Tensile Strength Of Blends Research Articles

Cellulose blends from gel extrusion and compounding with polylactic acid

AbstractCellulose, dissolved in ionic liquids (IL), can be used successfully in the processing of thermoplastics. To recover the ionic liquid while maintaining the thermoplastic properties, other spacers than IL might be introduced into the cellulose network. Such blend materials have been prepared before by solution blending as reported in the literature. In this study, the preparation and investigation of cellulose and polylactic acid (PLA) blends using an extrusion process with an ionic liquid and co‐solvent for intermediate compatibilization is reported. The obtained transparent films show a homogeneous morphology without phase separation. Thermal analysis showed no separated glass transition for PLA, and FTIR showed hydrogen bonding between cellulose and PLA chains. Thermal stability of the blends with a degradation onset around 270°C lies between regenerated cellulose and pure PLA. The blend tensile strength and elongation of ~40 MPa and 1.3%, respectively, were comparable to a multiphase composite containing twice the molecular weight of PLA. Generally, mechanical performance of the blends was strongly influenced by degradation reactions mainly caused by the ionic liquid used, as well as blend morphology. The study shows that transfer from solution to extrusion processing is generally possible to obtain novel cellulose blends.

Simultaneously improving the toughness and flame retardancy of Poly(lactic acid) by incorporating a novel bifunctional macromolecular ionomer

Improving the toughness or flame retardancy of poly(lactic acid) (PLA) has been widely concerned. However, due to the bad interfacial compatibilization and low efficiency of anti-flammability for these traditional additions, seldom researches can simultaneously and efficiently improve the toughness and flame retardancy of PLA. In order to make up the bland of study on bifunctional macromolecular additive for simultaneously improving the toughness and flame retardancy of PLA, the ionomer additive PBAUI was synthesized. This well-designed structure of PBAUI played a very important role in the modification of PLA. The hard segment of PBAUI not only improved interfacial compatibilization with PLA through hydrogen bonding interactions and ionic aggregation but also improved the flame-retardant efficiency through the phosphorus-containing ionic group. Based on the good interfacial compatibilization between PLA and PBAUI, the soft segment of PBAUI could further provide high quality toughening effect. Therefore, PLA/PBAUI blends achieved excellent toughness-strength balance, even the content of PBAUI was only 5 wt%, the tensile strength of blends still preserved as 86.6% of PLA, which was accompanied by the high tensile elongation at break (≥250%). At the same time, the fire safety of PLA was significantly improved by adding a very low content of PBAUI. Only 5 wt% PBAUI was added into PLA, the blend passed UL-94 V-0 rating and had a low peak heat release rate of 366 kW/m2, and the LOI value increased from 19.5 vol% for the neat PLA to 28.0 vol% for the blend. It is worth mentioning that the incorporation of PBAUI had tiny impact on the transparency of PLA. The transmittances of PLA/PBAUI blends still kept 48% at 800 nm when the content of PBAUI increased to 5 wt%. PLA/PBAUI blends possessing toughness, flame retardancy and transparency will benefit their application in the fields of plastic packaging, automotive industry, instruments shell, thin films and coatings.

Blends of Poly (Butylene Adipate-Co-Terephthalate) and Thermoplastic Whey Protein Isolate: A Compatibilization Study

This work assesses the influence of the plasticizer polyethylene glycol (PEG) on the compatibilization of poly (butylene adipate-co-terephthalate) (PBAT) and thermoplastic whey protein isolate (WPIT) blends. To prepare the blends, WPI was denatured at 90 °C, in the presence of PEG, to become a thermoplastic material. Dried WPIT was later mechanically blended with PBAT using a torque rheometer at 160 °C and 80 rpm. Two blends were prepared: 90% of PBAT/10% of WPIT (90_10) and 70% of PBAT/30% of WPIT (70_30). Scanning electron microscopy (SEM) analyses showed a homogenous blend morphology and good interaction between the dispersed phase and the matrix. Atomic force microscopy-based infrared spectroscopy (AFM-IR) showed PBAT and WPIT bands in all studied regions of both blends, which suggests that these materials presented partial miscibility. The viscosity ratio of the PBAT/WPIT system was less than 3.5 in the high shear rate region in complex viscosity curves, which indicates that droplet break-up of WPIT may occur by the drop fibrillation mechanism. The addition of WPIT reduced the degree of crystallinity of PBAT in the blends in comparison to pristine PBAT as shown by X-ray diffraction (XRD). Mechanical tests showed that blend tensile strength and elongation at break decreased with the addition of WPIT. Elastic modulus of the blends increased compared to pristine PBAT. Barrier properties were also evaluated showing that the oxygen permeability coefficient reduced by 20% for the blend with 30% of WPIT and vapor water permeability increased with the addition of WPIT.

Manipulating phase structure of biodegradable PLA/PBAT system: Effects on dynamic rheological responses and 3D printing

Poly (lactic acid) (PLA), as a biodegradable thermoplastic polyester, has many advantages but a crucial shortcoming of brittleness. It has been recognized that blending with biodegradable poly (butylene-adipate-co-terephthalate) (PBAT) is an effective way to toughen PLA. In this paper, an efficient compatibilizer of PLA-g-GMA (PLA grafted with glycidyl methacrylate) was prepared by melt grafting and then introduced to compatibilize the two phases in PLA/PBAT blends. The dynamic rheological responses were investigated to explore the effects of PLA-g-GMA on the rheological behaviors of PLA/PBAT. Furthermore, the mechanical properties of 3D printed PLA/PBAT/PLA-g-GMA specimens in longitudinal and transverse deposition were examined to compare with that by injection molding so as to reveal the functions of compatibilizer in 3D printing. The results show that the compatibilizer significantly improved the compatibility of PLA and PBAT, and the interface binding capacity of PLA and PBAT was positively related to the content of compatibilizer. Dynamic rheological analysis showed that when the content of compatibilizer reached 10 wt%, the blends has the maximum degree of molecular chain entanglement, complex viscosity and melt strength. It was also found that the compatibilizer significantly improved the interfacial adhesion between layers of 3D printing specimens. In addition, the filament orientation with microchannels was key factor affecting performance improvement of 3D printing specimens as well. Consequently, the tensile strength of blend PLA/PBAT = 70/30 with 10 wt% compatibilizer PLA-g-GMA up to 42.6 MPa and elongation at break over 200%, which is not only higher than that of the injection sample (33.7 MPa), but also higher than the maximum value reported in the literatures ever read.

Nghiên cứu chế tạo blend giữa polypropylene (PP) và cao su butadiene acrylonitril (NBR) Phần 2. Qui hoạch hóa thực nghiệm quá trình chế tạo blend NBR/PP

AbstractBlend of polypropylene and nitril rubber was conducted via dynamic vulcanization in Brabender Plasticoder. MA‐g‐PP was used as coupling agent in this blend. The optimum of blending process was investgated using Design Expert software with three factor PP/NBR ratio, MA‐g‐PP concentration, mixing time and two levels 23 to evaluate the effects of these factors on the the tensile strength of blend. Analysis of variance ANOVA was showed the interaction of these factors. The recurrence equation was as following: TS = 8.6‐1.29A + 0.72C + 0.74D + 0.35 AC. According to the recurrence equation, the PP/NBR ratio had the showed the greatest influence on the tensile strength of blend.

Improved morphology and mechanical properties of UPA6/TPEE blends by reactive compatibilization

In this study, series of blends were prepared by blending unextracted polyamide-6 (PA6) and thermoplastic ester elastomer (TPEE) in certain ratios. The morphologies, thermal behaviors, and mechanical properties of blends have been investigated. Scanning electron microscope results revealed that the morphology of blends was improved significantly when the content of TPEE is less than 50 wt%. Tensile fracture surface images confirmed reactive compatibilization and stress-induced crystallization in blends. The effect of unextracted PA6 content on the elasticity and tensile strength of blends was also studied, and higher elongation rate at break and breaking strength could be achieved when the content of TPEE is ≥50 wt%. The most interesting finding in this study is that the glass transition temperature for rubber phase of blends shifts to lower temperature and decreases with the increase of unextracted PA6 content at certain ratios range.

Esterification of Kraft lignin as a method to improve structural and mechanical properties of lignin‐polyethylene blends

ABSTRACTLignin is a promising candidate for blends with thermoplastic polymers. Still, this endeavour is a challenge due to poor compatibility between both components. In this article, the effect of lignin esterification on the improvement of the compatibility between hardwood Kraft lignin and high‐density polyethylene (PE‐HD) is investigated. For this purpose, lignin was esterified with acetic, propionic, and butyric anhydride; its amount in the blends varied from 10 to 40%. Light microscopic images of blends show a reduction in particle size and a more homogeneous distribution with increasing length of the ester carbon chains (C2 to C4). Modification of lignin enhances the moduli and strength characteristics of the blends. Butyrated lignin performs best, as tensile strength of blends can be retained near that of pure PE‐HD with up to 40% lignin content. An additional investigation of unmodified lignin with reduced particle size confirms that modification is the decisive factor to enhance blend properties; a sole reduction of particle size is insufficient. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44582.

Wood Sawdust/Natural Rubber Ecocomposites Cross-Linked by Electron Beam Irradiation.

The obtaining and characterization of some polymeric eco-composites based on wood sawdust and natural rubber is presented. The natural rubber was cross-linked using the electron beam irradiation. The irradiation doses were of 75, 150, 300 and 600 kGy and the concentrations of wood sawdust were of 10 and 20 phr, respectively. As a result of wood sawdust adding, the physical and mechanical properties such as hardness, modulus at 100% elongation and tensile strength, showed significant improvements. The presence of wood sawdust fibers has a reinforcing effect on natural rubber, similar or better than of mineral fillers. An increase in the irradiation dose leads to the increasing of cross-link density, which is reflected in the improvement of hardness, modulus at 100% elongation and tensile strength of blends. The cross-linking rates, appreciated using the Flory-Rehner equation, have increased with the amount of wood sawdust in blends and with the irradiation dose. Even if the gel fraction values have varied irregularly with the amount of wood sawdust and irradiation dose it was over 90% for all blends, except for the samples without wood sawdust irradiated with 75 kGy. The water uptake increased with increasing of fiber content and decreased with the irradiation dose.

Enhancing compatibility between poly(lactic acid) and thermoplastic starch using admicellar polymerization

ABSTRACTAn alternative method to improve the compatibility between poly(lactic acid) (PLA) and cassava starch (CS) is proposed and investigated. Admicellar polymerization is used to modify the surface of CS with poly(methyl methacrylate) (PMMA) in order to make it more hydrophobic and hence more compatible with PLA. The increased hydrophobicity of PMMA modified cassava starch (MS) is validated by contact angle measurement. Results from iodine test, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) confirm the formation of PMMA film on MS surface. Mechanical properties of PLA‐CS and PLA‐MS blends are investigated to compare their compatibility. Noticeable improvements in blend tensile strength and elongation at break evidently show that MS is more hydrophobic as well as more compatible with PLA than CS. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43755.

Properties of Bloodmeal/Linear Low‐density Polyethylene Blends Compatibilized with Maleic Anhydride Grafted Polyethylene

ABSTRACTNovatein thermoplastics from bloodmeal (NTP) were blended with linear low‐density polyethylene (LLDPE) using maleic anhydride grafted polyethylene (PE‐g‐MAH) as compatibilizer. The compatibilizing effect on mechanical, morphology, thermal properties, and water absorption were studied and compared with blends without compatibilizer. The amount of polyethylene added was varied between 20 and 70% in NTP with addition of 10% compatibilizer. An improvement in compatibility between NTP and LLDPE was observed across the entire composition range and the difference were more pronounced at higher NTP contents where the tensile strength of blends was maintained and never dropped below that of pure NTP. Theoretical models were compared to the results to describe mechanical properties. A finely dispersed small particles of NTP in compatibilized blends were observed using SEM. Improved compatibility has restricted chain movement resulting in slightly elevated Tg revealed by DMA. On the other hand, water absorption of the hydrophilic NTP has been decreased when blending with hydrophobic LLDPE. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1890–1897, 2013

Properties of Blends of Novatein Thermoplastic Protein from Bloodmeal and Polybutylene Succinate Using Two Compatibilizers

The use of dual compatibilizers, poly (2-ethyl-2-oxazoline) (PEOX) and polymeric methylene diphenyl diisocyanate (pMDI) in Novatein thermoplastic protein from bloodmeal (NTP) and PBS blends were investigated. A composition of 50% of NTP was used for all formulations with different percentage compatibilizer. Mechanical, morphology, thermal and water absorption were used as analysis methods to study blend properties. To improve compatibility, two different approaches to blending the compatibilizers were used. Firstly, PEOX was added before extrusion this has improved the blend's tensile strength. Secondly, addition of PEOX during NTP production followed by pMDI added before injection molding, showed a futher improvement in tensile strength. SEM revealed that PEOX has improved the dispersion of NTP and pMDI has strengthened the adhesion between phases consistent with mechanical property results. A broad tan δ peak in DMA analysis was obtained indicated improved compatibility in blends using two compatibilizers. In spite of that, the addition of dual compatibilizer has reduced the water resistance of PBS.

Preparation and Properties Research of PA6/PLA Blends Toughening Modified by TPU

Polyamide 6/Poly(lactic acid) (PA6/PLA) blends introduce the degradability of PLA to high performance PA6, but the bad toughness of both PA6 and PLA limits the application of blends. Aiming at this deficiency, thermoplastic polyurethane (TPU) was used as an additive for modifying the toughness of PA6/PLA blends. PA6/PLA/TPU blends at various compositions were prepared by melt blending, the effects of blend compositions on the morphology, thermal and mechanical properties of blends were investigated. The results showed that the addition of TPU improves the compatibilization between PA6 and PLA and makes the blends show more obvious plastic fracture behavior than PA6/PLA.When the content of PLA in PA6/PLA increases, the impact and tensile strength of blends decrease slightly with the intense decrease of the elongation at break, adding TPU into PA6/PLA blends strengthens the toughness of blends, but the tensile strength of blends decreases. Moreover, the crystallinity of PA6 /PLA blend is hampered by TPU.

Epoxy-Polyester IPNs modified with aromatic amines

Semi-interpenetrating polymer networks (Semi-IPNs) based on epoxy and unsaturated polyester resin (UPR; added in 5.9 and 11.1 wt %) have been prepared by chemical route. Room temperature curing was attempted using triethylene tetramine as a hardener. Blend with 11.1% UPR is found to exhibit best mechanical properties. Further, blends were also prepared by adding aromatic amines such as diphenylamine (DPA, secondary amine) and benzidine (Bz, primary amine). Structural elucidation of the samples through identification of functional groups was carried out with the help of Fourier transform infra red spectroscopy. Absence of peak at 915 cm−1 (characteristic of epoxy ring) confirmed complete curing in all the blends. The mechanical properties such as hardness, izod impact and tensile strength of blends were compared. The co-cured blends show decrease in shore hardness (≈ 1–6%), while, the izod impact exhibits an opposite trend. Blends with 10% DPA and Bz show an increase in izod impact by 268.6% and 38.8% respectively. Further, the tensile strength is observed to be enhanced by 45% in case of DPA while addition of Bz reduces it by 32.8%. Thermal properties were studied by thermogravimetric (TGA) and differential scanning calorimetric (DSC) analysis. TGA shows no significant change in onset and decomposition temperature but temperature at which it melts is lowered almost by 100–150°C together with the onset temperature (by ≈ 200°C) observed in DSC. Scanning electron micrographs reveal granular nature of the samples. The homogeneity of blends appears to be good. The blends co-cured with DPA are relatively crystalline compared with others. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Influence of Transesterification on the Properties of PET/MAPE Blends Prepared by Reactive Extrusion

Blends based on maleic anhydride grafted polyethylene (MAPE) and poly(ethylene terephthalate)(PET) were prepared through reactive extrusion in the presence of titanium tetrabutoxide (Ti(OBu)4) as transesterification catalyst. Mechanical properties of PET/MAPE blends(70wt./30wt.) were evaluated by mechanical tests. The Effects of Ti(OBu)4 on the structure and melt crystallization behavior of the blends were investigated by Fourier transform infrared spectroscopy(FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The addition of Ti(OBu)4 to the blends could improve the compatibility between PET and MAPE as was evidenced by the SEM micrograph in which filaments connected to a network structure was observed. With increasing the contents of Ti(OBu)4, the impact strength of the blends increased obviously, the flexural strength and tensile strength of blends did not change significantly, while the degradation of PET was gradually significant as was evidenced by FTIR analysis. Small amount of Ti(OBu)4 could hinder the crystallization of PET and make its melt peak shifted to higher temperature.

Surprising shape-memory effect of polylactide resulted from toughening by polyamide elastomer

Melt blending of polylactide (PLA) and biodegradable polyamide elastomer (PAE) has been performed in an effort to toughen the PLA. DMA tests showed good compatibility between PAE and PLA blends, and the PAE were dispersed in PLA matrix uniformly shown in SEM photos. Mechanical properties of blends with different PAE concentrations were observed. With the PAE contents increasing, the elongation at break of blends increased and the brittle break became ductile break. When the PAE content is 10%, the tensile strength of blend is similar to neat PLA, and the elongation increased to 194.6% significantly. Remarkably, the blends showed wonderful shape-memory effect. PAE domains act as stress concentrators in system with the stress release locally and lead to energy-dissipation process. These will prevent PLA matrix from breaking under high deformation, and lead to the PLA molecular orientation. Consequently, the blends occurred to deformation upon tensile load, and heating up the material will reform the shape back to the original shape.

Abrasive wear studies on maleic anhydride modified polypropylene and polyethylene terephthalate blends

Polypropylene and polyethylene terephthalate (PP/PET) blends have been developed, with and without maleic anhydride (MAH), by using a melt and mixing method. Abrasive wear loss in PP/PET blends having 5, 10, 20, and 50 wt% of PET, with and without MAH, has been determined. Addition of MAH reduced the density and impact strength and increased the tensile strength of blends. It has been found that at 3 N load the wear rate of PP/PET/MAH blends decrease. This reduction in wear rate at 3N load is due to the increased cross-linking created by the addition of small-size MAH. At 5 N load, abrasive wear rate reduced for PP/PET 95/5 and 90/10 blends on adding MAH. At 7 N load, wear rate of PP/PET(95/5) having MAH shows a reduction in wear rate compared to pure PP/PET blend. MAH addition on the wear rate of PP/PET blend at 7 N load shows that wear rate of PP/PET(95/5) blend for 6.4m sliding distance reduced from 3.85 × 10−10 to 3.38 × 10−10 m3/m. Wear rate, at 7 N load, for PP/PET(90/10) blend increased on adding MAH. Similarly, at 7 N load the PP/PET(80/20) and PP/PET(50/50) blends showed an increase in wear rate on adding MAH. Reversal of the wear rate trend from decrease to increase on adding MAH has been observed for more than 10 wt% blend at 7 N load. This can be explained based on the following two reasons: (a) at higher PET content, effective bonding between components of blends reduced and (b) higher loads would have increased the ploughing and cutting of the surface, which would have resulted in increased wear rate after 10 wt% PET loading. In the case of 50 PET loading, poor bonding of PP and PET was observed in worn surfaces. The majority of PET is present as second phase in the blend. In the case of PP/PET(50/50) blend, high wear rate is dominated by PET phase.

Mechanical characterization of vinyl acetate based emulsion polymer blends

Emulsion blends comprise an important commercial area of polymer blend utility. Surprisingly, the fundamental study of emulsion blends is rarely noted in the literature. This study investigates emulsion blends of poly(vinyl acetate) (PVAc) and vinyl acetate-ethylene copolymers (VAE), where both components employ poly(vinyl alcohol) (PVOH) as the protective colloid. PVOH comprises the continuous phase in the emulsion cast films for both the individual components and the blends. This provides an example whereby excellent adhesion can be expected between the particles comprising the blend. The combination of low Tg/high Tg emulsion blends has been noted to be of interest, and the PVAc/VAE emulsion blends noted here offer an excellent model to study. The PVAc/VAE blends protected with PVOH exhibit poor mechanical compatibility even though there is good adhesion. Conventional theory based on polymer/filler combinations predicts a rapid loss in elongation as filler content increases if excellent adhesion is observed. The PVAc/VAE blends (where PVAc is the filler) also exhibit similar behavior. This result implies excellent adhesion may not be desired where a compliance mismatch occurs for emulsion blends. The polymer/filler theories do not properly predict PVAc/VAE blend tensile strength results. A newer approach termed the equivalent box model (EBM) employing percolation theory agrees well with experimental results. Melt mixing of the low/high compliance PVAc/VAE emulsion blends yields a significant improvement in mechanical compatibility. This indicates that a heterogeneous mixture of the same components yields better mechanical results than an array of particles with excellent adhesion between the particles.

Reactive compatibilization of polypropylene/polyethylene terephthalate blends

AbstractThe reactive compatibilization of polypropylene/polyethylene terephthalate (PP/PET) blends by addition of glycidyl methacrylate grafted PP (PP‐g‐GMA) was studied. Two PP‐g‐GMA copolymers, containing either 0.2 or 1.2 wt% of GMA, were used as interface modifiers. These were incorporated into PP blends (with either 70 or 90 wt% PET), replacing 1/5 of PP in the system. The use of these modifiers changed the blends' tensile mechanical behavior from fragile to ductile. Blend tensile strength was improved by 10% and elongation at break showed 10 to 20‐fold increases while stiffness remained constant. Scanning electron micrographs showed the PP average domain size in injection molded specimens to decrease to the micron/sub‐micron size upon addition of the GMA modified resins, while the unmodified blends exhibited heterogeneous morphology comprising large lamellae 10–20 μm wide. The low‐GMA graft content PP seemed slightly more efficient than the high GMA content PP in emulsifiying PP/PET blends. The GMA grafting level on PP had very limited effects on the blends' mechanical behavior in the range of GMA graft density provided by the two modified resins investigated.

Properties of blends of starch and synthetic polymers containing anhydride groups. II. Effect of amylopectin to amylose ratio in starch

AbstractCorn starch with different amylopectin to amylose ratios was blended with styrene maleic anhydride copolymer (SMA) and ethylene–propylene‐g‐maleic anhydride copolymer (EPMA). The starch had an amylose content of approximately 0, 50, and 70%. The concentration of starch in the blend was kept constant at 60% by weight. The samples were melt blended in a corotating twin screw extruder. Scanning electron micrographs showed that the amount of starch granules remaining in the samples varied with the torque. Optical micrograph showed that starch/EPMA blends formed a cocontinuous phase in all blends irrespective of starch variety. For starch/SMA blends, the starch granules remained dispersed in the SMA phase. The torque during blending, tensile strength, water absorption, storage and loss modulus, and data on biodegradability of the blends are presented. Tensile strength and water absorption correlated well with the torque generated during blending: the higher the torque, the lower the tensile strength and the higher the water absorption. The tensile strength of blends containing SMA decreased when the humidity increased. Fractured surfaces of starch/SMA blends exhibited brittle failure; for the ductile starch/EPMA blends, shear tearing appeared to be the major failure mechanism. For blends containing EPMA, the percentage elongation increased with increased humidity. Dynamic mechanical analysis of the blends showed two sharp peaks for tan δ vs. temperature plot for starch/EPMA plots, but showed a single peak for starch/SMA blends. Starch/EPMA blends had a higher percentage of water aborption that became constant after 20 days. Using the ASTM test method D5902, the starch content in the samples was found to degrade. © 1995 John Wiley & Sons, Inc.

Polymer blends containing copolymers

AbstractBlends with random or block copolymers are discussed, where all components are made of one or both monomers of a given monomer pair. The critical copolymer compositions of blends of two random copolymers were determined, and phase morphologies were studied in blends close to and far from the critical point. Further, the tensile strength of blends of varying compatibility was tested. Microphase and macrophase structures of blends with one or two homopolymers and a symmetric block copolymer were characterized as a function of the chain length ratio of the components. Experiments were compared with model calculations.