Measurements of Optical Properties of Smoke Particulates Produced from Burning Polymers and Their Implications

A series of cone calorimetry experiments and simultaneous gravimetric sampling and light extinction (GSLE) measurements were performed to determine the optical properties (light obscuration and extinction characteristics) of smoke particulates produced from burning polymers. The polymer selected in the present study was acrylonitrile-butadiene styrene (ABS), which has a moderate smoke yield during combustion, and unplasticized polyvinyl chloride (UPVC), which has a lower smoke yield than ABS. The experiments show that the measured light obscuration for UPVC smoke particles is much lower than that for ABS smoke particles because of the low rate of smoke production during combustion. Results from the simultaneous GSLE measurements demonstrate more clearly that UPVC smoke particles represent a lower efficiency of light obscuration on a per-unit smoke mass basis, resulting in a 41.3% reduction in a mass specific extinction coefficient compared to the ABS smoke particles. Numerical analysis was performed to further elucidate the effect of optical properties on the smoke behavior using the Fire Dynamics Simulator (FDS) (Version 6.7.1, National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA). The numerical results clearly demonstrated that the UPVC combustion, with its relatively low heat release rate and mass specific extinction coefficient, caused a significant delay in detecting a fire with a smoke detector compared to ABS combustion.

KAJIAN AWAL SPEKTRUM SERAPAN UV−Vis SENYAWA HASIL EKSTRAK DAUN JERUK NIPIS (Citrus aurantifolia) ASAL TARUS KABUPATEN KUPANG

Abstrak Penelitian tentang kajian awal spektrum serapan UV−Vis senyawa hasil ekstrak daun jeruk nipis (Citrus aurantifolia) asal Tarus Kabupaten Kupang telah dilakukan. Tujuan penelitian ini adalah untuk menentukan nilai jangkauan serapan, koefisisen serapan, celah energi dan koefisien ekstingsi spesifiknya. Daun jeruk nipis kering dihaluskan sampai menjadi serbuk, diekstraksi secara maserasi,dievaporasi menggunakan evaporator, kemudian diencerkan dengan menggunakan pelarut etanol. Selanjutnya hasil tersebut dikarakterisasi menggunakan Spektrometer UV-Vis untuk mendapatkan spektrum serapannya. Berdasarkan hasil analisis spektrum serapannya, jangkauan serapan untuk konsentrasi 100 ppm, 200 ppm, dan 300 ppm berkisardari 200 nm sampai 700 nm. Nilai koefisien serapan maksimumnya pada 100 ppm sebesar4,387cm-1, 200 ppm sebesar6,589cm-1dan 300 ppm sebesar8,044cm-1. Nilai celah energinya sebesar 1,838 eV. Berdasarkan nilai celah energi tersebut senyawa hasil ekstraksi daun jeruk nipis dapat dikelompokan menjadi bahan semikonduktor. Nilai koefisien ekstingsi spesifik maksimumnyaadalah 15.841mL gram-1 cm-1pada panjang gelombang 212 nm. Kata Kunci: Daun jeruk nipis, spektrum serapan, jangkauan serapan, koefisien serapan, celah energi dan koefisien ekstingsi spesifik Abstract The preliminary study of the UV-Vis absorption compounds spectrums from the extraction of lime leaves (Citrus aurantifolia) from Tarus on Kupang regency was conducted. The purpose of this study is to determine the absorption range value, absorption coefficient, energy gap, and specific extinction coefficient. Dry lime leaves are mashed, extracted, evaporated, then diluted using ethanol solvent. Furthermore, the results were characterized using a UV-Vis spectrometer to obtain the absorption spectrum. Based on the results of the absorption spectrum analysis, the absorption range for concentrations of 100 ppm, 200 ppm, and 300 ppm ranges from 200 nm to 700 nm. The maximum absorption coefficient values at 100 ppm, 200 ppm, 300 ppm are 4,387 cm-1, 6,589 cm-1, 8,044 cm-1 respectively. The value of the energy gap is 1,838 eV. Based on the energy gap values, the compounds extracted from lime leaves can be classified as semiconductor materials. The maximum specific extinction coefficient value is 15.841 mL gram-1 cm-1at 212 nm. Keywords: Lime Leaves, Absorption spectrum, Absorption range, Absorption coefficient, energy gap, and specific extinction coefficient

Linear growth of marine microalgae culture

A new explanation for linear growth microalgae culture density is proposed. Equations describing the dependence of light absorption coefficient and the specific rate of biomass synthesis on chlorophyll concentration are obtained. The specific extinction coefficient for Tetraselmis virilis culture (0.008 m-2 · mg chlorophyll a) is calculated.

Comparison of Ultraviolet Absorption and Chlorine Analysis Methods for Composition of Butadiene-p-Chlorostyrene Copolymers

The percentage of chlorine in a copolymer containing chlorostyrene can be determined by amperometric titration of the chloride ion present after sodium fusion of the polymer. Since the percentage of chlorine is proportional to the percentage of chlorostyrene, the composition of a butadiene—chlorostyrene copolymer may be determined directly. This absolute method of composition determination affords a means of checking the ultraviolet spectrophotometric method which has been proposed for the determination of the composition of butadiene—styrene copolymers. In the application of the spectrophotometric method it is assumed that the specific extinction coefficient of the copolymer varies linearly with the percentage of styrene between the values of the same wave length for polybutadiene and polystyrene. The spectrophotometric measurements are made at 260.0 mµ or at 269.5 mµ for copolymers of butadiene with styrene or with p-chlorostyrene, respectively.

Spectrophotometric Determination of the Styrene Content of Butadiene-Styrene Copolymers

The ultraviolet absorption of polystyrene, with maximum absorption at 262 mµ, is due to the presence of phenyl residues in the polymer. The specific extinction coefficient is constant, i.e., independent of the molecular weight of the polymer. This shows that the extinction of the phenyl residues is additive. On the basis of this fact, it is shown that the styrene content of a butadiene-styrene copolymer (such as GR-S rubber) can be determined by ultraviolet spectrophotometry. The relative precision of the determination is about 1 per cent, the probable relative accuracy is about 3 per cent.

Further observations on the ultra-violet absorption spectra of the serum proteins. - The specific extinction coefficient of serum pseudo-globulin

Ill a recent paper (Smith, 1929) one of the present writers described the ultraviolet absorption spectra of the serum proteins. The object of this work was to establish absorption curves which could be taken as reliable and which could be used as a standard of reference in later investigations. The writers (Marrack and Smith, 1930), working on the composition of diphtheria toxinantitoxin floccules, have recently shown that these floccules are composed mainly of pseudo-globulin. In this investigation the writers’ conclusions as to the nature of the floccules were based mainly on their ultra-violet absorption curves. The value of 1.2 was used as the extinction coefficient at the head of the curve for a 0.1 per cent, solution of pseudo-globulin of 1 cm. thickness (Smith, 1929).