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The purpose of this study was to evaluate the effect of polyethylenimine (PEI) on the properties of emulsion styrene butadiene rubber (ESBR)/butadiene rubber (BR) blends. PEI with molecular weight (Mw) of 800, 2,000, 25,000, and 270,000 g/mol with various ratios was successfully incorporated into ESBR/BR blends via rubber compounding method. Study showed almost 100% decrease in scorch time, ts2 in lower Mw PEI (800 and 2000 g/mol), compared to higher Mw PEI (25,000 and 270,000 g/mol) in ESBR/BR blends. PEI incorporated ESBR/BR blends showed an overall improvement in terms of tensile strength. Lower Mw PEI induced better tensile strength with an optimum value at 1.22 MPa, while higher Mw PEI induced better tear strength and self-healing ability. Incorporation of 5 phr PEI 270,000 g/mol in the blend successfully achieved the optimum self-healing efficiency of 71.5% at 160°C for 1 h. Phase separation occurred between higher Mw viscous PEI with rubber matrix at crack region to promote thermal self-healing. PEI molecules were found to be accumulated and assembled on the interface of the rubber chain from scanning electron microscopy (SEM) images. It was suggested weak physical bond interaction such as Van der Waals holding both rubber chains and PEI together, without any changes in the rubber chain backbone.

Plastic pollution is a significant concern nowadays due to wastes generated from non-biodegradable and non-renewable synthetic materials. In particular, most plastic food packaging material ends up in landfills, creating mass wastes that clog the drainage system and pollute the ocean. Thus, studies on various biopolymers have been promoted to replace synthetic polymers in food packaging and consequently, the high number of research in biopolymers food packaging, especially in the characterization, properties and also the development of the biopolymer. For biopolymer-based food packaging, silk fibroin (SF) has been highlighted because of its biodegradability and low water vapor permeability properties. This review focuses on the different properties of SF films prepared through solution casting and electrospinning for food packaging. Discussions encompassed chemical properties, mechanical properties, permeability, and biodegradability. This review also discussed the studies that used SF as the biomaterial for food packaging.

Generally, only a few especially acrylic monomers have photoabsorption characteristics to allow for effective stereolithography (STL) to take place. Biomaterial product from palm oil, Acrylated Palm Olein (APO), is seen as an ideal alternative to petroleum-based polymers due the diminishing petrochemical supply and abundant of the natural polymer in the market. In this study, APO as a biopolymer is introduced to synthetic polymers Polyethylene Glycol Dimethylacrylate (PEGDMA) and Polyethylene Glycol Diacrylate (PEGDA), separately. All three polymers offer photoabsorption characteristics that enable them to be the resins for ultraviolet (UV) 3D printing. The crosslinking of both copolymers is optimized by comparing two different UV radiation techniques; UV cured machine and UV STL 3D printer. The degree of crosslinking for both APO-co-PEGDMA and APO-co-PEGDA through gel fraction analysis are studied and compared with their prepolymer resins. As predicted, the maximum degree of crosslinking of APO-co-PEGDMA and APO-co-PEGDA samples are achieved from the fabrication of samples by 3D printing and recorded at 67.50% and 59.50% respectively, comparing to the samples cured by UV cure machine, which recorded maximum crosslinking percentage at only 21.31%. Further analysis is done using swelling test to study water absorption capacities of copolymers and results shows that APO-co-PEGDMA able to retain water at maximum of 42.47% and APO-co-PEGDA at 52.02% from the 3D printed samples, and recorded lowest readings at 22.82% and 25.56% respectively. UV cured samples are recorded to have lowest readings at 3.89% for APO-co-PEGDMA, and 4.23% for APO-co-PEGDA. Fourier Transform Infrared (FTIR) Spectroscopy confirmed the successful crosslinked of the copolymers. Analysis of FTIR shows that there are presence of new peaks and shifting of peaks, indicating that APO is crosslinked with PEGDMA backbone as well as PEGDA backbone. These also suggest that both polymers are suitable to be incorporated with APO as new photopolymer resins, fabricated using UV radiation crosslinking, with PEGDMA shown a slightly better result. All results are agreeable with FTIR results.

Kenaf fibre as a natural lignocellulos is fast receiving encouraging attention in bio-composite material because it offers a range of properties that may be difficult to obtain with other synthetic reinforcements. The aim of this study is to compare the mechanical properties of kenaf bast and core fibre reinforced recycled poly(ethylene terephthalate) (rPET)/recycled poly(propylene) (rPP) composite with varying fiber loading i.e. 0, 5, 10, 15 and 20 phr. The fiber length use in this study is 250 µm. The injection moulding technique was used to prepare the composite specimens for tensile, flexural and impact tests in accordance to the ASTM D5083, ASTM D790 and ASTM D256 respectively. The overall results showed that the composites reinforced with kenaf bast fibre had higher mechanical properties than kenaf core fibre composites. The results also showed that the optimum fibre content for achieving highest tensile properties for bast and core composites was 5 phr. It was also observed that the elongation at break for both composites decreased as the fibre content increased. However, a remarkable enhancement in the impact strength of the composites were observed upon the addition of 20 phr of bast and core fibre loading.

Wollastonite has a huge potential to be utilized as a functional filler in the thermoplastic composites, providing an enhancement to the mechanical strength, as well as thermal stability and flame retardancy, thus replacing the other conventional fillers such as glass fibre and talc. Due to the reinforcing ability and good thermal stability of wollastonite, the wollastonite-filled polymer composites have attracted the attention of academicians and industrialists. Many studies are reported on the effect of wollastonite incorporation into the polymers, in the aspect of mechanical, thermal, and flammability properties, meanwhile exploring the potential of wollastonite usage in the desired applications. This review article will be focusing on the thermal and flammability properties of wollastonite-filled thermoplastic composites. The popular thermoplastics used as the matrix are polypropylene, polylactic acid, and poly(ethylene terephthalate). Studies on flammability properties of wollastonite-filled thermoplastic composites are relatively less compared to thermal properties. Generally, the properties of the composites are influenced by the wollastonite dispersion, loading, size and shape of wollastonite, and its interfacial adhesion with the polymer matrix. Most of the previous studies focused on thermoplastic filled natural micro-sized wollastonite composites. Thus, the effect of nano-sized synthetic wollastonite as a functional filler in polymers is worth investigating. Further research on hybrid wollastonite/nanofillers is also interesting to develop high-performance materials to meet the requirements of society and industries.

Rheological properties are useful in evaluating materials performance during processing operations. Rheology is a sensitive tool in identifying and/or detecting any microstructural changes that is directly related to mechanical properties of the final products. In order for polymer wastes to be reprocessed in standard plastics equipment and produce high yields of molded and film products, the rheological properties must first be understood. Recent development in the green polymer composite has attracted a significant interest to sustain the ecological friendliness of the Recycled poly(ethylene terephthalate):rPET (rPET) and recycled poly(propylene) (rPP) blend. The common problem during polymer recycling is the degradation of the polymer that leads to the reduction of its molecular weight (Mw). Reprocessing at high temperatures with thermal exposure, shear as well as the presence of moisture and physical contaminants (poly(ethylene) (PE), poly(vinyl chloride) (PVC, adhesives) lead to a remarkable Mw” loss. This chapter presents an overview of rheological properties of plastic waste blends and composites. It mainly focuses on rPET and rPP and natural fibers composites of recycled polymer.

Chitosan is a linear semi-crystalline polysaccharide prepared by purification and deacetylation of chitin, which shown as Fig. 21.1. Chitin or poly (β(1–4)-N-acetyl-D-glucosamine) is one of the most abundant polysaccharides from natural sources which can be found in the exoskeleton of crustaceans and insects and in the cell walls of most fungi and some algae (Ma et al. 2017; Muxika et al. 2017). To purify chitin from the shells of crustaceans, the shells are ground, processed with HCl to achieve demineralization and boiled in dilute NaOH to remove proteins (Puvvada et al. 2012; Arbia et al. 2012; Kumari et al. 2015). Deacetylation of chitin is achieved through alkaline treatment at more than 80 °C. The degree of deacetylation is dependent on the reaction condition. Treatment with 12.5 mol/L NaOH at 95 to 100 °C deacetylates chitin within 2 hours, yielding chitosan with a degree of deacetylation of 87 to 90% and an average MW of 160 to 1600 kDa (Puvvada et al. 2012).

The feasibility of developing kenaf fiber (KF) reinforced recycled polyethylene terephthalate (rPET) and recycled polypropylene (rPP) with comparison to two different reinforcing fillers, KF and montmorillonite (MMT) reinforced rPET/rPP was studied. In addition, the compatibilizer of ethylene vinyl acetate grafted maleic anhydride (EVA-g-MA) at composition 5 phr was used. Composites were prepared using twin-screw extruder and followed by injection molding. The optimum blend ratio of rPET/rPP was observed at 90 wt% rPET and 10 wt% rPP. The incorporation of 5 phr EVA-g-MA improved tensile and impact strength of the blends. Scanning electron microscopy (SEM) micrographs revealed that by adding EVA-g-MA, homogeneous dispersion of rPP was observed. The addition of KF into compatibilized blend decreased mechanical properties of tensile and impact strength of the blends while adding MMT improved significantly the mechanical properties

Polymer nanocomposites with enhanced performances are becoming a trend in the current research field, overcoming the limitations of bulk polymer and meeting the demands of market and society in tribological applications. Polytetrafluoroethylene, poly(ether ether ketone) and ultrahigh molecular weight polyethylene are the most popular polymers in recent research on tribology. Current work comprehensively reviews recent advancements of polymer nanocomposites in tribology. The influence of different types of nanofiller, such as carbon-based nanofiller, silicon-based nanofiller, metal oxide nanofiller and hybrid nanofiller, on the tribological performance of thermoplastic and thermoset nanocomposites is discussed. Since the tribological properties of polymer nanocomposites are not intrinsic but are dependent on sliding conditions, direct comparison between different types of nanofiller or the same nanofiller of different morphologies and structures is not feasible. Friction and wear rate are normalized to indicate relative improvement by different fillers. Emphasis is given to the effect of nanofiller content and surface modification of nanofillers on friction, wear resistance, wear mechanism and transfer film formation of its nanocomposites. Limitations from the previous works are addressed and future research on tribology of polymer nanocomposites is proposed.

The performance and properties of nanocomposites largely depend on its nanofiller and reinforcement. This chapter presents an overview of the different types of nanofiller and reinforcement in biopolymer nanocomposite. It mainly focuses on the preparation, processing, properties, and the application of the bio-nanocomposite. Bio-nanocomposite based on biopolymer such as poly(lactic acid) (PLA), poly(e-caprolactone) (PCL), poly(vinyl alcohol) (PVA), poly(hydroxybutyrate) (PHB), poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), and chitosan, and nanofiller such as graphene, carbon nanotube, layered silicate reinforcement, sepiolite, and halloysite nanofiller has become a topic of discussion, and their performance and future application become a focus of interest. Enhanced mechanical and thermal properties imparted by the nanofiller reinforcement on the bio-nanocomposite and its optimum loading had been reviewed. It can be concluded that the properties of bio-nanocomposite could be further enhanced by the utilization of compatibilizer, coupling agent, and nanofiller treatment in bio-nanocomposite, which play an important role in enhancing the compatibility between the component of bio-nanocomposite and state of nanofiller dispersion and distribution in bio-nanocomposite.

Nanotubes are one of the most important classes of 1D nanomaterial which can be used as reinforcing filler for the polymers and biopolymers. Out of several organic/inorganic nanotubes, carbon nanotubes (CNTs) and halloysite nanotubes (HNTs) were most studied due to their high aspect ratio, outstanding mechanical and thermal properties. Nanotubes have potential to increase the physical properties of the biopolymer even at very low loading. The properties of nanotube-filled nanocomposite depend on various parameters like the aspect ratio, dispersion, and interaction between filler and polymer. To improve the utilization and maximum potential of these fillers, it is important to understand the mechanisms of reinforcement. It will help the future researchers to find out the limitations and issues with existent processing method of nanotube-based nanocomposite which is required for further improvement. In this regard, this chapter will help the researchers to fully understand the current progress in processing method, issues, and possible methods to prepare an ideal nanotube and biopolymer-based nanocomposites. This chapter will discuss only biopolymer-based nanocomposites filled by the two most important 1D tubular nanofillers, which are CNT and HNT. This study has been divided into three subtopics, namely (i) thermoplastic nanocomposites, (ii) thermoset nanocomposites, and (iii) natural rubber (NR) nanocomposites. It focuses on the fabrication processes, properties, and potential applications of CNT and HNT biopolymer nanocomposites.

Recently development of high-performance polymer composites made from natural resources in the various sectors is increasing tremendously due to the environmental issues and health hazard possessed by the synthetic fibers during disposal and manufacturing. Among the many different types of natural resources, kenaf fibers have been extensively investigated as an alternative reinforcement for polymer composites over the past few years due to their low cost, good mechanical properties, high specific strength, nonabrasive, eco-friendly, and biodegradability characteristics. Kenaf is regarded as an industrial crop in Malaysia and grown commercially in other parts of the world for different applications. It is certainly one of the important plants cultivated for natural fibers globally which has great potential to use as automotive and construction materials. In many research studies, kenaf fibers have been used as reinforcement in unsaturated polyester (UPE) which perfectly improved the features of the polyester resin. The tensile properties of kenaf fiber reinforced UPE are mainly influenced by the interfacial adhesion between the fibers and the polyester resin. Several chemical modifications are employed to improve the interfacial bonding between kenaf fibers and polyester, resulting in the enhancement of mechanical properties of the composites. Therefore, this paper explores and highlights of the previous studies around kenaf fiber reinforced UPE composites, in terms of processing methods, mechanical, water absorption, and morphological properties to provide a perfect source of literature for doing further research in this topic.

In the past decade, growing interest in the use of carbon-based nanocomposites in industrial applications has been observed because of their excellent mechanical, thermal, electrical, physical, and barrier properties. Various carbon-based nanoparticles, including graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs), have very different physical and electrochemical properties from each other. In this chapter, an overview of carbon-based polymer nanocomposites is presented with special emphasis on the most important and novel studies conducted to explore the properties of polypropylene (PP) nanocomposites reinforced with GNPs and CNTs. Enhancement in the characteristic features of PP matrix with the incorporation of carbon-based nanoparticles has been observed. The nanocomposites reinforced with carbon-based nanoparticles having extraordinary specific strength and stiffness represent tremendous opportunity for application in the 21st century. Mechanical and thermal properties are the focus of this chapter as the properties are important for industrial applications. Further research in this area is also being proposed.

The objective of this study is to investigate the effect of halloysite nanotubes (HNTs) loading on mechanical and thermal properties of poly(ethylene terephthalate)/polycarbonate (PET/PC) nanocomposites. Nanocomposites containing 70PET/30PC and 2-8 phr HNTs were prepared by twin screw extruder followed by injection moulding. As the percentage of HNTs increased, the flexural modulus increased. However, the flexural strength decreased with increasing HNTs content. The impact strength also decreased when HNTs increased. Thermogravimetry analysis of PET/PC/HNTs nanocomposites showed higher thermal stability at high HNTs content. However, on further addition of HNTs up to 8 phr, thermal stability of the nanocomposites decreased due to the poor dispersion of HNTs.

The dinuclear indium catalyst [(NNO)InCl]2(μ-OEt)(μ-Cl), previously reported to be highly active for the living ring-opening polymerization of cyclic esters lactide (LA) and β-butyrolactone (BBL), was used to generate a series of triblock copolymers of poly(lactic acid) (PLA) and poly(hydroxybutyrate) (PHB). Copolymers PLLA–PDLLA–PLLA and PLLA–PDLLA–PDLA, synthesized via sequential monomer addition, showed low molecular weight distributions and excellent correlation between the calculated and experiment molecular weights. Significantly, triblock copolymers of the type PLA–PHB–PLA were also synthesized for the first time through a sequential addition technique. Analysis of polymers after each addition of monomer showed that although only 85% conversion was achieved after addition of BBL, the remaining chain ends were active and addition of more lactide yielded a triblock. Rheological studies of PLLA–PHB–PDLA indicated solid like behavior even well above the temperature at which stereocomplex formation was ...

In this study, different compositions of nearly monodispersed diblock copolymers of dl -lactide or d -lactide and l -lactide were synthesized by living ring-opening polymerization with a dinuclear indium catalyst. The effects of molecular weight and block length ratio on the rheological behavior of dl and l -lactide diblock copolymers in the disordered state were investigated. For comparison, blends of PDLLA and PLLA homopolymers of equivalent molecular weights to the diblock copolymers were prepared. We found that the time–temperature (t–T) superposition principle is applicable to the diblock copolymers PLLA- b -PDLLA and blends in the disordered state. However, the t–T superposition failed at low temperatures close to the temperature of crystallization. In contrast, diblock copolymers PLLA- b -PDLA formed stereocomplex crystallites of high melting point (slightly above 200 °C) that causes a viscosity enhancement. The failure of t–T superposition was found due to existing of micro homo or stereocomplex crystallites. The non-isothermal crystallization behavior was investigated using differential scanning calorimetry (DSC). The DSC thermograms of blends exhibited a single glass transition at 50–60 °C followed by melting point of PLLA at 177 °C. With decreasing of the PLLA content in the blends, the intensity of the melting peak decreased. In addition, different crystallization behavior was observed for diblock copolymers compared to their equivalent blends. Specifically, low temperatures and enthalpies of melting peaks were observed for diblock copolymers. These also show improvement in elongation at break and tensile strength as compared to their counterpart homopolymer blends.

The wall slip and melt fracture behaviour of several commercial polylactides (PLAs) as well as their rheological properties under shear and extensional have been investigated. The PLAs have had weight-average molecular weights in the range of 104–105 g/mol and studied in the temperature range of 160–200°C. The solution properties and linear viscoelastic behaviour of melts indicate linear microstructure behaviour. PLAs with molecular weights greater than a certain value were found to slip, with the slip velocity to increase with decrease of molecular weight. The capillary data were found to agree well with linear viscoelastic envelope once correction for slip effects was applied. The onset of melt fracture for the high molecular weight PLAs was found to occur at about 0.2 to 0.3 MPa, depending on the geometrical characteristics of the dies and independent of temperature. Addition of 0.5 wt.% of a polycaprolactone (PCL) into the PLA that exhibits melt fracture was found to be effective in eliminating and delaying the onset of melt fracture to higher shear rates. This is due to significant interfacial slip that occurs in the presence of PCL.

A series of controlled microstructure poly(lactide) (PLA) samples were synthesized using a novel chiral dinuclear indium catalyst capable of living polymerization of lactide. PLAs with different ratios of L- to D- monomer ratios of 100:0, 90:10, 75:25, 50:50, and 0:100 were investigated. The relationship between intrinsic viscosity and the absolute molar mass distribution of the samples obtained by light scattering gel permeation chromatography in tetrahydrofuran gives [η] = 0.014 + 0.75 Mw, a scaling law of typical coil dimensions of linear macromolecules in good solvent. The melt rheological study includes determination of zero-shear viscosity and its relationship with the molecular weight, the relaxation spectrum, and its relation with molecular weight characteristics, as well as plateau modulus and other important rheological parameters that are helpful in predicting the linear viscoelasticity of PLA. Emphasis is placed on the uniaxial melt behavior of these polymers. At low temperatures, significant strain hardening is observed, which gradually disappears with an increase in temperature and decrease of Hencky strain rate. The K-BKZ constitutive equation is used to model the experimental data. It is concluded that in spite of their linear structure, PLAs exhibit strain hardening which is not due to strain-induced crystallization, and it is solely due to the dynamics of molecular relaxation.

PA6/PP nanocomposites with either polyethylene octene elastomer grafted maleic anhydride (POEgMAH) or PP grafted maleic anhydride (PPgMAH) as compatibilizer were prepared using co-rotating twin-screw extruder followed by injection molding. The mechanical and microstructural properties of the composites were investigated by means of tensile, flexural, and impact testing and by scanning electron microscopy (SEM). X-ray diffraction (XRD) was used to characterize the formation of nanocomposites. The result indicated that the miscibility of PA6/PP nanocomposites was improved with the addition of POEgMAH and PPgMAH. The impact strength of PA6/PP nanocomposite with POEgMAH increased about 5 times higher than uncompatibilized composite. Increment in tensile properties was observed when PPgMAH was used as compatibilizer. XRD results revealed that PA6/PP nanocomposites were successfully formed. Uniform dispersion of PP in matrix were observed through SEM, which showed the improvement of the compatibility between polymers.

A series of nanocomposites consisting of a polyamide 6 (PA6) and polypropylene (PP) matrix (70:30) with a maleated polyethylene-octene elastomer (POEgMAH) and organophilic modified montmorillonite (MMT) were prepared by melt compounding in a co-rotating twin-screw extruder followed by injection moulding. The weight fraction of organoclay was adjusted from 2 – 10 wt% by increments of 2 wt% and the weight fraction of POEgMAH was fixed at 10 wt%. POEgMAH was used as an impact modifier as well as compatibiliser in the nanocomposites. Mechanical properties of the blends were investigated by tensile, flexural and impact testing. X-ray diffraction (XRD) was used to characterise the nanocomposites. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Addition of 4 wt% organoclay showed the highest tensile and flexural strengths for the blends. The Young's and flexural moduli were also improved with increasing the organoclay concentration but with a corresponding reduction in impact strength and elongation at break. XRD result revealed that the organoclay was dispersed uniformly (exfoliated) although the degree of exfoliation decreased with increasing organoclay content. The DSC analysis showed that the crystallinity of the blends decreased with increasing organoclay concentration. It was shown from the TGA analysis that the thermal stability of the PA6/PP nanocomposites was significantly improved in the presence of impermeable silicate layers in the blends.

Regenerated cellulose (RC)/ poly(3-hydroxybutyrate) (PHB) composite was prepared via melt compounding with different RC contents from 1 to 7 wt.%. Regenerated cellulose fiber was prepared in NaOH/urea aqueous solution. The properties of the cellulose and the regenerated cellulose were compared using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA), and Differential Scanning Calorimetry (DSC). The results of TGA and DSC revealed that the regenerated cellulose had lower thermal properties than cellulose. Meanwhile, the FTIR of regenerated cellulose showed that the intensity portrayed by a few peaks had reduced or disappeared as compared to cellulose. Besides, PHB composites were characterized using TGA and flexural testing. Moreover, thermal stability of the composites insignificantly changed with the incorporation of RC. Improvement in flexural strength and modulus were observed, whereas 3 wt.% was found to be the optimum RC content.

Biopolymer electrolytes are currently attracting a great deal of attention as substitute for synthetic polymers in electrochemical devices, as they are cost effective and eco-friendly. In this research, the biopolymer potato starch/chitosan blend polymer electrolyte film doped with LiCF3SO3 was prepared by solution casting method. Sample with 35wt. % LiCF3SO3 showed the highest ionic conductivity at room temperature. The dielectric studies reveal the non-Debye nature of the electrolyte. The Rice and Roth model was used quantitatively to explain the conductivity trends of the prepared electrolyte systems. The complexation of salt with the polymer host was studied using Fourier transform infrared (FTIR) spectroscopy.

In this study, the effect of maleic anhydride grafted styrene-ethylene-butylene-styrene (SEBS-g-MA) content on mechani- cal, thermal, and morphological properties of polyethylene terephthalate/polycarbonate/halloysite nanotubes (PET/PC/HNTs) nano- composites has been investigated. Nanocomposites of PET/PC (70:30) with 2 phr of HNTs were compounded using the counter rotating twin screw extruder. A series of formulations were prepared by adding 5-20 phr SEBS-g-MA to the composites. Incorpora- tion of 5 phr SEBS-g-MA into the nanocomposites resulted in the highest tensile and flexural strength. Maximum improvement in the impact strength which is 245% was achieved at 10 phr SEBS-g-MA content. The elongation at break increased proportionately with the SEBS-g-MA content. However, the tensile and flexural moduli decreased with increasing SEBS-g-MA content. Scanning elec- tron microscopy revealed a transition from a brittle fracture to ductile fracture morphology with increasing amount of SEBS-g-MA. Transmission electron microscopy showed that the addition of SEBS-g-MA into the nanocomposites promoted a better dispersion of HNTs in the matrix. A single glass transition temperature was observed from the differential scanning calorimetry test for compatibi- lized nanocomposites. Thermogravimetric analysis of PET/PC/HNTs nanocomposites showed high thermal stability at 15 phr SEBS-g- MA content. However, on further addition of SEBS-g-MA up to 20 phr, thermal stability of the nanocomposites decreased due to the excess amount of SEBS-g-MA. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42608.

The wall slip and melt fracture behaviour of several commercial polylactides (PLAs) and poly(e-caprolactone), (PCLs) have been investigated. PLAs with molecular weights greater than a certain value were found to slip, with the slip velocity to increase with decrease of molecular weight consistent with wall slip data reported in the literature for other systems. The onset of melt fracture for the high molecular weight PLAs was found to occur at about 0.2 to 0.3 MPa, depending on the geometrical characteristics of the dies and independent of temperature. Similarly, sharkskin and gross melt fracture was observed for the case of PCLs depending on the molecular characteristics of the resins and the geometrical details of the capillary dies. It was also found that the addition of a small amount of PCL (typically 0.5 wt.%) into the PLA and vice versa is effective in eliminating and delaying the onset of melt fracture to higher shear rates in the capillary extrusion of PLA and PCL respectively. This is due to significant interfacial slip that occurs in the presence of PCL or PLA as well as to the immiscibility of the PLA/PCL blend system at all compositions.

Rubber toughened polyamide 6/polypropylene (PA6/PP) nanocomposites containing 4 wt % of organophilic modified montmorilonite (OMMT) were produced by melt compounding followed by injection moulding. Four different types of elastomer were incorporated into the blends as a toughener, i.e., ethylene-octene elastomer (POE), ethylene-propylene elastomer (EPR), maleated POE (POEgMAH) and maleated EPR (EPRgMAH). The influences of maleating on the interfacial adhesion and mechanical properties of the nanocomposites were investigated in term of mechanical testing, the X-ray diffraction (XRD) and scanning electron microscope (SEM) observation. The results showed that modulus and strength of the nanocomposites was not significantly affected by types of elastomer and their functionality. However, the toughness of the nanocomposites toughened by maleated elastomer was higher than the unmaleated elastomer. The SEM observation revealed that rubber functionality reduces the elastomer particle size in the PA6/PP matrix due to the in situ formation of graft copolymer between maleated elastomer and PA6 during melt processing. XRD revealed that the type of elastomer and functionality did not affect the dispersion of the organoclay in the system.

A series of polyamide 6/polypropylene (PA6/PP) blends and nanocomposites containing 4 wt% of organophilic modified montmorillonite (MMT) were designed and prepared by melt compounding followed by injection molding. Maleic anhydride polyethylene octene elastomer (POEgMAH) was used as impact modifier as well as compatibilizer in the blend system. Three weight ratios of PA6/PP blends were prepared i.e. 80:20, 70:30, and 60:40. The mechanical properties of PA6/PP blends and nanocomposite were studied through flexural and impact properties. Scanning electron microscopy (SEM) was used to study the microstructure. The incorporation of 10 wt% POEgMAH into PA6/PP blends significantly increased the toughness with a corresponding reduction in strength and stiffness. However, on further addition of 4 wt% organoclay, the strength and modulus increased but with a sacrifice in impact strength. It was also found that the mechanical properties are a function of blend ratio with 70:30 PA6/PP having the highest impact strength, both for blends and nanocomposites. The morphological study revealed that within the blend ratio studied, the higher the PA6 content, the finer were the POEgMAH particles.