthesis of two Co-based isomers, namely CoCo-LDH and cobalt basic carbonate (CBC), with the construction of three different nanostructures of carbonate intercalated CoCo-LDH nanocage (LDH), single yolk@shell CBC@CoCo-LDH (s-CBC@LDH), and multi-yolk@shell CBC@CoCo-LDH (m-CBC@LDH). The thermal stability of CoCo-LDH is enhanced by controlling the reaction time. Moreover, CoCo-LDH from m-CBC@LDH decomposes at the right temperature while CBC nanoparticles further enhanced the flame retardancy. To demonstrate the high performance conjecture on the structure-property relationship, the as-synthesized Co-based isomers were individually integrated into the epoxy matrix to evaluate its comprehensive properties. Compared to LDH and s-CBC@LDH, m-CBC@LDH imparts superior thermal stability, flame retardancy, and comparable mechanical properties onto the epoxy composites. With the incorporation of 2 wt.% m-CBC@LDH, the peak of heat release rate and total heat release are decreased by 38.5% and 19.6%, respectively. This work provides a design direction for improving the flame retardant of epoxy resin.

Development and optimization of floating alginate microspheres of repaglinide using Box-Behnken experimental design

Background: Due to short-lasting action, fast clearance and enzymatic instability of anti-diabetic drugs result in low bioavailability as they are mainly absorbed from the stomach and the lower part of the gastrointestinal tract. The bioavailability of antidiabetic drugs can be significantly increased by enhancing the gastric residence time using gastroretentive drug delivery systems such as floating microspheres.
 Objectives: The present investigation deals with the development and optimization of floating microspheres for gastroretentive delivery containing repaglinide using Box-Behnken design and also investigates the effect of different process variables on the formation of the microsphere. Thereby, increasing the bioavailability and reducing the mentioned side effects of repaglinide.
 Materials and methods: Floating microspheres of repaglinide formulated by ionic gelation method and optimized using Box-Behnken design. The independent variables were the concentration of Hydroxy methylcellulose (HPMC) (A), Sodium alginate (B), and calcium chloride (C) while entrapment efficiency (R1), swelling index (R2), and in vitro drug release (R3) were considered as dependent variables. The optimized formulation of floating microspheres was characterized by various physicochemical properties, surface morphology, drug excipient interaction, in vitro release, and buoyancy studies.
 Results: Based on obtained 3D response surface plot factors A, B, and C were found to give a synergistic effect on R1, while factor A has a negative effect on R2. Interaction of AC was negative on R1 and R2 but positive on R3. The interaction of AC and BC was negative in all the responses. Scanning electron microscopy (SEM) revealed that microspheres were spherical with nearly smooth surface morphology. Good entrapment and buoyancy were observed for 12 h. The in vitro drug release was found to be controlled for more than 12 hours and followed the Higuchi model. The validations of response surface methodology (RSM) for three dependent variables were 100.09%, 99.68%, and 97.02%.
 Conclusion: Repaglinide floating microspheres were prepared and optimized by use of Box – Behnken process optimization software. The quantitative responses of particle size, entrapment efficiency, and in vitro drug release for different combinations of independent variables, sodium alginate as release retarding polymer, HPMC K100M as floating polymer, and calcium chloride as a cross-linking agent were obtained experimentally, and the results were found to fit the design model. The quantitative effect of these factors at different levels on the responses could be predicted using polynomial equations, and high linearity was observed between predicted and actual values of response variables. The results of the present study showed that the responses i.e, particle size, entrapment efficiency, and in vitro release are significantly affected by the concentration of polymer and a cross-linking agent. The formulation OF1 was found to be the optimum formulation predicted by the point prediction of the design expert software. The in vitro drug release was found to be controlled for more than 12 h and followed the Higuchi model. The validations of RSM for three dependent variables were 100.09%, 99.68%, and 97.02%. Therefore, it can be concluded that a floating microsphere for repaglinide was developed and optimized using a three-factor, three-level Box – Behnken design.

Flame Retardant Polymer Nanocomposites: An Overview

AbstractThe overwhelming use of polymer as substitutes for metal, glass, wood, and ceramic has posed the challenge to develop polymer with flame retardant behavior after chemical modification and making composites for effective use of polymer in a wide range of applications. In this context, the present review article describes the advances in the preparation of flame retardant polymer nanocomposite (FPNC) along with the mechanism and properties. The evolved properties of FPNCs are discussed along with illustration and applications such as coating, sheet, and films for different applications in the light chemical composition, size confinement, and dimension alignments.

Extra strong Cu2+-doped intumescent char to protect epoxy resin against fire

The intumescence, compactness, and strength of char are the key points to the intumescent flame retardant system. However, the char residues of flame retardant polymers rarely exhibit all three characteristics, especially strength. Herein, a novel Cu2+-doped intumescent flame retardant (Cu–CHP) was prepared without producing any waste. When Cu–CHP was exposed at a high temperature (∼1400 °C), it can rapidly expand and carbonize to form dense char. Surprisingly, the intumescent char residue of Cu–CHP can hold up more than 2000 times its own weight. Benefitting from the excellent intumescent charring capacity of Cu–CHP, the resultant EP/Cu–CHP18% composite can withstand around 600 s penetrating of butane flame (∼1400 °C) because of strong dense char protection, and only 0.9 wt% Cu2+ content resulted in the limiting oxygen index (LOI) of EP/Cu–CHP18% increases to 31% and the vertical burning (UL-94) reaches V-0 rating. Additionally, its peak heat release rate, total smoke production, and fire growth rate are significantly reduced by 70%, 53%, and 75%, respectively, compared with neat epoxy resin. Especially, the smoke density of EP/Cu–CHP18% was dramatically dropped by more than 68%. Because a Cu2+-doped intumescent, compact, and strong char residue was produced during burning. This work provides a new strategy to impart excellent flame retardancy and smoke suppression to highly flammable polymers by building metal-doped strong intumescent char residues.

Development of metformin HCl granules using brown flaxseed mucilage as a retardant polymer: effects of polymer and drug ratio

Development of metformin HCl granules using brown flaxseed mucilage as a retardant polymer: effects of polymer and drug ratio

Thermal Degradation and Carbonization Mechanism of Fe-Based Metal-Organic Frameworks onto Flame-Retardant Polyethylene Terephthalate.

Currently, the metal-organic framework (MOF) is a promising candidate for flame-retardant polymers. In this study, a Fe-based MOF, MIL-88B(Fe), was introduced to polyethylene terephthalate (PET) and 3-hydroxyphenylphosphinyl-propanoic acid copolymer (P-PET) to reduce the fire hazard involved in using PET. The limiting oxygen indexes (LOIs) of MIL-PET and MIL-P-PET improved by 27% and 30%, respectively. The UL-94 level achieved for MIL-P-PET was V-0 rating. The thermal degradation and carbonization mechanisms of MIL-PET and MIL-P-PET were systematically investigated through thermogravimetric analysis coupled with a Fourier transform infrared spectroscopy (TG-IR), pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), x-ray photoelectron spectroscopy (XPS), and Raman spectrum combined with quantum chemical molecular dynamics simulation. With the addition of MIL-88B(Fe), high graphitization and a hard flammability char residual were generated. Compared with neat PET, the ferric ions efficiently catalyzed the homolytic cleavage and dehydrogenation of PET to produce a large amount of CO2 and terephthalic acid for MIL-PET in gas phase. Rough and hierarchical char residual with ferric oxide was also generated when temperatures exceeded 600 °C. However, the carbonization process was inhibited due to the coordinated complex between phosphorus and ferric ions in MIL-P-PET, invaliding the decarboxylation and generating more benzoic acid and its precursor, which led to heavy smoke.

Recent advances in metal-family flame retardants: a review.

The use of polymer materials is inextricably linked to our manufacturing life. However, most of them are easily combusted in the air and the combustion process generates a large amount of toxic fumes and dangerous smoke. This can result in injuries and property damage, as well as limiting their use. It is essential to enhance the flame-retardant properties and smoke suppression performance by using multiple flame retardants. Metal-based flame retardants have a unique chemical composition. They are environmentally friendly flame retardants, which can impart good smoke suppression, flame retardancy to polymers and further reduce the production of toxic gases. The differences in the compounds formed between the transition metals and the main group metals make them act differently as flame retardants for polymers. As a result, this study presents the research progress and flame-retardant mechanism of flame-retardant polymers for flame retardants from different groups of metals in the periodic table of elements in a systematic manner. In view of the differences between the main group metals and transition metals, the mechanism of their application in flame retardant polymer materials is carefully detailed, as are their distinct advantages and disadvantages. And ultimately, prospects for the development of transition metals and main group metals are outlined. It is hoped that this paper will provide valuable references and insights for scholars in the field.

Formulation and Evaluation of Controlled Release Tablet of Irbesartan

The main aim of present work was to formulate and evaluate controlled release matrix tablets of Irbesartan. It releases drugs at fixed and expected rate in a controlled manner either by dissolution and diffusion control mechanism. The matrix tablet was prepared by wet granulation method using by various concentration of HPMC and ethyl cellulose with combination of various release retardant polymer. The powder mixtures were subjected to various pre- compression parameters such as angle of repose, bulk density, tapped density and Carr’s index shows satisfactory result and the compressed tablets are evaluated for post- compression parameters such as weight variation, thickness, hardness, friability, drug content and in- vitro dissolution studies. In- vitro dissolution studies were carried out for 24 hours using 0.1N HCL for first 2 hours and ph 6.8 phosphate buffers for 24 hours and the result showed that formulations F3 and F4 show good dissolution profile to control the drug release respectively. The drug content of the formulation was determined by using 0.1 N HCL at 262nm. The drug content was maximum with formulation F5 and minimum with formulation F3.