Influence of maleic anhydride on the compatibility of thermal plasticized starch and linear low‐density polyethylene

In the presence of dicumyl peroxide, the compatibility of thermal plasticized starch/linear low‐density polyethylene (TPS/LLDPE) blends using maleic anhydride (MAH) as compatibilizer was investigated. The thermal plasticization of starch and its compatibilizing modification with LLDPE was accomplished in a single‐screw extruder at the same time. We prepared three types of blends containing different percentages of TPS and MAH. The content of MAH based on LLDPE was 0, 1, and 2 wt %, respectively. The morphology of the blends was studied by SEM. It was found that, with the addition of MAH, the blends have good interfacial adhesion and finely dispersed TPS and LLDPE phases, which is reflected in the mechanical and thermal properties of the blends. The blends containing MAH showed higher tensile strength, elongation at break, and thermal stability than those of blends without MAH. The rheologic properties of the blends demonstrated the existence of processing. Finally, the dynamic thermal mechanical analysis results indicated that, with the addition of MAH, the compatibility between TPS and LLDPE in the blends was substantially improved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 686–695, 2004     

The effect of various anhydride modifications on mechanical properties and water absorption of oil palm empty fruit bunches reinforced polyester composites

The chemical modification of oil palm empty fruit bunches (EFB) using non‐catalysed reaction with acetic, propionic and succinic anhydrides were investigated. Proof of modification was indicated by the increase of weight and was confirmed by Fourier‐transform infrared analysis (FT‐IR). The mechanical and water‐absorption properties of all anhydride‐modified EFB composites were evaluated at different volume fractions (V_f). The properties were improved for these modified fibres, whereas unmodified EFB fibres exhibited poor mechanical properties and higher water absorption. Acetic anhydride modification showed the greatest benefit on composite properties, followed by propionic and succinic anhydride modification. © 2001 Society of Chemical Industry     

Mechanical,thermal, and biodegradability properties of PLA/modified starch blends

Three different kinds of modified starch (MS) were prepared as fillers to assess the compatibility between them and poly(lactic acid) (PLA) resin. The blends were prepared by incorporating 15 wt% of the MS into PLA using a twin‐screw extruder. Through morphology analysis, it can be seen that the dispersion state of MS granules was greatly different. Investigations of thermal behavior indicated that the addition of MS decreased thermal properties which found expression in the decrease of melting temperature and vicat softening temperature (VST). But thermal stability of PLA/maleic anhydride grafted starch (MA‐g‐ST) was slightly higher than those of other blends. PLA/MA‐g‐ST blend exhibited the highest notched impact strength, elongation at break, and tensile strength, which means MA‐g‐ST was suitable as a filler improving the toughness of PLA. It was also proved that biodegradability rate of blends increased dramatically and reached up to 1.80, 1.89, 1.44 g day⁻¹ after 60 days, respectively. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Toughening of polyamide 11 via addition of crystallizable polyethylene derivatives

BACKGROUND: Conventional rubber‐like toughening modifiers are soft and amorphous, and when used to toughen polyamide 11 (PA11) they commonly induce a decrease in the tensile strength and modulus. In this study, crystallizable polyethylene (PE) derivatives, i.e. linear low‐density polyethylene (LLDPE) and maleic anhydride‐grafted polyethylene (PE‐g‐MA), were adopted to toughen PA11. RESULTS: Compared to pure PA11, a highest improvement by a factor of eight in the impact toughness was achieved; also, the tensile strength and modulus could be maintained at a relatively high level. PE‐g‐MA acted as a compatibilizer for PA11 and LLDPE, bringing strong interfacial adherence, and especially a domain‐in‐domain morphology observed in PA11/PE‐g‐MA/LLDPE (70/10/20 by weight) blends. The observation that PA11 was toughened by the crystallizable PE derivatives is discussed in depth, based on the combined effect of surface crystallization of LLDPE on pre‐formed PA11 crystallites and interfacial compatiblization between PA11 and PE‐g‐MA. CONCLUSION: The crystallizable PE derivatives LLDPE and PE‐g‐MA were shown to be effective toughening modifiers for the proportions PA11/PE‐g‐MA/LLDPE 70/10/20 (by weight), which is considered to be an optimum composition: special domain‐in‐domain morphology was observed indicating a good dispersion of PE in the PA11 matrix and strong interfacial adherence between PE phase and PA11 phase. The reason why strength and modulus were maintained at a high level in the as‐prepared blends was attributed to the existence of rigid crystalline domains in PE. Copyright © 2009 Society of Chemical Industry     

Effects of propionyl content on the morphology,mechanical properties,and biodegradability of esterified cassava starch/polycaprolactone blends

The chemical structure of cassava starch was modified via an acylation with two different reaction systems: propionic anhydride in an aqueous sodium hydroxide solution and propionic anhydride in dimethyl sulfoxide/triethylamine mixtures. The acylation was carried out by the variation of reaction parameters to generate modified starches with a variety of propionyl contents. After that, the modified starch was blended with polycaprolactone (PCL) at a 30/70 weight composition in a twin‐screw extruder. The results from the tensile testing of the various modified starch/PCL blends show that the moduli and tensile stresses of the materials were higher than those of the unmodified starch/PCL blend. The elongation values of the modified starch/PCL blends, however, decreased with the propionyl content. Scanning electron micrographs of the blends containing modified starch with 62 and 80% propionyl were also different from those of blends containing modified starch with 16 and 28% propionyl in term of phase contrast. Finally, the rate of biodegradation of the blends decreased with increasing propionyl content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2154–2162, 2005     

Fusion bonding of maleated polyethylene blends to polyamide 6

Blends of linear low-density polyethylene (LLDPE) and linear low-density polyethylene–grafted maleic anhydride (LLDPE-gMA) were used to promote the adhesion to polyamide 6 (PA) in a three-layer coextruded film without using an additional adhesive or tie layer. The effect of bonding time and molecular weight (MW) of different maleated polyethylenes on the peel strength of the joints was analyzed. Direct evidence of a copolymer formed in-situ at the interfaces is also considered. The peel strength of fusion bonded layers of LLDPE/LLDPE-gMA blends with PA strongly depends on bonding time and molecular weight of the maleated polymer. Tensile properties of three-layer films, made up of PA as the central layer and LLDPE/LLDPE-gMA blends as the two external layers, are improved with increases in the maleic anhydride (MA) content in the blend. The in-situ formation of a copolymer between the MA in the blend and the terminal amine groups of the PA was confirmed by the Molau test, infrared (IR) spectroscopy, and thermal analysis (DSC).     

PA6/LLDPE共混物的制备与增容作用研究

以乙烯-丙烯酸甲酯-甲基丙烯酸缩水甘油酯三元共聚物(E-MA-GMA)为相容剂,用熔融法在双螺杆挤出机上制备了聚酰胺6/线型低密度聚乙烯(PA6/LLDPE)共混物,并加入降解聚乙烯(DPE)来改变LLDPE的黏度。结果表明:加入10 phr E-MA-GMA可以有效降低PA6/LLDPE(80/20)共混物的分散相尺寸;当LLDPE/DPE=19/1时,共混物的复数黏度和储能模量达到最大值;DPE的加入对共混物的拉伸性能没有明显影响,但使其缺口冲击强度下降。     

MORPHOLOGY,CRYSTALLIZATION BEHAVIORS,AND MECHANICAL PROPERTIES OF PA1010/HIPS AND PA1010/HIPS-g-MA BLENDS

The binary blends of polyamide 1010 (PA1010) with the high-impact polystyrene (HIPS)/maleic anhydride (MA) graft copolymer (HIPS-g-MA) and with HIPS were prepared using a wide composition range. Different blend morphologies were observed by scanning electron microscopy according to the nature and content of PA1010 used. Compared with the PA1010/HIPS binary blends, the domain sizes of dispersed-phase particles in PA1010/HIPS-g-MA blends were much smaller than that in PA1010/HIPS blends at the same compositions. It was found that the tensile properties of PA1010/HIPS-g-MA blends were obviously better than that of PA1010/HIPS blends. Wide-angle x-ray diffraction analyses were performed to confirm that the number of hydrogen bonds in the PA1010 phase decreased in the blends of PA1010/HIPS-g-MA. These behaviors could be attributed to the chemical interactions between the two components and good dispersion in PA1010/HIPS-g-MA blends.     

A facile route for preparing stable co-continuous morphology of LLDPE/PA6 blends with low PA6 content

A facile method is employed to prepare a series of LLDPE/PA6 blends with co-continuous morphology with low PA6 content via reactive extrusion. In these blends, co-continuous morphology is obtained by introducing graft copolymers with both high and low molecular weight trunk chains to the interface simultaneously. Maleic anhydride functionalized polybutadine (PB-g-MAH, and MAH content = 10 wt%) is first melt grafted onto the LLDPE backbones with dicumyl peroxide (DCP) as an initiator. Part of PB-g-MAH is grafted onto LLDPE to form LLDPE-g-PB-g-MAH copolymer. During reactive extrusion, in-situ formed Copolymer II (polybutadiene-graft-polyamide, PB-g-PA6) with a low molecular weight trunk chain (PB) is obtained from the reaction between the maleic anhydride group of free or non-grafted PB-g-MAH and the amino group on PA6 molecules; while Copolymer I (LLDPE-g-PB-g-PA6) is obtained via the reaction between the maleic anhydride group of the grafted PB-g-MAH (i.e., LLDPE-g-PB-g-MAH) and the amino group of PA6. Copolymer I with a high molecular weight trunk chain, LLDPE, should strengthen the interface and favor stress transfer, enabling the deformation of PA6; and Copolymer II (PB-g-PA6) with a low molecular weight trunk chain, PB, facilitates the formation of a flat interface between LLDPE and PA6, thus promoting an elongated PA6 phase. Therefore, co-continuous morphology of LLDPE/PA6 blend is successfully prepared with only 25 wt% PA6 by controlling suitable amounts of Copolymers I and II in the blend.     

Structure-property relationships of short fiber reinforced polypropylene-polyamide blends

Short fiber composites based on polypropylene (PP)-polyamide (PA) blends were studied using compatibilizers comprising maleic anhydride modified polypropylene. Results have shown that the structure and morphology developed and the resultant mechanical properties of the blend composites strongly depend on the number of acid functional groups in the compatibilizers. The impact strength and tensile modulus of the PP-PA blend composite more than doubled compared with PA and PP short fiber composites, respectively. Furthermore, analytical methods characterizing nonisothermal crystallization were used to investigate the crystallization of fiber containing blends in constrained matrix nucleation mode. Results have shown that interphase interactions are the dominant ones with respect to morphology development. Synergistic effects were obtained that were due to the effect of fibers.     

Structure and oxygen‐barrier properties of (linear low‐density polyethylene/ethylene–vinyl alcohol copolymer)/linear low‐density polyethylene composite films prepared by microlayer coextrusion

Ethylene–vinyl alcohol copolymer (EVOH) and linear low‐density polyethylene (LLDPE) blends with 5% LLDPE grafted with 1% maleic anhydride (MAH; EVOH/LLDPE/LLDPE‐g‐MAH), created to increase the interfacial compatibility, were coextruded with pure LLDPE through the microlayer coextrusion technology. The phase morphology and gas‐barrier properties of the alternating‐layered (EVOH/LLDPE/LLDPE‐g‐MAH)/LLDPE composites were studied by scanning electron microscopy observation and oxygen permeation coefficient measurement. The experimental results show that the EVOH/LLDPE/LLDPE‐g‐MAH and LLDPE layers were parallel to each other, and the continuity of each layer was clearly evident. This structure greatly decreased the oxygen permeability coefficient compared to the pure LLDPE and the barrier percolation threshold because of the existence of the LLDPE/EVOH/LLDPE‐g‐MAH blend layers, and the LLDPE layers diluted the concentration of EVOH in the whole composites. In addition, the effects of the layer thickness ratio of the EVOH/LLDPE/LLDPE‐g‐MAH and LLDPE layers and the layer number on the barrier properties of the layered composites were investigated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42211.     

Mechanical and thermal properties of wood fibers reinforced poly(lactic acid)/thermoplasticized starch composites

Thermoplasticized starch (TPS) filled poly(lactic acid) (PLA) blends are usually found to have low mechanical properties due to poor properties of TPS and inadequate adhesion between the TPS and PLA. The purpose of this study was to investigate the reinforcing effect of wood fibers (WF) on the mechanical properties of TPS/PLA blends. In order to improve the compatibility of wood with TPS/PLA blends, maleic anhydride grafted PLA (MA‐g‐PLA) copolymer was synthesized and used. TPS, TPS/PLA blends, and WF reinforced TPS/PLA composites were prepared by twin‐screw extrusion and injection molded. Scanning electron microscope and crystallinity studies indicated thermoplasticity in starch. WF at two different weight proportions, that is, 20% and 40% with respect to TPS content were taken and MA‐g‐PLA at 10% to the total weight was chosen to study the effect on mechanical properties. At 20% WF and 10% MA‐g‐PLA, the tensile strength exhibited 86% improvement and flexural strength exhibited about 106% improvement over TPS/PLA blends. Increasing WF content to 40% further enhanced tensile strength by 128% and flexural strength by 180% with respect to TPS/PLA blends. Thermal behavior of blends and composites was analyzed using dynamic mechanical analysis and thermogravimetric analysis. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46118.     

Mechanical,Water Absorption and Enzymatic Degradation Properties of Sago Starch Filled Linear Low Density Polyethylene

Abstract

Sago starch filled linear low density polyethylene (LLDPE) composites, have been prepared by melt mixing of the granular starch and LLDPE in a HAAKE internal mixer. The tensile, water absorption and enzymatic degradation properties of the composites have been determined. Incorporation of sago starch into LLDPE led to decrease in tensile strength and elongation at break of the composites. Up to 15 wt.% of sago starch could be added to LLDPE without adverse effects on the tensile properties. The water uptake increased with immersion time and the rate of absorption is strongly controlled by the immersion temperatures. Dramatic reduction in tensile properties were observed in the composites that were immersed in water at 90[ddot]C. The recovery of the tensile strength and elongation at break upon redrying is about 37.5 and 1.6% respectively. The permanent damage to the composites was attributed to severe hydrolysis of the starch particles. The enzymatic degradation study using oc-amylase revealed that both tensile strength and elongation at break reduced with time of treatment. Mode of failures of both LLDPE matrix and its sago starch filled composites, assessed by fracto-graphic analysis in a scanning electron microscope (SEM) are discussed.     

Effect of Fiber Esterification on Fundamental Properties of Oil Palm Empty Fruit Bunch Fiber/Poly(butylene adipate-co-terephthalate) Biocomposites

A new class of biocomposites based on oil palm empty fruit bunch fiber and poly(butylene adipate-co-terephthalate) (PBAT), which is a biodegradable aliphatic aromatic co-polyester, were prepared using melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 wt% and characterized. Chemical treatment of oil palm empty fruit bunch (EFB) fiber was successfully done by grafting succinic anhydride (SAH) onto the EFB fiber surface, and the modified fibers were obtained in two levels of grafting (low and high weight percentage gain, WPG) after 5 and 6 h of grafting. The FTIR characterization showed evidence of successful fiber esterification. The results showed that 40 wt% of fiber loading improved the tensile properties of the biocomposite. The effects of EFB fiber chemical treatments and various organic initiators content on mechanical and thermal properties and water absorption of PBAT/EFB 60/40 wt% biocomposites were also examined. The SAH-g-EFB fiber at low WPG in presence of 1 wt% of dicumyl peroxide (DCP) initiator was found to significantly enhance the tensile and flexural properties as well as water resistance of biocomposite (up to 24%) compared with those of untreated fiber reinforced composites. The thermal behavior of the composites was evaluated from thermogravimetric analysis (TGA)/differential thermogravimetric (DTG) thermograms. It was observed that, the chemical treatment has marginally improved the biocomposites' thermal stability in presence of 1 wt% of dicumyl peroxide at the low WPG level of grafting. The improved fiber-matrix surface enhancement in the chemically treated biocomposite was confirmed by SEM analysis of the tensile fractured specimens.     

Studies on Linear Low-Density Polyethylene Functionalized by Ultraviolet Irradiation and Its Compatibilization

Summary Some groups containing oxygen such as C-O, C-OH and C=O were introduced onto the molecular chains of linear low-density polyethylene (LLDPE) through ultraviolet irradiation in air. The concentration of these groups containing oxygen increased with increasing irradiation time. After irradiation, the molecular weight of the LLDPE decreased, and its distribution widened. It was found that the gelation occurred after the LLDPE was irradiated for 12 h, and the gel content increased with increasing irradiation time. The crystal shape and space of the crystalline plane for irradiated LLDPE remained. Compared with those of LLDPE, the melt flow index, tensile strength and elongation at break of the irradiated LLDPE decreased, but its hydrophilicity increased and its toughness retained good. The polyamide 66 (PA66)/LLDPE/irradiated LLDPE blends were prepared by blending a small percentage of irradiated LLDPE with PA66. The melting temperature and crystallinity of both the LLDPE and PA66 components in the blends decreased with increasing irradiation time. The compatibility, dispersion and interfacial interaction between PA66 and LLDPE were improved after blending. With the addition of 5% LLDPE irradiated for 36 h, the tensile strength, bending strength and notched impact strength of the blends was enhanced from 48.3 MPa, 64.8 MPa and 30.8 J/m to 57.4 MPa, 71.5 MPa and 101.2 J/m, respectively.     

Influence of different compatibilizers on the morphology and properties of PA6/PET/glass fiber composites

Three kinds of compatibilizers, ethylene–ethyl acrylate copolymer (EEA), ethylene–ethyl acrylate–glycidyl methacrylate copolymer (EAG), and ethene–maleic anhydride–glycidyl methacrylate copolymer (EMG), were introduced to PA6/PET/GF blends for the first time to study the effect of different compatibilizers on composite. EEA, EAG, and EMG showed different effect on the properties of PA6/PET/GF blends. An observation of the GF–resin interface by scanning electronic microscope indicated EAG and EMG enhanced the adhesion of resin to GF, while EEA exhibited no improvement. Differential scanning calorimetry analysis showed that both EMG and EAG increased the degree of crystallinity of the PA6/PET/GF blends, whereas EEA declined. According to dynamic mechanical analysis, EAG, and EMG remarkably increased the storage modulus of composites. For the composites at a given GF content of 30 wt %, EMG increased the tensile strength from 140.6 to 156.3 MPa. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46429.     

A study of LLDPE functionalized through ultraviolet irradiation and interfacial interaction of PA66/functionalized LLDPE blends

Some oxygen‐containing groups, such as C? O? C, C? OH, C?O, C(?O)O, and C(?O)OH, were introduced onto linear low‐density polyethylene (LLDPE) chains during ultraviolet irradiation under air, without adding any monomers and auxiliaries and without environmental pollution. After ultraviolet irradiation, the molecular weight of LLDPE decreased and its distribution became wider. The melting temperature and crystallinity of irradiated LLDPE decreased with irradiation time. The copolymer LLDPE‐g‐PA66 was formed by reaction between oxygen‐containing groups of irradiated LLDPE and amine or carboxyl end groups and amide linkage of polyamide 66 (PA66) during preparation of PA66/irradiated LLDPE blends. Compared with PA66/LLDPE blend, the mechanical properties of PA66/irradiated LLDPE blends were improved greatly because of the improved interface interaction and dispersion. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

改性淀粉/LLDPE共混体系生物降解材料性能的研究

将自制接枝改性淀粉与LLDPE、玉米淀粉以及另外两种相容剂进行共混。通过对共混体系的形态结构、力学性能、流变性能、热性能以及对共混物薄膜的生物降解性能等的研究说明:复合相容剂MAH-g-PE+LA-g-starch的加入改善了淀粉和LLDPE的相容性,使得共混物体系具有适宜的拉伸强度及断裂伸长率;LLDPE/淀粉/(MAH-g-PE+LA-g-starch)共混物薄膜具有很好的生物降解性能。     

Properties of blends of starch and synthetic polymers containing anhydride groups

Corn starch was blended with styrene maleic anhydride copolymer (SMA), ethylene-propylene-g-maleic anhydride copolymer (EPMA), and corresponding nonfunctional polystyrene and ethylene propylene copolymers. The concentration of starch in the blend was varied between 50 and 80% by weight. The torque generated during blending is reported increasing starch content for starch/SMA blends: the reverse was true for starch/EPMA blends. The torque was higher for the blends of the anhydride functional polymers compared to the blends of corresponding nonfunctional polymers. Water absorption of the blends increased with an increase in the starch content. Starch/SMA blends made at higher mixer speed or time were more water sensitive. Blends containing EPMA absorbed less water than SMA blends containing the same weight fraction of starch. Tensile strengths of blends containing functional groups were superior compared to the blends made from nonfunctional polymers. When the starch contents increased from 60 to 70%, the tensile strength remained unchanged for SMA blend but increased for EPMA blend. All samples supported the growth of microorganisms, which increased with increasing starch content. © 1994 John Wiley & Sons, Inc.     

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

Corn 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.