Structural,thermal and physico-chemical properties of high density polyethylene/natural rubber/modified cassava starch blends

The utilization of cassava starch as one of the components in high density polyethylene (HDPE)/natural rubber (NR) blends were investigated. The true challenge in producing new materials based on natural resources is to design materials that could level the mechanical properties of existing conventional polymers. In this study, we have focused on characterizing the HDPE/NR blends incorporated with cassava starch in the form of granulates (native and silanized) as well as plasticized starch. Cassava starch acted as a biodegradation component in the HDPE/NR blends and the incorporation of cassava starch reduced thermal stability and the degree of crystallinity in general. Several series of cassava starch modifications were performed in order to improve the final properties of the blends. Cassava starch was treated with a silane coupling agent, and proved to be effective in improving tensile strength. The better dimensional stability and compatibility between the blend phases were obtained in the silane-treated cassava starch, as observed in the dynamic mechanical analysis results. Cassava starch was also converted into a plasticized form (TPS), and from the results, the degree of TPS adhesion at the inter-phase ofthe HDPE/NR-TPS blend was clearly improved, as indicated in the morphology study. Through the comparison of thermal degradation results, the HDPE/NR/TPS blends proved to be superior to the HDPE/NR/particulate starch counterparts.     

Morphology and tensile properties of high-density polyethylene/natural rubber/thermoplastic tapioca starch blends: The effect of citric acid-modified tapioca starch

The effect of citric acid on the tensile properties of high density polyethylene (HDPE)/natural rubber (NR)/thermoplastic tapioca starch (TPS) blends was investigated. The ratio between HDPE/NR was fixed at 70/30 and used as the matrix system. TPS loadings, after modification with citric acid (TPSCA) and without modification (TPS), were varied from 0 to 30 wt %. The morphologies and tensile properties of HDPE/NR blends were evaluated as a function of TPS loadings. The tensile strength, Young's modulus, and elongation at break were found to decrease with increasing TPS loading. However, a slight improvement in the tensile strength of HDPE/NR/TPSCA blends at 5 and 10 wt % TPS loadings were observed. TPS can be partly depolymerised to produce a low viscosity product when processed with citric acid. TPS with low viscosity can easily disperse in the thermoplastic natural rubber (TPNR) system and reduce the surface tension at the interphase of TPS-HDPE/NR as shown by scanning electron microscopy (SEM). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effects of polyethylene‐grafted maleic anhydride as a compatibilizer on the morphology and tensile properties of (thermoplastic tapioca starch)/ (high‐density polyethylene)/(natural rubber) blends

Effects of polyethylene‐grafted maleic anhydride as a compatibilizer on the tensile properties of (high‐density polyethylene)/(natural rubber)/(thermoplastic tapioca starch) (HDPE/NR/TPS) blends were investigated. The ratio of HDPE/NR was fixed at 70/30, and these materials were blended with TPS in concentrations varying from 5 to 30% by using a Haake Rheomix 600 mixer. Two series of HDPE/NR/TPS blends were prepared, i.e., with and without compatibilizer. Morphology and tensile properties of the HDPE/NR/TPS blends were evaluated as a function of TPS loading. The tensile strength and elongation at break decreased with the increase of TPS content. However, an improvement in the tensile strength was obtained for compatibilized blends as compared to uncompatibilized blends. The degrees of TPS adhesion and dispersion in HDPE/NR blends were revealed by scanning electron microscopy (SEM). Results showed that a smaller‐sized dispersed phase was achieved for compatibilized blends as compared to that for their uncompatibilized counterparts. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

High‐density polyethylene/natural rubber blends filled with thermoplastic tapioca starch: Physical and isothermal crystallization kinetics study

High‐density polyethylene/natural rubber (HDPE/NR) blends filled thermoplastic tapioca starch was studied. In this blend system, thermoplastic starch (TPS) acted as an inert component, and the influence of TPS incorporation was studied in terms of tensile properties and crystallization kinetics. Tensile properties of the blends were affected by the addition of TPS particles, which reflects the incompatibility and lack of adhesion at the interface. The effect of TPS incorporation on the crystallization behavior of the HDPE/NR blends was also evaluated at different predetermined crystallization temperatures. The isothermal crystallization data obtained in this study were analyzed by using the Avrami equation. The Avrami exponent for HDPE/NR and HDPE/NR‐10% TPS blends varied around 2.0 and slightly decreased around 1.8 for HDPE/NR‐30% TPS, implying the nucleation process is heterogeneous and the crystal growth is 2D. J. VINYL ADDIT. TECHNOL., 22:191–199, 2016. © 2014 Society of Plastics Engineers     

Effects of dynamic vulcanization on the physical,mechanical, and morphological properties of high‐density polyethylene/(natural rubber)/(thermoplastic tapioca starch) blends

Blending of high density polyethylene (HDPE), natural rubber (NR), and thermoplastic tapioca starch (TPS) have been studied. Two series of samples having 5–30 wt% of TPS were prepared: (a) unvulcanized blends (control) and (b) dynamically vulcanized HDPE/NR/TPS blends. The composition of the HDPE/NR was constant and fixed at a blend ratio of 70/30. Morphology studies by SEM showed that the TPS particles were homogeneously dispersed and well‐embedded in vulcanized HDPE/NR matrix. The SEM micrographs showed agreement with the tensile strength and elongation at break values. Tensile strength improved significanly when the HDPE/NR/TPS blends were vulcanized by using sulfur curative system. The enhancement in tensile properties is attributed to the crosslinking reaction within the NR phase. J. VINYL ADDIT. TECHNOL., 18:192–197, 2012. © 2012 Society of Plastics Engineers     

Study on the structure and properties of nanocomposites based on high-density polyethylene/starch blends

The effects of nanoclay on the structure and final properties of high density polyethylene (HDPE)/thermoplastic starch (TPS) blends were investigated. Neat blends as well as nanoclay containing samples were prepared by melt blending in an internal mixer. Also, a poly (ethylene-g-maleic anhydride) (PE-g-MA) copolymer was used as compatibilizer in some of the formulations. Nanocomposites with intercalated structures were obtained in the samples lacking the compatibilizer, based on the rheological, X-ray diffraction (XRD) and transmission electron microscopy (TEM) results. However, some of the silicate layers were nearly exfoliated in the presence of the compatibilizer. The nanoclay was located preferably in the HDPE matrix as well as at the interface of the HDPE matrix and TPS dispersed phase. The ability of the nanoclays in decreasing the average size of TPS phase in the HDPE matrix was confirmed by scanning electron microscopy (SEM) observations. Furthermore, thermo-gravimetric analysis (TGA) showed that the nanoclays could enhance the thermal stability of the samples. It seems that nanoclays performed as an insulator and mass transport barrier to the small molecules generated during decomposition, and assisted in the formation of char after thermal decomposition of the polymer matrix. All the samples containing the compatibilizer possessed higher tensile strength and elongation at break, but lower modulus, compared to the corresponding un-compatibilized samples. Finally, incorporation of the nanoclays was found to be in favor of developing nanocomposites with higher biodegradability as evidenced through a biodegradation test by fungi as well as water uptake experiments.     

Interface/morphology relationships in polymer blends with thermoplastic starch

In this paper, the interface/morphology relationship in polyethylene/TPS blends prepared by a one-step extrusion process is examined in detail. Emulsification curves tracking the change in phase size with added quantity of PE-g-MA copolymer are used to identify the critical concentration required for saturation of the interface as well as to estimate the areal density of grafted copolymer chains at the interface. The level of glycerol content in the TPS is shown to lead to different emulsification behaviors. Dynamic mechanical analysis clearly shows a partial miscibility between glycerol and starch in the TPS with glycerol-rich and starch-rich peaks being clearly identified. This phase separation is more evident in the case of high glycerol levels in the TPS (>24% glycerol). Furthermore, the glycerol-rich peak decreases in intensity with added PE-g-MA graft copolymer. At high glycerol contents (>24% glycerol) in the TPS, a 20% thermoplastic starch-based binary blend with polyethylene can reach an elongation at break value as high as 200%. When also modified at the appropriate level with a PE-g-MA copolymer, this elongation at break further increases to 600%. However, at lower glycerol contents, the elongation at break is comparatively low at 20-50% even after the addition of PE-g-MA copolymer. We explain these results through a proposed double mechanism of interfacial modification between the HDPE matrix and the TPS dispersed phase. Under dynamic melt-mixing conditions, it is suggested that a small portion of the low molecular weight glycerol-rich phase tends to migrate to the HDPE-TPS interface as predicted by Harkins spreading theory. Once at the interface, this glycerol-rich outer layer is readily deformed by an applied stress and this stress is then transferred to the starch-rich phase due to their mutual partial miscibility. Added PE-g-MA copolymer initially reacts with the glycerol-rich outer layer but if the level of copolymer is high enough, it then reacts with the starch-rich phase via a classic interfacial modification protocol. Also, both the elongation at break and impact properties dramatically increase at a copolymer level associated with interfacial saturation. The above mechanism effectively explains all the emulsification and mechanical property observations.     

The effect of thermoplastic starch on the properties of HDPE/TPS blends during UV-accelerated aging

The influence of thermoplastic starch (TPS) on the properties of UV-irradiated TPS/high-density polyethylene (HDPE) blends was investigated. Changes in chemical structure, molecular weight, crystallinity, and mechanical properties, as a function of exposure time, were determined using FTIR-spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and tensile tests. The inclusion of TPS influence neither the evolution of carbonyl index nor the molecular weight reduction of HDPE/TPS. In contrast, the presence of TPS in the blends increased the fusion enthalpy because of starch retrogradation. This increasing resulted in a corresponding increase of Young??s modulus of HDPE/TPS blends.     

Radiation effects on HDPE/EVA blends

In this article, we discuss the radiation effects of high‐density polyethylene (HDPE)/ethylene–vinyl acetate (EVA) copolymer blends. In comparison with the low‐density polyethylene/EVA blends, the EVA content in the HDPE/EVA blends had a lower enhancement effect on radiation crosslinking by γ‐ray irradiation in air. The phenomenon is discussed with the compatibility, morphology, and thermal properties of HDPE/EVA blends. The HDPE/EVA blends were partly compatible in the amorphous region, and radiation crosslinking of the HDPE/EVA blend was less significant, although increasing the amorphous region's content of the HDPE/EVA blends and the vinyl acetate content of EVA were beneficial to radiation crosslinking. The good compatibility was a prerequisite for the enhancement effect of EVA on the radiation crosslinking of the polyethylene/EVA copolymer. The radiation crosslinking and the degradation mechanism of HDPE/EVA blends were examined quantitatively by a novel method, the step analysis process of irradiated HDPE/EVA blends with a thermal gravimetric analysis technique. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 553–558, 2002     

Novel ternary blends of natural rubber/linear low-density polyethylene/thermoplastic starch: influence of epoxide level of epoxidized natural rubber on blend properties

Novel degradable materials based on ternary blends of natural rubber (NR)/linear low-density polyethylene (LLDPE)/thermoplastic starch (TPS) were prepared via simple blending technique using three different types of natural rubber (i.e., unmodified natural rubber (RSS#3) and ENR with 25 and 50 mol% epoxide). The evolution of co-continuous phase morphology was first clarified for 50/50: NR/LLDPE blend. Then, 10 wt% of TPS was added to form 50/40/10: NR/LLDPE/TPS ternary blend, where TPS was the particulate dispersed phase in the NR/LLDPE matrix. The smallest TPS particles were observed in the ENR-50/LLDPE blend. This might be attributed to the chemical interactions of polar functional groups in ENR and TPS that enhanced their interfacial adhesion. We found that ternary blend of ENR-50/LLDPE/TPS exhibited higher 100 % modulus, tensile strength, hardness, storage modulus, complex viscosity and thermal properties compared with those of ENR-25/LLDPE/TPS and RSS#3/LLDPE/TPS ternary blends. Furthermore, lower melting temperature (T _m) and heat of crystallization of LLDPE (?H) were observed in ternary blend of ENR-50/LLDPE/TPS compared to the other ternary blends. Also, neat TPS exhibited the fastest biodegradation by weight loss during burial in soil for 2 or 6 months, while the ternary blends of NR/LLDPE/TPS exhibited higher weight loss compared to the neat NR and LLDPE. The lower weight loss of the ternary blends with ENR was likely due to the stronger chemical interfacial interactions. This proved that the blend with ENR had lower biodegradability than the blend with unmodified NR.     

VC／BA共混物增容PVC／HDPE共混体系的研究

采用氯乙烯—丙烯酸丁酯(VC/BA)共混物作为聚氯乙烯(PVC)/高密度聚乙烯(HDPE)共混物的增容剂,通过冲击实验、拉仲实验、动态力学分析,系统地研究了共混体系性能与其结构之间的关系。通过Brabender流变仪测定了VC/BA共混物增容PVC/HDPE共混体系的流变性能。结果表明,VC/BA共混物是PVC/HDPE共混体系的良好增容剂。在一定范围内,VC/BA共混物与HDPE对PVC有协同增韧效应。vC/BA和HDPE的加入改善了PVC的塑化和流变性能     

Peroxide cured natural rubber/fluoroelastomer/high‐density polyethylene via dynamic vulcanization

In this work, blends of fluoroelastomer (FKM), natural rubber (NR) along with high‐density polyethylene (HDPE) by dynamic vulcanization using peroxide (DBPH, DCP) as a curing agent were prepared. HDPE was melt‐mixed with NR and FKM at different compositions (HDPE/FKM/NR i.e. 30/60/10, 30/55/15, 30/50/20, and 30/35/35%wt) using an internal mixer at 150°C and 50 rpm rotor speed. The mechanical properties and oil swelling resistances of these blends were analyzed according to ISO 37 (Type 1) and ASTM D471, respectively. The results suggest that DBPH works better as a curing agent for the dynamic vulcanization system than DCP. The optimum mechanical properties and oil resistance were revealed in 30/50/20 and 30/60/10 HDPE/FKM/NR, being dynamic vulcanized with DBPH, respectively. In addition, was found that a dispersed HDPE phase shows the percent crystallinity in the range of 53% to 55% upon increasing the NR content. The SEM micrographs reveal the NR phase is well dispersed in FKM as small particles. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers .     

Development of isotropic compatible HDPE/PP blends for structural applications

In an attempt to provide superior products for the structural applications, this study aimed at preparing isotropic compatible high density polyethylene (HDPE)/ polypropylene (PP) blends without the use of the expensive compatibilization technique. Morphological and structural characterizations of the homopolymers and blends were carried out. In addition, some of the structurally important mechanical and thermal properties were characterized. Such characterizations were performed to investigate whether or not the blends are compatible and therefore acceptable for the structural applications. Scanning electron microscope (SEM) micrographs of the blend samples indicate that the interfacial adhesion between HDPE and PP phases is intimate in the 5/95 HDPE‐PP, good in the 85/15 HDPE‐PP and 95/5 HDPE‐PP, fair in the 30/70 HDPE‐PP and very poor in the 50/50 HDPE‐PP. Similarly, mechanical and thermal responses of the first three blends are remarkable. The 30/70 HDPE‐PP blend displays a fairly good performance. Whereas, the properties of the 50/50 HDPE‐PP blend are very poor. This decides that the first three blends are compatible and, therefore, structurally attractive materials. The fourth is partially compatible and, as a consequence, can be rather acceptable for the structural applications. However, the fifth is incompatible and, of course, is not acceptable for such applications. On the other hand, SEM micrographs and differential scanning calorimetry results indicate that the crystalline structures of individual polymers are appreciably affected by blending. Additionally, the study reveals that the end use performance of blends is strongly dependent on the crystalline structure changes occurring in each component due to blending as well as the compatibility between the blend components. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚氯乙烯/氯乙烯-丙烯酸乙酯共聚物/高密度聚乙烯合金的制备及其性能研究

以氯乙烯-丙烯酸乙酯共聚物(VC/EA)作为聚氯乙烯(PVC)和高密度聚乙烯(HDPE)的增容剂,研究了共混物的相容性和加工性能,在此基础上研制了聚氯乙烯/氯乙烯-丙烯酸乙酯共聚物/高密度聚乙烯合金,进而研究了合金的力学性能。结果表明,合适配比的共混体系具有一定程度的相容性和良好的流动性能,明显改善了PVC的加工性能,并在保持PVC材料拉伸强度、弯曲强度等具有较高保持率的前提下,显著提高了材料抗冲性能。     

E-TMB中弹性体含量对HDPE/E-TMB共混物性能的影响

以高密度聚乙烯(HDPE)为基体树脂,(乙烯/丙烯)共聚物和(苯乙烯/丁二烯)共聚物为增韧剂研制出5种弹性体含量不同的聚乙烯增韧母料(E-TMB),将E-TMB与HDPE热机械共混制得弹性体总含量均为6.3%的5种HDPE/E-TMB共混物,研究了E-TMB中弹性体含量对共混物力学性能和热性能的影响。结果表明,当E-TMB中弹性体含量为44%时,共混物的综合力学性能最好,悬臂梁缺口冲击强度是HDPE的5.65倍,拉伸屈服强度和弯曲弹性模量保留率分别为90.8%和73.7%;共混物的熔点和热分解温度随E-TMB中弹性体含量的增加而升高,结晶温度随E-TMB中弹性体含量的增加而降低。     

High performance modified thermoplastic starch/linear low‐density polyethylene blends in one‐step extrusion

In this study, the morphology and the mechanical properties of thermoplastic starch (TPS)/linear low‐density polyethylene (LLDPE) blends prepared by one‐step and two‐step extrusion processing conditions were contrasted. In the presence of citric acid (CA), the compatibility of TPS/PE blends were proved to transfer to a high continuous dispersion in one‐step extrusion process by scanning electron microscopy analysis. By increasing the interaction between two phases, the mechanical properties of the blends were markedly improved, even reached the levels of the conventional plastics. The rheological study proved that the viscosity (η) of TPS and TPS/PE blends were both decreasing with increase in the content of CA at the same temperature, which ascribed to the acidity of CA was propitious to fragmentation and dissolution of cornstarch granules, deteriorated the chain entanglement in starch, and weakened the interaction of starch molecules. Both FTIR spectroscopy and thermal properties analysis of TPSs and TPS/PE blends showed that the interactions between starch and plasticizer became stronger in the presence of CA. POLYM. COMPOS. 28:89–97, 2007. © 2007 Society of Plastics Engineers     

The effect of Ag,ZnO, and CuO nanoparticles on the properties of the compatibilized polyethylene/thermoplastic starch blend films

In this study, the effects of Ag, ZnO, and CuO nanoparticles (NPs) on the mechanical, thermal, and biodegradability properties of the compatibilized polyethylene (PE)/thermoplastic starch (TPS) blends were investigated. Polyethylene-grafted maleic anhydride (PE-g-MA) was used as the compatibilizer. The compatibilized PE/TPS blends with different NPs were prepared by melt mixing method in a laboratory scale extruder and then pressurized in the press machine. The use of ZnO NP together with the compatibilizer in PE/TPS-based films significantly increased the tensile stress values. The use of different type NPs did not cause any significant change in the thermal stability of PE/TPS-based films. However, the effects of NPs were observed on the TPS degradation steps. The prepared films with different NPs showed an antibacterial activity between 60% and 70%. The highest crystallinity value was obtained in Ag NP containing films, among others. According to scanning electron microscopy analysis, better distribution was observed for ZnO and Ag NPs than CuO NP. In general, it can be said that the addition of NPs to PE/TPS-based blends significantly reduces the partial biodegradability of the resulting films.     

Studies on recyclable composites: nylon fibre reinforced high density polyethylene composites

Abstract

A commercial grade of high density polyethylene (HDPE) matrix reinforced with nylon fibre up to 30 wt-% of HDPE was studied as a potential candidate for recyclable composites. These composite materials show improvement in mechanical properties such as tensile strength and flexural strength. Modification using styrene maleic anhydride – grafted HDPE significantly improved the mechanical and thermal properties. The HDPE/nylon composites/blends obtained by recycling of the composites also show good mechanical properties.     

Melt Rheological and Thermoresponsive Shape Memory Properties of HDPE/PA6/POE-g-MAH Blends

High density polyethylene (HDPE)/nylon6 (PA6) blends were prepared by means of melt extrusion and using ethylene – octane copolymer graft maleic anhydride (POE-g-MAH) as a reactive compatibilizer. Phase morphology, rheological and thermoresponsive shape memory properties of the blends had been studied. The results showed that addition of POE-g-MAH could increase compatibility and phase-interfacial adhesion between HDPE and PA6, decrease the temperature sensitivity of the melt, improve the shape memory property and processability of HDPE/PA6 blends. The shape recovery rate of HDPE/PA6/POE-g-MAH (80/20/10) blend is 96.5% when the stretch ratio is 75% and optimal shape recovery response temperature is 135°C.     

Morphology and mechanical properties of styrene–ethylene/butylene–styrene triblock copolymer/high‐density polyethylene composites

The morphology and mechanical properties of a styrene–ethylene/butylene–styrene triblock copolymer (SEBS) incorporated with high‐density polyethylene (HDPE) particles were investigated. The impact strength and tensile strength of the SEBS matrix obviously increased after the incorporation of the HDPE particles. The microstructure of the SEBS/HDPE blends was observed with scanning electron microscopy and polar optical microscopy, which illustrated that the SEBS/HDPE blends were phase‐separation systems. Dynamic mechanical thermal analysis was also employed to characterize the interaction between SEBS and HDPE. The relationship between the morphology and mechanical properties of the SEBS/HDPE blends was discussed, and the toughening mechanism of rigid organic particles was employed to explain the improvement in the mechanical properties of the SEBS/HDPE blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008