Recycled High Density Polyethylene Research Articles

RSM and ANN Modeling for Production of Newbouldia Laevies Fibre and Recycled High Density Polyethylene Composite: Multi Objective Optimization Using Genetic Algorithm

In this study response surface methodology (RSM), artificial neural network (ANN) and non-dominated sorting genetic algorithm-II (NSGA-II) were used for modeling and multi objective optimization of Newbouldia Laevies Fibre and recycled high density polyethylene (RHDPE) composite for fiberboard application. The fiberboard properties optimized were modulus of rupture (MOR), modulus of elasticity (MOE), internal bonding (IB), thickness swelling (TS) and water absorption (WA) whose values vary in response to changes in production process variables namely: Fibre/RHDPE (%), press pressure, press time and temperature. An experimental design using central composite design (CCD) was used to develop an RSM model for modeling the variations in physical and mechanical properties of the fiberboard in response to variations in process parameters. An ANN model was equally used to predict the properties of the fiberboard. Subsequently the ANN was used as the fitness function for multi objective optimization of the fiberboard using NSGA-II. A comparative algorithm was later developed with a traditional multi objective optimization algorithm known as desirability function using the RSM model. The results of the study showed that RSM and ANN effectively modeled the properties of the fiberboard. The optimized Pareto front of the NSGA-II algorithm was found to be an excellent design guide for practical applications of the composite. The superiority of NSGA-II algorithm over the desirability function as a multi objective optimization tool was demonstrated.

Effect of nanosilica and aluminum hydroxide on thermal, flammability, and morphology properties of nanocomposite made of recycled high-density polyethylene and OCC flour

Effects of nanosilica and aluminum hydroxide were considered relative to thermal, flammability, and morphological properties of nanocomposites from recycled high-density polyethylene (rHDPE) and old corrugated container (OCC) pulp. Amounts of 50% recycled high-density polyethylene and 50% OCC flour were used. The nanosilica was used at three weight levels of 0%, 5%, and 10%. Lastly, aluminum hydroxide at a constant level of 5% and maleic anhydride grafted polyethylene at a constant level of 3% were mixed by twin screw extruders. The samples were made using a hand-press. The thermal and flammability properties were then measured. To consider the structure and function of nanosilica, the morphological characteristics of wood-plastic composites (WPC) were studied by X-ray diffractograms (XRD) and scanning electron microscopy (SEM) analyses. The results showed that increasing the nanosilica content up to 10% increased the thermal stability, and more charcoal was retained. Moreover, the limited oxygen index increased. X-ray diffractograms showed that the width and peak intensity decreased with the increased intake of silica nanoparticles. The SEM images showed that more adaptability was achieved through increasing the amount of nanosilica. Additionally, better and more homogenous bonds were observed between the fibers and connection matrix, and fewer gaps and pores were observed.

Non-intentionally added substances (NIAS) in recycled plastics

The demand for high quality recycled polymers in the European plastic industry is on the increase, likely due to the EU’s Plastic Strategy intended to implement the circular economy model in this sector. The problem is that there is not enough recycled plastic in the market. In terms of volume, post-consumer plastic waste could be key to meet the current and future demand. Nevertheless, a high level of contamination originated during the product’s life cycle restricts its use. The first step to change this must be identifying the undesired substances in post-consumer plastics and performing an effective risk assessment. The acquired knowledge will be fundamental for the development of innovative decontamination technologies.In this study, 134 substances including volatile and semi-volatile compounds have been identified in recycled LDPE and HDPE from domestic waste. Headspace and solvent extraction followed by GC/MS were used. The possible origin of each substance was studied. The main groups were additives, polymer and additives breakdown products, and contamination from external sources. The results suggest that recycled LDPE contains a broader number of additives and their degradation products. Some of them may cause safety concerns if reused in higher added value applications. Regarding recycled HDPE, the contaminants from the use phase are predominant creating problems such as intense odors. To reduce the number of undesired substances, it is proposed to narrow the variety of additives used in plastic manufacturing and to opt for separate waste collection systems to prevent cross-contamination with organic waste.

Fabrication of Porous Recycled HDPE Biocomposites Foam: Effect of Rice Husk Filler Contents and Surface Treatments on the Mechanical Properties.

In this study, a biodegradable, cheap and durable recycled high-density polyethylene (rHDPE) polymer reinforced with rice husk (RH) fibre was fabricated into a foam structure through several processes, including extrusion, internal mixing and hot pressing. The effect of filler loading on the properties of the foam and the influence of RH surface treatments on the filler–matrix adhesion and mechanical properties of the composite foam were investigated. The morphological examination shows that 50 wt.% filler content resulted in an effective dispersion of cells with the smallest cell size (58.3 µm) and the highest density (7.62 × 1011 sel/cm3). This small cell size benefits the mechanical properties. Results indicate that the tensile strength and the Young’s modulus of the alkali-treated RH/rHDPE composite foam are the highest amongst the treatments (10.83 MPa and 858 MPa, respectively), followed by UV/O3, which has shown considerable increments compared with the untreated composite. The flexural and impact tests also show the increment in strength for the composite foam after chemical treatment. Although the UV/O3 surface treatment has minor influence on the mechanical enhancement of the composite foam, this method may be a reliable surface treatment of the fibre-reinforced composite.

Study of the Structural and Mechanical Properties of Recycled High Density Polyethylene/Palm Kernel Shell Ash Bio-Composite

This study examined the structure and mechanical properties of recycled high density polyethylene(RHDPE)/palm kernel shell ash (PKSA) bio-composite. The reinforcement was added to the polymer matrix in concentrations of 5, 10, 15, 20 and 25wt% and particle sizes of 100, 150, 200, 250, 300µm. The composite samples were produced using injection moulding technique and subjected to mechanical and tribological property tests for percentage elongation, ultimate tensile strength, and hardness. The structure of the composite samples was analyzed using an optical metallurgical microscope. Results of the structural analysis revealed that the reinforcement of small particle size (100µm) formed a better interfacial bond with the polymer matrix compared with that of other particles sizes. The structural analysis also revealed uniform distribution of hard and brittle particles of the reinforcement in the polymer matrix. Mechanical test results showed that addition of palm kernel shell ash to the polymer matrix decreased its percentage elongation and impact strength by 24.5% and 22% respectively but significantly increased the tensile strength and hardness by 107.9% and 72% respectively. The ultimate tensile strength, and hardness of the developed composite increased with decrease in reinforcement particle size. Maximum ultimate tensile strength of 131MPa was obtained by the RHDP containing 10wt% PKSA of 100µm particle size while maximum hardness value of 86BHN was obtained at 25wt% palm kernel shell ash of 100µm particle size addition. Palm kernel shell ash reinforced recycled high density polyethylene bio-composite of improved mechanical properties that can be applied in production of engineering components. Keywords: Palm kernel shell ash, RHDPE, Percentage elongation, Ultimate tensile strength, Hardness. DOI : 10.7176/CPER/62-05 Publication date: January 31 st 2020

An experimental study on recycled polypropylene and high-density polyethylene and evaluation of their mechanical properties

Globally around 300 million tonnes of plastic are produced, of which, less than 10% is recycled. Implementing recycled plastics in manufacturing i.e., by reusing them helps in the reduction of waste plastic scrap eventually. In this paper, an experimental study on recycled Polypropylene (RPP) and recycled High-Density Polyethylene (RHDPE) is carried out. The mechanical properties of the materials such as tensile strength, hardness, Young’s modulus, Impact strength, heat deflection temperature are evaluated using ASTM standards and further, the results are compared with the virgin Polypropylene & High-Density Polyethylene. Dynamic mechanical analysis is also performed on the samples to study the storage modulus, loss modulus, and tan delta values. In the investigations performed, it is observed that the Recycled materials have a lesser tensile strength, impact resistance, hardness when compared to the virgin materials. However, RHDPE has shown fairly good results when compared to RPP in impact resistance and tensile strength hence can be used in construction, military, and industrial applications. On the other hand, RPP has shown good results in terms of Hardness and Young’s Modulus, hence can be utilized in aircraft, automotive and engineering applications.

Alkali Treatment Effect on the Tensile and Impact Properties of Recycled High-Density Polyethylene Composites Reinforced with Short Cantala Fiber

In this study, an environmentally friendly composite was prepared from cantala fiber and recycled high-density polyethylene. Alkali treatment was utilized to improve the fiber–matrix interface of cantala fiber. The alkali treatment was carried out with a 2% NaOH solution for periods of 0, 4, 8, 12, 16, 20, and 24 hours. Various recycled high-density polyethylene composites reinforced with treated and untreated short cantala fiber were produced by hot press. The tensile and impact properties of the composites were examined to reveal the effect of alkali treatment. Changes in fiber–matrix bonding were investigated via composite fractography using scanning electron microscopy. A study of fiber morphology and other supporting tests, such as the fiber tensile test, X-ray diffraction, and Fourier transform infrared microscopy were also carried out. The results show that the addition of alkali-treated fiber to recycled high-density polyethylene composites enhanced the composites’ tensile and impact performance: Tensile strength improved by 15.5% and impact strength by 24.8%.

Life‐Cycle Assessment of Recycling Postconsumer High‐Density Polyethylene and Polyethylene Terephthalate

This study aims to quantify the overall environmental performances of mechanical recycling of the postconsumer high‐density polyethylene (HDPE) and polyethylene terephthalate (PET) in Jordan. The life‐cycle assessment (LCA) methodology is used to assess the potential environmental impacts of recycling postconsumer PET and HDPE. It quantifies the total energy requirements, energy sources, atmospheric pollutants, waterborne pollutants, and solid waste resulting from the production of recycled PET and HDPE resin from the postconsumer plastic. System expansion and cut‐off recycling allocation methods are applied. The analysis has been carried out according to the LCA standard, series UNI EN ISO 14040‐14044:2006. A standard unit of output (functional unit) is defined as “one ton of PET flake” and “one ton of HDPE pellet.” The results of the production of virgin resin are compared with the “cut‐off” and “system expansion” recycling results. Depending on the allocation methods applied, a nonrenewable energy saving of 40–85% and greenhouse gas emission saving of 25–75% can be achieved. Based on two allocation methods, PET and HDPE recycling offers important environmental benefits over single‐use virgin PET and HDPE. LCA offers a powerful tool for assisting companies and policy‐makers in the waste plastic industry. Furthermore, the “system expansion” recycling method is not easy to apply because it requires detailed data outside of the life cycle of the investigated product.

Utiziling Recycled High Density Polyethylene Caps of Polyethylene Terephthalate Bottles in Composite Plates

In this study, composite plates that are consisted of recycled HDPE polymer matrix and reinforced with woven fabrics (cellulosic fiber content; flax and jute) are manufactured in order to contribute polymer waste management. Used HDPE bottle caps are collected for recycling and hot press method is used to produce HDPE matrix plates. Plates are than reinforced with 100% jute and 100% flax woven fabrics with different sequence combinations by hot press machine. Temperature, production time, pressure and cooling rate are the crucial parameters that are optimized for forming composite materials. These bi-layered and three-layered composite plates are physically and mechanically tested for appropriate end use areas.

Uncertainty in the life cycle greenhouse gas emissions and costs of HDPE pipe alternatives

High density polyethylene (HDPE) is a thermoplastic used in many engineering applications but one that imposes environmental burdens when produced and environmental costs at end-of-life (EOL). Replacing pristine HDPE with post-consumer recycled (PCR) HDPE or bio-based polymer (bio-HDPE) in long-lived goods could mitigate those impacts. We investigate cradle-to-gate and cradle-to-grave greenhouse gas (GHG) emissions and costs of four alternative resins, pristine HDPE, pristine/PCR HDPE, bio-HDPE and nanoclay-pristine/PCR HDPE composite, and their use in 100-year drainage pipe, respectively. We construct stochastic LCA models that combine service life prediction from experiments with parametric and scenario uncertainty modeling using Monte Carlo simulation and non-parametric bootstrapping. Results differ significantly on a resin versus pipe product basis owing to the functional unit requirement for meeting pipe service life, if governed by crystallinity and fracture energy, properties that call for greater quantities of material in recycled and nanoclay composite HDPE compared to pristine HDPE. The nanocomposite pipe has varying GHG emissions compared to all alternatives due to high mass requirement if assuming crystallinity and fracture energy govern failure, but this predicted mass may be reduced given that the nanoclay can prolong fracture time, which would reduce GHG emissions and pipe production cost. Despite a large GHG reduction relative to pristine HDPE, the bio-HDPE resin has the highest material production cost; however, considering life cycle costs, the incremental difference among all alternatives is small over a range of discount rates, rendering the bio-HDPE pipe a promising solution for addressing climate change in long-lived thermoplastic assets.

Properties of eco-friendly composites: palm kernel shell treated with sodium bicarbonate filled recycled high-density polyethylene

Palm kernel shells (PKS) treated by commercial sodium bicarbonate (SB) filled recycled high-density polyethylene (rHDPE) were produced using melt compounding. These environmentally friendly composites were prepared using twin-screw extruder by varying untreated and treated filler loading (0, 10 and 30 php). In this study, the tensile properties of untreated rHDPE/PKS and treated rHDPE/PKS-SB were investigated. The composites were subjected to tensile test and the fracture surfaces were observed under scanning electron microscope (SEM). The results showed that SB treatment improved the filler-matrix adhesion and interaction of composites. Meanwhile, the SEM micrographs on the fracture surfaces confirmed that SB treatment which may influence the tensile properties of these composites.

Selective Localization of Carbon Black in Bio-Based Poly (Lactic Acid)/Recycled High-Density Polyethylene Co-Continuous Blends to Design Electrical Conductive Composites with a Low Percolation Threshold.

The electrically conductive poly (lactic acid) (PLA)/recycled high-density polyethylene (HDPE)/carbon black (CB) composites with a fine co-continuous micro structure and selective localization of CB in the HDPE component were fabricated by one-step melt processing via a twin-screw extruder. Micromorphology analysis, electrical conductivity, thermal properties, thermal stability, and mechanical properties were investigated. Scanning electron microscope (SEM) images indicate that a co-continuous morphology is formed, and CB is selectively distributed in the HDPE component. With the introduction of CB, the phase size of the PLA component and the HDPE component in PLA/HDPE blends is reduced. In addition, differential scanning calorimetry (DSC) and thermos gravimetric analysis (TGA) results show that the introduction of CB promotes the crystallization behavior of the PLA and HDPE components, respectively, and improves the thermal stability of PLA70/30HDPE/CB composites. The electrically conductive percolation threshold of the PLA70/30HDPE/CB composites is around 5.0 wt %, and the electrical conductivity of PLA70/30HDPE/CB composites reaches 1.0 s/cm and 15 s/cm just at the 10 wt % and 15 wt % CB loading, respectively. Further, the tensile and impact tests show that the PLA70/30HDPE/CB composites have good mechanical properties. The excellent electrical conductivity and good mechanical properties offer the potential to broaden the application of PLA/HDPE/CB composites.

On secondary recycling of ZrO2-reinforced HDPE filament prepared from domestic waste for possible 3-D printing of bearings

In this study, an innovative route for secondary recycling (with zirconium oxide (ZrO2) reinforcement) has been proposed based on melt processing of high-density polyethylene (HDPE) in low-temperature bearing applications. Initially, secondary recycled HDPE, acrylonitrile butadiene styrene, and nylon 6 thermoplastic composites were investigated for melt flow index (MFI) according to ASTM D1238 standard. Based on the acceptable MFI, secondary recycled HDPE matrix was selected for second-stage processing on twin screw extrusion (TSE). The final process involves reinforcement of ZrO2 into HDPE matrix by TSE in 60:40 ratio (by weight %) for preparation of feedstock filament (for possible 3-D printing of bearings). The results of the study suggest that for processing of HDPE, 40% ZrO2 composite matrix, 50 r min−1 screw speed, 190°C barrel temperature, and 15 kg applied load are the best setting of TSE (for maximizing the tensile strength of feedstock filament). The results are also supported by wear properties, thermal stability, and morphological analysis (based on scanning electron microscopy and electron-dispersive X-ray analysis).

Fabrication and characterization of phosphotungstic acid - Copper oxide nanoparticles - Plastic waste nanocomposites for enhanced radiation-shielding

A novel (R-HDPE/CuO-NP-PTA) nanocomposite was designed based on doping recycled high-density polyethylene (R-HDPE) with phosphotungstic acid (PTA) and copper oxide nanoparticles (CuO NPs). It was prepared and investigated for the ability to shield γ-rays. The composite samples were fabricated using the compression molding technique and their characteristics were identified using the Fourier transform infrared spectrophotometer (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and a high-resolution transmission electron microscope (HR-TEM). The assembled nanocomposites were found to be highly protective from γ-rays due to the presence of high-density materials, such as phosphotungstic acid and copper oxide nanoparticles. The γ-rays attenuation coefficients were measured as a function of the percentage of PTA and CuO NPs using several γ-ray energies with point sources; 356 keV from 133Ba, 662 keV from 137Cs, 1173 and 1332 keV from 60Co. When comparing between the addition of phototungstic acid (PTA) and that of CuO NPs to R-HDPE, it was found that PTA increased the electron density (Nel), mass attenuation coefficient (μm), and effective atomic number (Zeff) of the prepared composites more than CuO NPs. The theoretical values of the mass attenuation coefficient were calculated using the XCOM program.

Identification of properties of recycled high­density polyethylene composites when filled with waste mud solids

The possibility of increasing recycling volumes of drilling waste using as a filler for producing polymer composites is considered. As a result of the research, modification of recycled high-density polyethylene with waste mud in the form of fine filler particles is carried out.Recycled high-density polyethylene polymer composites, filled with drilling waste with a content up to 30 % are obtained. As a result of the study, regularities of changes in impact strength, ultimate bending and water absorption, depending on the waste mud solids (WMS) content in the recycled polymer are found.It is shown that the introduction of WMS in the form of fine filler particles in recycled high-density polyethylene significantly increases their strength characteristics without a substantial deterioration in water absorption (up to 2.9 % when filled with waste up to 30 %).It is found that the optimum content of drilling waste in recycled high-density polyethylene polymer composites is 20 wt %. At the same time, the maximum values of impact strength and ultimate bending are achieved for the composite with bentonite clay WMS up to 63.3 kJ/m2 and 200.1 MPa, and for the composite with salt WMS up to 38.1 kJ/m2 and 207.4 MPa, respectively. The resulting polymer composites outperform the known similar polymers with the use of such fillers as talc and kaolin. This allows recommending joint recycling of drilling and polymer waste

Evaluation of the efficiency of odor removal from recycled HDPE using a modified recycling process

A series of recent global and local policymaking processes is promoting or demanding developments in the recycling of post-consumer plastic packaging waste. After successfully clearing most hurdles in the PET bottle sector to promote a successful market launch of the recycled PET products, it is now important to take measures to meet the challenges associated with the recycling of polyolefins such as HDPE. In this respect, the need to further improve recycling technologies is currently prevalent because the quality parameters of the recycled materials do not yet meet the strict industrial requirements. In this context, apart from optical or mechanical properties, there is increasing awareness of odorous contaminants in the recycled products. Therefore, in this study, a modified HDPE recycling method was evaluated for its ability to reduce odors. For the aim of mapping and understanding the odor of recycled HDPE pellets with different residence times in a special decontamination reactor a combinatory sensory and instrumental-olfactometric approach was applied. Furthermore, based on the characterization of the causative odorants by gas chromatography-olfactometry and two-dimensional gas chromatography-mass spectrometry/olfactometry, quantitative determination of selected odorants was carried out over time using stable isotope dilution analysis. With regard to the decontamination efficacy of the evaluated decontamination process, we observed that the decrease in the concentration profiles of the monitored odorants went along with a sensorially relevant overall odor minimization of the recycled HDPE. The results of the study are aiding the adaptation of technological procedures for smell reduction or complete decontamination.

Cyclic Extrusion of Recycled High Density Polyethylene/Banana Fiber/Fly Ash Cenosphere Biocomposites: Thermal and Mechanical Retention Properties

AbstractDisposal of composite materials used vastly in structural applications raises the need to study the reprocessability of these systems for environmental benefits. In this paper, composites of recycled high density polyethylene (R) containing 30 wt.% banana fiber (BF)/7.5 wt.% fly ash cenospheres (FACS) were prepared with 3 wt.% maleic anhydride grafted high density polyethylene (MA-g-HDPE) as a coupling agent using twin screw extrusion followed by injection molding. The effects of thermal cycles (two times extrusion followed by injection molding) were studied on R and its composites. The samples were characterized by using tensile, flexural, izod impact tests, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetry (TGA) and dynamic mechanical analysis (DMA). The tensile and flexural properties were improved by addition of both BF/FACS into the R matrix. The percentage retention in tensile properties of R/BF/FACS(E2) biocomposites (i.e. two times extrusion followed by injection molding) is more than 80 %, while that for flexural properties is more than 90 %. This indicates that R/BF/FACS composites exhibit good retention ability in mechanical properties after subjecting to two times twin-screw extrusion followed by injection molding. DSC results revealed that repeated extrusion improved the crystallization temperature and crystallinity of the composites with a slight reduction in melting temperature. From the TGA results, it was observed that the thermal stability (e.g. Tonset) of R was reduced by the addition of BF/FACS. However, repeated extrusion showed an improvement in thermal stability of the composites.

Effect of groundnut shell powder on the viscoelastic properties of recycled high density polyethylene composites

In the quest to clean up the environment and produce economically viable materials from plastic wastes and readily available natural fibres, groundnut shell powder reinforced recycled high density polyethylene composite was prepared via two roll melt mixing and compression moulding technique. The dynamic mechanical properties of the composites such as storage modulus (E'), loss modulus (E''), and damping parameter (Tan ∂) were investigated using 242E dynamic mechanical analyzer in a temperature range from 30oC 100oC at a frequency of 1 Hz. It was found that the storage modulus of all the composites decrease with increase in temperature with composite containing 25%wt fibre having maximum E' value of 1158.47MPa compared to 1033.58MPa of the unreinforced recycled high density polyethylene. These results indicated that the thermal stability and load bearing capacity of the recycled high density polyethylene have been improved with the incorporation of groundnut shell powder. Scanning Electron micrographs showed better interfacial adhesion between treated groundnut shell powder in the polymer matrix; this explained the observed improvement in the viscoelastic properties of the composites.Keywords: Mechanical Properties, Groundnut Shell Powder, Recycled polyethylene, Viscolastic, Composites.

Analysis and Identification of the Mechanism of Damage and Fracture of High-Filled Wood Fiber/Recycled High-Density Polyethylene Composites.

The damage and fracture of fiber reinforced polymer composites are vital constraints in their applications. To understand the mechanism of damage of wood fiber (WF) reinforced high density polyethylene (HDPE) composites, we used waste WF and recycled HDPE (Re-HDPE) as the raw materials and prepared high-filled WF/Re-HDPE composites via extrusion. The damage and fracture mode and failure mechanism of the composites with different WF contents (50%, 60%, and 70%) was studied under a three-point bending test by combining the acoustic emission (AE) technique and scanning electron microscope (SEM) analysis. The results show that AE technology can better assist in understanding the progress of damage and fracture process of WF/Re-HDPE composites, and determine the damage degree, damage accumulation, and damage mode. The damage and fracture process of the composites presents three main stages: the appearance of initial damage, damage accumulation, and destructive damage to fracture. The matrix deformation, fiber breakage, interface delamination, fiber-matrix debonding, fiber pull-out, and matrix cracking were the dominant modes for the damage of high-filled WF/Re-HDPE composites under bending load, and the AE signal changed in different damage stages and damage modes. In addition, the WF content and repeated loading had a significant influence on the composite’s damage and fracture. The 50% and 60% WF/Re-HDPE composites produced irreversible damage when repeated load exceeded 75% of the maximum load, while 25% of the maximum load could cause irreversible damage for 70% WF/Re-HDPE composites. The damage was accumulated owing to repeated loading and the mechanical properties of the composites were seriously affected.

Effect of gamma radiation on the physico mechanical properties of recycled HDPE/modified sugarcane bagasse composite

In this work, the sugarcane bagasse (SCB) fibers were used as reinforcing filler for recycled high density polyethylene (rHDPE) to form eco-friendly composite. The SCB surface was chemically modified to improve the compatibility with rHDPE matrix. The SCB fibers were alkali modified using 10% sodium hydroxide (SCBm) and acetylated using acetic anhydride (SCBac). The chemically modified SCB fibers were characterized using Fourier transform infrared (FTIR) and scanning electronic microscopy (SEM). The composites were prepared by mixing of rHDPE with 15 phr (parts per hundred parts rHDPE) of different SCB samples. Neat rHDPE and its composites with SCB were irradiated by gamma radiation dose of 50–250 kGy. The Effect of gamma radiation on the water up-take, mechanical properties and the thermal stability of (rHDPE) and its composites was studied. The effect of gamma radiation on the compatibility between rHDPE and SCB was also investigated. The results showed that the combination between the chemical modification of fibers and the irradiation of polymer composites were more effective in compatibility improvement than chemical modification alone. The irradiated (at 100 kGy) composite containing of SCBac gave the best mechanical properties, lowest water up-take and the highest thermal stability.