Effect of different compatibilizers on the mechanical and thermal properties of starch/polypropylene blends

Starch was treated with three kinds of compatibilizers (coupling agents or modifying agents), KH‐550, KH‐570, and glycerin monostearate. Blends of polypropylene (PP) and treated starch were prepared by a twin‐screw extruder. The effects of the starch before and after treatments and the kinds and contents of the compatibilizers on the mechanical and thermal properties of the PP/starch blends were investigated in this study. We found that the mechanical properties (tensile strength, impact strength, and elongation at break) of the blends were obviously improved with increasing content of different kinds of compatibilizers. Meanwhile, the most significant improvement in the mechanical properties was obtained in the samples containing just a 1 wt % loading of compatibilizers, and KH‐570 had the best improved effects among the different kinds of compatibilizers. The results of thermogravimetric analysis demonstrate that to some extent, the thermal stability of the PP/starch blends was improved after the addition of compatibilizers. Scanning electron microscopy showed that the dispersion of starch in the PP matrix and adhesion between the starch and PP matrix were obviously improved after the addition of compatibilizers. KH‐570 not only had the best improved effects among the coupling agents but also still acted as a similar plasticizer. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43332.     

Fast‐swelling superabsorbent polymers with polymerizable macromolecular surfactant as crosslinker

Fast‐swelling superabsorbent polymers (SAPs) have been prepared by micellar cross‐linking copolymerization of acrylic acid and acrylamide using polymerizable macromolecular surfactants (PMSs) as multifunctional crosslinkers, with a foaming technique. Sodium bicarbonate (NaHCO₃)/acetone and Pluronic F127 were used as foam (or porosity) generators and stabilizer, respectively. It has been found that the PMSs with different polyethylene glycol (PEG) chain length have little effect on the swelling rate of the SAPs, while the foam generators are crucial. In addition, the monomer concentration and the concentration of the PMS are important to the fast swelling rate of the SAPs. For a balance of a relatively fast‐swelling rate, high water absorbency under load and low cost in drying, a monomer concentration of above 50%, 0.08% PMS, and 5% NaHCO₃ are preferable. The water absorbency of SAP prepared under optimal conditions could reach half of equilibrium water absorbency in 30 seconds and the saline water absorbency under load could reach 18.4 g/g. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44173.     

Structure‐property relationship in polyurethane elastomers containing starch as a crosslinker

Polyurethane elastomers were synthesized using polypropylene glycol (PPG 2000) as the polyol and starch as the multifunctional crosslinker in varying concentrations. Thermal and mechanical properties were measured by DSC, DMA and tensile tests. The morphology was examined by SEM. The swelling behavior of the polyurethanes in various solvents was investigated and the solubility parameter was determined. All these properties were compared with those of polyurethanes containing 1,1,1 ‐trimethylol propane (TMP) as the crosslinker. Starch‐based polyurethanes exhibited better mechanical properties. The effect of varying the starch:TMP ratio on the mechanical strength was also studied. With increasing starch content, the tensile strength and elongation increased. The starch‐based PUs exhibited two glass transitions, whereas TMP‐based PUs exhibited one T_g. No significant difference in the T_gs of the two PUs was observed. The activation energy of St‐PU calculated from DMA was 69 kcal/mol. Soil degradation tests indicated greater biodegradability in polyurethanes containing starch than in those containing TMP.     

The Effect of glycerol on the crystalline,thermal, and tensile properties of CaCl2‐doped starch/PVA films

Starch/poly(vinyl alcohol) (PVA) films with the addition of 10 wt% CaCl₂ and various content of glycerol were prepared. The effect of glycerol on the crystalline, thermal, and tensile properties of CaCl₂‐doped starch/PVA films was studied by X‐ray diffraction, thermogravimetric analysis (TGA), and tensile testing, respectively. The effect of glycerol on the miscibility of CaCl₂‐doped starch/PVA films was studied by scanning electron microscopy. The CaCl₂‐doped starch/PVA film became more homogeneous after the addition of glycerol. The addition of glycerol would increase the crystallinity of CaCl₂‐doped starch/PVA film. With the addition of 10 wt% glycerol and 10 wt% CaCl₂, the starch/PVA film showed the highest degree of crystallinity. The TGA results show that the thermal stability of CaCl₂‐doped starch/PVA film increased after the addition of glycerol. The toughness of CaCl₂‐doped starch/PVA films was enhanced with the addition of glycerol. The starch/PVA film with the addition of 10 wt% CaCl₂ and 20 wt% glycerol showed the tensile strength of 17 MPa and the elongation at break of 428%. Moreover, the water sorption of CaCl₂‐doped starch/PVA film decreased after the addition of glycerol at the low and intermediate relative humidity of 33 and 54%. POLYM. COMPOS., 37:3191–3199, 2016. © 2015 Society of Plastics Engineers     

Effects of nanosilica on retrogradation properties and structures of thermoplastic cassava starch

Composites of thermoplastic cassava starch (TPS) and nanosilica (SiO₂) were prepared by the melting method. The effect of nano‐SiO₂ on the retrogradation properties and structures of cassava starch was investigated. The retrogradation degree of TPS/nano‐SiO₂ composites increased with increasing retrogradation time. The retrogradation rate of TPS significantly increased after the addition of nano‐SiO₂, but excessive nano‐SiO₂ content leads to a decrease in the retrogradation rate of TPS. According to the Fourier transform infrared spectroscopy results, the retrogradation degree of TPS/nano‐SiO₂ composites increased with the increase of retrogradation time and addition of nano‐SiO₂. Scanning electron microscopy analysis indicated that nano‐SiO₂ particles were uniformly and finely dispersed in the starch materials, but the nano‐SiO₂ particles aggregated in the cassava starch with a further increase in nano‐SiO₂ content. X‐ray diffraction revealed that the crystalline structure of the starch was gradually altered from A‐type to V‐type with the increase of retrogradation time. TPS/SiO₂ composites indicated a mixture of A+V types, and the intensity of the V‐type strengthened with the increase of retrogradation time and SiO₂ content. Polarized light microscopy analysis revealed clear Maltese cross patterns, and the number of spherulites in TPS/nano‐SiO₂ composites increased with increasing retrogradation time and nano‐SiO₂ content, but the retrogradation of starch was inhibited with further increases of nano‐SiO₂ content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45687.     

Extruded foams prepared from high amylose starch with sodium stearate to form amylose inclusion complexes*

Extruded starch foams were prepared from high amylose corn starch with and without sodium stearate and poly(vinyl alcohol) (PVOH) to determine how the formation of amylose–sodium stearate inclusion complexes and PVOH addition would affect foam properties. X‐ray diffraction and Differential Scanning Calorimetry (DSC) showed that amylose–sodium stearate inclusion complexes were formed by low temperature extrusion and did not dissociate during foam formation by a second extrusion at higher temperatures. In the absence of PVOH, water absorption, and foam shrinkage at 95% RH were decreased because of the hydrophobicity of the complex. PVOH addition increased both the expansion ratio and the shrinkage of the foam, although shrinkage at 95% RH was still less than that observed with uncomplexed amylose. The structural integrity and some tensile properties of stearate‐containing foams were improved by PVOH addition. These results provide the manufacturer of biodegradable starch foams with an inexpensive method for tailoring foam properties for specific end‐use applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43251.     

Improving viscoelasticity and rebound resilience of crosslinked low‐density polyethylene foam by blending with ethylene vinyl acetate and polyethylene‐octene elastomer

To obtain high‐rebound resilience of crosslinking low‐density polyethylene (LDPE) foam and decrease the foam density at the same content of foaming agent, the melt viscoelasticity of LDPE with different compositions (ethylene vinyl acetate [EVA], polyethylene‐octene elastomer, and crosslinking agent) was investigated by dynamic rheology test. Then, LDPE/EVA/(polyethylene‐octene elastomer) foams with different composition ratios were produced by a continuous foaming process and investigated by the rebound resilience test. The results show that the melt viscoelasticity behavior of LDPE and its blends in the molten state possessed more melt elasticity behavior after the crosslinking was introduced. Meanwhile, the rebound resilience of LDPE foam was increased 54% at the lower foam density (0.031 g/cm³). It could meet the requirements of sports mats for high‐rebound resilience (>50%) and decrease the material cost when EVA was introduced into the foaming system. J. VINYL ADDIT. TECHNOL., 22:61–71, 2016. © 2014 Society of Plastics Engineers     

Morphology and mechanical properties of PP/POE/nano‐CaCO3 composites

The mechanical properties including tensile, flexural, and impact of the nanometer on calcium carbonate (nano‐CaCO₃) filled polypropylene (PP)/poly (ethylene‐co‐octene) (POE) composites were measured at room temperature to identify the effects of the POE content on the mechanical properties. It was found that the Young's modulus, tensile strength, and tensile elongation at break decreased nonlinearly while the tensile fracture strength varied slightly with increasing the POE weight fraction; the V‐notched and unnotched Izod impact fracture strength increased nonlinearly with an increase of the POE weight fraction; the flexural modulus and strength decreased roughly linearly with increasing the POE weight fraction. Furthermore, the impact fracture surface of the specimens was observed by means of a scanning electronic microscope to discuss the toughening mechanisms. POLYM. COMPOS., 37:539–546, 2016. © 2014 Society of Plastics Engineers     

聚乳酸/淀粉发泡片材的制备及性能

以甘油为增塑剂,偶氮二甲酰胺为发泡剂(AC发泡剂),采用模压法制备聚乳酸/淀粉发泡片材。通过对材料的力学性能,发泡密度、发泡倍率等测试研究了发泡剂含量、发泡温度、发泡时间及发泡压力对片材性能的影响。结果表明,发泡温度、发泡时间及发泡压力对片材的力学性能影响较大,AC发泡剂对材料发泡性能影响显著。当AC发泡剂用量为0.6份,发泡温度为200℃,发泡时间为4 min,压力为10 MPa时片材的拉伸强度达到27.91 MPa,断裂伸长率为3.65%,此时材料的发泡密度为1.08 g/cm3,发泡倍率为1.16,综合性能最佳。     

Reactive blends of gelatinized starch and polycaprolactone‐g‐glycidyl methacrylate

Blends of the modified polycaprolactone (PCL) and the gelatinized starch with glycerin were prepared. The modified PCL, PCL‐g‐glycidyl methacrylate (GPCL), was synthesized by melt reaction of PCL and glycidyl methacrylate (GMA) in the presence of benzoyl peroxide (BPO) in a Brabender mixer. The size of the dispersed starch in the GPCL matrix was found to be smaller than that in the PCL matrix. As the relative content of the GMA groups in the GPCL increases, the elongation at break of the blend showed the highest value at a grafted GMA content of 4.2 wt %. With the increase of the glycerin content in the starch, an abrupt change of the mechanical properties of the blend were observed between 40 and 50 wt % glycerin content based on the starch weight. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1507–1516, 2001     

Sulfonated polyphenylsulfone asymmetric membranes: Effect of coagulation bath (acetic acid‐NaHCO3/isopropanol) on morphology and antifouling properties

Sulfonated polyphenylsulfone porous asymmetric membranes, S‐PPSU with different sulfonation degrees, 21, 33, 50 wt %, were prepared by phase inversion. Two different coagulation baths were explored for asymmetric membrane preparation: acetone/isopropanol and acetic acid (AA)‐NaHCO₃/isopropanol. The latter bath allows better morphology control for the nucleation and pore formation of the membrane. Scanning electron microscopy of membranes shows that pore interconnectivity is improved, when the mixture of AA‐NaHCO₃/isopropanol was used for asymmetric S‐PPSU ultrafiltration membranes preparation. S‐PPSU asymmetric membranes show an increasing hydrophilicity with increasing sulfonation degree. Asymmetric membrane antifouling properties improve as the concentration of sulfonic groups increases in the membrane showing twice the flux recovery ratio and lower BSA protein absorption in static and dynamic flux tests. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44502.     

Effects of calcium carbonate as the expanding inhibitor on the structural and mechanical properties of expanded starch/polyvinyl alcohol blends

In this study, expanded starch/PVA/CaCO₃ blends (ESPCs) were prepared using the pilot system composed of a supermixer and a twin‐screw extruder to investigate the effects of CaCO₃ as the expanding inhibitor on the structural and mechanical properties of ESPCs. The pore ratio of ESPCs with the interconnecting open‐cell structure decreased with increasing CaCO₃ content and the structure of ESPCs became more compact. The inhibiting process of CaCO₃ during the expansion of starch/PVA blends was proposed and certified by FTIR spectroscopy and X‐ray diffraction. At least two parts of CaCO₃ were required to obtain a sufficient inhibiting effect on the expansion. The mechanical properties of ESPCs such as tensile strength, elongation at break, modulus, and specific work of rupture were improved by the addition of CaCO₃ as the expanding inhibitor. As CaCO₃ content increased from one to four parts, the tensile strength increased 2.6‐fold, from 70 to 180 kPa, whereas elongation at break increased about 1.5‐fold. The moduli of ESPCs also increased with increasing CaCO₃ content. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1762–1768, 2004     

Mechanical and dynamic mechanical properties of epoxy syntactic foams reinforced by short carbon fiber

Epoxy syntactic foams were prepared with diglycidyl ether of bisphenol‐A (DGEBA) epoxy resin, 2.4.6‐tri(dimethylaminomethyl)phenol (DMP‐30), coupling treated microsphere and short carbon fiber. The density of the foam was maintained between 0.56 and 0.91 g/cm³ for all compositions. Compressive, flexural, tensile and dynamic mechanical properties of the foams were investigated with respect to hollow glass microsphere (HGM) and carbon fiber (CF) content. A considerable improvement in the mechanical properties viz. compressive, flexural and tensile strengths was observed for the foams on incorporation of a small quantity of CF. The storage modulus were higher for the foam composites containing CF. The presence of HGM has significant influence on T_g of the syntactic foams, spherical filler diminished the T_g of the syntactic foams due to the plasticizing effect of the coupling treatment of HGM, that is helpful for enhancing damping properties of syntactic foams. POLYM. COMPOS., 37:1960–1970, 2016. © 2015 Society of Plastics Engineers     

A novel natural rubber‐graft‐cassava starch foam for oil/gasohol absorption

The objective of this work was to study a novel foam prepared from natural rubber grafted with cassava starch (NR‐graft‐CSt) with the addition of super cell (SC) as a blowing agent. The effects of the blowing agent and grafting versus non‐grafting of the starch and the natural rubber on the properties of the foam were investigated. The results show that the optimum curing time decreases with increasing SC loading as observed using a moving die rheometer. The porosity, the number of cells per unit volume and the cell size of the NR/CSt blend increase as a function of the SC loading in the foam. A more open cell structure is produced by higher loadings of SC. The greatest number of cells per unit volume is found at 2 and 6 phr SC for NR‐graft‐CSt and NR/CSt blend, respectively. The foam produced was used as an absorbent for oil. The NR‐graft‐CSt foam shows a maximum percentage oil absorption of around 7 g g^?1. The NR‐graft‐CSt foam is able to be reused as an oil absorbent for a maximum number of over 30 times. The NR‐graft‐CSt foam shows better toluene resistance than the NR/CSt blend. © 2016 Society of Chemical Industry     

Study on the mechanical properties of hybrid reinforced rigid polyurethane composite foam

The mechanical properties of hybrid reinforced rigid polyurethane (PU) foams were investigated with the reinforcing agent SiO₂ and fibers. The effect of content of SiO₂ and fibers and the effect of length of fibers on the properties of the PU composite foam were emphatically analyzed. The experiment results show that the tensile strength of the PU composite foam is optimal when the content of SiO₂ and glass fiber is 20 and 7.8%, respectively. Furthermore, the reinforcing effect of glass fiber, Nylon‐66 fiber, and PAN‐matrix carbon fiber were compared and the results show that the tensile strength of the PU composite foam reinforced with 3–5% carbon fiber is optimal. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1493–1500, 2004     

Study on poly(butylene adipate‐co‐terephthalate)/starch composites with polymeric methylenediphenyl diisocyanate

To lower the cost of poly(butylene adipate‐co‐terephthalate) or PBAT, starch was used as a filler in this study. To increase tensile strength of PBAT/starch composites, polymeric methylenediphenyl diisocyanate (pMDI) was used as a compatibilizer. PBAT was melt‐mixed with starch in a kneader, and then the mixtures were compression‐molded. The effects of starch and pMDI content on the tensile strength and elongation at break of PBAT/starch composites were examined. The morphology and biodegradability of the composites in soil were also studied. The tensile strength of PBAT and PBAT/starch composites increases with increasing content of pMDI. The increase of weight average molecular weight of PBAT and improved interaction between PBAT and starch were observed with increasing content of pMDI. The weight average molecular weights of buried PBAT and the composites in soil significantly decrease. Especially, the reduction of the weight average molecular weight of PBAT/starch (70/30) composite is the most significant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41884.     

Effects of silica on the morphology,structure, and properties of thermoplastic cassava starch/poly(vinyl alcohol) blends

Thermoplastic cassava starch (TPS)/poly(vinyl alcohol) (PVA)/silica (SiO₂) composites were prepared by a melt‐mixing method. The effects of the content and surface properties of SiO₂ on the processing, mechanical properties, thermal stability, morphology, and structure of the TPS/PVA/SiO₂ composites were investigated. With increasing SiO₂ content, the plasticizing times of the TPS/PVA/SiO₂ composites were shortened. After the SiO₂ surface was treated with a silane coupling agent (KH550), the plasticizing times of the TPS/PVA/SiO₂ composites decreased significantly. The tensile strength, elongation at break, and Young's modulus of the TPS/PVA/SiO₂ composites increased. The mechanical properties of the TPS/PVA/SiO₂ composites containing treated SiO₂ were higher than those with untreated SiO_2. The thermal decomposition temperatures of the TPS/PVA/SiO₂ composites were improved with the addition of SiO₂. The presence of inorganic fillers was beneficial to the improvement of the thermal stability of the polymers. The reaction between the treated SiO₂ and the starch molecules was beneficial to the formation of more stable structures. The treated SiO₂ indicated good interfacial adhesion and uniform dispersion in the matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44020.     

Effect of nano‐silica on the mechanical,thermal, and crystalline properties of poly(vinyl alcohol)/nano‐silica films

Poly(vinyl alcohol)/nano‐silica (PVA/nano‐SiO₂) films were prepared through extrusion blowing with the addition of water and glycerin as plasticizer. The characteristic properties of PVA/nano‐SiO₂ films were investigated by differential scanning calorimetry, dynamic mechanical analysis, Haake torque rheometry, and atomic force microscopy (AFM). The results showed that the mechanical properties of PVA/nano‐SiO₂ were improved dramatically. The tensile strength of the nanofilms increased from 62 MPa to 104 MPa with loading 0.3 wt % nano‐SiO₂ and the tear strength was improved from 222 KN/m to 580 KN/m. The crystallinity of the films loaded with 0.4 wt. % nano‐SiO₂ decreased from 32.2% to 21.0% and the AFM images indicated that the amorphous region of nanofilms increased with increasing nano‐SiO₂ content. The storage modulus and loss modulus increased to two and nearly three times with 0.3 wt % nano‐SiO₂ loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of low‐density polyethylene/banana starch films containing compatibilizer and photosensitizer

Composite films containing various percentages of banana starch and low‐density polyethylene (LDPE) were prepared. The effects of the compatibilizer, banana starch content, and photosensitizer content on the thermal and tensile properties of these films were investigated. The banana starch content was varied from 5 to 20 wt % of LDPE, whereas benzophenone was added as a photosensitizer in three different amounts (0.25, 0.5, and 1 wt %) based on LDPE. In these films PE‐graft‐maleic anhydride (PE‐g‐MA) was used as a compatibilizer at 10 wt % banana starch. It was found that the thermal stability of the composite films remained unchanged with respect to the amount of banana starch and benzophenone content. The addition of banana starch had no effect on the melting temperature and degree of crystallinity of the films. Similarly, PE‐g‐MA had no effect on the melting temperature but decreased the degree of crystallinity of the LDPE phase. Benzophenone caused an increase in the melting temperature but decreased the degree of crystallinity of LDPE in the films. Increasing the amount of banana starch decreased the tensile properties of the composite films. The addition of PE‐g‐MA as a compatibilizer increased the tensile properties compared with the uncompatibilized films. However, benzophenone had no effect on the tensile properties of the blend films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2717–2724, 2006     

The influence of maltodextrins on the structure and properties of compression‐molded starch plastic sheets

Starch plastic sheets were prepared by compression molding of starch‐based plastic granulates. The granulates were prepared by extrusion processing of mixtures of granular potato starch and several maltodextrins (5% w/w) in the presence of glycerol and water as plasticizers and lecithin as melt flow accelerator. The materials were semicrystalline, containing B‐type, V_h‐type, and E_h‐type crystallinity. The properties were dependent on water content. For the materials, a brittle‐to‐ductile transition occurred at a water content in the range of 11–12%, which was in accordance with the observed glass transition temperature. The structural and mechanical properties were a function of starch composition and maltodextrin source as well as molding temperature. The amount of granular remnants and residual B‐type crystallinity decreased with increasing processing temperature. The amount of recrystallized single‐helical amylose increased with increasing temperature. At molding temperatures in the range of 180–200°C, a sharp decrease in starch molecular mass occurred. The influence of molding temperature was reflected in a sharp increase in elongation at molding temperature above 160°C and a gradual decrease in elastic modulus. The tensile strength showed an initial small increase up to 160°C and a sharp decrease at higher molding temperatures. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2207–2219, 1999