Percolation effects in degradable polyethylene‐starch blends

Peanasky, John; Long, Jiang; Wool, Richard P.

doi:10.1002/polb.1991.090290506

Cited by 106 publications

(65 citation statements)

References 16 publications

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“…increase in intensity after 18 weeks. The concentration of hydroperoxides passes through a maximum in the 30 pm samples, whereafter it ceases upon depletion of the SBS.…”

Section: Autoxidation Processmentioning

confidence: 89%

“…This is also illustrated in Figure 6 showing DSC scans obtained in the isothermal mode. The isothermal mode is even more sensitive to differences in composition than is the dynamic mode.3s The peak observed for the unaged sample and for the sample aged for 18 weeks originates from of the LDPE. No effects were observed, either by CL or by DSC, in the samples containing only starch or in those consisting of pure LDPE.…”

Section: Autoxidation Processmentioning

confidence: 98%

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Degradation of enhanced environmentally degradable polyethylene in biological aqueous media: Mechanisms during the first stages

Albertsson

Barenstedt

Karlsson

1994

J of Applied Polymer Sci

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SYNOPSISDegradation of LDPE films containing a biodegradable starch filler and a pro-oxidant formulation was performed in aqueous media inoculated with bacteria or fungi at ambient temperatures for 1 year. The samples were characterized with the aim of elucidating the mechanisms that occur during the first stages and that are responsible for initiating the degradation of the LDPE matrix. Two interactive mechanisms were observed The basal salt medium (water containing trace elements ) triggered autoxidation of the pro-oxidant through decomposition of trace hydroperoxides, which, in synergistic combination with biodegradation of the starch, eventually initiated autoxidation of the LDPE matrix as monitored by chemiluminescence (CL) , differential scanning calorimetry (DSC) , and confocal scanning laser microscopy (CSLM) . The length of the induction period was dependent on the sample thickness and on the activity of the microbiological system. Up to 48% of the starch was consumed during the first year as revealed by polarized-light microscopy. I NTRO DU CTlO NRelatively inert synthetic polymers, e.g., polyethylene, can be rendered enhanced degradable by introducing prodegradant additives into the matrix. These additives provide the plastic materials with different potential degradation mechanisms that can be triggered upon environmental exposure. Several techniques in which starch is used as a biodegradable additive have been patented since the 1970s. The main problem associated with the use of starch as a filler is its hydrophilic nature and the generally hydrophobic nature of the polymer matrix. The starch particle size limits the amount to be incorporated if the composition is to be blown to a thin film, but this is not such a limitation for sheets or injection-molded articles. The starch can be used in * To whom correspondence should be addressed. its natural granular form, in the gelatinized form, or in the destructurized form. Griffin has invented formulations based on granular starch. In his early patents,lS2 the starch was surface-treated in order to improve the compatibility between the starch and the synthetic polymer matrix, whereas in a later patent,3 the starch is used together with a thermoplastic elastomer that functions both as a compatibilizer and as a n autoxidant.Willett4 presented in a recent patent a composition that includes granular starch and a copolymer carrier resin. Starch in its gelatinized form is utilized in formulations developed by Otey and W e~t h o f f .~'~ Together with the complexing agent, ethylene acrylic acid copolymer (EAA) and ammonia, it is possible to incorporate up to about 60% gelatinized starch in blown films. Bastioli et al.7 patented a technology based on destructurized starch. By combining synthetic thermoplastic polymers and copolymers and destructurized starch to which a boron compound has been added, a material is obtained that can be used as film, sheet, or fiber. We have studied polyethylene (LDPE) in which corn starch and pro-oxidants have been included in the...

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“…increase in intensity after 18 weeks. The concentration of hydroperoxides passes through a maximum in the 30 pm samples, whereafter it ceases upon depletion of the SBS.…”

Section: Autoxidation Processmentioning

confidence: 89%

Section: Autoxidation Processmentioning

confidence: 98%

Degradation of enhanced environmentally degradable polyethylene in biological aqueous media: Mechanisms during the first stages

Albertsson

Barenstedt

Karlsson

1994

J of Applied Polymer Sci

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“…By considering the reported data in light of the percolation theory, as applied to starch filled polyethylene films (24), one may infer a better accessibility of starch in the HDPE samples than in the LDPE samples. HDPE appears to be less prone than LDPE to allow homogeneous dispersion of the starch granules, at least when In no case was weight loss accompanied by a macroscopic variation at visual Fig.…”

Section: And Discussionmentioning

confidence: 99%

Effects of intensive microbial metabolism on starch-filled polyethylene films in controlled compositing windows.

Vallini

Corti

Pèra

et al. 1994

J. Gen. Appl. Microbiol.

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Low density (LDPE) and high density (HDPE) polyethylene films filled with starch up to a maximum level of 20% by weight were tested for biodegradation under different environmental conditions. Composting windrows consisting of various putrescible waste and assembled for controlled biostabilization management under static conditions were used. The physical and chemical deterioration of the polyethylene-starch films exposed to a controlled composting environment were recorded and analyzed with respect to the different composting evolution and were compared with the data collected in pure culture systems and in bench scale tests simulating an aerobic biostabilization process. Evidences are presented on the partial removal of starch from the different films as a consequence of massive surface colonization by various microorganisms. Loss of starch is accompanied by a small but significant drop in the average molecular weight and decrement in mechanical strength. In the case of a composting trial experiencing prolonged severe temperature conditions, a small but spectroscopically detectable oxidation of the polyethylene matrix was also observed. Efficiency of the controlled composting systems can be claimed in assessing reproducible conditions in an accelerated biostabilization of putrescible matter and hence versatility in the evaluation of the degradation of plastic manufacts.Polyolefins such as polyethylene with a degree of polymerization higher than 20 are particularly recalcitrant to microbial attack (1,14,26). Biodegradation of polyethylene as well as of many other thermoplastic polymers (e.g. polypropylene, polyvinyl chloride, polystyrene) has been indeed considered as a phenomenon to be

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“…This observation is in agreement with the predictions of percolation theory in LDPE blends with pure starch. 29 The results in Figure 7b indicate that pure ionomer is not biodegradable. Its weight remains unchanged even after 60 days.…”

Section: Biodegradationmentioning

confidence: 95%

“…The soil burial method is well known to be a slow process, mainly because of the low percolation rate. 29 However, it is noteworthy that the burial soil test reflects the real life condition more than any other test, although soil composition varies from place to place.…”

Section: Biodegradationmentioning

confidence: 99%

Tensile properties, morphology, and biodegradability of blends of starch with various thermoplastics

Park

Lee

Chowdhury

et al. 2002

J of Applied Polymer Sci

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ABSTRACT:In the present study, blends of starch with different thermoplastics were prepared by a melt blending technique. The tensile properties and morphology of the blends were measured. It was found that with increasing starch content in starch/ionomer blends, the tensile strength and modulus increase. But for starch/low-density polyethylene (LDPE) and starch/aliphatic polyester (APES) blends, tensile strength and modulus decrease with increasing the starch loading. Elongation at break values of all the blend systems decrease with increasing starch loading. The scanning electron micrographs (SEM) support the findings of tensile properties. Better homogeneity is observed in starch/ ionomer systems compared with that in starch/APES and starch/LDPE systems. Up to 50% starch content, the starch/ ionomer blends appear as a single phase. The extent of phase interactions of starch/APES system lies in between the starch/LDPE and starch/ionomer systems. From the biodegradability studies of the blends it was found that, although the pure LDPE and ionomer are not biodegradable, the starch/LDPE and starch/ionomer blends are biodegradable with an appreciable rate. The rate of biodegradation of the starch/APES is very high as both the components are biodegradable.

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Percolation effects in degradable polyethylene‐starch blends

Cited by 106 publications

References 16 publications

Degradation of enhanced environmentally degradable polyethylene in biological aqueous media: Mechanisms during the first stages

Degradation of enhanced environmentally degradable polyethylene in biological aqueous media: Mechanisms during the first stages

Effects of intensive microbial metabolism on starch-filled polyethylene films in controlled compositing windows.

Tensile properties, morphology, and biodegradability of blends of starch with various thermoplastics

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