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1.
El Miloud Maafi Fouad Malek Lan Tighzert Philippe Dony 《Journal of Polymers and the Environment》2010,18(4):638-646
Polyurethane (PU) based on polycaprolactone (PCL) and 4,4′ diphenyl methylene diisocyanate (MDI) was synthesized using a two-step
method. The PU obtained was then blended with various amounts of cellulose extracted from alfa stems to prepare composite
materials. The influence of cellulose on the thermal and mechanical properties of different composites was demonstrated by
means of several characterization techniques such as Fourier transform infrared spectroscopy (FTIR), differential scanning
calorimetry (DSC), scanning electron microscopy (SEM)… 相似文献
2.
This study investigated weathering effects on polyvinyl chloride (PVC) based wood plastic composites (WPC), with a focus on
the color and structure that is attributed to the material composition. It is directed towards quantifying the main chemical
modifications, such as carbonyl and vinyl groups which are formed during weathering. These composites were subjected to three
weathering regimes: exterior, accelerated xenon-arc, and accelerated UVA. The change in color was monitored using colorimetry.
Fourier transform infrared spectroscopy was used to identify and quantify the chemical modifications (carbonyl formation and
vinyl propagation) due to weathering. Additionally, scanning electron microscopy was employed to observe the physical morphological
changes that occurred. The results showed that exterior and accelerated xenon-arc and UVA weathering regimes increased the
degree of lightness, total color change, carbonyl concentration, and wood loss on the surfaces of the weathered composites.
The increased carbonyl concentration during weathering implied that degradation had occurred by oxidation process. Also, oxidation
and lignin (from the wood) degradation influenced the color (lightness) of PVC based WPC upon weathering. 相似文献
3.
M. S. Islam K. L. Pickering N. J. Foreman 《Journal of Polymers and the Environment》2010,18(4):696-704
30 wt% aligned untreated long hemp fibre/polylactic acid (AUL) and aligned alkali treated long hemp fibre/polylactic acid
(AAL) composites were produced by film stacking and subjected to hygrothermal ageing environment along with neat polylactic
acid (PLA). Hygrothermal ageing was carried out by immersing samples in distilled water at 25 and 50 °C over a period of 3 months.
It was found that both neat PLA and composites followed Fickian diffusion. Higher temperature generally increased the Diffusion
coefficient, D of neat PLA and composites, as well as shortening the saturation time. Neat PLA had the lowest D value followed by AAL composites and then AUL composites. After hygrothermal ageing, tensile and flexural strength, Young’s
and flexural modulus and K
Ic were found to decrease and impact strength was found to increase for both AUL and AAL composites. AUL composites had greater
overall reduction in mechanical properties than that for AAL composites after hygrothermal ageing. Crystallinity contents
of the hygrothermal aged composites support the results of the deterioration of mechanical properties upon exposure to hygrothermal
ageing environment. 相似文献
4.
Linbo Wu Yan Zhang Hong Fan Zhiyang Bu Bo-Geng Li 《Journal of Polymers and the Environment》2008,16(1):68-73
As an attempt to synthesize new biodegradable polymers from renewable cellulose resources, melt polycondensation of 5-hydroxylevulinic
acid (5-HLA) was reported for the first time. The resulting product, poly(5-hydroxylevulinic acid) (PHLA), was synthesized
and characterized with GPC, FTIR, 1H NMR and DSC. The in vitro degradation behaviors in phosphate-buffered saline (PBS) and in deionized water (DW) were also
examined. The molecular weight of PHLA is not high (several 1,000s), but it possesses unordinary high glass transition temperature
(as high as 120 °C). This is very different from existing aliphatic polyesters that usually have T
gs lower than 60 °C. The high T
g is attributed to the formation of inter- and/or intramolecular hydrogen bonds due to a characteristic keto–enol tautomerism
equilibrium in the polymer structure. PHLA readily degraded hydrolytically in aqueous media. 相似文献
5.
Cameron Way Katherine Dean Dong Yang Wu Enzo A. Palombo 《Journal of Polymers and the Environment》2011,19(4):849-862
Polylactic acid (PLA)—maple fibre composites have been synthesised using a series of sequentially modified cellulose fibres
(namely alkylation followed by either acetylation or silanation). Confirmations of the sequential modifications were made
using Fourier Transform Infrared Spectroscopy and Inductively Coupled Plasma—Atomic Emission Spectroscopy and the new surface
morphologies analysed using Scanning Electron Microscopy. The key advantage of the use of sequential treatments (with initial
alkali treatment) was the allowance for direct grafting of suitable chemical groups onto the cellulose in the fibre due to
the removal of lignin, hemicellulose and other surface impurities. However, a balance was found to exist between alkali exposure
time, concentration and resulting fibre integrity. The conditions used resulted in a loss in fibre weight, fibre moisture
content and tensile strength. Sequential treatments with acetylation or silane resulted in a 15–21% strength recovery from
that of the alkali treated composite. Factors that influenced this recovery in strength were the improved fibre-polymer interface,
namely the hydrophilic balancing of the fibres and this further affected the thermal-hydrolysis of the PLA during composite
fabrication. 相似文献
6.
Amanda C. Lima Sergio N. Monteiro Kestur G. Satyanarayana 《Journal of Polymers and the Environment》2012,20(1):245-253
In recent times, environmental safety has been on priority in the development of new materials leading to a recycling and
reuse approach to conserve the materials resources. This has resulted in more focus on the application of natural materials
such as lignocellulosic fibers. This paper presents the characterization of continuous and aligned jute fabrics obtained from
new and used sacks as well as the preparation and characterization of their composites incorporated into recycled polyethylene
or as isolated pieces up to 40 wt%. These environmentally friendly composites were subjected to bend test and the fracture
surface analyzed by SEM. The fabric from new sacks showed greater damage tolerance than that from the used sacks. The flexural
stress increased steadily with increasing used fabric content up to 30 wt%, which is explained using fractographic studies
on ruptured specimens. Used jute fabric composites are found to be viable alternative materials for low strength conventional
materials based on cost–performance comparison with conventional materials. 相似文献
7.
Maria T. B. Pimenta Antonio J. F. Carvalho Fabiola Vilaseca Jordi Girones Joan P. López Pere Mutjé Antonio A. S. Curvelo 《Journal of Polymers and the Environment》2008,16(1):35-39
Treated sisal fibers were used as reinforcement of polypropylene (PP) composites, with maleic anhydride-grafted PP (MAPP)
as coupling agent. The composites were made by melting processing of PP with the fiber in a heated roller followed by multiple
extrusions in a single-screw extruder. Injection molded specimens were produced for the characterization of the material.
In order to improve the adhesion between fiber and matrix and to eliminate odorous substances, sisal fibers were treated with
boiling water and with NaOH solutions at 3 and 10 wt.%. The mechanical properties of the composites were assessed by tensile,
bend and impact tests. Additionally, the morphology of the composites and the adhesion at he fiber–matrix interface were analyzed
by SEM. The fiber treatment led to very light and odorless materials, with yields of 95, 74 and 62 wt.% for treatments with
hot water, 3 and 10 wt.% soda solution respectively. Fiber treatment caused an appreciable change in fiber characteristics,
yet the mechanical properties under tensile and flexural tests were not influenced by that treatment. Only the impact strength
increased in the composites with alkali-treated sisal fibers. 相似文献
8.
Nikushi S. Yatigala Dilpreet S. Bajwa Sreekala G. Bajwa 《Journal of Polymers and the Environment》2018,26(11):4188-4200
With growing interest in the use of eco-friendly composite materials, biodegradable polymers and composites from renewable resources are gaining popularity for use in commercial applications. However, the long-term performance of these composites and the effect of compatibilization on their weathering characteristics are unknown. In this study, five types of biodegradable biopolymer/wood fiber (WF) composites were compatibilized with maleic anhydride (MA), and the effect of accelerated UV weathering on their performance was evaluated against composites without MA and neat biopolymers. The composite samples were prepared with 30 wt% wood fiber and one of the five biodegradable biobased polymer: poly(lactic) acid (PLA), polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), Bioflex (PLA blend), or Solanyl (starch based). Neat and composite samples were UV weathered for 2000 h (hours), and characterized for morphological, physical, thermal, and mechanical properties before and after weathering. Compared to composites without MA, composites containing MA grafted polymers exhibited improved properties due to increased interfacial adhesion between the fiber and matrix. Upon accelerated weathering, thermal and mechanical properties of 70% of the samples substantially decreased. Surfaces of all the samples were roughened, and drastic color changes were observed. Water absorption of all the samples increased after weathering exposure. Even though the compatibilization is shown to improve composite properties before weathering, it did not affect weathering of samples, as there were no considerable differences in properties exhibited by the composites with MA and without MA after weathering. The results suggest that compatibilization improves properties of biodegradable biobased composites without affecting its UV degradation properties. 相似文献
9.
James S. Fabiyi Armando G. McDonald David McIlroy 《Journal of Polymers and the Environment》2009,17(1):34-48
The effects of weathering on the constituents of wood and polymer matrix behavior in wood plastic composites (WPCs) were investigated.
WPCs were produced from pine, extractives-free pine, and pine holocellulose fibers (60%) together with HDPE (40%). These composites
were subjected to xenon-arc accelerated and outside weathering for a total of 1200 h and 120 days, respectively. The color
and chemical changes that occurred on the surface of the WPCs were analyzed using a set of analytical techniques. For pine
and extractive-free pine filled composites, the results showed that the total color change, lightness, and oxidation increased,
while the lignin content decreased. In addition, the weight average molecular weight (Mw) and number average molecular weight (Mn) of extracted HDPE decreased with an increase in exposure time of the composites. However, HDPE crystallinity increased with
longer exposure time. Lightness of holocellulose-based WPC changed the least while the change in its HDPE crystallinity was
not significant compared to the other composite types. Therefore, holocellulose-based WPC may be preferred for applications
where color stability is of high priority. 相似文献
10.
Md. Rezaur Rahman Md. Nazrul Islam Md. Monimul Huque 《Journal of Polymers and the Environment》2010,18(3):443-450
In the present work, sawdust reinforced polypropylene composites were fabricated using an extruder and an injection molding
machine. Raw sawdust was chemically treated with benzene diazonium salt in order to improve the mechanical properties of the
composites. The effect of the chemically treated sawdust reinforced PP composites was evaluated from their mechanical and
surface morphological properties. The values of the mechanical properties of the chemically treated sawdust–PP composites
were found to be significantly higher than those of the raw ones. Water uptake tests revealed that composites prepared from
the chemically treated sawdust absorb lower amount of water compared to the ones prepared from raw sawdust, suggesting that
hydrophilic nature of the cellulose in the sawdust has significantly decreased upon chemical treatment. The surface morphology
obtained from scanning electron microscopy (SEM) showed that raw sawdust–PP composites possess surface roughness with extruded
filler moieties, and weak interfacial adhesion between the matrix and the filler while the chemically treated one showed improved
filler–matrix interaction. This indicates that better dispersion of the filler with the PP matrix has occurred upon chemical
treatment of the filler. 相似文献
11.
Graft copolymerization of cellulosic biopolymers with synthetic polymers is of enormous interest because of its application
in biofiltration, biosorption, biomedical, biocomposites and various other eco-friendly materials. Synthesis of graft copolymers
of methyl acrylate onto mercerized Grewia optiva
biofibers using ferrous ammonium sulfate–potassium per sulfate as redox initiator in air was carried out. Different reaction parameters
such as amount of solvent, monomer concentration, initiator molar ratio, reaction time and reaction temperature were optimized
to get the maximum percentage of grafting. The graft copolymers thus formed were characterized by Fourier transform infrared
spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis and differential thermogravimetric
techniques. A plausible mechanism for explanation of the graft copolymerization reactions pattern shown is offered. The effect
of grafting percentage on the physico–chemical properties of raw as well as grafted Grewia optiva
biofibers has also been investigated. The graft copolymers have been found to be more moisture resistant and also showed better chemical
and thermal resistance. Green polymer composites were also successfully prepared through compression molding technique by
using grafted Grewia optiva
biofibers as reinforcement. 相似文献
12.
Tara Sankar Pathak Jung-Ho Yun Se-Jong Lee Dae-Jin Baek Ki-Jung Paeng 《Journal of Polymers and the Environment》2010,18(1):45-56
Alginates, extracted from algae are linear unbranched polymers containing β-(1→4)-linked d-mannuronic acid (M) and α-(1→4)-linked l-guluronic acid (G) residues. The conversion of alginic acid into the metal alginate is confirmed using FTIR spectroscopy.
Asymmetric and symmetric stretching of free carboxyl group present in metal alginate occurs almost at the same position in
various solvent compositions. Total intrusion volume of metal alginate prepared in propanol (0.0742 mL/g) is greater compared
to those in ethanol (0.0648 mL/g) and methanol (0.0393 mL/g) as solvent. Surface morphology as well as porosity and pore size
distribution of metal alginate are greatly influenced by solvent. It can be seen from thermal analysis results that calcium
alginate prepared using different solvent compositions started decomposing at 100 °C, but rapid degradation started around
200 °C. The results showed a stepwise weight loss during thermal sweep, indicating different types of reactions during degradation.
First and second step of rapid degradation was situated around 200–300 and 300–550 °C, respectively; whereas the final step
is situated around 550–650 °C. The trend of degradation was similar for all the solvents, although the amount of final residue
varied from one solvent to another. At the same time, lower thermal stability was also observed with higher heating rates.
Additionally, a kinetic analysis was performed to fit with TGA data, where the entire degradation process has been considered
as three consecutive first order reactions. 相似文献
13.
Fahmida Parvin Mubarak A. Khan A. H. M. Saadat M. Anwar H. Khan Jahid M. M. Islam Mostak Ahmed M. A. Gafur 《Journal of Polymers and the Environment》2011,19(4):1013-1022
Blends based on different ratios of starch (35–20%) and plasticizer (sugar; 0–15%) keeping the amount of poly(vinyl alcohol)
(PVA) constant, were prepared in the form of thin films by casting solutions. The effects of gamma-irradiation on thermal,
mechanical, and morphological properties were investigated. The studies of mechanical properties showed improved tensile strength
(TS) (9.61 MPa) and elongation at break (EB) (409%) of the starch-PVA-sugar blend film containing 10% sugar. The mechanical
testing of the irradiated film (irradiated at 200 Krad radiation dose) showed higher TS but lower EB than that of the non-radiated
film. FTIR spectroscopy studies supported the molecular interactions among starch, PVA, and sugar in the blend films, that
was improved by irradiation. Thermal properties of the film were also improved due to irradiation and confirmed by thermo-mechanical
analysis (TMA), differential thermo-gravimetric analysis (DTG), differential thermal analysis (DTA), and thermo-gravimetric
analysis (TGA). Surface of the films were examined by scanning electron microscope (SEM) image that supported the evidence
of crosslinking obtained after gamma irradiation on the film. The water up-take and degradation test in soil of the film were
also evaluated. In this study, sugar acted as a good plasticizing agent in starch/PVA blend films, which was significantly
improved by gamma radiation and the prepared starch-PVA-sugar blend film could be used as biodegradable packaging materials. 相似文献
14.
In this study, ozone treatment was used to improve the surface wettability of waste tire rubber (WTR) powders. Fourier transform
infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) were performed in order to characterize the surface composition
of the treated samples. The progress of surface modification was also monitored by contact angle measurements of different
test liquids (water and liquid paraffin). The surface energy values were evaluated in terms of the Owens’ method and the contact
angle data were compared with the results obtained by the surface analytical methods (i.e. FTIR and XPS measurements). These
results showed that ozone treatment lead to a remarkable decrease in water contact angle owing to the implantation of oxygen-containing
functional groups. Using XPS and FTIR, the oxygen-containing groups can be identified as C–O, O–C=O and C=O. With prolongation
of ozone treatment time, WTR exhibited increasing oxygen-containing groups, surface energy and wettability. 相似文献
15.
The weathering of municipal solid waste incineration (MSWI) residues consists of complicated phenomena. This makes it difficult to describe leaching behaviors of major and trace elements in fresh/weathered MSWI bottom ash, which was relevant interactively to pH neutralization and formation of secondary minerals. In this study, mineralogical weathering indices for natural rock profiles were applied to fresh/landfilled MSWI bottom ash to investigate the relation of these weathering indices to landfill time and leaching concentrations of component elements. Tested mineralogical weathering indices were Weathering Potential Index (WPI), Ruxton ratio (R), Weathering Index of Parker (WIP), Vogt’s Residual Index (V), Chemical Index of Alternation (CIA), Chemical Index of Weathering (CIW), Plagioclase Index of Alternation (PIA), Silica–Titania Index (STI), Weathering Index of Miura (Wm), and Weatherability index of Hodder (Ks). Welch’s t-test accepted at 0.2% of significance level that all weathering indices could distinguish fresh and landfilled MSWI bottom ash. However, R and STI showed contrasted results for landfilled bottom ash to theoretical expectation. WPI, WIP, Wm, and Ks had good linearity with reclamation time of landfilled MSWI bottom ash. Therefore, these four indices might be applicable as an indicator to indentify fresh/weathered MSWI bottom ash and to estimate weathering time. Although WPI had weak correlation with leachate pH, other weathering indices had no significant correlation. In addition, all weathering indices could not explain leaching concentration of Al, Ca, Cu, and Zn quantitatively. Large difficulty to modify weathering indices correctly suggests that geochemical simulation including surface sorption, complexation with DOM, and other mechanisms seems to be the only way to describe leaching behaviors of major and trace elements in fresh/weathered MSWI bottom ash. 相似文献
16.
Divia P. Sreenivasan A. Sujith C. Rajesh 《Journal of Polymers and the Environment》2018,26(7):2720-2729
Biocomposites of acrylonitrile butadiene rubber (NBR) reinforced with chicken feather fibre (CF) were prepared using dicumyl peroxide (DCP) as vulcanizing agent. Composites with three series of chicken feather fibres were studied i.e., raw (RCF), sterilized (SCF) and alkali treated (ACF). The cure characteristics of composites were studied. The mechanical properties of NBR were found to be improved by the incorporation of chicken feather fibre in all forms. Surface modification of the fibre was done by alkaline treatment to improve the interfacial adhesion and it characterised by FTIR. Better properties are shown by the composites with ACF. The swelling behaviour of the composites in N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide and water were analyzed for the swelling coefficient values. The biodegradable characteristics of CF reinforced NBR composites were studied by soil burial test which indicated that it is an eco-friendly and acceptable material. Scanning electron microscopy studies support the results of mechanical properties. The outcome obtained from this study is believed to assist the development of environmentally–friendly composites especially for specific product applications like oil seals, hoses and automobile bushes etc. 相似文献
17.
Suvangshu Dutta Niranjan Karak Jyoti Prasad Saikia Bolin Kumar Konwar 《Journal of Polymers and the Environment》2010,18(3):167-176
Mesua ferrea L. seed oil (MFLSO) modified polyurethanes blends with epoxy and melamine formaldehyde (MF) resins have been studied for
biodegradation with two techniques, namely microbial degradation (broth culture technique) and natural soil burial degradation.
In the former technique, rate of increase in bacterial growth in polymer matrix was monitored for 12 days via a visible spectrophotometer
at the wavelength of 600 nm using McFarland turbidity as the standard. The soil burial method was performed using three different
soils under ambient conditions over a period of 6 months to correlate with natural degradation. Microorganism attack after
the soil burial biodegradation of 180 days was realized by the measurement of loss of weight and mechanical properties. Biodegradation
of the films was also evidenced by SEM, TGA and FTIR spectroscopic studies. The loss in intensity of the bands at ca. 1735 cm−1 and ca. 1050 cm−1 for ester linkages indicates biodegradation of the blends through degradation of ester group. Both microbial and soil burial
studies showed polyurethane/epoxy blends to be more biodegradable than polyurethane/MF blends. Further almost one step degradation
in TG analysis suggests degradation for both the blends to occur by breakage of ester links. The biodegradation of the blends
were further confirmed by SEM analyses. The study reveals that the modified MFLSO based polyurethane blends deserve the potential
to be applicable as “green binders” for polymer composite and surface coating applications. 相似文献
18.
Effect of Orientation on the Morphology and Mechanical Properties of PLA/Starch Composite Filaments 总被引:1,自引:0,他引:1
Randal L. Shogren Gordon Selling J. L. Willett 《Journal of Polymers and the Environment》2011,19(2):329-334
Polylactic acid (PLA)/starch fibers were produced by twin screw extrusion of PLA with granular or gelatinized starch/glycerol
followed by drawing through a set of winders with an intermediate oven. At 30% starch, fibers drawn 2–5x were highly flexible
(elongation 20–100%) while undrawn filaments were brittle (elongation 2–9%). Tensile strength and moduli increased with increasing
draw ratio but decreased with increasing starch content. Mechanical properties were better for composites made with gelatinized
starch/glycerol than granular starch. In conclusion, orientation greatly increases the flexibility of PLA/starch composites
and this may be useful not only in fibers but also possibly in molded articles. Other advantages of starch addition could
include fiber softness without added plasticizer, moisture/odor absorbency and as a carrier for active compounds. 相似文献
19.
V. L. Finkenstadt C.-K. Liu P. H. Cooke L. S. Liu J. L. Willett 《Journal of Polymers and the Environment》2008,16(1):19-26
Sorbitol and glycerol were used to plasticize sugar beet pulp-poly(lactic acid) green composites. The plasticizer was incorporated
into sugar beet pulp (SBP) at 0%, 10%, 20%, 30% and 40% w/w at low temperature and shear and then compounded with poly(lactic
acid) (PLA) using twin-screw extrusion and injection molding. The SBP:PLA ratio was maintained at 30:70. As expected, tensile
strength decreased by 25% and the elongation increased. Acoustic emission (AE) showed correlated debonding and fracture mechanisms
for up to 20% w/w plasticizer and uncorrelated debonding and fracture for 30–40% sorbitol and 30% glycerol content in SBP–PLA
composites. All samples had a well dispersed SBP phase with some aggregation in the PLA matrix. However, at 40% glycerol plasticized
SBP–PLA composites exhibited unique AE behavior and confocal microscopy revealed the plasticized SBP and PLA formed a co-continuous
two phase system.
相似文献
V. L. FinkenstadtEmail: |
20.
K. Abdel Tawab M. M. Magida Sayeda M. Ibrahim 《Journal of Polymers and the Environment》2011,19(2):440-446
Blends of water—soluble polymers based on Poly vinyl alcohol (PVA) and Polyethylene glycol (PEG) have been prepared by the
solution casting technique. The effect of various doses of γ-radiation on the structural properties of PVA/PEG polymer blends
with all its compositions has been investigated. From the visual observation of all the blend compositions, it was found that,
the best compatibility of the blend is up to 40% PVA/60%PEG. The structure–Property behavior of all the prepared blends before
and after γ-irradiation was investigated by IR Spectroscopy, thermogravimetric analysis (TGA), mechanical properties and Scanning
electron microscope (SEM). The gel content and the swelling behavior of the PVA/PEG blends were investigated. It was found
that the gel content increases with increasing irradiation dose and PVA concentration in the blend. Swelling percent increased
as the composition of PEG increased in the blend. The results obtained by FTIR analysis and SEM confirm the existence of possible
interaction between PVA and PEG homopolymers. TGA of PVA/PEG blend, before and after γ-irradiation, showed that the unirradiated
and irradiated PVA/PEG blends are more stable against thermal decomposition than pure PVA. Improvement in tensile mechanical
properties of PVA/PEG blends was occurred. 相似文献