PE Sample Research Articles

Particle size effects on silyl‐chromate/VOx/silica bimetallic catalyst for UHMWPE/HDPE in‐reactor blends

AbstractIn this work, four kinds of silica with similar textural properties but different particle size (PS) from 6 to 60 μm were selected as support to prepare silyl‐chromate/VOx/silica bimetallic catalysts for ethylene polymerization, thus making it possible to conduct convincing investigation on the effects of catalyst PS over catalytic behaviors and polymer properties. It is found, owing to mass‐ and heat‐transfer limitations, the catalysts with smaller PS showed higher initial activity, while the deactivation in the later stage was more remarkable. Meanwhile, catalysts with smaller PS synthesized bimodal ultrahigh molecular weight polyethylene/high‐density polyethylene in‐reactor blends (UHMWPE/HDPE IRBs) with higher molecular weight (MW) and narrower molecular weight distribution (MWD). Four PE sample couples with MW increasing from 5 × 105 to 10 × 105 g mol−1 and PS from 40 to 460 μm were selected for tensile and rheological tests. For each couple with similar MW and MWD, the sample with smaller PS always had larger tensile strength and breaking elongation. The cryogenically fractured surface of the samples made by smaller PE particles showed fewer delamination defects and unfused small particles. The rheological results indicate that higher homogeneity was achieved for the sample with smaller PS, which was reflected by the unexpected higher viscosity and storage modulus.

High molecular weight bimodal polyethylene elastomers using N,N'-nickel catalysts appended with methoxy and trifluoromethoxy functionality

Polyolefinic materials displaying bimodal molecular weight distributions are of interest since they can potentially provide mechanical toughness from the high molecular weight component without losing processability on account of the low molecular weight component. With this in mind, a series of nickel(II) complexes, [1-[2,6-{(4-MeOC6H4)2CH}2–4-(F3CO)C6H2N]-2-(ArN)C2C10H6]NiBr2 (Ar = 2,4-Me2C6H3Ni1, 2,6-Et2C6H3Ni2, 2,6-iPr2C6H3Ni3, 2,4,6-Me3C6H2, Ni4, 2,6-Et2-4-MeC6H2Ni5, 2,6-Me2C6H3Ni6) have been synthesized and have shown, following treatment with MMAO or Et2AlCl, excellent activity for the polymerization of ethylene (up to 19.87 × 106 g (PE) mol−1 for Ni4/Et2AlCl) generating high molecular weight branched polyethylene. More importantly, the elastomeric material produced using Et2AlCl as activator displays bimodal characteristics as well as low crystallinity and a medium to high branching density. By contrast, the material prepared using MMAO was more unimodal and showed higher crystallinity and lower branching density. Stress–strain and stress–strain recovery tests performed on the bimodal PE’s revealed a range of tensile properties with a sample prepared using Ni5/Et2AlCl combining both high tensile strength and high fracture strength (σ = 20.3 MPa, ε = 892.0 %). Conversely, a PE sample prepared using Ni4/Et2AlCl showed the highest elastic recovery with a stress relaxation (SR) value of 67.6 %. Besides branching analysis, molecular weight determinations and mechanical tests on the polymers, all nickel complexes and precursor 1,2-bis(arylimino)acenaphthenes, have been characterized by a combination of spectroscopic techniques, elemental analysis and in the cases of Ni1(OH2) and Ni4 by single crystal X-ray diffraction. A theory is also proposed to explain the observed bimodality.

Abstract P136: First Steps In Uncovering Mechanisms In Late Onset Preeclampsia

Preeclampsia is a leading cause of maternal morbidity and mortality worldwide, complicating 2-8% of pregnancies. The etiology of PE is poorly understood, the role of placental extracellular matrix (pECM) in PE is understudied. Extravillous trophoblasts (HTR8/svneo) and pECM are crucial in placental blood vessel formation, including spiral arteries. The objective is to identify changes in signaling mechanisms in late onset PE and how HTR8/svneo respond. Additionally, we explored a novel therapeutic to restore HTR8/svneo phenotype by phototherapy using a 670nm LED light. Western blot analysis shows eNOS, phospho-eNOS and Hsp90 expressions are unchanged in late onset PE placental samples despite previous reports in early onset of PE. The association of Hsp90 to eNOS and eNOS to phospho-eNOS is reduced in the PE sample. Soluble Flt, a diagnostic marker for PE, levels are increased in media from HTR8/svneo trophoblasts cultured on PE pECM. Endothelial function is significantly reduced in an isolated vessel as determined by acetylcholine stimulation. 670nm light reverses this impairment. Migration of HTR8/SVneo on PE pECM is reduced (control 86.29±18.58, PE 30.16±15.49) but proliferation of HTR8/SVneo on PE pECM is unaffected in patients (control: 59.125±6262.9, PE:67.125±7706.5). Proliferation and migration are improved by 670nm light (proliferation control 101.375±2075.4; PE 106.875±4870.7, migration control 125±11.97, PE 144.84±16.01). An increase of apoptotic HTR8/SVneo cultured on PE pECM is observed compared to healthy pECM in patients control 2.4±0.24, PE 3±0.4 samples. 670nm light treatment decreases the number of apoptotic cells, control 1.2 ±0.58, PE 1.4±0.5. Conclusion: In late onset preeclampsia, endothelial function is decreased, sFlt release is increased, the eNOS/Hsp90/p-eNOS axis is slightly reduced pointing to O 2 - synthesis. Migration is decreased likely due to impaired trophoblast invasion, but proliferation is unaffected. 670nm light treatment can reverse some of the effects of the preeclamptic microenvironment. Extracellular matrix is altered in late onset PE leading to an abnormal HTR8/SVneo phenotype. 670nm light restores the phenotype of HTR8/SVneo on PE pECM suggesting 670nm light as a therapeutic treatment.

Influence of ionic liquids on mechanical and thermal properties of polyethylene from renewable resources

Polyethylene from renewable resources produced using sugarcane as raw material was modified with phosphonium ionic liquids. Tensile properties and thermal behavior of modified biopolyethylene in air and nitrogen atmosphere were studied. The thermal degradation of ionic liquids and their influence on thermal degradation of polyethylene from renewable resources were studied by thermogravimetric analysis (TGA). In general, modification of biopolyethylene with phosphonium ionic liquids resulted in improvement of tensile properties, i.e., tensile strength and Young’s modulus. Thermal degradation of biopolyethylene modified with phosphonium ILs proceeds in one step in the range of 400–500 °C in nitrogen atmosphere. Modification of polyethylene with trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate ionic liquid resulted in increase in DTGpeaks and T10% temperatures toward higher temperature for modified polyethylene in comparison with unfilled PE sample both in air and nitrogen atmosphere.

High-Throughput Preparation of Antibacterial Polymers from Natural Product Derivatives via the Hantzsch Reaction.

SummaryThe Hantzsch and free-radical polymerization reactions were combined in a one-pot high-throughput (HTP) system to simultaneously prepare 30 unique polymers in parallel. Six aldehydes derived from natural products were used as the starting materials to rapidly prepare the library of 30 poly(1,4-dihydropyridines). From this library, HTP evaluation methods led to the identification of an antibacterial polymer. Mechanistic studies revealed that the dihydropyridine group in the polymer side-chain structure plays an important role in resisting bacterial attachment to the polymer surface, thus leading to the antibacterial function of this polymer. This research demonstrates the value of multicomponent reactions (MCRs) in interdisciplinary fields by discovering functional polymers for possible practical applications. It also provides insights to further developing new functional polymers using MCRs and HTP methods with important implications in organic chemistry, polymer chemistry, and materials science.

Assessment of destruction of polyethylene modified with pro-oxidants in the context of environmental safety

The paper presents the results of the evaluation of the destruction of polyethylene LDPE (hereinafter-PE), modified by prooxidants based on iron, copper and cobalt carboxylates (in the amount of 1.5 mass. % ) with accelerated thermal and ultraviolet aging for 192 hours. The assessment of degradation in the context of environmental safety included the determination of the degree of compliance of the materials with the requirements of state standard 33747-2016 "Oxo-biodegradable packaging", according to which the criterion of the efficiency of oxobiodestructionpolyolefins may be a decrease in strength and elongation at break of the sample at accelerated aging, as well as the quantitative determination of the release of formaldehyde during thermal degradation modified with prooxidants PE for comparison with the maximum permissible concentration. The rheological parameters of the materials were studied and a comparative assessment of the melt viscosity reduction and reduction with respect to elongation at break in the dynamics of accelerated thermal and UV aging of the PE modified with prooxidants in the selected time interval of 192 hours of exposure was carried out. A decrease in the relative elongation at rupture of PE containing cobalt - based prooxidant by 94% at thermal aging for 192 hours, and by 46% at ultraviolet was established. For PE modified with copper carboxylate, these values were 64 and 33 %, respectively, for PE modified with iron carboxylate – 35% and 40%, respectively. The reduction of strength by 95% of the initial value for 192 hours of temperature exposure was achieved in a sample modified with cobalt, which confirms its compliance with state standard 33747-2016. For other samples, the degree of strength reduction in the selected time interval does not allow to assess compliance with the specified standard. The release of formaldehyde during thermal aging for 192 hours per 1 g of the PE sample modified with cobalt carboxylate was 0.051 mg/m3, for PE modified with copper carboxylate – 0.032 mg/m3, for PE modified with iron carboxylate – 0.034 mg/m3. Installed excessive concentrations of formaldehyde in air hood PH with the carboxylate of cobalt 1.2 times under thermal aging 96 hours and 1.5 times the thermal ageing of a maximum of 192 hours. The reduction of the viscosity of PE containing cobalt – based prooxidant by 90% at thermal aging for 192 hours and by 10% at ultraviolet was recorded. For PE modified with copper carboxylate, these values were 9 and 2 %, respectively, for PE modified with iron carboxylate – 8 and 5%, respectively.

Altering the hierarchical morphology distribution of injection molded polyethylene by the introduction of crosslink network and periodical shear

High density polyethylene (HDPE) with moderate content of crosslink network (CPE) was successfully prepared through chemical method. Specimens for structural characterization have been molded by conventional injection molding (CIM) and pressure vibration injection molding (PVIM). Influence of crosslink network on hierarchical morphology distribution and mechanical properties was systematically studied. Polarized light microscopy (PLM) revealed that both CIM and PVIM PE samples have a typical “skin-core” structure and the thickness of shear layer of CIM PE and PVIM CPE samples obviously increase. Scanning electron microscopy (SEM) showed that shish-kebab structures are clearly observed in shear layer of CIM CPE sample, indicating that the crosslink network can surely improve the formation of shish-kebab structures. Moreover, we suppose that shish-kebab structures emerged in shear and core layer of PVIM CPE sample. Wideangle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) confirmed that more orientation and shish-kebab structures form even in core layer of PVIM CPE sample, which demonstrated that the hierarchical morphology was apparently altered by periodical shear and crosslink network. Finally, the mechanical properties revealed that this oriented structure increase the tensile strength from 31 MPa of CIM PE sample to 46 MPa of PVIM CPE sample. However, the tensile behavior tended to change from ductile fracture to brittle fracture.

The health of California's immigrant hired farmworkers

Hispanic immigrant workers dominate California's hired farm workforce. Little is known about their health status; even less is known about those lacking employment authorization. The California Agricultural Workers Health Survey (CAWHS) was a statewide cross-sectional household survey conducted in 1999. Six hundred fifty-four workers completed in-person interviews, comprehensive physical examinations, and personal risk behavior interviews. The CAWHS PE Sample is comprised mostly of young Mexican men who lack health insurance and present elevated prevalence of indicators of chronic disease: overweight, obesity, high blood pressure, and high serum cholesterol. The self-reported, cumulative, farm work career incidence of paid claims for occupational injury under workers compensation was 27% for males and 11% for females. The survey finds elevated prevalence of indicators of chronic disease but lack of health care access. Participants without employment authorization reported a greater prevalence of high-risk behaviors, such as binge drinking, and were less knowledgeable about workplace protections.

Simple, Efficient, and Cost-Effective Multiplex Genotyping with Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry of Hemoglobin Beta Gene Mutations

A number of common mutations in the hemoglobin beta (HBB) gene cause beta-thalassemia, a monogenic disease with high prevalence in certain ethnic groups. As there are 30 HBB variants that cover more than 99.5% of HBB mutant alleles in the Thai population, an efficient and cost-effective screening method is required. Three panels of multiplex primer extensions, followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were developed. The first panel simultaneously detected 21 of the most common HBB mutations, while the second panel screened nine additional mutations, plus seven of the first panel for confirmation; the third panel was used to confirm three HBB mutations, yielding a 9-Da mass difference that could not be clearly distinguished by the previous two panels. The protocol was both standardized using 40 samples of known genotypes and subsequently validated in 162 blind samples with 27 different genotypes (including a normal control), comprising heterozygous, compound heterozygous, and homozygous beta-thalassemia. Results were in complete agreement with those from the genotyping results, conducted using three different methods overall. The method developed here permitted the detection of mutations missed using a single genotyping procedure. The procedure should serve as the method of choice for HBB genotyping due to its accuracy, sensitivity, and cost-effectiveness, and can be applied to studies of other gene variants that are potential disease biomarkers.

Tribocharging of Granular Plastic Mixtures in View of Electrostatic Separation

The output of any electrostatic separation process is strongly dependent on the effectiveness of particle charging. A novel laboratory-scale fluidized-bed tribo-charging device has been described in a previous paper. The aim of the present work is to asses the effectiveness of two materials, aluminium and polypropylene, that could be employed for the manufacturing of the tribo-charging chamber of that device. The electrostatic separation experiments designed in this purpose were carried out on three samples of a granular polyethylene/polyvinyl chloride mixture, characterized by different compositions. Aluminium and polypropylene were found to be equally effective for the tribo-electrostatic separation of the 50% PVC, 50% PE sample. For the other two samples (10% PVC, 90% PE; 90% PVC110% PE), the best results were obtained with the polypropylene tribo-charging chamber.

Fe(acac)3-bis(imino)pyridine/MAO: A new catalytic system for ethylene polymerization

New catalytic systems, composed of bis(imino)pyridine (2,6-bis[1-(2,6-diisopropylphenylimino)ethyl]pyridine (A1), methylene-bridged bis(imino)pyridine (A2)), iron (III) acetylacetonate (Fe(acac)3), and methylaluminoxane (MAO), are highly active for ethylene polymerization. The performance of this new catalytic system was evaluated with respect to catalytic activity and polymer properties. The highest catalytic activity of Fe(acac)3-A1/MAO (catA) system and Fe(acac)3-A2/MAO (catB) system at optimum condition reaches 10.5 × 106 g PE·(mol Fe h)−1 and 17.3 × 106 g PE·(mol Fe h)−1, respectively. The product viscosity-average molecular weight (Mη) of two catalytic systems range from 0.40 to 8.7 × 105. GPC characterizations of PE obtained show that the PE has bimodal molecular weight distribution (MWD). 13C NMR and DSC analysis of PE sample indicates that the PE is highly linear and crystalline. Analysis of UV–vis absorption spectra, ethylene polymerization results, and prepared polyethylene structures indicate that Fe(acac)3-bis(imino)pyridine/MAO catalytic system could generate same active species as bis(imino)pyridyliron catalytic systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Model-free kinetics analysis of waste PE sample

Vyazovkin model-free approach is applied to study non-isothermal decomposition of waste PE sample using various temperature integral approximations such as Coats and Redfern, Gorbachev, Agrawal & Siva Subramanian and a new approximation [J. Cai, F. Yao, W. Yi, F. He, AIChE J. 52 (2006) 1554] and a new method for direct integration. E α dependency on α is compared with several literature data. Initial strong and increasing E α dependency on α in case of non-isothermal decomposition is associated with initiation at the weak links. Weak but increasing E α dependency on α in the later stages is possibly due to dependence of distribution of size of volatile products on heating rate and random scission. Weak and decreasing followed by weak but increasing function of α in case of isothermal decomposition is possibly due to existence of two opposite effects, nucleation, and distribution of size of volatile products. The sample used follows neither perfectly the LDPE trend nor the HDPE trend. Thus, it becomes mandatory to study the decomposition behaviour of any waste material before design of an incinerator and/or pyrolysis unit without using blindly the information available for standard samples. Optimum E α dependencies from non-isothermal data at 15 K min −1 heating rate best predicted the isothermal data.

Directed Crystallisation of Synthetic Polymers by Low‐Molar‐Mass Self‐Assembled Templates

AbstractA novel and powerful method of microstructure control in polyolefins is presented. By dispersing tiny amounts of sorbitol derivatives in the polymer, the subsequent crystal growth can be controlled with modest prior flow‐fields; in particular high levels of preferred orientation are generated in the resultant crystals. Under shear flow, the additive forms highly extended crystals which lie parallel to the flow‐field and which serve to direct the crystallisation of the polymer leading to a massive amplification of the anisotropy present in the melt.TEM image of a carbon replica taken from an etched surface of a PE sample containing 1% of DBS.magnified imageTEM image of a carbon replica taken from an etched surface of a PE sample containing 1% of DBS.

DSC studies on the melting crystallization of polyethylenes prepared from alkanes of varying molecular size

The melting crystallization behavior of narrow-disperse polyethylene sample prepared from alkane solutions was studied by using differential scanning calorimetry. Avrami analysis of isothermal crystallization of these samples indicates that the PE sample prepared from n-octadecane has significantly higher crystallization rate than that from n-octane.

Effect of the components' molar mass and of the mixing conditions on the compatibilization of PE-LCP blends by PE-g-LCP copolymers

The rheology, morphology, and mechanical properties of blends of high-density polyethylene (HDPE) with a semiflexible liquid crystalline copolyester (SBH) were studied in order to assess the compatibilizing ability of added PE-g-SBH copolymers, and its dependence on the molar mass of the PE matrix, and on the technique used for blend preparation. The PE-g-SBH copolymers were synthesized as described in previous articles, either by the polycondensation of the SBH monomers in the presence of a functionalized PE sample containing free carboxyl groups, or by reactive blending of the latter polymer with preformed SBH. Two samples of HDPE having different molar masses, and two samples of SBH with different melt viscosity and different microstructure, were used for preparing the blends. The two components and the compatibilizer were either blended in a single batch or used to prepare binary master blends to which the third component was added at a later stage. The results indicate that the PE-g-SBH copolymers do, in fact, compatibilize the PE–SBH blends and that the effect is more pronounced with the lower molar mass PE matrix and with the SBH sample having lower viscosity. The experiments carried out on blends prepared with different techniques show that the compatibilizing ability of the graft copolymer is improved if the latter is first blended with either of the two main components. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 603–613, 1999

The effect of degassing on the measurement of transverse relaxation times in molten polymers

Three commercially produced polymer samples (polyethylene, polypropylene, and polystyrene) have been analyzed in the melt state using proton nuclear magnetic resonance (NMR) T 2 relaxation methods using the Carr-Purcell-Meiboom-Gill (CPMG) spin-echo pulse sequence. Samples were run with exposure to air and again after extensive degassing at a vacuum of 10 -4 mmHg for periods of not less than 96 h. The comparison is made by initially considering the presence of microscopic voids in the samples as a source of local field inhomogeneity and how they affect the T 2 relaxation behavior. For PP and PS samples, degassing caused a decrease in all T 2 time constants associated with the multicomponent decays. The component intensities each of the time constants was also significantly altered. For the PE sample, degassing caused a decrease in the time constants associated with the amorphous material in the molten polymer. Examination of the fastest relaxing component of the three component decay showed approximate invariance in the T 2 decay constant. This result supports our previously reported model in which that fast relaxing component is attributable to regions of local order or high segmental density within the molten polyethylene, a remnant of the crystalline material which exists in the premelting bulk polymer. The results of this research are of particular significance to those who wish to use this NMR technique as a quantitative method of determination of NMR distinct morphological regions within heterogeneous polymers

Aromatic Hydrocarbon Emissions from Burning Poly(styrene), Poly(ethylene) and PVC Particles at High Temperatures

A study on the semi-volatile aromatic hydrocarbon emissions from the pyrolysis/combustion of poly(styrene) (PS), poly(ethylene) (PE) and PVC particles was conducted. Dispersions (aerosols) or batches (fixed beds) of the above types of polymer particles, 90-300 μm in diameter, were burned in bench-scale, drop-tube or muffle-type electrically-heated furnaces, respectively. In the drop-tube furnace, pyrolysisis/combustion took place at gas temperatures ranging from 900 to 1200°C and particle heating rates were in the order of 10 3 -10 4 °C/s. The total residence times of the gases in the furnaces were 1 or 2 s ; envelope flames surrounding the particles lasted for 6-130 ms, while residence times in the post-flame region were 0.3-1.8 s depending on the polymer. Semi-volatile organic emissions were captured from the gas and solid phases using XAD-4 adsorbers and glass fiber filters, respectively, and analysis was conducted with gas chromatography coupled with mass spectrometry (GC-MS). The combustion characteristics of single particles of the three plastics were studied in earlier experiments using optical pyrometry and high-speed cinematography. Gaseous diffusion, chemical kinetics and pyrolysis kinetics were inferred, therein, to govern combustion of PS, PVC and PE particles, respectively. The types of the aromatic hydrocarbon emissions were found to depend on the polymer burned, while their relative amounts were influenced by combustion parameters such as temperature, residence time, etc. Substituted poly-aromatic hydrocarbons (PAHs), oxygenated compounds and chlorinated aromatics were detected in the combustion products of PVC. PAHs with fused rings were emitted from the combustion of PE. PAHs, either substituted or with fused rings were emitted from the combustion of PS. As the gas temperatures and residence times increased, the amount of PAH emissions from all polymers decreased. The results indicated that as the size of PVC sample decreased, in the presence of oxygen, the amount of PAHs decreased. However, as the size of PE sample decreased, or when oxygen was present, the amount of PAHs did not necessarily decrease. The behavior of PS was found to be between that of PVC and PS.

屋外ばくろ試験におけるポリエチレン試料の特性変化予測 : 高分子系建築材料の耐久性予測モデル(その1)

In order to predict service life of polymeric building materials, the application of several mathematical formulations is being discussed recently. As the first approach, the most simple polymer, unstabilized polyethylene film was studied in this paper. This PE sample is specified by "JIS K 7200-1986, Standard Reference Test Specimens for Calibrating a Laboratory Light Exposure Apparatus, SR-LS-PE-8604". Photo-oxidation reaction in PE produces carbonyl groups, which can be quantified by infrared abrsorbtion spectrum. The absorbance ratio, A_r, of carbonyl absorbance to methylene is an index of degradation. A_r=A_<1715>/A_<2030> where, A_<1715> : IR carbonyl absorbance at 1715 cm^<-1> and A_<2030> : IR methylene absorbance at 2030 cm^<-1> From the result of preliminary thermal degradation test of PE specimens, the effect of heat under outdoor exposure test was estimated to be negligible. Samples were exposed outdoor on 0°, 30° and 90° planes facing to south in Tsukuba, Japan, lat. 36°7' 38"N, long. 140°4'39"E, every month from November 1986 to Octber 1988. Collected absorbance ratios were expressed as various functions of fructuating outdoor solar ultraviolet energy and temperature of samples. Among the all these models, Koike and Tanaka's Model, [numerical formula] where, C_u : ultraviolet degradation constant, -, U_v :solar ultraviolet energy in 10 minutes, KJ/m^2, α : power number, ultraviolet degradation constant, -, E_u : activation energy of ultraviolet degradation reaction, KJ/mol, R : gas constant, 8.314×10〜<-3> KJ/mol/K and T_p : temperature of sample observed every 10 minutes, K. produced most acceptable accordance of calculated Ar with observed A_r. Obtained degradation constants and correlation factor, r, between observed and calculated Ar are as follows : number of samples, n=72, C_u=1.29×10^<3>, α=0.0165, E_u=36.2, r= Degradation constants, which produce the least error between observed and calculated Ar, are : number of samples, n=24, C_s=2.66×10^5, γ=0.235, E_s=39.6, r=0.9899 Introducing these values and meteorological data at Asahikawa, Choshi and Okinawa, the absorbance ratios of samples exoosured were estimated and compared with the observed ones.0.9882 The value of α is far more smaller than it has been estimated. This predicts that ultraviolet ray initiates photo-oxidation reaction and that oxigen dispersion dominates degradation rate. The absorbance ratios of samples exposured horizontally could be expressed as a function of meteorological factors, solar radiation energy and ambient temperature in daytime : [numerical formula] where, C_s : solar degradation constant, -, S_p : daily amount of solar radiation energy, KJ/m^2, γ : power number, solar degradation constant, -, E_s : activation energy of degradation reaction, KJ/mol, T_D : average ambient temperature in daytime, K, T_D=(T_6/2+T\9,+T_<12>+T_<15>+T_<18>/2)/4 ; sub-number means observed o'clock, JST (Japan Standard Time)

A method for measuring the charging tendency of powder in pneumatic conveyance through metal pipes

The charging tendencies of powders of some synthetic high polymers are measured with a newly developed charging apparatus. The sample is continuously transported through a bent metal pipe using an air flow and is electrified by multiple frictions and collisions against the inner wall of the metal pipe. The transport speed V and the solid load d of the sample are changed from 1.4 to 2.8 m/s and 1.9 to 5.2 kg/m 3, respectively. The charge build-up of each examined is given by the empirical equation: Q = Q s [1 − k exp (−t/τ)]. The saturation charge Q s and the initial rate of charge accumulation q o [ = (d Q/d t) t=0 ] are found to depend on the transport speed and the material of the pipe. The initial rate of charge accumulation q o also depends on the solid load and in the case of a spherical PE sample, it can be described by an experimental equation obtained with aluminium pipe: q o = −2.47 V 0.4 d −1.07 × 10 −6 C/kg s. The saturation charge Q s of each sample used in this measurement at the same transport speed corresponds to the position of each sample in the familiar previously published triboelectric series [1–3].

Structural changes occurring in the annealing and melting of oriented polyethylene

The kinetics of the annealing and melting of oriented medium-density polyethylene (PEMD) have been investigated both in the free state, and under isometric conditions. By means of the special apparatus used for the investigation provision was made both for visual observation and for the recording of low- and wide-angle X-ray diffraction patterns with short exposures. Changes in the annealing temperature of oriented PE were accompanied by smooth changes in the position and intensity of the low-angle reflection. The melting of oriented PE in the free stateor under isometric conditions is not accompanied by the complete disorientation of crystallites. The melt obtained during the annealing of oriented PE in the vicinity of the melting point, under isometric conditions, contains oriented crystalline phase. Two sorts of structure are formed as a result of this type of system, one corresponding to highly-oriented c-texture, and the other to scattered c-texture. On changing from the free oriented PE sample to the isometric PE, while at the same time increasing the drawing ratio it was found that both the melting point and the growth in the maximum long period during annealing were increased.