Crystal structure and thermal properties of poly(vinylidene fluoride)-carbon fiber composite films with various drawing temperatures and speeds

PVDF-CF composite films were prepared using a melt pressing method. The PVDF-CF composite films were cut into rectangular shapes with a gauge length and width of 10 and 5 mm, respectively. The films were drawn using a universal testing machine equipped with a hot chamber. The drawing temperatures and speeds were 50∼150 °C and 100∼000 %/min, respectively. The crystal structure and physical properties of the resulting PVDF-CF films were investigated by wide angle X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis and scanning electron microscopy. The crystal form of the initial films was the 〈alpha〉 phase (non polarity, lamellar structure) of PVDF. The maximum draw ratio was 4.2. The drawn PVDF-CF films prepared at 100 °C were mainly the 〈beta〉 phase (polarity, fibrillar structure) of PVDF. With increasing drawing speeds, the 〈alpha〉 phase became the dominant phase of PVDF in the PVDF-CF films. The thermal properties of the PVDF-CF films improved with increasing drawing temperature, and the dynamic mechanical properties improved with increasing drawing speed.     

Effect of conformation on the properties of uniaxially drawn polylacide films upon drawing temperature

Polylactide(PLA) films were drawn at various drawing temperature of 65, 90 and 120 °C. The effects of drawing temperature on structural conformation and properties of PLA films were investigated. It was confirmed that the PLA films at drawing temperature of 65 and 90 °C were composed of α′ phase crystal form. The strain-induced crystallization and molecular orientation increased with increasing the draw ratio, which result in improving the mechanical and thermal properties of α′ phase PLA films. However, at drawing temperature of 120 °C, the strain-induced crystallization and molecular orientation of PLA films were not distinctly detected. It was supposed that the rate of the chain relaxation was faster than chain orientation and strain-induced crystallization during uniaxial drawing process.     

Tensile behavior and structural evolution of poly(lactic acid) monofilaments in glass transition region

A series of amorphous poly(lactic acid) (PLA) monofilaments with various D-isomer contents of 1∼9 mol% have been prepared and then elongated uniaxially at 25∼65 °C in the glass transition region. Both initial modulus and maximum strength of PLA monofilaments are appreciably decreased with increasing the temperature, especially at ∼50 °C, and they were somewhat lower for the monofilament with higher D-isomer content. Structural evolution, chain orientation, and thermal properties of PLA monofilaments drawn uniaxially with various draw ratios at 65 °C were then investigated by using wide-angle X-ray diffraction, polarized Raman spectroscopy, and differential scanning calorimetry, respectively. X-ray diffraction patterns clearly exhibited the development of chain orientation and stain-induced crystallization of the monofilaments as a function of draw ratio (DR). The dichroic ratio, a measure of the chain orientation, was quantitatively evaluated from the polarized Raman spectra. It was revealed that the dichroic ratios increased up to DR=4 and decreased slightly at DR>4 owing to the strain-induced crystallization for PLA monofilaments with D-isomer contents of 1 and 4 mol%. The glass transition and cold-crystallization temperatures of PLA monofilaments increased and decreased, respectively, with the increment of DR. The strain-induced enthalpy relaxation endothermic peak appearing in glass transition region became intense with increasing the DR.     

Crystal structure and thermal properties of poly(vinylidene fluoridehexafluoropropylene) films prepared by various processing conditions

Poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP) films were prepared using either a melt pressing or solution casting methods. The resulting PVDF-HFP films were drawn uniaxially at various drawing temperatures and speeds. The mp-PVDF-HFP films were more transparent and had more drawability than the sc-PVDF-HFP films. The crystal form of the initial films was the alpha-phase (non polarity) of PVDF. The maximum draw ratio was 7.6. The mp-PVDF-HFP films were prepared at a drawing speed of 2500 %/min at 100 °C. With increasing drawing speed, the beta-phase (polarity) became the dominant phase of PVDF in mp-PVDF-HFP films. The thermal properties of the resulting PVDF-HFP films improved with increasing drawing temperature.     

Preparation and characterization of melt-spun PVC filament yarns

Polyvinyl chloride (PVC) fibers were melt-spun to prepare mono and multifilament yarns. To find optimum spinning and drawing conditions, various parameters such as spinning temperature, spinneret diameter, drawing temperature, and drawing ratio were examined. From the observation of the spinnability under various conditions, we found that the optimum conditions were as following: the extrusion temperature and die temperature were 175–180°C and 185–190°C, and the drawing temperature and drawing ratio were 85–95°C and 3.4, respectively. Under these conditions, the spinneret diameter could be reduced to the minimum value, 0.5 mm. Spun PVC filament yarns were subjected to the different yarn texturing process of stuffing box and pin false-twist method. The PVC yarn fabric was prepared by the knitting of textured yarns. Finally, the anion-emission and antibiotic properties of the knitted PVC fabrics were precisely evaluated.     

Carbon nanofiber/poly(vinylidene fluoride-hexafluoro propylene) composite films: The crystal structure and thermal properties with various drawing temperatures

Carbon nanofiber (CNF)/polyvinylidene fluoride-hexafluoro propylene (PVDF-HFP) composite film was prepared by solution casting and melt pressing. The resultant 2 % CNF/PVDF-HFP composite films were uniaxially drawn at 50 °C, 75 °C, and 100 °C, respectively. In the SEM images, the morphology of drawn CNF/PVDF-HFP composite film confirmed the orientation of the CNF and the polymer matrix. The WAXD results showed the coexistence crystal phase of PVDF-HFP. The drawn CNF/PVDF-HFP composite film demonstrates improved electrical properties. The DSC thermogram results indicated no change in the melting temperature but slightly increased crystallinity with increasing drawing temperature. Dynamic mechanical analysis and tensile test showed an improvement in the storage modulus and stress at a drawing temperature of 75 °C.     

Amylolytic activity in stored potato tubers. 2. The effect of low-temperature storage on the activities of α-and β-amylase and α-glucosidase in potato tubers

Summary Tubers of the potato cultivars Record, Wilja, Pentland Dell and Brodick (formerly clone 137371) were sampled before and after storage at either 4°C or 10°C. Reducing sugar content stayed constant during storage at 10°C in all four cultivars but rose greatly during the first 6–12 weeks of storage at 4°C in Record, Wilja and Pentland Dell but not in Brodick. Amylolytic activity was determined after 5 weeks storage using blockedp-nitrophenyl maltoheptaoside as substrate for α-amylase,p-nitrophenyl maltopentaoside as substrate for β-amylase, andp-nitrophenylglucopyranoside as substrate for α-glucosidase. The values obtained from tubers stored at 4°C were higher than those from tubers stored at 10°C, the differences being much less in Brodick than in the other three cultivars.     

Changes in the content of L-ascorbic acid,glucose, fructose,sucrose and total glycoalkaloids in potatoes (cv. Bintje) stored at 7, 16 and 28°C

Summary We investigated the changes in the content of L-ascorbic acid (L-AA), glucose, fructose, surose and total glycoalkaloids (TGA) during storage of potatoes, cv. Bintje, for 12 weeks at 7,16 and 28°C. The initial amount of L-AA was 8.2 mg/100g fresh weight; after 12 weeks' storage at 7°C it had decreased, while at 16 and 28°C it had increased. The sugar content went up most in potatoes stored at 28°C, but remained below the level at which potatoes taste sweet. The sugar content rose slightly at 16°C, while it decreased in tubers stored at 7°C. The initial TGA content, in equivalent amounts of α-solanine, was 3.6 mg/100 g fresh weight; after 12 weeks' storage it had decreased slightly at all three storage temperatures.     

Effect of home processing and storage on ascorbic acid and β-carotene content of bathua (Chenopodium album) and fenugreek (Trigonella foenum graecum) leaves

The present investigation was conducted to study the effect of selected processing and storage methods on the concentration of ascorbic acid and β-carotene in Bathua and fenugreek, leaves. Methods included storage of leaves with or without polythene bags for 24 and 48 h in a refrigerator at 5°C; at 30°C in polythene bags; drying (sun and oven); blanching (5, 10, 15 min); open pan and pressure cooking. Ascorbic acid content of fresh leaves was 220.97 to 377.65 mg and β-carotene content was 19.00 to 24.64 mg/100 g, DW. The percent loss of ascorbic acid ranged from 2.03 to 8.77 and 45.15 to 66.9 while lower losses (0.0 to 1.75 and 1.63 to 2.84) of β-carotene were observed in leaves, stored in, the refrigerator and at 30°C, respectively. A markedly greater reduction in ascorbic acid and β-carotene was observed in dried, blanched and cooked leaves. The study data suggest that storage of leaves in refrigeration, drying in oven, blanching for a short time and cooking in a pressure cooker results in better retention of these two vitamins.     

Influence of Drawing and Annealing on the Crystallization,Viscoelasticity, and Mechanical Properties for Middle-molecular-weight Polyethylene Fishing Monofilaments

The influence of drawing and annealing on the crystallization, viscoelasticity and mechanical properties for middle-molecular-weight polyethylene (MMWPE) fishing monofilaments was investigated. It was found that the drawing procedure had a positive effect on the crystallization of the MMWPE fishing monofilaments. Meanwhile, the glass transition temperature of the MMWPE monofilaments shifted to higher temperature, and the α-relaxation associated with crystalline phases became higher and broader with the increase in the drawing ratio. Moreover, the breaking strength of MMWPE fishing monofilaments can be effectively improved by increasing the drawing ratio. Meanwhile, the knot strength increased first and then decreased. However, the increase in annealing temperature improved the knot strength. With increasing annealing temperature, the orientation factor decreased and induced the γ-relaxation peak at high magnitude. This indicated that the amorphous structure could become disordered during annealing treatment. In addition, the annealing temperature can clearly influence the working temperature dependence of the stress-strain behavior. When the working temperature rose from 20 °C to 30 °C, the MMWPE monofilaments after annealing at 120 °C exhibited low modulus loss due to their high α- transition temperature. Thus, an important method for improving the mechanical properties by controlling the drawing and annealing conditions was established.     

Hybrid organic-inorganic POSS (polyhedral oligomeric silsesquioxane)/polypropylene nanocomposite filaments

Octamethyl-POSS and Octaphenyl-POSS reinforced polypropylene nanocomposite monofilaments were prepared by melt blending route. It was observed that incorporation of Octamethyl-POSS and Octaphenyl-POSS in polypropylene show improvement in mechanical as well as thermal properties. Octaphenyl POSS/PP nanocomposites show significant increase in thermal stability even at very low concentration as compared to neat polymer matrix. An increase of 100 and 140 °C was observed in thermal degradation temperature at 5 wt% loss and maximum degradation over neat PP filaments respectively at low OP-POSS loadings (<5 wt%). Both Octamethyl-POSS and Octaphenyl-POSS act as lubricating agents facilitating drawing which results in improvement in orientation as well as mechanical properties.     

Improvement of mechanical and electrical properties of poly(ethylene glycol) and cyanoresin based polymer electrolytes

Ionic conductivity and mechanical properties of a mixed polymer matrix consisting of poly(ethylene glycol) (PEG) and cyanoresin type M (CRM) with various lithium salts and plasticizer were examined. The CRM used was a copolymer of cyanoethyl pullulan and cyanoethyl poly(vinyl alcohol) with a molar ratio of 1:1, mixed plasticizer was ethylene carbonate (EC) and propylene carbonate (PC) at a volume ratio of 1:1. The conductive behavior of polymer electrolytes in the temperature range of 298∼338 K was investigated. The PEG/LiClO₄ complexes exhibited the highest ionic conductivity of ∼10⁻⁵ S/cm at 25°C with the salt concentration of 1.5 M. In addition, the plasticized PEG/LiClO₄ complexes exhibited improvement of ionic conductivity. However, their complexes showed decreased mechanical properties. The improvement of ionic conductivity and mechanical properties could be obtained from the polymer electrolytes by using CRM. The highest ionic conductivity of PEG/CRM/LiClO₄/(EC-PC) was 5.33×10⁻⁴ S/cm at 25°C.     

Isothermal crystallization behavior of PAR/PBT composite prepared by island-in-a-sea fiber method

The PAR fiber reinforced PBT composite was manufactured using the PAR/PBT island-in-a-sea fiber. The isothermal crystallization kinetics of the PAR/PBT composite and the neat PBT resin were investigated in the temperature range of 187–199 °C. To calculate the Avrami parameters for analyzing the crystallization behavior, crystallization peaks were measured and analyzed in terms of the crystallization temperature and the inclusion of the PAR fiber. The crystallization rate of the PBT is faster than that of the PAR/PBT composite from the analysis of their relative crystallinity. Consequently, it is considered that the PAR fiber interrupted the crystal nucleation and growth of the PBT matrix. It can be confirmed with the crystallization half time and the crystalline morphologies at the chosen isothermal temperatures.     

Shelf life study of some Nigerian fruit juices inoculated with ascospores ofNeosartorya spp.

Mango, orange and pineapple juices containing various concentrations of sucrose were dispensed in 100 ml volumes into 100 ml conical flasks with stoppers. Each juice in a flask was inoculated with ascospores of one local isolate of eitherNeosartorya fischeri, N. fischeri var.spinosa orN. quadricincta to a final concentration of 120–140 ascospores/ml of juice, and then pasteurized at 80°C for 30 min. A set of 36 inoculated flasks with 12 controls was stored at 4–5°C and two sets, one protected with 100 mg/l sodium benzoate, were stored at room temperature (25–28°C). A shelf life study was carried out on all the juices for 64 days. Only fruit juices stored at 4–5°C and those containing sodium benzoate stored at room temperature were protected from spoilage by these fungi for 64 days. Addition of sucrose at levels of 9% to mango juice, 30% to pineapple juice and 31.5% to orange juice significantly (p=0.05) protected ascospores from inactivation during cold storage.     

<Emphasis Type="Italic">Carica papaya</Emphasis> Lipase: A Naturally Immobilized Enzyme with Interesting Biochemical Properties

Triacylglycerol (TAG) lipases have been thoroughly characterized in mammals and microorganisms, whereas very little is known about plant TAG lipases. The lipolytic activity occurring in all the laticies is known to be associated with sedimentable particles, and all attempts to solubilize the lipolytic activity of Carica papaya latex have been unsuccessful so far. However, some of the biochemical properties of the lipase from Carica papaya latex (CPL) were determined from the insoluble fraction of the latex. The activity was optimum at a temperature of 37°C and a pH of 9.0, and the specific activities of CPL were found to be 2,000 ± 185 and 256 ± 8 U/g when tributyrin and olive oil were used as substrates, respectively. CPL was found to be active in the absence of any detergent, whereas many lipases require detergent to prevent the occurrence of interfacial denaturation. CPL was inactive in the presence of micellar concentrations of Triton X-100, sodium dodecyl sulfate (SDS) and tetradecyl trimethylammonium bromide (TTAB), and still showed high levels of activity in the presence of sodium taurodeoxycholate (NaTDC) and the zwitterionic Chaps detergent. The effects of various proteases on the lipolytic activity of CPL were studied, and CPL was found to be resistant to treatment with various enzymes, except in the presence of trypsin. All these properties suggest that CPL may be a good candidate for various biotechnological applications.     

Einfluss von Lagerung und Sorte auf die Verteilung der Glykoalkaloide in der Kartoffelknolle

Zusammenfassung Fünf Speisekartoffelsorten wurden w?hrend einer sechsmonatigen Lagerung fünfmal auf α-Solanin und α-Chaconin untersucht. Es wurden vier Gewebebereiche der Knolle getrennt überprüft. Der Gesamtglykoalkaloidgehalt betrug im Augenbereich 164, in der restlichen Schale 101 und in der Gef?ssbündelzone mit ?usserem Speichergewebe 8mg/100g. Trockensubstanz. Im restlichen Innenk?rper waren nur noch Spuren (0.164mg/100g TS) nachzuweisen. Zwischen den Sorten und diesen Gewebepartien traten statistisch gesicherte Wechselwirkungen auf, die im wesentlichen von einer Sorte verursacht wurden. W?hrend der Lagerung sind die Alkaloidgehalte leicht, aber statistisch nicht gesichert gesunken. α-Solanin und α-Chaconin kamen generell im Verh?ltnis von etwa 1∶1.5vor; die Korrelation zwischen beiden Formen ist sehr eng (r=0.865). Bezogen auf die gesamte Knolle lagen die Gesamtglykoalkaloide je nach Sorte zwischen 2.4 und 8mg/100g Frischsubstanz und damit im gesundheitlich unbedenklichen Bereich.

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Summary Five table potato cultivars (Erna, Granola, Gusto, Ulse, Margit) from the same source were examined for their content of α-solanine and α-chaconine during a sixmonths storage period. For the testing and subsequent analysis the tubers were dissected into four kinds of tissues: eye-zone, peel, vascular bundle region, medulla. The total glycoalkaloid content (TGA) in the total tuber mass varied between 2.4 and 8mg per 100g fresh matter depending on cultivar (Fig. 1). Despite significant differences between cultivars (Table 1), all potato cultivars remained within the safe range during the entire storage period. Remarkable differences in TGA per 100g dry matter could be noted in the tuber parts. For the eye-zones a TGA of 164mg was found; the peel region showed 101mg and the vascular bundle zone 8mg. The medulla of the tubers contained only traces of TGA (0.164mg/100g dry matter, Fig. 2). The statistical analysis only revealed significant interactions between cultivars and tuber parts (Table 1), mainly caused by the cultivar Gusto which showed higher contents of α-solanine and α-chaconine in its vascular bundle regions (Figs 3–5). The ratio between amounts of α-solanine and α-chaconine was approximately 1∶1.5, and after eliminating effects of cultivar, storage and tuber parts, the correlation coefficient between amounts was 0.865. This close correlation can be used for breeding. The non-significant, slightly negative effect of the six-months storage period on alkaloid content was noteworthy. It is assumed that only after long storage periods or through inappropriate storage (sprouting of tubers) a significantly higher glycoalkaloid content may be expected.

     

Influence of nitrogen nutrition,daylength and temperature on contents of gibberellic and abscisic acid and on tuberization in potato plants

Summary In water culture experiments, plants grown under inducing climatic conditions (20°C and 12 h) and continuous supply of N had a relatively low ABA and a high GA content in the shoot. These plants failed to form tubers. The combination of these same climatic conditons with interruption of the N supply led to an increase in the ABA and the simultaneous decrease in the GA content, i.e. a high ABA/GA ratio. Coincidently tuberization occurred. Restoration of the N supply cáused an inversion of the ABA/GA ratio and was often accompanied by regrowth of tubers. Under non-inducing climatic conditions (30°C or 18 h) interruption of the N supply still increased the aBA content but failed to decrease the GA content. Under these conditions tuberization was not observed. The results indicate that N nutrition, like photoperiod and temperature, may control tuberization in potato plants mainly by changing the ABA/GA ratio.

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Zusammenfassung In Wasserkulturversuchen wurden der Einfluss von kontinuierlichem und diskontinuierlichem N-Angebot bei unterschiedlicher Temperatur (20°C bzw. 30°C) und Tagesl?nge (12 bzw. 18 Std.) auf den Gehalt an Abscisins?ure (ABA) und Gibberellins?ure (GA) im Spross und auf die Knolleninduktion untersucht. Die Pflanzen (S. tuberosum cv. Ostara) wuchsen in Klimakammern. Bei kontinuierlichem N-Angebot wurde die NO₃-Konzentration der N?hrl?sung st?ndig h?her als 1 mM gehalten, w?hrend bei diskontinuierlich-N das N-Angebot periodisch für 6 Tage unterbrochen wurde (3 Tage+N und 6 Tage-N). Die unterschiedlich mit N ern?hrten Pflanzen wurden im Abstand von 3 Tagen geerntet und in den Sprossen die ABA- und GA-Gehalte untersucht. ABA wurde gaschromatographisch und GA mit dem Salathypokotyltest bestimmt. Bei kontinuierlichem N-Angebot wurde die Knolleninduktion auch bei induktiven Klimabedingungen (12 Std. Tagesl?nge und 20°C) verhindert. Die Wachstumsrate der Sprosse blieb hoch. Unterbrechung des N-Angebotes (diskont. N) verminderte die Wachstumsrate der Sprossen und führte zu Knolleninduktion. Bei kontinuierlichem N-Angebot waren in den Sprossen die ABA-Gehalte niedrig und die GA-Gehalte hoch (Abb. 2). Unterbrechung des N-Angebotes führte zu raschem Anstieg der ABA-Gehalte und Abfall der GA-Gehalte (ABA/GA=1,5). Gleichzeitig mit dieser Verschiebung trat Knolleninduktion auf. Nach erneutem N-Angebot kam es durch Abnahme der ABA- und Zunahme der GA-Gehalte wieder zur Umkehrung dieses Verh?ltnisses (ABA/GA ∼0,8). Ein überh?htes N-Angebot unmittelbar nach der Induktion führte zum ‘Durchwachsen’ der Knollen (Abb. 3), offenbar die Folge des ver?nderten Phytohormonverh?ltnisses. Im Langtag (18 std.) oder bei konstant hohen Temperaturen (30°C) unterblieb auch nach Unterbrechung des N-Angebotes die Knolleninduktion. Unter diesen Bedingungen stieg zwar der ABA-Gehalt an, der GA-Gehalt jedoch ebenfalls, wodurch sich das ABA/GA-Verh?ltnis nur leicht erh?hte. Auffallend war, dass auch nach Unterbrechung des N-Angebots im Langtag die Wachstumsrate der Sprosse hoch blieb, und bei hoher Temperatur die Wurzelentwicklung stark beeintr?chtigt war (Abb. 5). Die Versuchergebnisse sprechen dafür, dass für den Anstieg der ABA-Gehalte im Spross bei Unterbrechung des N-Angebotes die Wurzeln eine zentrale Rolle spielen. Dagegen scheint der GA-Gehalt des Sprosses eng mit der meristematischen Aktivit?t der Sprosspitzen korreliert zu sein. Umweltfaktoren, die besonders das Sprosswachstum f?rdern (kont. N; hohe Temperaturen), k?nnten auf diesem Weg das ABA/GA-Verh?ltnis verkleinern und dadurch die Knolleninduktion verhindern.

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Résumé L'apport continu et discontinu d'azote aux plantes cultivées en hydroponie et exposées à des températures de 20°C et 30°C, à des longueurs de jour de 12 et 18 heures, a été examiné en relation avec la teneur d'acides abcissique (ABA) et gibberellique (GA), dans les pousses ainsi que l'effet sur la tubérisation. Les plantes (S. tuberosum cv. Ostara) ont été cultivées en chambre de croissance. Par l'apport continu d'azote, la concentration de la solution nutritive en NO₃ a été maintenue constamment au-dessus de 1 mM. Tandis que par l'apport discontinu d'N, il a été observé un arrêt d'apport d'azote pendant 6 jours (3 jours+N et 6 jours-N). Les plantes soumises aux différents traitements ontété récoltées à intervalles réguliers de 3 jours. L'ABA et le GA ont été dosés à partir des tiges. L'ABA a été dosé par chromatographie en phase gazeuse et le GA avec l'aide du test de l'hypocotyle de salade. Par l'apport continu d'azote, l'induction de la tubérisation n'a pas eu lieu, même par des conditions de climat favorables (longueur du jour 12 h et 20°C). Le taux de croissance des tiges était très élevé. L'apport discontinu d'N diminuait la croissance des tiges en déclenchant la tubérisation. Lors d'apport continu d'azote, les teneurs en ABA dans les tiges étaient basses et celles en GA élevées (fig. 2). L'interruption d'apport d'N provoque un accroissement rapide de la teneur en ABA et une diminution de GA (ABA/GA=1,5). Ce changement était en relation avec la tubérisation. Par un nouvel apport l'ABA diminuait et le GA augmentait, et la relation a été inversée (ABA/GA∼0,8). Un surdosage d'N sit?t après la tubérisation a provoqué la germination des tubercules (fig. 3), probablement en raison du changement des relations entre les phytohormones. Par jour long (18 h) ou par une température constante de 30°C, il n'y eut pas de formation de tubercules, même après un arrêt de l'apport d'N. Par ces conditions, la teneur en ABA augmentait, et celle de GA également; le rapport de la relation ABA/GA n'a été que légèrement élevé. Par jour long, la croissance des tiges restait élevée même après avoir interrompu l'apport d'N. La croissance des racines était fortement perturbée par températures élevées (fig. 5). Les résultats d'essais démontrent que les racines jouent un r?le important sur l'augmentation du taux d'ABA dans les tiges, lors de l'arrêt d'apport d'N. Par contre, il semblerait que le taux de GA est étroitement corrélé avec l'activité méristématique des sommets des pousses. Les facteurs du milieu qui favorisent la croissance des tiges (N continu, températures élevées) pourraient par cette voie diminuer la relation ABA/GA et ainsi empêcher toute tubérisation.

     

Film preparation by melt- or compression-process using poly(vinyl chloride) powder swollen with dimethylformamide

A melt-process was used to prepare high molecular weight Poly(vinyl chloride) (PVC) films without the use of a conventional plasticizer and heat stabilizer. Rigid PVC powder was swollen with dimethylformamide containing 4∼10 vol% water to reduce its melting temperature. The swollen powder was pressed at a relatively low temperature of 75∼125 °C to form a film shape, and then washed and dried. The visible light transmittance, X-ray diffraction, density and the tensile properties of the resulting films were examined to estimate the success or failure of film formation. The films could be produced by not only the melt-process but also a compression-process using the rigid, highly swollen PVC powder. The resulting films had no voids, which are generally observed in PVC products formed by a solution process. The minimum temperature for these processes decreased with decreasing water content in the mixture: The minimum temperatures according to the water content in the mixture to produce faultless films through the melt-process were 4 %–105 °C, 6 %–115 °C, 8 and 10 %–125 °C, while those through the compression process were 4 %–95 °C, 6 and 8 %–105 °C, 10 %–115 °C.     

Coloration of ultra high molecular weight polyethylene fibers using alkyl-substituted anthraquinoid blue dyes

UHMWPE fibers were dyed with a series of anthrquinoid blue dyes having different length of alkyl substituents at general dyeing condition. The dyeability was investigated at various conditions and fastness of the dyeings was examined. As the length of alkyl substituents increased, the dyeability toward UHMWPE fibers tends to be improved gradually. Color strength of the fabrics was increased with the increase of dyeing temperature from 100 to 130 °C. From the dyeing rate, equilibrium dyeing at 130°C was achieved at 2–3 h. The tensile strength of UHMWPE fibers after dyeing at 130 °C for 1 h was maintained at a level of 95 % of untreated fiber. However, at prolonged dyeing time at 130 °C, the tensile strength was significantly decreased to a practically unacceptable level. The color fastnesses to washing, rubbing and light of the dyeings were very good showing higher than 4 ratings.     

The effect of potato seed tuber age and soil temperature on the phenomenon of non-emergence

Summary In three experiments seed tubers of cvs Jaerla, Bintje and Alpha, stored at 12 °C in the dark, were planted in glasshouses on various dates at soil temperatures varying from 8 °C to 28 °C to study the phenomenon of ‘non-emergence’ with ageing seed tubers. In general the tubers were desprouted before planting. At all plantings cv. Alpha produced normal plants. The cvs Jaerla and Bintje, however, showed high proportions of the ‘little potato’ phenomenon when planted in cold soil, and high proportions of decayed tubers more frequently in warm soil. When using physiologically older seed at later planting dates, both the range of soil temperatures became wider and the proportions of seed tubers experiencing both ‘little potato’ and decay increased.