Thermoplastic Monomer Research Articles

Antifungal Action of Thyme and Basil Extracts on Different Denture Base Materials

Statement of problem: The use of medical plants has expanded as a result of increased resistance of microbes to chemical medications, as well as their negative effects and excessive costs. Ocimum basilicum (basil) and Origanum Syriacum (Thyme), were studied for their antifungal activities against Candida albicans (C. albicans) species. Purpose: The goal of this study is to see if two plant extracts, Ocimum basilicum (basil) and Origanum Syriacum (Thyme), have antifungal effects on different denture base materials (long cycle heat-polymerized methyl methacrylate PMMA, short cycle heat-polymerized PMMA, and thermoplastic monomer free microcrystalline polymer karadent). Material and methods: Plant extracts (basil and thyme) were tested for antifungal activity using the pores method. The effect of plant extracts on various denture base surfaces was determined using a disc diffusion test. Fifty-four discs of 6mm diameter and 2mm thickness were prepared from long cycle heat-polymerized methyl methacrylate PMMA, short cycle heat-polymerized PMMA, and thermoplastic monomer free microcrystalline polymer karadent and distributed into three groups:-ve control, basil, and thyme. The diameter of growth inhibition zones was determined after these discs were placed on a Sabouraud Dextrose agar surface and incubated for 24 hours at 37 C. Results: Both Origanum syriacum, and Ocimum basilicum were efficient against Candida albicans. Origanum Syriacum extracts showed a superior antifungal effect compared to the Ocimum basilicum extract with long and short curing cycle acrylic resin, but in Karadent the values of Ocimum basilicum were higher than those of Origanum syriacum extract.

Evaluation of bond strength between nanohybrid composite teeth and two different denture base materials (comparison study )

Purpose: aim of the study was to compare the bond strength of nanohybrid composite artificial teeth (NHC) and two types of denture base material ( acrylic denture base material and thermoplastic monomer free semi-rigid micro crystalline polymer denture base material (Karadent) . Material and Methods : nanohybrid composite teeth (premolars) was sliced equally , grooved for increasing contact surface and attached to 16 discs of denture base material (8 for each group), then the discs where grouped into two groups . The samples were subjected to tensile forces till failure by using the Instron Universal testing machine. Results : bonded nanohybrid composite teeth (NHC) to conventional acrylic denture base disc specimens showed better results in comparison to thermoplastic monomer free semi-rigid micro crystalline polymer denture base materials ones. Conclusion : it is recommended to use NHC teeth more often with conventional acrylic denture bases than thermoplastic monomer free semi-rigid micro crystalline polymer denture base materials.

Monomer Selection for In Situ Polymerization Infusion Manufacture of Natural-Fiber Reinforced Thermoplastic-Matrix Marine Composites.

Awareness of environmental issues has led to increasing interest from composite researchers in using “greener” materials to replace synthetic fiber reinforcements and petrochemical polymer matrices. Natural fiber bio-based thermoplastic composites could be an appropriate choice with advantages including reducing environmental impacts, using renewable resources and being recyclable. The choice of polymer matrix will significantly affect the cost, manufacturing process, mechanical properties and durability of the composite system. The criteria for appropriate monomers are based on the processing temperature and viscosity, polymer mechanical properties, recyclability, etc. This review considers the selection of thermoplastic monomers suitable for in situ polymerization during resin, now monomer, infusion under flexible tooling (RIFT, now MIFT), with a primary focus on marine composite applications. Given the systems currently available, methyl methacrylate (MMA) may be the most suitable monomer, especially for marine composites. MMA has low process temperatures, a long open window for infusion, and low moisture absorption. However, end-of-life recovery may be limited to matrix depolymerization. Bio-based MMA is likely to become commercially available in a few years. Polylactide (PLA) is an alternative infusible monomer, but the relatively high processing temperature may require expensive consumable materials and could compromise natural fiber properties.

Bond strength of hard and soft relining materials to thermoplastic monomer free microcrystalline polymer ( In-vitro comparative study)

Purpose analysis of bond strength of various denture relining materials to recently introducedthermoplastic monomer free semi rigid microcrystalline polymer and heat cured denture basematerials.Materials and methods: designed with cylindrical –shaped silicon patterns with dimensions20 mm in length and 8mm in diameter. Samples branched into four groups(20 samples for eachgroup):GI: heat cured acrylic resin samples with hard relining material, GII: heat cured acrylic resinsamples with soft relining material. GIII: thermoplastic monomer free semi-rigid microcrystallinepolymer (karadent) samples with hard relining material, GIV: thermoplastic monomer free semirigidmicrocrystalline polymer samples with soft relining material .Tensile and shear bond strength of hard & soft reliner to the two denture base materialsexamined by Instron Universal Testing Machine . Multiple group comparisons was assisted byone-way ANOVA test followed by T- test for pair wise comparisons to estimate any significantdifferences between groups. The tests deemed significant when p ≤ 0.05 and highly significantwhen p ≤ 0.001.Results: Highly significant differences for both tensile and shear bond strength mean valueswas found between groups regarding the mean applied loads, P-value ≤ 0.001. The t- test forcomparison showed a extremely significant variance in the mean tensile & shear bond strengthbetween groups. Hard relining material showed greater mean values of both shear and tensile bondstrength regarding the heat cured denture base material (GI) followed by karadent one (GIII) . Thelowest mean values was found in soft relining material, specially that with karadent denture basematerial ( GIV) for both shear and tensile bond strength.Conclusion: supporting on the results of this research, it might be terminated that newlyintroduced thermoplastic monomer free semi rigid microcrystalline polymer successfully acceptrelining specially with hard relining material .It overcomes the main problems of thermoplasticresins that can’t accept relining

Ultra-high-speed processing of nanomaterial-reinforced woven carbon fiber/polyamide 6 composites using reactive thermoplastic resin transfer molding

High-speed molding of continuous carbon fiber-reinforced composites was carried out by thermoplastic resin transfer molding using a very-low-viscosity thermoplastic monomer. After dispersing 0.1 wt.% of various nanomaterials in ε-caprolactam, a monomer of anionic polymerized polyamide 6 (A-PA6), the processing temperature and catalyst-activator contents were optimized based on the polymerization induction time required for resin injection in the mold. Additionally, the dispersion stability, solidification time, monomer conversion, crystallinity and mechanical properties of the composites were evaluated. Higher dispersion stability of the nanomaterials in A-PA6 resulted in a significantly shortened process cycle time – on the order of seconds –and higher crystallinity in the composite. In addition, carbon fibers treated with atmospheric plasma were used to increase the rate of resin impregnation into fibers. These factors not only increased composite fabrication productivity but also enhanced its mechanical properties.

Efektivitas karet alam termoplastik sebagai peningkat indeks viskositas minyak pelumas kendaraan

Diversification of rubber goods are highly needed to enhance natural rubber domestic consumption. One of the efforts is by using thermoplastic natural rubber that is synthesized from emulsion graft copolymerization of natural rubber latex with thermoplastic monomer as index viscosity improver of lubricating oil. The research aimed to study the effect of thermoplastic natural rubber (natural rubber–styrene copolymer) addition, at various concentration, into base paraffinic lube oil (HVI 60 and HVI 650) on index viscosity value of lubricating oil. The result showed that emulsion graft copolymerization at composition ratio of natural rubber to styrene monomer 85:15, at 65oC for 7 hours, with addition of 1% ammonium peroxidisulfate as initiator and 2% sodium dodecyl sulfate as surfactant produced thermoplastic natural rubber (TPNR, copoly NR-ST) with grafting efficiency of 56,48%. The TPNR can be functioned properly as index viscosity improver at 5% concentration to base paraffinic lube oil either HVI 60 or HVI 650. The obtaining new lubricating oils could fulfill the index viscosity standard requirement refered to Decree of Directorat General of Oil and Gas No 85K/34/DDJM/1998, and could compete with the commercial lubricating oil type 20W-50, 10W-40, and 15W-40.

Pengaruh Rasio Karet Alam Terdeproteinisasi dengan Monomer Vinil terhadap Karakteristik Karet Alam Termoplastik

<em>Chemical modification of natural rubber latex by emulsion graft copolymerization with thermoplastic monomer produces thermoplastic natural rubber (TPNR). Ratio composition of natural rubber to thermoplastic monomer determines the TPNR properties. TPNR has good mechanical properties of natural rubber and high processability of plastic material thus enhancing its application in industry. The research, which was conducted at research laboratory of Indonesian Rubber Research Institute, from June to December 2014, aimed to study the effect of the ratio of deproteinized natural rubber (DPNR) latex to vinyl monomer (VM: methyl methacrylate and styrene) on physical and mechanical properties of TPNR produced from batch graft copolymerization. Batch graft copolymerization was conducted at certain ratios of DPNR latex with methyl methacrylate and styrene </em><em>(70:30; 60:40; and 50:50) at (65°C, 5 hours), and subsequently at (70°C, 1 hour)</em>.<em> The result showed that batch technique tend to cause the formation of homopolymer vinyl which also affected the TPNR properties. Visually, the TPNR had white color, hard and brittle texture yet easier to process as shown by low time and energy consumption during compounding. The ratio of DPNR to VM at 70:30 was regarded as the optimum ratio for its balanced properties between elastomeric material of DPNR and thermoplastic material of VM.</em>

Evaluation of a Newly Formulated Thermoplastic Monomer Free Complete Denture Base Material (Microbiological Study)

Evaluation of a Newly Formulated Thermoplastic Monomer Free Complete Denture Base Material (Microbiological Study)

Application of GPC in the Study of Stereospecific Block Copolymers

Abstract Three different techniques involved in the preparation of Stereospecific block copolymers were studied using gel permeation chromatography (GPC). These techniques involved the use of a monofunctional organo-lithium catalyst, a difunctional organolithium catalyst, and a combination of a monofunctional organolithium catalyst and a coupling technique. GPC curves were obtained on the block copolymers using two different column sequences and solvents. The ABA block copolymers studied contained styrene, vinyl toluene, or α-methyl styrene as thermoplastic monomers and butadiene as the elastomeric monomer. The results obtained showed that block copolymers prepared using monomers and catalyst systems free of impurities generally exhibited single peaked GPC curves. In systems where impurities were found to be present, small amounts of A block homopolymer and AB block copolymer were formed. In such cases, the GPC curves were observed to have two or three peaks.