Synthesis and tensile properties of a novel composite of Chlorella and polyethylene

A novel composite of the green microalga Chlorella sp. with polyethylene (PE) was synthesized through chemical modification of PE with maleic anhydride (MA), with respect to the biological fixation of CO₂ with Chlorella sp. The interaction of Chlorella grains with a PE matrix is strikingly enhanced by the chemical modification of PE with MA. The tensile strength of a Chlorella–MA‐modified PE composite (Ch–MPE) with a Chlorella content of 40 wt % is more than 2 times greater than that of a composite derived from unmodified PE. The marked increase in tensile strength is attributed to the formation of chemical bonds between Chlorella grains and the PE matrix, from IR and SEM studies. Because of the satisfactory thermal plasticity of Ch–MPE, it can be easily shaped into plate and dishlike moldings by a heat‐pressurizing method. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 812–816, 2004     

Photosynthetic production of biomass and starch by Chlorella in chemostat culture

A high temperature strain of Chlorella was grown photosynthetically with nitrogen limitation of growth over a range of dilution rates up to the critical value of 0.22 h^?1. The “total cell dry weight” is distinguished from the “real biomass” which is total cell dry weight less starch. Nitrogen-limited growth of Chlorella, in terms of real biomass, obeyed the simple Monod model of chemostat culture. In a low EDTA medium (about 1 mol of EDTA per mol Fe³⁺) ferric hydroxide precipitated at pH 7 and caused iron-limited growth to occur at high dilution rates. Iron precipitation and consequently iron-limited growth, were prevented by increasing the EDTA to 2 mol per mol Fe³⁺. It was deduced that Fe³⁺ was available to the cells only as Fe-EDTA complex, not as free Fe³⁺ in the medium. A glycogen-like starch was stored in the cells and the starch content approached 50% of the total dry weight of cells at low dilution rates. The starch content of the total cell dry weight was practically independent of the growth temperature over the range 28–40°C and the pH over the range 5.5–8.5. The specific rate of starch production (q_starch) reached 0.05 g of starch/g real biomass h.     

Interactions between an alga and three bacterial species in a consortium selected for photosynthetic biomass and starch production

A four-membered consortium (MA003) of an algal species and bacteria was selected from a natural source for its ability to grow at 37°C and produce starch photosynthetically from carbon dioxide. The photosynthetic culture consisted of a Chlorella-like green alga (A003) and three heterotrophic bacteria, Alcaligenes sp. (B001), Flavobacter sp. (B002) and Serratia sp. (B003). The substrates for the bacterial growth were probably organic nitrogen and carbon compounds excreted by the alga at specific rates which were independent of the algal specific growth rate. The maximum specific growth rate of the alga was decreased by an inhibitor produced by bacterium B002. Bacterium B001 removed the inhibitor of algal growth released by bacterium B002, and bacterium B003 decreased the growth of bacterium B002 and consequently the production of algal growth inhibitor. The growth of bacterium B003 was greatly suppressed in the four-member consortium MA003. The coexisting bacteria in toto, did not affect the growth rate, yield and starch production of the algal member, but did help to establish a stable ecosystem and increase the biomass available. A culture density up to 36 g dry weight dm^?3 was achieved without significant variation in the ratio of the species in the culture.     

Daily doses of light in relation to the growth of Scenedesmus obliquus in diluted three‐phase olive mill wastewater

BACKGROUND: The use of olive‐oil mill wastewater (OMW) from a three‐phase centrifugation process used in the olive‐oil industry, has been studied in relation to the production of the microalga Scenedesmus obliquus CCAP 276/3A. The chemical characteristics of OMW indicated nitrogen deficiency. RESULTS: S. obliquus is able to assimilate nutrients present in a culture medium (water‐OMW 5%) and grow at its maximum specific growth rate of 0.026 h^?1, both under mixotrophic as well as heterotrophic conditions. The different daily doses of light (DDL) used, in the range 0–36 E m^?2 d^?1, determined light‐limited and light‐inhibited cultures. The light‐inhibited mixotrophic cultures bore characteristics similar to those of the heterotrophic cultures, and became more so when the dose of light received was higher. The low protein yield (258 mg g^?1) and high percentage of carbohydrates of the biomass (65.8%) confirmed a nutritional‐stress situation associated with nitrogen limitation. CONCLUSION: The similarity between the fatty‐acid composition of the heterotrophic and mixotrophic cultures strongly inhibited by light appeared to indicate the cancelling of the photosynthetic behaviour of the cells at high DDL values. The biomass generated can be used for biofuels. The maximum elimination of biological oxygen demand (BOD₅) per unit of biomass was achieved in the heterotrophic cultures. Copyright © 2009 Society of Chemical Industry     

Growth of Thiobacillus ferrooxidans on ferrous iron in chemostat culture: Influence of product and substrate inhibition

Thiobacillus ferrooxidans was grown at pH 1.6 in continuous flow chemostat culture on ferrous sulphate as growth limiting substrate at dilution rates between 0.02–1.33 h^?1. Iron oxidation and growth were subject to product inhibition by ferric iron and under some conditions substrate inhibition by ferrous iron. Product inhibition could be predominantly competitive or non-competitive, and the mode observed depended partly on previous steady state conditions. The inhibition phenomena resulted in unique anomalous washout curves and complex relationships between steady-state substrate, product and biomass concentrations, for which mathematical models are developed. For the growth states subject to non-competitive inhibition by Fe³⁺ at D 0.073–0.99 h^?1, the growth yield coefficient corrected for maintenance (Y_G) was 1.33 g dry wt (g atom Fe²⁺ oxidized)^?1 and the maintenance coefficient (m) was 0.43 g atom Fe²⁺ oxidized (g dry wt)^?1 h^?1). For predominantly competitive states (D, 0.05–0.268 h^?1) with 2–70 mM Fe³⁺ in steady states, Y_G was 0.36–0.38 and m was 0–0.04. A consequence of product inhibition and substrate inhibition was the possibility of more than one steady state product value and yield for a single steady state substate concentration. This was demonstrated experimentally. Substrate saturation coefficient, K_s (giving half maximum specific growth rate) for Fe²⁺, was 0.7–2.4 mM and maximum specific growth rate (μ_m) 1.25–1.78 h^?1. The results presented reveal unusual and novel properties of T. ferrooxidans relevant to describing its activities in natural environments or in mineral leaching systems.     

Effects of light quality on the accumulation of oil in a mixed culture of Chlorella sp. and Saccharomyces cerevisiae

BACKGROUND: Chlorella strains rather than terrestrial oil crops having higher oil content and shorter generation time have been considered as promising candidates for alternative biodiesel. Since the influence of light quality on oil formation of microalgae in either monoculture or mixed culture has been shown to be either inconsistent or ambiguous, a light‐emitting diode (LED) photo‐bioreactor with different light sources and intensities was used in this study to investigate a cost‐effective lipid production process. RESULTS: The oil accumulation in a mixed culture of Chlorella sp. and Saccharomyces cerevisiae was higher than that in the monoculture under the different light sources used. Results of the influence of light quality on the mixed culture indicated that the optimal light wavelength and intensity for biomass formation was red LED light at 1000 lux, whereas the optimum for oil formation was blue LED light at 1000 lux. A novel two‐stage LED photo‐bioreactor was thus proposed and the highest P_max and productivity in this study were obtained as 261 mg L^?1 and 8.16 mg L^?1 h^?1, respectively. CONCLUSION: A novel two‐stage LED photo‐bioreactor using a mixed culture to optimize microalgal oil production was proposed and successfully demonstrated in this study. Copyright © 2011 Society of Chemical Industry     

Modified Photobioreactor for Biofixation of Carbon Dioxide by Chlorella vulgaris at Different Light Intensities

The performance of a modified bioreactor inside a light enclosure for carbon dioxide biofixation by Chlorella vulgaris was investigated. The influence of different light intensities on the CO₂ biofixation and biomass production rates was evaluated. The results showed that the photon flux available to the microalgal cultures can be a key issue in optimizing the microalgae photobioreactor performance, particularly at high cell concentrations. Although the optimal pH values for C. vulgaris are in the range of 6–8, cell growth can take place even at pH 4 and 10. Batch microalgae cultivation in the photobioreactor was used to investigate the effect of different light intensities. The maximum biomass concentration of 1.83 g L^?1 was obtained at a light intensity of 100 μmol m^?2s^?1 and under aeration with 2 L min^?1 of 2 % CO₂‐enriched air.     

A tubular bioreactor for photosynthetic production of biomass from carbon dioxide: Design and performance

A theory of photobioreactor design is developed. A photobioreactor was constructed in the form of a loop made from 52 m of glass tubing of 1 cm bore; the loop covered about 0.5 m². The culture was illuminated with mercury halide lamps to reproduce sunlight. Computer control was used to maintain constant biomass concentration. The influence of radiation on the reactor temperature is quantitatively predicted. An air lift system was preferred to a liquid pump for culture recycle. The energy required for culture recycle in the loop with Reynolds number 2000 was 0.6 W m^?2. The CO₂ gas/liquid transfer rate achieved was sufficient to meet the maximum possible demand with solar irradiation. The O₂ gas/liquid transfer rate was sufficient to meet the maximum respiration demand at night. The maximum algal biomass concentration achieved exceeded 20 g dry weight litre^?1. A biomass concentration of 8 g dry weight litre^?1 was found to be convenient for normal operation. The maximum uptake of light in the available wavelength range (400–700 nm) was 38 W m^?2, this corresponds to utilisation of solar irradiation up to 89 W m^?2. Below the maximum light uptake rate the efficiency of storage of light energy in the biomass corresponded to 16.6% of solar energy.     

Hydrogen-gas production with Citrobacter intermedim and Clostridium pasteurianum

Citrobacter intermedius and Clostridium pasteurianum were grown in 14-dm³ batch reactors on glucose and measured for biomass and H2 production. Gas production with C. intermedius was found to be growth related, whereas that with C. pasteurianum was entirely produced during the stationary phase of growth. The maximum yield and productivity of H₂ with C. intermedius was 60% H₂ or 1 mol of H₂ mol^?1 of glucose at a maximum of 3.7 mmol of H₂ h^?1 and 85% H₂ or 1.5 mol of Ha mol^?1 of glucose at a maximum of 9.0 mmol of H₂ h^?1 with C. pasteurianum. The overall H₂ productivity (QH₂) was 2.5 mmol of H₂ h^?1 g^?1 dry biomass for C. pasteurianum at a glucose concentration of 7.6 g dm^?3. As the glucose concentration was increased from 7.6 to 15.4 g dm^?3, up to 44% of the gas produced with C. pasteurianum was growth associated. The remainder of the gas was produced in the stationary phase. In this case the overall Ha productivity (QH₂) was 1.2 mmol of H₂ h^?1 g^?1 dry biomass. The comparative experiments indicate that maximum yields and rates of H₂ production were achieved with C. pasteurianum.     

Photosynthetic production of Dunaliella biomass from natural salt water and carbon dioxide

A Dunaliella strain has been isolated and grown in a medium containing saline lake water. Using 40% saline water and mixture of CO₂-air (4% CO₂) the algae grew with a specific growth rate of 0.073 h⁻¹. The maximum cell concentration was 5.6 × 10⁷ cells cm⁻³ which corresponded to 3.63 g dm⁻³ of dry biomass. Using 80% saline water, a glycerol concentration of 1.47 g glycerol g⁻¹ of, protein was obtained which amounted to 44.3% of Dunaliella dry weight. Fermentor CO₂ from a continuous yeast culture was also used as carbon source for photosynthetic growth. At 2.5% CO₂ in the exit gas a decrease of the specific growth rate was observed but the final concentration attained was comparable to that obtained with CO₂-air mixtures.     

New polymer to enhance the permanent memory effect of polymer dispersed liquid crystal films

Conventional polymer dispersed liquid crystals (PDLC) are devices with recognized applications. New PDLCs with permanent memory effect (PME) can be used as digital memory devices. The synthesis and characterization of a new monomer [pentaerythritoltetramethacrylate (PE4MA)] is here described. A PDLC was produced using the synthesized monomer (PE4MA) copolymerized with commercially available monomethacrylate oligomer poly(propyleneglycol) methacrylate (PPGMA) and 70% (w/w) liquid crystal (E7), showing 98% permanent memory effect, with 72% memory state contrast (MSC) and an electric field required to achieve 90% of the maximum transmittance (E₉₀) of 3 V µm^?1. The synthesized monomer (PE4MA) copolymerized with PPGMA seems to be a prospective material for preparation of PDLC with permanent memory effect with a view to application for digital memory devices based on write‐read‐erase cycles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43482.     

Gasoline permeation behavior and mechanical properties of polyamide 6/nanoclay,polyamide 6/PE‐g‐maleic anhydride blend,and polyamide 6/PE‐g‐maleic anhydride/clay nanocomposite

In this article, polyamide 6 (PA6)/clay nanocomposites, PA6/polyethylene grafted maleic anhydride (PE‐g‐MA) blends, and PA6/PE‐g‐MA/clay nanocomposites were prepared and their gasoline permeation behavior and some mechanical properties were investigated. In PA6/clay nanocomposites, cloisite 30B was used as nanoparticles, with weight percentages of 1, 3, and 5. The blends of PA6/PE‐g‐MA were prepared with PE‐g‐MA weight percents of 10, 20, and 30. All samples were prepared via melt mixing technique using a twin screw extruder. The results showed that the lowest gasoline permeation occurred when using 3 wt % of nanoclay in PA6/clay nanocomposites, and 10 wt % of PE‐g‐MA in PA6/PE‐g‐MA blends. Therefore, a sample of PA6/PE‐g‐MA/clay nanocomposite containing 3 wt % of nanoclay and 10 wt % of PE‐g‐MA was prepared and its gasoline permeation behavior was investigated. The results showed that the permeation amount of PA6/PE‐g‐MA/nanoclay was 0.41 g m^?2 day^?1, while this value was 0.46 g m^?2 day^?1 for both of PA6/3wt % clay nanocomposite and PA6/10 wt % PE‐g‐MA blend. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40150.     

Multiobjective optimization of microalgae (Chlorella sp.) growth in a photobioreactor using Box‐Behnken design approach

This study investigates a parameter optimization approach to maximize the specific growth rate of the Chlorella vulgaris microalgae species, its biomass productivity, and CO₂ capture rate. For this purpose, the Box‐Behnken experimental design technique is applied with temperature, nitrogen to phosphorus ratio, and light‐dark cycle per day, as the growth controlling parameters. For each response, a quadratic model is developed separately describing the algal specific growth rate, biomass productivity, and CO₂ capture rate, respectively. The maximum specific growth rate of 0.84 d^?1 is obtained at 25 °C, with a nitrogen to phosphorus ratio of 3.4:1, and light‐dark cycles of 24/0 h. Maximum biomass productivity of 147.3 mg L^?1 d^?1 is found at 30 °C, with a nitrogen to phosphorus ratio of 3:1, and light‐dark cycles of 12/12 h. In addition, the maximum CO₂ capture rate of 159.5 mg L^?1 d^?1 is also obtained at 30 °C, with a nitrogen to phosphorus ratio of 4:1, and light‐dark cycles of 23/1 h. Finally, a multi‐response optimization method is applied to maximize the specific growth rate, biomass productivity, and CO₂ capture rate, simultaneously. The optimal set of 30 °C, a nitrogen to phosphorus ratio 3:1, and light‐dark cycles 16/8 h, provide the maximum specific growth rate of 0.66 per day, biomass productivity of 147.6 mg L^?1 d^?1, and CO₂ capture rate of 141.7 mg L^?1 d^?1.

     

Degradation of Pentachlorophenol by Microalgae

A microalga (VT-1) was isolated from pentachlorophenol (PCP) treated water. Its growth and PCP tolerance was compared with two known strains of Chlorella and it was found to be more tolerant with an IC₅₀ (24–25 mg dm⁻³) value twice that of C. vulgaris. The ability of VT-1 to degrade PCP was tested using uniformly labelled PCP, and ¹⁴CO₂ was released, indicating mineralisation. ¹⁴CO₂ was not released in the presence of the other microalgae and only occurred in the light. Release was also stimulated by the presence of glucose in the light. © 1997 SCI.     

Conversion of waste plastics to single-cell protein by means of pyrolysis followed by fermentation

Waste plastics (e.g. polyethylene, polystyrene and polypropylene) have been converted to single-cell protein using pyrolysis followed by fermentation. Conversion efficiencies of plastics to pyrolysate were 75–90% for polyethylene, 10–56% for polystyrene and 40–50% for polypropylene. Unpyrolysed residues were formed with polystyrene (6–14%) and polypropylene (14–30%), but not with polyethylene. Polyvinyl chloride produced hydrogen chloride fumes, together with 33–39% unpyrolysed residue, no fermentable pyrolysis products being formed. Polyethylene pyrolysate was fermented by the yeast, Candida tropicalis. Batch fermentation was carried out at 31°C and pH 5.5 on polyethylene pyrolysate in shaken flasks (100 cm³ culture) and in an aerated fermenter (500 cm³ culture). Maximum growth rate was 0.168 h^?1, cell yield was 0.47 ± 0.02 g g^?1 pyrolysate used (n = 3) and doubling time was 4–5 h, after 72 h growth on 1.0g pyrolysate 100 cm^?3 culture. Continuous culture (dilution rate 0.10 h^?1) gave a dry cell yield of 0.39 g g^?1 pyrolysate utilised. Utilisation of pyrolysate was 49.0% in batch culture and 33.0% in continuous culture. The efficiency of conversion of polyethylene to biomass was 34–42% in batch culture. Emulsification and pristane-solubilisation were studied as a means of dispersing waxy pyrolysates in culture media. Pristane did not support growth whereas the emulsifier [lecithin, Tween 85 and sodium glycocholate (1:2:2 by weight)] could support up to 27% of the growth observed on polyethylene pyrolysate. Although growth would occur without either emulsifier or pristane, use of pristane increased both dry cell yield (g g^?1 pyrolysate used) and pyrolysate utilisation by 1.3 times in flask cultures. Crude protein content of cells cultured on polyethylene pyrolysate was 46.7 ± 2.4% (n = 3) for batch culture cells, and 43.8 ± 0.3% (n = 4) for continuous culture cells. The true protein content of Candida cells was about 17%. The protein had a favourable nutritional quality as judged by in-vitro chemical tests.     

Intermediate accumulation and efficiency of anaerobic digestion treatment of surfactant (alcohol sulfate)‐rich wastewater at increasing surfactant/biomass ratios

Textile (eg cotton) finishing industry wastewater is characterised by high concentrations of surfactants (up to 2 g dm^?3) and of readily biodegradable biopolymers (COD 5–15 g dm^?3). The anionic surfactant decyl sulfate (DS) was chosen as model surfactant and soluble starch (size) as model compound for the readily biodegradable fraction of the wastewater. Twenty‐two batch experiments with increasing DS/biomass ratio (and starch/biomass ratio) were started simultaneously. Biomass concentrations ranged from 50 to 15 000 mg dm^?3. Minor inhibition effects were found for the surfactant degradation itself at all DS/biomass ratios (maximum biodegradation rate 7.7 mg_DS g_biomass^?1 h^?1). The starch hydrolysis started without a lag‐phase at DS/biomass ratios of up to 0.15 g_DS g_biomass^?1. The lag‐phase was prolonged to about 100 h at a very high DS/biomass ratio (3 g_DS g_biomass^?1). The relative importance of the accumulated intermediates was dependent on the DS/biomass ratio. Above 0.3 g_DS g_biomass^?1 10% of the substrate organic carbon accumulated as ethanol, but no ethanol accumulation was observed at low DS/biomass ratios. Moderate DS/biomass ratios caused a considerable delay of the methanogenesis; high DS/biomass ratios prevented the methanogenesis almost completely. © 2002 Society of Chemical Industry     

Production of cyclodextrin glycosyltransferase by batch and chemostat culture of Bacillus macerans in chemically defined medium

A chemically defined medium for cultivation of Bacillus macerans is reported. Growth rates and cyclodextrin glycosyltransferase (CGT) titres obtained were similar to those obtained using media containing potato extract. The proteins in supernatant fluids from a batch culture were separated by disc electrophoresis and results obtained showed that CGT was produced after growth ceased, in agreement with results of activity measurements. The maximum growth rate in the chemostat considerably exceeded that in batch culture; this anomalous effect is unexplained. High CGT titres were produced at low dilution rates (0.03 to 0.05 h^?1) but residual starch was present at higher dilution rates and CGT synthesis was repressed. Enzyme titres obtained in chemostat cultures at D = 0.03 h^?1 using defined medium containing 13 g starch/1 were 2.75 times greater than the maximum obtainable by batch cultivation and about 20 times greater than those reported by other workers using medium containing diced potato and CaCO₃. A two-stage chemostat cultivation was performed using dilution rates of 0.1 h^?1 and 0.033 h^?1 in the first and second stages, respectively. The CGT activity in the second stage increased by 57 per cent when a maintenance feed of starch was supplied at 0.08 g g^?1 dry biomass h^?1. Only negligible CGT titres were obtained when a dilution rate of 0.5 h^?1 was used in the first stage. For reasons not understood, DM medium would not support biomass yields greater than 5 g 1^?1. This limitation was not due to production of an inhibitor, or to deficiency of N, Fe, Zn, Mn, thiamine or biotin.     

Potential fuel oils from the microalga Choricystis minor

BACKGROUND: Continuous culture of the freshwater microalga Choricystis minor was investigated for possible use in producing lipid feedstock for making biofuels. The effects of temperature (10–30 °C) and dilution rate (0.005–0.017 h^?1) on lipid productivity in a nutrient sufficient medium in a 4 L stirred tank bioreactor under continuous illumination at an incident irradiance level of 550 µE · m^?2s^?1 and a controlled pH of 6 under carbon dioxide supplemented conditions are reported. RESULTS: The maximum lipid productivity was 82 mg L^?1 d^?1 at 25 °C and a dilution rate of 0.014 h^?1. Lipid contents of the biomass were 21.3 ± 1.7 g per 100 g of dry biomass, irrespective of the culture temperature and dilution rate. After the biomass had been grown in nutrient sufficient conditions in continuous culture, it was recovered and subjected to various postharvest treatments. With the best postharvest treatment, the neutral lipid contents of the algal biomass were raised ～6‐fold relative to untreated biomass. CONCLUSION: At 82 mg L^?1 d^?1, or 21 000 L ha^?1 year^?1, the lipid productivity of C. minor was nearly four times the lipid productivity of oil palm, a highly productive crop. Therefore, C. minor is potentially a good source of renewable lipid feedstock for biofuels. Copyright © 2009 Society of Chemical Industry     

Effects of light wavelength and intensity on the production of ethanol by Saccharomyces cerevisiae in batch cultures

BACKGROUND: Photoreceptors have been identified in Saccharomyces cerevisae, however, the influence of light on the performance of ethanol fermentation of S. cerevisiae is not yet clear. The aims of this study are to elucidate the influence of light wavelength and intensity on the growth and ethanol production of S. cerevisiae and to describe a novel two‐stage LED light process to optimize ethanol fermentation. RESULTS: Experimental results indicated that maximum biomass concentration X_max of the batch under red LED light increased monotonically with light intensity, and the optimal specific product yield Y_p/x was 13.2 g g^?1 at 600 lux. Maximum ethanol concentration P_max of the batch under blue LED light increased monotonically with light intensity, and the optimal Y_p/x was 18.4 g g^?1 at 900 lux. A novel two‐stage LED light process achieved maximum P_max, of 98.7 g dm^?3 resulting in 36% improvement compared with that of the batch in the dark. CONCLUSION: The light wavelength and its intensity significantly affected cell growth and ethanol formation of S. cerevisiae. Red LED light (630 nm) stimulated cell growth but slightly inhibited ethanol formation. In contrast, blue LED light (470 nm) significantly inhibited cell growth but stimulated ethanol formation. A novel two‐stage LED light process has been successfully demonstrated to optimize ethanol fermentation of S. cerevisiae. Copyright © 2009 Society of Chemical Industry     

Structure and properties of maleated high-density polyethylene

Possible changes in the structure and properties of maleated polyethylene (HDPE–MA) at different degrees of grafting (D.G.) were examined. At the level of 1.6 maleic anhydride (MA)/100 ethylene units E, 70–80% of crystallinity of the parent PE was retained (DSC and WAXD). Both melting temperature and crystallization temperature decreased only slightly with increase in D. G. The lattice constants a and b of the orthorhombic PE crystallites remained constant, although c was constantly at a larger value. The presence of MA groups hampered the packing of PE chains, leading to an increase in PE crystallite sizes of L?₁₁₀ and L?₂₀₀ with maleation. Of the viscoelastic relaxations, dynamic mechanical analysis showed easier segmental motions and thus lowering in γ-, α- and β-relaxation temperatures with maleation. The breaking strength (σ_b) increased slightly with maleation, whereas the elongation at break (ε_b) lowered due to interaction between the MA groups. In all, in HDPE-MA up to a D. G. of 1.6 MA/100 E, PE properties were maintained to be used per se or as a compatibilizer for blends involving PE or in any other usage where retention of PE properties is desired. © 1994 John Wiley & Sons, Inc.