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Thermogravimetry, differential scanning calorimetry, and wide-angle Xray scattering techniques were used to study changes in the composition, relative heat of fusion, and mean crystal size of blends made from low-density polyethylene (LDPE) and sugar cane bagasse (SCB), before and after exposure to the fungus Phanerochaete chrysosporium for 32 days. The initial blends contained equal weights of each component. The composition of the blend LDPE/SCB at 32 days changed to the value (66 { 3)/(34 { 3). The relative heat of fusion of LDPE increased during the first 16 days, but then it showed a tendency to decrease and remain constant. The estimated mean crystal size of polyethylene decreased but then remained almost constant. These changes indicate that the microorganisms mainly digest SCB in the first stage of the experiment, but later they also digest LDPE. The crystalline morphology of the LDPE is modified; the crystalline domains are divided into smaller crystallites.

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“…crystalline blocks in the crystalline mosaic. 9, 10 With the consumption of part of this latter amor-…”

Section: Resultsmentioning

confidence: 99%

Effect of the growth of Phanerochaete Chrysosporium in a blend of low density polyethylene and sugar cane bagasse

Manzur¹,

Cuamatzi²,

Favela³

1997

J. Appl. Polym. Sci.

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“…These effects were explained in terms of the stress relaxation, which always is present. 13 When the deformation takes place in a short time (i.e., high strain rate), the effect of the stress relaxation is small. In the opposite extreme case, when the deformation is applied slowly (50 times smaller), the stress value is smaller because the relaxation has sufficient time to reduce the stress.…”

Section: Stress-strainmentioning

confidence: 99%

Crystallinity variations in the double yield region of polyethylene

Manzur

Rivas

2007

J of Applied Polymer Sci

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Numerous specimens of a linear low density polyethylene sample were uniaxially deformed up to different elongations to study the double yield phenomenon. Extruded samples were analyzed to calculate the crystallinity and to estimate the mean crystal size, under stressed state and released state (after removal of the stress), using the wide angle X-ray scattering technique. The crystallinity degree and the mean crystal dimension associated to the (110) orthorhombic reflection of the specimen without deformation were of 55% and 16 nm. These parameters in the stressed state, as functions of the elongation, presented a multi-step behavior. A decrement after the first yield point (48%, 13 nm), then another decrement, and an abrupt increment followed by a decrement at higher strain values around the second yield point (28, 40, and 30%; 12, 14.5, and 11 nm). The behavior was more notorious in the stressed state than in the released state. The latter results were interpreted in terms of a partial melting followed by a recrystallization process. These experimental findings show that the second yield is not only associated with the deformation of the crystalline region. This partial meltingrecrystallization process is one of the main mechanisms of the double yield phenomenon.

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“…[6] Plaza et al have studied the double yield points in triblends of low density PE, linear low density PE and EPDM, and observed that the double yield phenomenon decreased until it disappeared with increasing EPDM component. [11] The experimental results from Brooks et al have shown the existence of double yield points over a range of temperatures for three PE samples with differing degrees of short-chain branching. [1] Xu et al…”

Section: Introductionmentioning

confidence: 98%

“…[5] To date, various studies have shown the existence of the double yielding phenomenon. [6][7][8][9][10][11][12][13] Segulea et al have observed the double yield behavior of several PE and related copolymers. [6] Plaza et al have studied the double yield points in triblends of low density PE, linear low density PE and EPDM, and observed that the double yield phenomenon decreased until it disappeared with increasing EPDM component.…”

Section: Introductionmentioning

confidence: 99%

Morphology Dependent Double Yielding in Injection Molded Polycarbonate/Polyethylene Blend

Huang

Yang

et al. 2004

Macro Materials & Eng

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Summary: Polycarbonate (PC)/polyethylene (PE) blend was injection molded at different molding temperatures. The morphological observation by scanning electronic microscope (SEM) indicated that the sample molded at 190 °C contained only uniformly dispersed spherical PC particles. The samples molded at 230 and 275 °C had a typical skin‐core structure, and there were many injection‐induced PC fibers in the subskin. While the sample molded at 190 °C had the usual stress‐strain behavior, the samples obtained at 230 and 275 °C showed apparently double yielding behavior. It was suggested that the double yielding points were morphology‐dependent. The first one was the result of the yielding of PE at low strain, and the second one was caused by the yielding of the PC fibers. Moreover, it is the frictional force in the interfaces between PC and PE that transferred the stress to the PC fibers, hence giving rise to the reinforcement of PE by PC.Stress‐strain curves of PC/PE blends injection molded at various temperatures showing first (I) and second (II) yielding points.magnified imageStress‐strain curves of PC/PE blends injection molded at various temperatures showing first (I) and second (II) yielding points.

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Cited by 30 publications

References 7 publications

Effect of the growth of Phanerochaete Chrysosporium in a blend of low density polyethylene and sugar cane bagasse

Effect of the growth of Phanerochaete Chrysosporium in a blend of low density polyethylene and sugar cane bagasse

Crystallinity variations in the double yield region of polyethylene

Morphology Dependent Double Yielding in Injection Molded Polycarbonate/Polyethylene Blend

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