Miscibility Studies of Polysaccharide Xanthan Gum/PVP Blend

Miscibility characteristics of Xanthan gum and Poly (vinyl pyrrolidone) (PVP) in common solvent water were studied by viscometry, ultrasonic velocity and density techniques at 30 and 50 °C. Blend films of Xanthan gum/PVP were prepared by solution casting method and characterized by scanning electron microscopic (SEM) and differential scanning calorimeter (DSC) techniques. Using the viscosity data, interaction parameters of Chee’s (μ) and Sun’s (α) were computed to determine their miscibility. The values obtained revealed that blends were miscible when PVP content is up to 70% in blend at 30 °C. Xanthan gum/poly (vinyl pyrrolidone) blends showed miscibility in all composition at 50 °C. The results were then confirmed by ultrasonic velocity, density, and DSC techniques. Compatibility in the above compositions may be due to the formation of hydrogen bonding between the carbonyl group in PVP and hydroxyl group in Xanthan gum. Further, the results revealed that change in temperature had significant effect on the miscibility of Xanthan gum/Poly (vinyl pyrrolidone) blends.     

Blending of Epoxidised Palm Oil with Epoxy Resin: The Effect on Morphology, Thermal and Mechanical Properties

Epoxy resin prepared by the reaction of a diglycidyl ether of bisphenol A (DGEBA) and m-xylylenediamine (m-XDA) was modified with 10% wt of epoxidized palm oil (EPO). The EPO was first pre-polymerized with m-XDA at various temperatures and reaction times. The resulting product was then mixed with the epoxy resin at 40?°C and allowed to react at 120?°C for another 3?h. The fully reacted DGEBA/m-XDA/EPO blend was characterized by using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis, tensile test, hardness indentation and dynamic mechanical analysis. The SEM study shows that different types of morphology, ranging from phase separated to miscible blends were obtained. A miscible blend was obtained when the m-XDA and EPO were reacted for more than 2?h. The results from DSC analysis show that the incorporation of EPO at 10% wt in the epoxy blend reduced the glass transition temperature (T _g). The lowered T _g and mechanical properties of the modified epoxy resins are caused by a reduction in crosslinking density and plasticizer effect.     

Action of soil microorganisms on PCL and PHBV blend and films

Poly(hydroxybutyrate-co-valerate) (PHBV) and poly(ε-caprolactone) (PCL) PCL/PHBV (4:1) blend films were prepared by melt-pressing. The biodegradation of the films in response to burial in soil for 30 days was investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG). The PHBV film was the most susceptible to microbial attack, since it was rapidly biodegraded via surface erosion in 15 days and completely degraded in 30 days. The PCL film also degraded but more slowly than PHBV. The degradation of the PCL/PHBV blend occurred in the PHBV phase, inducing changes in the PCL phases (interphase) and resulting in an increase of its crystalline fraction.     

Conversion of Mixed Low-Density Polyethylene Wastes into Liquid Fuel by Novel CaO/SiO<Subscript>2</Subscript> Catalyst

Plastic wastes disposal can be done by various methods such as landfill, incineration, mechanical and chemical recycling but these are restricted due to some environmental, economic and political problems. Conversion of these plastic wastes into valuable products by degradation is the best option. In the present work waste low density polyethylene was degraded by catalytic process using CaO/SiO₂ as mixed catalyst. The conditions for catalytic degradation were optimized for the production of maximum liquid fuel. It was found that the yield of liquid product was up to 69.10 wt% at optimum condition of temperature (350 °C), time (90 min) and catalyst feed ratio (1:0.4). Liquid fuels obtained from the catalytic degradation were further separated into various fractions by fractional distillation. Composition of liquid fuels was analyzed by FTIR spectroscopy, which showed that the liquid fuels mostly consist of paraffinic and naphthenic hydrocarbons. Different fuel properties such as density, specific gravity, American petroleum institute gravity (API gravity), viscosity, kinematic viscosity, refractive index, refractive intercept and flash point of both the parents and various fractional fuels were determined. All the properties of the obtained fuels are in close agreement with the fuel properties of gasoline, kerosene and diesel. It was found that our catalyst is very much efficient in terms of time, degradation temperature and amount of catalyst.     

Effect of Poly(Vinyl Acetate) on Mechanical Properties and Characteristics of Poly(Lactic Acid)/Natural Rubber Blends

Natural rubber grafted with poly(vinyl acetate) copolymer (NR-g-PVAc) was synthesized by emulsion polymerization. Three graft copolymers were prepared with different PVAc contents: 1 % (G1), 5 % (G5) and 12 % (G12). Poly(lactic acid) (PLA) was melt blended with natural rubber (NR) and/or NR-g-PVAc in a twin screw extruder. The blends contained 10–20 wt% rubber. The notched Izod impact strength and tensile properties were determined from the compression molded specimens. The effect of NR mastication on the mechanical properties of the PLA/NR/NR-g-PVAc blend was evaluated. Characterization by DMTA and DSC showed an enhancement in miscibility of the PLA/NR-g-PVAc blend. The temperature of the maximum tan δ of the PLA decreased with increasing PVAc content in the graft copolymer, i.e., from 71 °C (pure PLA) to 63 °C (the blend containing 10 % G12). The increase in miscibility brought about a reduction in the rubber particle diameter. These changes were attributed to the enhancement of toughness and ductility of PLA after blending with NR-g-PVAc. Therefore, NR-g-PVAc could be used as a toughening agent of PLA and as a compatibilizer of the PLA/NR blend. NR mastication was an efficient method for increasing the toughness and ductility of the blends which depended on the blend composition and the number of mastications.     

Improving Water Resistance of Soy-Based Adhesive by Vegetable Tannin

In this research tannic acid was used to prepare soy-based adhesives for making plywood and fiber board. The different resin formulations were analyzed by Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and its derivative as a function of temperature (DTG) and Fourier Transform Infra-red (FTIR) spectroscopy. The results showed that the addition of tannic acid to soy-based adhesive decreased soy-based adhesive viscosity and its pH. The DSC analysis showed that the denaturation temperature of soy-based adhesives decrease by adding tannic acid. The TGA and DTG curves showed that the thermal degradation of soy flour starts above 146 °C. The FTIR spectroscopy results also showed that the soy flour amino acids appeared to react well with tannic acid. Furthermore, delamination and shear strength test results showed the good water resistance of plywood bonded with soy-based tannic acid-modified adhesive. The mechanical and physical properties such as MOR, MOE, IB, and water resistance of fiberboard were improved, by adding tannic acid to the soy-based adhesive.     

Biodegradable Copoly(Amino Acid)s Based on 6-Aminocaproic Acid and l-Leucine

Biodegradable copoly(amino acid)s based on 6-aminocaproic acid and l-leucine were prepared by melt condensation polymerization and characterized by Fourier transform infrared spectrometry (FTIR), proton nuclear magnetic resonance spectrometry (¹H NMR), and X-ray diffraction (XRD). The intrinsic viscosity and the density of the copoly(amino acid)s were measured. Thermal properties of the copoly(amino acid)s were performed by differential scanning calorimetry (DSC). Results showed that by increasing leucine content of the comonomers, the intrinsic viscosity, melting point, and melting enthalpy of copoly(amino acid)s decrease while the density increases. The enzymatic degradation of the polymers films was tested using papain; results showed that the copoly(amino acid)s are degradable and the enzymatic degradation rate increases with increasing leucine content in the comonomers.     

Processing and Properties of Mixtures of PHB-V with Post-consumer LDPE

Mixtures of poly-β-(hydroxybutyrate-co-valerate) PHB-V with virgin and post-consumer low density polyethylene (LDPE) were prepared by melt mixing in proportions of 100/0, 90/10, 80/20, 70/30 and 0/100 (wt/wt%). The mixtures were analysed by infrared spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), melting flow index (MFI), tensile tests, scanning electron microscopy (SEM) and biodegradation in simulated soil. The DMTA and DSC curves of post-consumer LDPE suggested that this polymer was a mixture of LDPE and linear low density polyethylene (LLDPE). Virgin and post-consumer LDPE had lower MFI than PHB-V, but the blends showed higher index as the content of LDPE increased. The addition of LDPE reduced the tensile strength and Young’s modulus of the mixtures compared with PHB-V. SEM indicated poor interfacial adhesion between PHB-V and LDPE. PHB-V degraded slow and gradually, while both LDPE showed virtually no degradation under the conditions studied. The biodegradability of the blends depended on their composition and of the type of LDPE. LDPE improved the biodegradability of the mixtures.     

Effect of Hexadecyl Lactate as Plasticizer on the Properties of Poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide) Films for Food Packaging Applications

In this study, poly(l-lactide) (PLA) films were fabricated by melt processing and the plasticizing effect of hexadecyl lactate (HL) (0, 5, 7.5, 10, and 12.5 wt% on PLA were investigated by scanning electron microscopy (SEM), differential scanning calorimetry, thermogravimetric analysis, tensile, transparency, and water vapor permeability tests. The SEM analysis revealed that PLA with 10 wt% HL appeared uniform with extra small bumps, confirmed the interaction between PLA and HL. The thermal analysis revealed a glass transition temperature of 57.4 °C for neat PLA film, but the addition of HL elicited a decrease in the temperature of the peak (43.8 °C). The incorporation of plasticizer into PLA resulted in the increase of elongation at break, as well as the decrease of tensile strength and tensile modulus. Even though a decrease in transparency was recorded, the PLA/HL blend films appeared transparent by visually observation. The water vapor permeability of PLA/HL blend films increased with the increase of HL. The PLA/HL blend films could effectively extend the shelf-life of fresh-cut pears as the commercial low density polyethylene films. The results indicated that the properties of PLA films can be modified with the addition of HL and PLA/HL blend films could serve as an alternative as food packaging materials to reduce environmental problems associated with synthetic packaging films.     

Biodegradability of PMMA Blends with Some Cellulose Derivatives

High polymer blends of Polymethyl methacrylate (PMMA) with cellulose acetate (CA) and Cellulose acetate phthalate (CAP) of varying blend compositions have been prepared to study their biodegradation behavior and blend miscibility. Films of PMMA–CA, and PMMA–CAP blends have been prepared by solution casting using Acetone and Dimethyl formamide(DMF) as solvents respectively. Biodegradability of these blends has been studied by four different methods namely, soil burial test, enzymatic degradation, and degradation in phosphate buffer and activated sludge degradation followed by water absorption tests to support the degradation studies. Degradation analysis was done by weight loss method. The results of all the tests showed sufficient biodegradability of these blends. Degradability increased with the increase in CA and CAP content in the blend compositions. The miscibility of PMMA–CA and PMMA–CAP blends have been studied by solution viscometric and ultrasonic methods. The results obtained reveal that PMMA forms miscible blends with either CA or CAP in the entire composition range. Miscibility of the blends may be due to the formation of hydrogen bond between the carbonyl group of PMMA and the free hydroxyl group of CA and CAP.     

Thermal,Rheological, Mechanical and Morphological Behavior of High Density Polyethylene and Carboxymethyl Cellulose Blend

In this study water soluble sodium carboxymethyl cellulose (CMC) was blended with high density polyethylene (HDPE) by peroxide-initiated melt compounding technique. The compatibility of the blended polymers were carried out by silane crosslinking agent. A series of blends were prepared by varying the CMC contents up to a maximum of 50 phr. The physical properties of non-crosslinked and crosslinked blends were investigated in detail. FTIR analysis of crosslinked blend confirmed the presence of Si–O–Si and Si–O–C absorption peaks at 1050 and 1159 cm^?1. Thermal stability of crosslinked blends improved as compared to its non-crosslinked congener. Rheological study of crosslinked blends illustrated high complex viscosity and dynamic shear storage modulus. The tensile strength of virgin polyethylene was 8.1 MPa whereas the maximum tensile strength of 19.6 MPa was observed in crosslinked blend. Similarly lower deformation was observed in crosslinked blends under static load. Scanning electron microscopy of crosslinked formulations also showed strong adhesion between the polymers interface. The compatibility of HDPE and CMC is attributed to both free radical and condensation reactions.     

Novel Biodegradable Cast Film from Carbon Dioxide Based Copolymer and Poly(Lactic Acid)

Poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) blends with different levels of chain extender were prepared and cast into films. The effect of chain extender on the mechanical, thermal and barrier properties of the films were investigated. With the inclusion of the chain extender, the compatibility and interfacial adhesion between the two polymer phases were significantly improved by a mean of forming a PLA–chain extender–PPC copolymer. Reactions between the chain extender, PLA and PPC were observed through FTIR study. SEM study also confirmed the improved compatibility and interfacial adhesion. The elongation at break of the compatibilized film with optimal amount of chain extender showed dramatic increase by up to 1940 %. DSC studies revealed that chain extender hindered the crystallization of the film which explained the decrease in both water and oxygen barrier when adding chain extender. PLA was found to be able to enhance both oxygen and water barrier of the blend as compared to neat PPC, while in the case of the blend with chain extender, oxygen and water barrier properties exhibited reduction at the beginning. However, when increasing chain extender concentration, these two barrier performance exhibited an upward trend. It was found that PLA/PPC blend showed much better oxygen barrier property than both parent polymers, which can be ascribed to the acceleration effect of PPC on the crystallization of PLA.     

Reactive Compatibilization of Biobased Polyurethane Prepolymer Toughening Polylactide Prepared by Melt Blending

Polylactide (PLA) is a major biodegradable polymer, which has received extensive interests over the past decades and holds great potential to replace several petroleum-based polymeric materials. Nevertheless, the inherent brittleness and low impact strength have restricted its invasion to niche markets. In this paper, the authors demonstrate that the entirely bio-sourced blends, namely PLA and castor oil-based polyurethane prepolymer (COPUP), were first melt-compounded in an effort to prepare novel biodegradable materials with an excellent balance of properties. NCO-terminated COPUP was successfully synthesized and subsequently mixed with variable concentration of PLA matrix using melt-compounded by twin-screw extrusion technique. The miscibility, phase morphology, mechanical properties, and thermal resistance of the blends were investigated. During FTIR analysis, it suggests that the interfacial compatibilization between COPUP and PLA phase occurred by the reaction of –NCO group of MDI with terminal hydroxyl group of PLA. DMA analysis showed that COPUP and PLA showed some limited miscibility with shifted glass transition temperature. The morphologies of fracture surface showed a brittle-to-ductile transition owing by the addition of COPUP. The crystallization behavior was studied by differential scanning calorimeter (DSC). The strain at break and notched impact strength of PLA/COPUP blends were increased more than 112–15.4 times elegant of neat PLA; the increase is superior to previous toughening effect by using petroleum-based tougheners. Furthermore, the thermal resistances and melt flow properties of the materials were also examined by analysis of the melt flow index and heat deflection temperature use in the work. With enhanced toughness, the PLA/COPUP blends could be used as replacements for some traditional petroleum-based polymeric materials.     

Biodegradation of LDPE/Modified Starch Blends Sterilized with Gamma Radiation

Blends of LDPE/modified starch were prepared, sterilized by gamma radiation and investigated with respect to their microbial degradation by a mixture of fungal strains in liquid medium after 90 days, was analyzed by carbon dioxide (CO₂) production (Sturm test). Biodegradation of blends was evaluated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction; mechanical testing, scanning electron microscopy (SEM). The biodegradation of LDPE/modified starch blends was attributed to microbiological attack, with alterations in the chemical structure of the blend with an increase in the carbonyl and vinyl indices and the appearance of new crystalline symmetry generating a crystalline domain not existing before in the blend and decrease in the mechanical properties.     

Synthesis of Polyurethane and Characterization of its Composites Based on Alfa Cellulose Fibers

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)…     

Role of Crosslinker on the Biodegradation Behavior of Starch/Polyvinylalcohol Blend Films

The effect of crosslinkers on the biodegradation behavior of starch/polyvinyl alcohol (PVA) blend films was investigated by weight loss study, Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Starch/PVA films were prepared by solution casting method and 5 weight% of four different crosslinking agents like epichlorohydrin, formaldehyde, zinc oxide and borax were used in four different sets to crosslink the films. These crosslinked starch/PVA films were biodegraded in compost. Weight loss study showed that crosslinking retarded the biodegradation of the films in the first 15?days, but after that, there was a significant increase in weight loss. The DSC analysis revealed that the consumption of starch and consequent rearrangement of the PVA molecules were distinctly different in the crosslinked films due to the effect of different crosslinking agents.     

Biodegradation of Pro-oxidant Filled Polypropylene Films and Evaluation of the Ecotoxicological Impact

The biodegradability of calcium stearate (CaSt) and cobalt stearate (CoSt) filled polypropylene (PP) films were investigated in this work. The PP films were prepared using melt blending technique followed by hot press moulding. On the basis of their tensile properties, the optimum amount of pro-oxidants was taken as 0.2 phr. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used for the characterization of optimized films. Presence of pro-oxidant in the PP was confirmed by the FTIR studies. Addition of pro-oxidants in the films decreased the thermal stability as revealed by TGA analysis. Crystallinity of the pro-oxidant filled PP decreased with addition of pro-oxidants as showen by DSC. The maximum biodegradation of CaSt and CoSt containing PP films was showen 7.65 and 8.34%, respectively with 0.2 phr. Both the microbial test and plant growth test (on corn and tomato) indicated that biodegradation intermediates were non toxic.     

Processing and Characterization of Recycled Polypropylene and Acrylonitrile Butadiene Rubber Blends

In this paper investigation on thermoplastic elastomers (TPE) and thermoplastic vulcanizates (TPV) derived from waste polypropylene (WPP) of Municipal Solid Waste (MSW) and acrylonitrile-butadiene rubber (NBR) are reported. The WPP was segregated, cleaned, dried and melt processed with NBR at 180 °C in a Brabender Plasticorder at different blend ratios. TPV was prepared by dynamic vulcanization of the TPE with conventional sulfur accelerator curing system. The mechanical properties measured were found to decrease with increase in NBR proportion in the blend; however the dynamic vulcanization of the nitrile rubber phase enhanced the strength properties of the corresponding TPE. The crystallinity of the WPP reduced with increase in NBR ratio. The dynamic modulus decreased with nitrile rubber content in the TPE. Interestingly, the storage modulus of the TPV at higher rubber content enhanced significantly and damping characteristics increased sharply. The rheology studies reveal that the damping of the blend has been reduced with the addition of high storage modulus rubber at melt processing conditions and hence increased viscosity. The amorphous rubber content with higher storage modulus imparts higher viscosity for the polypropylene (PP) matrix at the processing temperature. The SEM study reveals that the dynamic vulcanization of the rubber phase in the blend caused a smoother and finer surface morphology.     

Biodegradable Poly(butylene succinate) and Poly(butylene adipate-co-terephthalate) Blends: Reactive Extrusion and Performance Evaluation

Two biodegradable polyesters, poly(butylene adipate-co-terephthalate) (PBAT) and poly(butylene succinate) (PBS) were melt-compounded in a twin screw extruder to fabricate a novel PBS/PBAT blend. The compatibility of the blend was attributed to the transesterification reaction that was confirmed by Fourier transform infrared spectroscopy. The Gibbs free energy equation was applied to explain the miscibility of the resulting blend. Dynamic mechanical analysis of the blends exhibits an intermediate tanδ peak compared to the individual components which suggests that the blend achieved compatibility. One of the key findings is that the tensile strength of the optimized blend is higher than each of the blended partner. Rheological properties revealed a strong shear-thinning tendency of the blend by the addition of PBAT into PBS. The phase morphology of the blends was observed through scanning electron microscopy, which revealed that phase separation occurred in the blends. The spherulite growth in the blends was highly influenced by the crystallization temperature and composition. In addition, the presence of a dispersed amorphous phase was found to be a hindrance to the spherulite growth, which was confirmed by polarizing optical microscopy. Furthermore, the increased crystallization ability of PBAT in the blend systems gives the blend a balanced thermal resistance property.     

Melt Flow Behavior and Processability of Polylactic Acid/Polystyrene (PLA/PS) Polymer Blends

The present investigation dealt with the flow behavior and processability of polylactic acid/polystyrene (PLA/PS) polymer blends using a capillary rheometer. For this purpose, PLA/PS blends with different ratios of the concentrations were prepared using a single screw extruder. The shear viscosity, shear stress, shear rate, power-law index, viscous activation energy at a constant shear stress, and elongational stress were determined. PLA/PS blends exhibited a typical shear-thinning behavior over the entire range of shear rates tested, and the viscosity values of the blends would tend to decrease with increasing amount of PLA. In addition, the polymer blend of 70 % PLA and 30 % PS was found to be relatively less sensitive to the processing temperature, implying that the extrusion process was more desirable for fabrication of PLA/PS polymer blend than the injection process.