Mechanism of viscoelastic absorption in polyethylene at higher temperatures than room temperature

Takayanagi, Motowo; Aramaki, Teruo; Yoshino, Masatsugu; Hoashi, Koji

doi:10.1002/pol.1960.1204614824

Cited by 55 publications

(8 citation statements)

References 4 publications

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“…From a parallel between the thermograms and the DMA response summarized in Figure , it is easy relating the tan(ϕ) and modulus values measured within the temperature range between around 320 and 390 K to the melting of the crystallites in XLPE. In fact, the ML peak, whose peak temperature is around 360 K is related to the melting of the primary crystallites in PE, in agreement with several works . The increase in the peak height in samples aged in water [see empty triangles in Figure (a)], is promoted by the increase in the volume fraction of crystals during aging in agreement with the DSC results and previous works .…”

Section: Discussionsupporting

confidence: 91%

“…It is interesting to note that XLPE insulator can operate continuously at low as well as high voltages, at conductor temperatures of 363 K, and in emergency situations, it could stand temperatures up to 403 and 523 K in shortcut conditions . In fact, the temperature for in‐service working of the XLPE insulator is well inside the temperature range for the melting of the crystalline zones in PE . In addition, it has been shown the effect of the crystallinity on the behavior of the dielectric strength in ethylene‐propylene‐diene M‐class rubber (EPDM) used in the housing of outdoor electrical insulators .…”

Section: Introductionmentioning

confidence: 99%

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Mechanical energy losses in commercial crosslinked low‐density polyethylene in the temperature range between 200 and 400 K

Lambri

Bonifacich

Garcı́a

et al. 2019

J of Applied Polymer Sci

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Aging treatments in water and in air and controlled neutron irradiation were performed on commercial crosslinked lowdensity polyethylene (XLPE) for promoting different mesostructural arrangements of crystallites and crosslinking degree. Infrared spectroscopy, differential scanning calorimetry, differential thermal analysis, thermogravimetry, and dynamic mechanical analysis were used as characterization techniques. The relaxation peak related to the mobility of the grain boundaries from crystalline zones in XLPE was identified at around 260 K (at 7 Hz), involving an activation energy of 90 AE 4 kJ mol −1 . The usual equation for describing the grain boundary mobility in metals involving the movement of grain boundary dislocations was adapted for studying the mobility of the boundaries among the crystalline zones, successfully. In addition, a new mechanical relaxation peak that appears at around 300 K (at 7 Hz), which involves an activation energy of 94 AE 5 kJ mol −1 , was found. The driving force controlling this peak was determined as the dragging of the polymer chains at the amorphous zones adjacent to the crystals controlled by the mobility of the crystallites boundaries. The chains movement was done with break away from the physical pinning points.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Mechanical energy losses in commercial crosslinked low‐density polyethylene in the temperature range between 200 and 400 K

Lambri

Bonifacich

Garcı́a

et al. 2019

J of Applied Polymer Sci

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“…By substituting the measured values of E:/Ei in Figure 6 to eqs. (7), (8), and (9), & and B are obtained for the PP composites filled with 160-A Si02 particles. Figure 8 shows & and B of the PP composites filled with 160-A SiOz filler as a function of filler volume fraction.…”

Section: Resultsmentioning

confidence: 99%

Dynamic mechanical properties of polypropylene composites filled with ultrafine particles

Sumita

Tsukihi

Miyasaka

et al. 1984

J of Applied Polymer Sci

100

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SynopsisThe dynamic moduli of isotactic polypropylene (PP) filled with ultrafine SiOn and micron sized glass particles are measured in the temperature range 30-130°C at frequency 10 Hz. The storage moduli of PP composites, E;, increase with filler content and decreasing filler size in the whole range of temperature. The loss moduli of PP composites, Ef, increase with filler content and decreasing filler size above 4OOC. The intensity of the broad dispersion which appears at ca. 60°C increases with filler content and decreasing filler size. By assuming that the energy is not dissipated in the effective volume, namely, filler volume plus that of immobilized interfacial region, the effective volume fraction is evaluated from the relative loss modulus, E:/EU at 60°C. The effective volume fraction increases with filler content and decreasing filler size. The effect of addition of ultrafine particles on the broad dispersion at ca. 6OoC resembles the effect of increasing crystallinity of pure PP. It is concluded that the broad dispersion which appeared at ca. 60°C seemed to be assigned to the grain boundary of PP composites or crystalline boundary of pure PP. INTRODUCTIONIn a previous paper we have studied the reducible properties of drawing temperature, rate of strain, and filler content with respect to the tensile yield stress of PP composites filled with ultrafine particles. The yield stress is reducible by three factors, i.e., drawing temperature, strain rate, and filler content. The conversion law is relatively simple':(1) The first shift factor, a T , is the Arrhenius type for temperature and for strain rate. The activation energy is not dependent on the filler volume fraction and size.(2) The logarithm of the second shift factors, log a,, for strain rate and for filler content is proportional to the square root of the filler volume fraction.The Arrhenius plots of shift factor, log aT, against the reciprocal temperature have two breaks at 60°C and llO°C for filled and nonfilled PP. These breaks are related to some kinds of transition of matrix PP. Many authors have reported about the nature of the broad dispersion which appears at ca. 60°C of isotactic PP. However, the assignment of this transition is not known clearly.24 In the present study, we discuss the effect of filler content and size on this dispersion from the measurement of dynamic modulus of PP filled with ultrafine particles. Table I shows the average diameters of these particles. Mixing and Molding. Polymer and filler were mixed in a two-roll mill for 15 min a t 180°C. The content of the fillers was 5,10,15 and 20 wt %. Films about 0.5 mm thick were molded from the mixtures a t 200°C under a pressure of 100 kg/cm2. Since thermal degradation of matrix polymer took place more or less during the mixing and molding, films without filler were prepared by the same procedures. It was assumed that the degradation of polymer took place in the composites to the same extent as in the pure polymer sample. All the samples were annealed a t 130°C for 1 h. EXPERIM...

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“…Muitos autores [29][30][31][32] demonstraram que a transição α em polietilenos consiste na verdade em dois picos superpostos designados como relaxações α 1 e α 2 em ordem decrescente de temperatura, onde a primeira é relacionada a um processo de escorregamento intralamelar (ou fenômeno de contorno de grão) e/ou mobilidade da região intercristalina e a segunda relacionada à mobilidade intracristalina que envolve o movimento translacional de segmentos de cadeia ao longo do eixo c dentro da célula unitária.…”

Section: Passador F R Et Al -Nanocompósitos De Blendas Hdpe/lldpe unclassified

Nanocompósitos de Blendas HDPE/LLDPE e OMMT Parte I: Avaliação das Propriedades Termo-Mecânicas e da Resistência ao Intemperismo

Passador¹,

Backes²,

Travain³

et al. 2013

Polímeros

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Resumo: Nanocompósitos de blendas de polietileno de alta densidade (HDPE) com polietileno linear de baixa densidade (LLDPE) e OMMT (montmorilonita organofílica) foram preparados sob fusão em extrusora de duplarosca, utilizando HDPE-g-MA como agente compatibilizante. A caracterização estrutural foi realizada por análises de difração de raios X em alto ângulo (WAXD), microscopia eletrônica de transmissão (MET). Os resultados indicam que a adição do agente compatibilizante favoreceu a formação da microestrutura predominantemente intercalada. Estudos dinâmico-mecânicos mostraram que a adição do agente compatibilizante aumentou as interações entre a carga e a matriz poliolefínica. As diferentes condições de intemperismo as quais os materiais foram submetidos influenciaram no comportamento mecânico dos nanocompósitos de blenda HDPE/LLDPE. Os tratamentos realizados em estufa com circulação forçada de ar e em água proporcionaram o alívio de tensões residuais presentes no sistema, enquanto que o tratamento realizado em câmara de envelhecimento acelerado levou à formação de grupos carbonílicos, de pequena massa molar, que diminuíram o grau de cristalinidade e o módulo elástico dos nanocompósitos. Palavras-chave: Nanocompósitos, HDPE/LLDPE, intemperismo. HDPE/LLDPE Blend-based Nanocomposites -Part I: Evaluation of Thermo-mechanical Properties and Weathering ResistanceAbstract: Nanocomposites from high density polyethylene/ linear low density polyethylene (HDPE/LLDPE) blends were prepared at the melt state in an extruder, using HDPE-g-MA as compatibilizer agent. The structural characterization was performed through wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The results showed that adding the compatibilizer induced formation of a predominant intercalated microstructure. Dynamic-mechanical studies showed that the addition of the compatibilizer increases the interactions between the nanoclay surface and the polyolefin matrix. The weathering conditions affected the mechanical behavior of HDPE/LLDPE blend-based nanocomposites. Both treatments performed in hot water and in a forced convection air oven provided the relief of residual stresses in the polymer matrix, while the treatment in an accelerated aging chamber provided the formation of carbonyl groups that lead to a decreased degree of crystallinity and elastic modulus of the nanocomposites.

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Mechanism of viscoelastic absorption in polyethylene at higher temperatures than room temperature

Cited by 55 publications

References 4 publications

Mechanical energy losses in commercial crosslinked low‐density polyethylene in the temperature range between 200 and 400 K

Mechanical energy losses in commercial crosslinked low‐density polyethylene in the temperature range between 200 and 400 K

Dynamic mechanical properties of polypropylene composites filled with ultrafine particles

Nanocompósitos de Blendas HDPE/LLDPE e OMMT Parte I: Avaliação das Propriedades Termo-Mecânicas e da Resistência ao Intemperismo

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