Mechanical, thermal, and fire properties of polylactide/starch blend/clay composites

Polylactide (PLA)/starch blend/clay and PLA/clay composites are prepared by melt blending. Structural and thermal characterizations are performed by differential scanning calorimetry, X-ray diffraction analysis, and thermogravimetric analysis. The fire properties are assessed on a dual cone calorimeter. Combustion residue and char formation is characterized by optical microscopy and attenuated total reflection infrared spectroscopy. Although the clay is not fully intercalated/exfoliated, the composites exhibit a higher thermal stability and much reduced peak heat release rate, and the PLA/starch blend composite retains its mechanical properties. For the PLA/starch blend composite, smoke release is also considerably reduced. Catalyzed, oxidative decomposition is shown to occur early in the thermal decomposition of the composites, prior to increased thermal stability. The inclusion of clay promotes char formation and increases the quantity of carbonaceous char in the combustion residue. There is minimal migration of the clay to the surface prior to ignition and char is formed mainly after ignition and during burning. During the later stages of burning some of the char formed is converted to CO₂.     

HPTLC Densitometric Quantification of Glycyrrhizin,Glycyrrhetinic Acid,Apigenin, Kaempferol and Quercetin from Glycyrrhiza glabra

Glycyrrhiza glabra Linn., commonly known as liquorice, is a reputed drug of Ayurveda. In the present work we developed and validated densitometric methods for quantification of glycyrrhizin, glycyrrhetinic acid, apigenin, kaempferol and quercetin using HPTLC. The developed methods were found to be precise and accurate. The amount of glycyrrhizin, glycyrrhetinic acid, and quercetin was found to be 1.070, 0.84 and 0.271% w/w, respectively. Apigenin and kaempferol were quantified in free (0.007 and 0.033% w/w) as well as bound (0.021 and 0.074% w/w) forms. This is the first report of simultaneous quantification of glycyrrhetinic acid and apigenin as well as kaempferol and quercetin from G. glabra. Furthermore, no TLC densitometric methods have been reported for the quantification of apigenin, kaempferol and quercetin from G. glabra.

     

HPTLC Densitometric Quantification of Glycyrrhizin, Glycyrrhetinic Acid, Apigenin, Kaempferol and Quercetin from Glycyrrhiza glabra

Glycyrrhiza glabra Linn., commonly known as liquorice, is a reputed drug of Ayurveda. In the present work we developed and validated densitometric methods for quantification of glycyrrhizin, glycyrrhetinic acid, apigenin, kaempferol and quercetin using HPTLC. The developed methods were found to be precise and accurate. The amount of glycyrrhizin, glycyrrhetinic acid, and quercetin was found to be 1.070, 0.84 and 0.271% w/w, respectively. Apigenin and kaempferol were quantified in free (0.007 and 0.033% w/w) as well as bound (0.021 and 0.074% w/w) forms. This is the first report of simultaneous quantification of glycyrrhetinic acid and apigenin as well as kaempferol and quercetin from G. glabra. Furthermore, no TLC densitometric methods have been reported for the quantification of apigenin, kaempferol and quercetin from G. glabra.     

Isolation and TLC Densitometric Quantification of Gallicin, Gallic Acid, Lupeol and β-Sitosterol from Bergia suffruticosa, a Hitherto Unexplored Plant

Bergia suffruticosa (Elatinaceae family) is an important Indian medicinal plant hitherto unexplored for its chemical constituents and its pharmacological activity. In the present paper we report our work on isolation of gallicin, gallic acid, lupeol and β-sitosterol from the plant. To the best of our knowledge, this is the first report of these four compounds from this plant. Further, these four marker compounds were quantified by thin layer chromatography densitometric methods using high performance thin layer chromatography. The thin layer chromatography densitometric methods were found to be precise with RSD for intra-day in the range of 0.61–1.83, 1.14–1.57, 0.38–0.52 and 0.15–0.52 and for inter-day in the range of 0.97–1.45, 0.58–1.27, 0.42–0.50 and 0.26–0.61 for different concentrations of gallicin, gallic acid, lupeol and β-sitosterol. Instrumental precision was 1.05, 1.20, 0.65 and 0.85 (% RSD) for gallicin, gallic acid, lupeol and β-sitosterol. Accuracy of the method was checked by conducting recovery studies at three different levels for the four compounds and the average percentage recoveries obtained were 99.89, 100.58, 99.79 and 100.11%. B. suffruticosa sample was found to contain 0.34% w/w of gallicin, 0.288% w/w of gallic acid, 0.064% w/w of lupeol and 0.034% w/w of β-sitosterol.     

Development of Hemp Fibre – PP Nonwoven Composites

Summary: Nonwoven mats from hemp and polypropylene fibres in various proportions were produced and hot pressed to make composite material. The effect of hemp fibre content and anisotropy in nonwoven mats resulting from the carding technology were examined on the basis of the three-point bending, tensile and impact properties of the resultant composite materials. Because of the hydrophilic nature and poor dimensional stability of cellulosic fibres due to swelling, the effect of water sorption on mechanical performances was also investigated. Optimal mechanical properties were achieved in composites made from 40–50% of hemp fibre by weight. As it was expected, better mechanical properties were found in the specimens cut from the composite sheets parallel to the direction of carding. A strong decrease in three point bending properties was noticed after immersing the composite samples in distilled water for 19 days, while the impact strength increased. Double carding of raw materials resulted in a decreased anisotropy in composite material.     

Functionalisation of polypropylene non-woven fabrics (NWFs)

Surface oxyfluorination had been carried out on polypropylene non-woven fabric (PP NWF) samples of different morphologies and pore sizes. The modified surfaces were characterised by Attenuated Total Reflectance Fourier Transform InfraRed (ATR-FTIR)-spectroscopy, FTIR imaging microscopy, X-Ray Photoelectron Spectroscopy (XPS), Electron Spin Resonance (ESR) spectroscopy, Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), dynamic rheometry and Thermo-Gravimetry (TG). ATR-FTIR and XPS techniques revealed the presence of ?CCF, ?CCF₂, ?CCHF and ?CC(O)F groups. The formed ?CC(O)F groups mostly got hydrolysed to ?CCOOH groups. The C=O groups of alpha-haloester, and the C=C stretching of the formed ?CCF=C(OH)?C groups could also be detected. Long-lived radicals could be detected on the functionalised surfaces as middle-chain peroxy radicals by ESR spectroscopy. SEM micrographs showed slight roughening of the oxyfluorinated surfaces. Oxyfluorination had no significant effect on the crystalline structure and phase composition of the PP NWF samples supported by DSC and XRD measurements. The molecular mass of the samples were unaffected by the oxyfluorination treatment as proved by oscillating rheometry. The surface modification, however, significantly affected the thermal decomposition but not affected the thermo-oxidative decomposition of PP NWFs. Different morphologies and pore sizes of PP NWF samples resulted in reproducibility of the findings, although did not substantially affect surface functionalisation.