Recycled Poly Research Articles

Influence of Poly(Vinyl Butyral) on the Dynamic-Mechanical and Mechanical Properties of Polypropylene/Wood Flour Composites

This study reports the influence of recycled poly (vinyl butyral) (PVB) in dynamic mechanical and mechanical properties of polypropylene (PP)/wood flour composites prepared in a twin screw extruder. After extrusion, the PP/wood flour composites were injection molded to obtain specimens for tensile, flexural, impact and dynamic mechanical (DMA) tests. The morphology of the composites was analyzed by scanning electron microscopy (SEM). The addition 10 wt% of PVB in PP/wood flour composite reduced from 5°C to-10°C the β transition (glass transition) peak temperature of the loss modulus. In a temperature range between 40°C and 100°C the composites containing PVB presented the highest peak in the loss modulus. The most intense tan delta peaks between 50°C and 100°C for composites containing PVB were attributed to the combined effects of PP α transition with the PVB glass transition temperature. The PP/wood flour composites with PVB presented a tendency to increase the absorbed energy by impact.

Structure and Properties of r-PET/TPEE/LDPE-g-AA Blends

The blends of recycled poly (ethylene terephthalate) (r-PET)/thermoplastic polyester-ether elastomer (TPEE)/acrylic acid grafted low density polyethylene (LDPE-g-AA) were prepared by extrusion and injection molding. The mechanical, morphological and rheological properties of the blends were investigated by mechanical test, SEM and torque rheometer, respectively. The results show that the Charpy impact strength of the blends increases to the maximum when adding 3 wt % LDPE-g-AA and then decreases with the further increase of LDPE-g-AA contents, while the tensile strength of the blends decreases with the increase of LDPE-g-AA contents. The SEM shows that the particle sizes of TPEE in the blend containing 3wt% LDPE-g-AA become much smaller than that in the uncompatibilized blends, and a more uniform and better islands-in-sea morphology is obtained. Furthermore, the addition of LDPE-g-AA decreases the viscosity of the blends, leading to an overall improvement of processability. From these results above, it can be concluded that the introduction of LDPE-g-AA increases the compatibility and processability of r-PET/TPEE blends effectively.

Effect of MMT concentrations as reinforcement on the properties of recycled PET/HDPE nanocomposites

Abstract The objective of this research is to investigate the effect of incorporating montmorillonite (MMT) on the mechanical, morphological, rheological, and thermal properties of recycled poly(ethylene terephthalate) (rPET) and high-density polyethylene (HDPE) nanocomposites. The MMT contents in 90:10 rPET/HDPE and 70:30 rPET/HDPE ranged from 1 to 5 wt.%. rPET/HDPE nanocomposites were prepared by using a single screw extruder, and injection molded to prepare mechanical test specimens. The samples underwent rheological tests by using a capillary rheometer, and the morphology of the nanocomposites was investigated by scanning electron microscopy (SEM). The thermal stability of the nanocomposites was tested using thermogravimetric analysis (TGA). The results showed that MMT acts as compatibilizing agent and improves phase dispersion and interfacial adhesion in the nanocomposites. The maximum tensile strength was found at 3 and 1 wt.% of MMT for the 90:10 and 70:30 rPET/HDPE blends. However, the tensile modulus decreased significantly with the incorporation of MMT. The impact strength for both the 90:10 and 70:30 blends reached a maximum at 3 wt.% and started to decrease beyond 3 wt.%. The incorporation of MMT increased the shear viscosity of the 90:10 and 70:30 blends, which reached a maximum value at 3 and 1 wt.%. SEM micrographs showed a good interaction of MMT that improved the adhesion between the two phases of blends and led to an increase in the mechanical properties of rPET/HDPE nanocomposites.

Analysis of recycled poly (styrene-co-butadiene) sulfonation: a new approach in solid catalysts for biodiesel production

The disposal of solid waste is a serious problem worldwide that is made worse in developing countries due to inadequate planning and unsustainable solid waste management. In Mexico, only 2% of total urban solid waste is recycled. One non-recyclable material is poly (styrene-co-butadiene), which is commonly used in consumer products (like components of appliances and toys), in the automotive industry (in instrument panels) and in food services (e.g. hot and cold drinking cups and glasses). In this paper, a lab-scale strategy is proposed for recycling poly (styrene-co-butadiene) waste by sulfonation with fuming sulfuric acid. Tests of the sulfonation strategy were carried out at various reaction conditions. The results show that 75°C and 2.5 h are the operating conditions that maximize the sulfonation level expressed as number of acid sites. The modified resin is tested as a heterogeneous catalyst in the first step (known as esterification) of biodiesel production from a mixture containing tallow fat and canola oil with 59% of free fatty acids. The preliminary results show that esterification can reach 91% conversion in the presence of the sulfonated polymeric catalyst compared with 67% conversion when the reaction is performed without catalyst.

Mechanical and thermal properties of date palm leaf fiber reinforced recycled poly (ethylene terephthalate) composites

Development of a recycled poly (ethylene terephthalate) (PETr) reinforced with surface treated date palm leaf fiber (DPLF) composites with enhanced mechanical properties have been studied. Surface modified date palm leaf fiber reinforced PETr composites were prepared using twin-screw extruder followed by injection molding and the influence of the DPLF content on the mechanical and thermal behavior of the PETr matrix was evaluated. Upon the addition of fibers, remarkable enhancements in the mechanical properties of the composites were observed. Scanning electron microscopy (SEM) images taken from DPLF fibers showed significant enhancements in the fiber’s surface topography after the surface treatment process. Dynamic mechanical analysis (DMA) indicated that the addition of DPLF to PETr matrix increased the composites toughness. The crystallization behavior of the samples, analyzed by differential scanning calorimetry (DSC) indicated an increase in the onset crystallization temperature and showed a higher degree of crystallinity of the composites as compared to PETr, demonstrating that DPLF particles could act as nucleating agents. The results point to the composite’s potential in wider indoor applications.

Effect of carbon nanotube reinforcement on the properties of the recycled poly(ethylene terephthalate)/poly(ethylene naphthalate) (r-PET/PEN) blends containing functional elastomers

In this study, the mechanical, thermomechanical, thermal, electrical properties and the morphology of the composites, based on blends of recycled poly(ethylene terephthalate) (r-PET) and poly(ethylene naphthalate) (PEN) that were mixed with functional elastomers and multi walled carbon nanotube (CNT) were investigated. Two types of functional elastomers; terpolymer of ethylene–ethyl acrylate–maleic anhydride (E-EA-MAH) and terpolymer of ethylene–methyl acrylate–glycidyl methacrylate (E-MA-GMA), were used to ensure the miscibility between PET and PEN during the preparation of the blends and composites. All composite and blend samples were extruded by using a laboratory scale twin screw microcompounder. Test samples were prepared via laboratory scale injection molding machine. According to the results of the thermomechanical tests, usage of both elastomers enhanced the miscibility between r-PET and PEN. Morphological analyses showed that the blends and composites which contain E-EA-MAH exhibited better elastomer phase dispersion with smaller domain sizes when compared with the samples with E-MA-GMA. Samples prepared with E-EA-MAH had better mechanical properties than the ones containing E-MA-GMA due to the better elastomer phase dispersion. Moreover, addition of CNT also improved the mechanical properties of the samples for both elastomer types. In contrast to mechanical test results, samples prepared with E-MA-GMA had higher electrical conductivity values when compared with those of the ones containing E-EA-MAH due to the differences in the selective distribution of CNT particles between the polymer phases in the samples.

Utilization of recycled poly vinyl chloride (PVC) in combination with wood particles and urea formaldehyde resin as binder to produce multi-layer particle board

Particle board generally suffers from severe thickness swelling and water absorption which limits its utilisation such as cabinetry, table tops, shelving, wall, floor panel and in humid places such as bathrooms also. To overcome such limitation, addition of recycled PVC into the middle layer of multi layered particle board was investigated. In this study physical and mechanical property of the wood plastic particle board (WPPB) made using Poplar spp. (Poplus deltoides) particles were evaluated. The content of urea formaldehyde resin used as 10 % total weight of the particle board. For Poplar spp. (P. deltoides) particles slenderness ratio was maintained around 160–180 for face particle and around 50–80 for core particle. Addition of PVC was 10, 20, 30 and 40 % mixed with core particle to the middle layer. The multi layered WPPB were produced applying press temperature of 150 °C for 7 min of compression cycle at 24 kg/cm2 and 8 min of curing cycle at 12 kg/cm2 for the manufacture of WPPB. The boards were tested according to IS: 3087-2005 Gr II.

Molecular weight control of poly(ethylene terephthalate) in extrusion process

A control strategy is developed to control molecular weight of recycled poly(ethylene terephthalate), PET, to overcome its degradation through an extrusion process. To obtain dynamic model of a twin screw extruder, steady-state, and unsteady-state experiments were performed. Discrete convolution models between inputs and outputs were obtained. Process inputs were considered as screw speed (SS), feed rate, and barrel temperatures and the output was viscosity average molecular weight (Mv) of the extrudate. SS and molecular weight of the product were chosen as the manipulated, controlled variable pair by considering singular value decomposition (SVD) technique. Model based PID controller and model predictive controller were used in the designed control scheme. By the simulation studies, both controllers were found to be successful for set-point tracking, disturbance rejection cases; and were proven to be robust under modeling errors. POLYM. ENG. SCI., 54:459–465, 2014. © 2013 Society of Plastics Engineers

Preparation and properties of recycled poly(ethylene terephthalate) powder/halloysite nanotubes hybrid-filled natural rubber composites

Recycled poly(ethylene terephthalate) (R-PET) was partially replaced with halloysite nanotubes (HNTs) as fillers in natural rubber (NR) composites. The composites were prepared by incorporating hybrid filler into NR using a laboratory size two-roll mill. The total amount of hybrid filler in each formulation was kept constant at 20 phr. Results revealed that scorch time, cure time, maximum torque, cross-link density and thermal stability increased with the replacement of R-PET by HNTs. Due to its reinforcing effect and ductility of the HNTs, the moduli, tensile strength, elongation at break and fatigue life were found to increase consecutively with increasing HNTs content. Morphological study of the tensile fracture surfaces of the composites exhibited that HNTs has better adhesion and is well-dispersed in NR matrix as compared to R-PET particles. However, R-PET exhibited positive effect by reducing the curing time of the hybrid NR composites.

Effect of recycled poly(ethylene terephthalate) core layer on the mechanical properties of three-layer poly(ethylene terephthalate) films

We report a comparative analysis of three-layered poly(ethylene terephthalate) films. The first set of three-layered films was prepared entirely from virgin poly(ethylene terephthalate). The second set of films was prepared from a recycled poly(ethylene terephthalate) core layer and virgin poly(ethylene terephthalate) skin layers. The resistance of the films to impact was tested using the free falling drop dart method. The selected strength properties of various thicknesses of these films were also tested. It was shown that the poly(ethylene terephthalate) film containing a layer of recycled polymer has properties similar to the film obtained from virgin polymer and can thus be successfully used in the manufacturing of packaging materials.

Rheological and mechanical properties of recycled poly(ethylene terephtalate)/high density polyethylene blends

Triphenylphosphite (TPP) has been used as a chain extender to regenerate polyethylene terephtalate (PET) and high density polyethylene (HDPE) wastes and to improve the properties of PET/HDPE system based on recycled materials. TPP incorporation in PET and HDPE showed a noticeable increase of the torque as a function of the mixing time and proved that the degradation reactions are considerably decreased. In the case of PET/ HDPE blends, the increase of the torque was strongly dependent on the composition of the homopolymers and on the time of mixing. TPP incorporation contributed to significant variations of the rheological and mechanical properties of the regenerated PET and HDPE and their blends.

Effect of short fiber reinforcement on the properties of recycled poly(ethylene terephthalate)/poly(ethylene naphthalate) blends

In this study, short carbon (CF), glass (GF) and hybrid carbon/glass fiber reinforced recycled poly(ethylene terephthalate)/poly(ethylene 2,6-naphthalate) (r-PET/PEN) blends were prepared by melt mixing method. The mechanical, thermal and morphological properties of composites were investigated by using tensile tests, differential scanning calorimeter, dynamic mechanical analyzer and scanning electron microscopy. The microscopic analysis showed that there is a better interfacial interaction between fiber and polymer matrix for CF reinforced composite. It was found that addition of short fiber reinforcement to the r-PET/PEN blend improved the tensile strength and Young’s modulus values more than the addition of PEN into r-PET. According to DMA analysis, fiber reinforcement increased the storage modulus of composites when compared with r-PET/PEN blend and among them storage modulus of CF reinforced composite was the highest. It was concluded that mechanical properties of r-PET can be enhanced with addition of PEN and more efficiently with short fiber reinforcement.

Porous polyurethane foams based on recycled poly(ethylene terephthalate) for oil sorption

AbstractIn using recycled poly(ethylene terephthalate) (PET) as a petroleum sorbent we tried to achieve two important objectives simultaneously. PET waste was glycolized using trimethylolpropane (TMp) or pentaerytheritol (PEr) to produce suitable polyol oligomers for polyurethane (PU) foams. The glycolysis was carried out in the presence of manganese acetate as a catalyst under normal pressure in m‐cresol at 220 °C. Producing polyols, PEr degraded PET into lower molecular weights than TMp. So prepared oligomers were reacted with 2,4‐toluene diisocyanate providing several types of PU foam. The effect of various variables (polyol reactivity, water content, type of catalyst, isocyanate amount and surfactant) on the foam structure and properties were analyzed. Porosity of the PU foams was examined using environmental scanning electron microscopy. Foams based on glycolized TMp contain small uniform cells whereas other foams form less uniform cells with varying sizes including closed cells. Dynamic mechanical analysis gives much lower storage moduli for TMp‐based PUs that for those based on PEr, an effect of dangling ethylene chains in the former case. The glass transition temperatures Tg are higher when PEr rather than TMp is used. Our PU foams show good sorption properties and sufficient reusability. Copyright © 2012 Society of Chemical Industry

Thermal and mechanical evaluation of the stability of recycled poly(ethylene terephthalate) applied as sand control agent in petroleum wells

In petroleum wells, the granular sand control agents commonly employed are basically inorganic compounds, which are used in operations to prevent the production of sand, from unconsolidated sandstone formations, that contaminates the produced hydrocarbons. In this work the viability of applying recycled poly(ethylene terephthalate) (PETrec) as sand control agent, in an environment that simulated the conditions of the wells, was evaluated. Virgin PET (PETvir) was tested as a standard for comparison means. Pellets of each polymer (PETrec and PETvir) were confined into metallic cells filled with sea water or petroleum, under conditions observed in some sandstone formations that are normally subjected to sand control, in Campos Basin (Rio de Janeiro, Brazil). The cells systems were submitted to a controlled temperature of 70 °C and pressure of 24.1 MPa, and rolled during the experiment period. The total exposure time was approximately six months (172 days), with scheduled sampling periods. Thermal, mechanical and granulometric properties of the pellets before and after the exposition were evaluated. The samples were characterized by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TG). Mechanical experiments were performed, in order to determine the grain pack permeability, by the end of the exposition period, according to API RP 58 and API RP 61 standard methods. Particle size of the grains, before and after the exposure process, was compared. Test results showed that PETrec and PETvir samples did not present significant physical changes or evidences of degradation, nor in water neither in petrol, suggesting that the use of recycled PET as sand control agent seemed to be viable within the experiment conditions.

Molecular and structural analysis of epoxide‐modified recycled poly(ethylene terephthalate) from rheological data

AbstractA multifunctional epoxide chain extender (ADR4370S) was used to increase the molecular weight of recycled poly(ethylene terephthalate) (R‐PET). The extension processing was carried out by melt mixing reaction. The effects of ADR4370S content on the molecular structure [molecular weight, molecular weight distributions (MWDs), branching, and gel‐like structures] of modified R‐PET were rheologically investigated. The results showed that the complex and apparent viscosity of the modified R‐PET were larger than those of unmodified one. The solid‐like behavior of R‐PET was enhanced after the reactive modification. The increments of balancing torque, reaction peak, and shear‐thinning behavior became more pronounced by increasing the concentration of ADR4370S. Reactive modification was characterized by the presence of long‐chain branching resulted in a wider MWD. Modified Cole–Cole plots demonstrated a shift toward higher storage modulus values at a given loss modulus value for the modified R‐PET samples. High concentration of ADR4370S (>1.5 wt%) resulted in a polymeric structure near the sol–gel transition point whose linear viscoelastic properties obeyed scaling law. The relaxation time was prolonged with the amount of ADR4370S increase. The decrease in the melt point and crystallization temperature of the modified R‐PET was correlated to the presence of chain branching. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Melt rheological and compatibility properties of recycled poly(ethylene terephthalate)/ poly(acrylonitrile‐butadiene‐styrene) blends

AbstractIn this study, a series of maleic anhydride (MA)‐grafted poly(acrylonitrile‐butadiene‐styrene) (ABS‐g‐MAH) were prepared via a melt banbury process on a RM‐200B torque rheometer and used as a compatibilizer for recycled poly(ethylene terephthalate)/poly(acrylonitrile‐butadiene‐styrene) (R‐PET/ABS) blends. The melt rheological and compatibility properties of R‐PET/ABS blends were investigated. It had been found that 5 wt % of MA was an optimum concentration for the preparation of ABS‐g‐MAH. About 1 wt % of ABS‐g‐MAH prepared at the MA optimum conditions shows good compatibility for the basic blend of R‐PET/ABS 85/15 w/w. Rheological and SEM characterizations confirmed that the phase reversal of blends occurred at R‐PET/ABS ratio of 75/25 w/w. DMA results indicated that R‐PET was partially miscible with ABS, and ABS‐g‐MAH was an efficient compatibilizer for R‐PET/ABS blends. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Effectiveness of high frequency heating on drying and intrinsic viscosity enhancement of recycled poly(ethylene terephthalate)

AbstractThe effectiveness of a high radio frequency (HF) heating technique as a tool for drying and for enhancement of intrinsic viscosity (IV) in recycled poly(ethylene terephthalate) (R‐PET) pellets is described. R‐PET that was sourced mainly from postconsumer drinking bottles would generally attain lower molecular weight due to hydrolytic degradation when exposed to repeated thermal processing cycles and also the presence of impurities. Hence, the IV of R‐PET would be significantly lower as compared to virgin PET (V‐PET), which could affect its processability and significantly limit its application. In this study, R‐PET pellets were exposed to HF and their IV and moisture content were monitored with time. HF was found to be a less time consuming method to enhance the IV of R‐PET although it was not reliable to be used for drying purposes. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Assessment of the properties of poly(L-lactic acid) sheets produced with differing amounts of postconsumer recycled poly(L-lactic acid)

The properties of sheet containing mechanically recycled postconsumer poly(L-lactic acid) bottle flakes blended with virgin poly(L-lactic acid) resin were assessed. Poly(L-lactic acid) bottles were flaked, cleaned, blended with virgin resin and then extruded and thermoformed into trays. The molecular weight, physical, optical, thermal and mechanical properties of the sheet containing 0, 20, 40, 60, 80 and 100 wt.% poly(L-lactic acid) recycled content were evaluated. The best cleaning conditions were found by using a mixed-level fractional factorial design. Cleaning conditions of 15 min, at 85°C, 1 wt.% NaOH and 0.3 wt.% surfactant were adopted for cleaning the poly(L-lactic acid) flakes. Cast-extruded virgin poly(L-lactic acid) sheet had superior mechanical and optical properties than recycled poly(L-lactic acid) sheet. Recycled poly(L-lactic acid) sheets were darker and absorbed more ultraviolet light in the 260 to 285 nm range when 20% or more recycled content was added. At 40% poly(L-lactic acid) recycled content, the sheet had increased blue and red tones and the mechanical properties in the cross-machine direction decreased. At 60% poly(L-lactic acid) recycled content or above, reduction of weight average molecular weight, tensile strength and tensile strength at yield in the machine direction were found. At 80% poly(L-lactic acid) recycled content, the melting temperature and modulus of elasticity in the machine direction decreased. All sheet samples were successfully thermoformed into trays showing the potential to use post-consumer poly(L-lactic acid) flakes in the production of poly(L-lactic acid) containers.

The Effects of Chain Extender on Viscosity and Mechanical Properties of Poly (Buthylene Terephthalate) Blending with Recycled Poly (Ethylene Terephthalate)-glass Fiber Composite

In this study, multi-functional styrene-acrylic oligomers was used as the chain extender in poly butylenes terephthalate/recycled glass-filled polyethylene terephthalate (PBT/RGF-PET) blends. Normally, usage of recycled plastics is favourable but somehow, during the reprocessing causes loss of properties. Thus, chain extender was added to restore the viscosity and mechanical properties of PBT/PET blends due to the incorporation of recycled poly (ethylene terephthalate) has lowered viscosity and molecular weight. Chain extender at 0.50 and 0.65 wt% was added into 50/50 PBT/RGF-PET using melt compounding method to compare viscosity and mechanical properties with virgin PBT and RGF-PET, respectively. Addition of chain extender has improved the viscosity of the PBT/RGF-PET which was in relation to the increment of molecular weight. When 0.50 w\.% of chain extender was added to PBT/RGF-PET blend at ratio of 50:50, the flexural modulus increased 9.6% to 3530 1.1Pacompared to the original flexural modulus at 3220 1.1Pa. This showed that a small amount of chain extender was successfully to improve the flexural modulus. The increment of molecular weight as induced by the addition of chain extender improved the impact resistance of the PBT/RGF-PET from 17 to 20.3 kJ m? for addition of 0.50 wt.% chain extender

Compatibilization of recycled poly(ethylene terephthalate) and polypropylene blends: Effect of compatibilization on blend toughness, dispersion of minor phase, and thermal stability

AbstractBlending of recycled polyethylene terephthalate (RPET) from waste bottles with polypropylene (PP) was performed in an attempt to enhance the processability of RPET. The idea of blending RPET with PP sprouted from the intention of recycling PET bottles together with their PP‐based caps. Therefore, preliminary blending of RPET with neat PP (RPET/PP) was performed at various PP and compatibilizer contents. Morphological analyses on the extruded pellets of uncompatibilized blends indicate that the PP particle size and state of dispersion at skin and core regions were vastly different. The particles at the skin were at least 10 times smaller than that at the core although the size distribution was very wide. With the incorporation of just 5 phr of compatibilizer, the particles at the core region became significantly smaller and appeared to emulate that of the skin region. Furthermore, the overall homogeneity of the blends was vastly improved irrespective of PP content in the blend. The reduction in particle size and improved homogeneity inherently reduced stress concentration points and enhanced the mechanical performance of the blends. More importantly, the incorporation of PP into RPET significantly increased the degradation temperature of the blends, provided the dispersion of PP phase in RPET was excellent. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011