Morphology and mechanical properties of semi-interpenetrating polymer networks from polyurethane and benzyl konjac glucomannan

A series of semi-interpenetrating polymer network (semi-IPN) films coded as UB from castor oil-based polyurethane (PU) and benzyl konjac glucomannan (B-KGM) were prepared, and they have good or certain miscibility over entire composition range. Morphology, miscibility and properties of the UB films were investigated by using scanning electron microscopy (SEM), differential scanning calorimetry, dynamic mechanical analysis, ultraviolet spectrometer, wide-angle X-ray diffraction and tensile test. The results indicated that the UB films exhibited good miscibility when B-KGM content was lower than 15 wt%, resulting in relatively high light transmittance, breaking elongation and density. With an increase of the B-KGM content from 20 to 80 wt%, a certain degree of phase separation between PU and B-KGM occurred in the UB films. The tensile strength of the films UB increased from 7 to 45 MPa with an increase of B-KGM content from 0 to 80 wt%. By extracting the B-KGM with N, N-dimethylformamide from the semi-IPN, the morphology and phase domain size of the UB films were clearly observed by SEM. A continuous phase and dual-continuous phase model describing the semi-IPN were proposed to illustrate the morphology and its transition.     

Fabrication and characterisation of thermoplastic starch/poly(butylene succinate) blends with maleated poly(butylene succinate) as compatibiliser

Thermoplastic starch/poly(butylene succinate) (TPS/PBS), an entirely biodegradable polymer blend, was prepared by a two-step extrusion method. Maleic anhydride grafted PBS (rPBS) was successfully synthesised as an interfacial compatibiliser. The miscibility, morphology, thermal behaviour and mechanical properties of the TPS/PBS blends were investigated. The results demonstrated that the strength and elongation at break of TPS/PBS blends were greatly increased with the addition of rPBS in PBS blends due to improved interfacial miscibility. Better distribution and smaller phase domain were observed in the blends with higher content of compatibilisers. The water resistance was also enhanced by incorporation of rPBS. It was indicated that compatibilised TPS/PBS blends possessed a combination of good biodegradability, improved strength and high water resistance. TPS/PBS blend was expected to serve as a promising packing material.     

Synthesis and characterization of novel UV-curable polyurethane–clay nanohybrid: Influence of organically modified layered silicates on the properties of polyurethane

Nanohybrids based on UV-curable polyurethane acrylate (PU) and cloisite 20B (C-20B) have been synthesized by solution blending method using different loading levels of C-20B. The structures of PU/C-20B nanohybrids were confirmed by Fourier transform infrared spectroscopy (FTIR) while X-ray diffraction and transmission electron microscopy (TEM) showed the intercalation of PU into layer silicates. The thermal properties of PU and PU/C-20B nanohybrids were investigated by thermal gravimetric analysis (TGA) and differential scanning calorimetric (DSC). TGA tests revealed that the thermal decomposition temperature (T_d10%) of the nanohybrid containing 5 wt% of C-20B increased significantly, being 61 °C higher than that of pure PU while DSC measurements indicated that the introduction of 5 wt% of clay increased the glass transition temperature from 89.7 to 101 °C. Accordingly, the mechanical and anti-water absorption properties proved also to be enhanced greatly as evidenced by nanoindentation anylsis and water absorptions data in which the nanohybrid containing 5 wt% of clay have highest elastic modulus (4.508 GPa), hardness (0.230 GPa) and lowest water absorption capacity. Thus the formations of nanohybrids manifests through the enhancement of thermal, mechanical and anti-water absorption properties as compared with neat PU due to the nanometer-sized dispersion of layered silicate in polymer matrix.     

表面光交联对热塑性淀粉力学和耐水性能的影响

通过挤出注塑工艺制备了热塑性淀粉（TPS）,将溶于乙醇的光引发剂二苯甲酮制成溶液涂覆于TPS表面后进行紫外光照射,研究了紫外光照射时间对TPS力学性能、动态热力学性能及耐水性能的影响。结果表明,当辐照时长为15 min时,TPS表面能形成最佳的交联网络状结构,使力学和耐水性能得到显著改善;此时TPS的拉伸强度、弯曲强度、冲击强度最高分别为5.28、5.83 MPa和73.99 kJ/m2,储存模量提高,损耗因子峰值对应的转变温度分别提高到-45.40、60.60 ℃,接触角最高为96.8 （° ）。     

High-pressure solution blending of poly(?-caprolactone) with poly(methyl methacrylate) in acetone + carbon dioxide

The miscibility of blends of poly(?-caprolactone) (PCL, M_w = 14,300) with poly(methyl methacrylate) (PMMA, M_w = 15K or 540K) in acetone + CO₂ mixed solvent has been explored. The liquid-liquid phase boundaries at different temperatures have been determined for mixtures containing 10 wt% total polymer blend, 50 wt% acetone and 40 wt% CO₂. The PCL and PMMA contents of the blends were varied while holding the total polymer concentration at 10 wt%. The polymer blend solutions all displayed LCST-type behavior and required higher pressures than individual polymer components for complete miscibility. Complete miscibilities were achieved at pressures within 40 MPa. The DSC scans show that the blends are microphase-separated. The blends display the melting transition of PCL and the glass transition temperature of the PMMA phases. The presence of PMMA is found to influence the crystallization and melting behavior of PCL in the blends. The DSC results on heat of melting and the FTIR spectra, specifically the changes at 1295 cm⁻¹ band show the changes (decrease) in overall crystallinity of the blend upon addition of PMMA.     

本体光交联对热塑性淀粉塑料性能的影响

将光引发剂二苯甲酮直接与淀粉和甘油共混,并通过挤出注塑工艺制备了热塑性淀粉（TPS）塑料,研究了不同紫外光照时长对其力学、动态热力学、热稳定和耐水性能的影响。结果表明,当紫外光照时长为15 min时,TPS可形成最佳的交联网络结构,显著提高其性能,拉伸强度,弯曲强度,冲击强度分别可达4.57 MPa、7.1 MPa及69.39 kJ/m2;储能模量有所提高,玻璃化转变温度达到最高,Tβ和Tα分别为-35.63 ℃和53.96 ℃;最大分解速率对应的峰值温度（Tp）由TPS的317.81 ℃提高到330.48 ℃;表面接触角由纯TPS的42.3 °增加至77.2 °,显著提高了耐水性能。     

Effects of AN-contents and shear flow on the miscibility of PC/SAN blends

The miscibility of polycarbonate (PC) with styrene-co-acrylonitrile random copolymer (SAN) has been systematically investigated as functions of acrylonitrile content and shear flow. Various AN-contents ranged from 11 to 74 wt% and different simple shear flow values up to 90 s⁻¹ have been used to explore the effect of both material and proceeding parameters on the miscibility of PC and SAN blends. The finest phase dispersion of the SAN particles was observed at AN=25 wt% for PC/SAN=70/30 blends under the same processing condition using scanning electron microscope (SEM). The obtained morphologies indicated that PC and SAN could form a partial miscibility blend and the maximum miscibility occurred at AN=25 wt%. This observation was supported by considering the shifts in the glass processes of the two rich phases of the blend using the dynamical mechanical analysis (DMA) measurements. The optimum interaction of the two components at AN=25 wt% calculated from ellipsometric technique was found to be the only responsible parameter for the high miscibility of the blend. The viscoelastic properties of the pure polymer components were found to play a minor role in the obtained morphologies. The effect of simple shear flow on the morphology of PC/SAN-25=70/30 blend has been also investigated using a special shear apparatus of parallel plate geometry. It has been found that the dispersed phase of SAN was elongated and broken-up in the direction of flow with weaker contrast at high shear rates. The shear rate was found to enhance the miscibility of SAN (dispersed phase) in the PC matrix to a great extent as seen in the weak contrast of the two phases observed by transmission electron microscope (TEM).     

Fabrication and properties of thermoplastic starch/montmorillonite composite using dialdehyde starch as a crosslinker

The poor mechanical properties and high water solubility of biodegradable thermoplastic starch (TPS) represent the main disadvantages of TPS in many applications. In this work, TPS film was prepared from a water solution of corn starch modified by 5 wt% dialdehyde starch (DAS) as crosslinking agent and 3 wt% montmorillonite (MMT) as reinforcing additive. Interactions occurring in the TPS films were investigated by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, XRD, DSC, dynamic mechanical thermal analysis (DMTA) and TGA. The results obtained fom FTIR spectroscopy and DSC suggest the formation of hydrogen bond interactions between the hydroxyl group of starch, DAS, the MMT layers and glycerol. DMTA indicated that the relaxation of films with DAS and MMT appears in a higher and broader temperature range due to the starch backbone stiffness; the extreme increase in the storage modulus confirmed the suggested interactions. The determination of the weight loss of the films in water indicated a significant increase of the water resistance of TPS due to incorporation of DAS and MMT. Changes in mechanical properties of the films containing DAS and clay were determined, showing a substantial increase in tensile strength from 2.7 to 6.7 MPa, while Young's modulus increased by 15 times for TPS modified with 5% DAS and 3% MMT. Therefore, the outcomes of this study confirmed that DAS is a suitable biomacromolecule crosslinker for starch and can significantly enhance TPS and TPS/MMT properties. © 2019 Society of Chemical Industry     

Rheology, phase morphology, mechanical, impact and thermal properties of polypropylene/metallocene catalysed ethylene 1-octene copolymer blends

Blends of a polypropylene (PP) and a metallocene catalysed ethylene-octene copolymer (EOC) were prepared using a single screw extruder fitted with a barrier screw design. The EOC used had 25 wt% 1-octene content and the weight fraction of EOC in the blends covered the range 1-30 wt.% Viscosity values for the blends determined experimentally from dual capillary rheological studies were similar to those calculated theoretically using the log additivity principle described by Ferry. This result together with scanning electron microscopy (SEM) observations and evidence from tan δ curves from dynamic mechanical thermal analysis showed PP and EOC to be partially miscible for blends having 10 wt% EOC or less. The tensile modulus, break strength and flexural modulus of the blends decreased with respect to virgin PP as the weight fraction of EOC was increased to 30 wt.% The diminution in mechanical properties was concomitant with an initial increase in elongation at break from 40% for neat PP to 140% for the blend with 15 wt% EOC before decreasing to 65% when 30 wt% EOC was blended. The optimum impact modification of the PP used in this study, in the temperature range −40 to 23 °C, was achieved by blending with between 20 and 30 wt% EOC.     

Miscibility, free volume behavior and properties of blends from cellulose acetate and castor oil-based polyurethane

A series of blend films from cellulose acetate (CA) and castor oil-based polyurethane (PU) were prepared. Morphology, miscibility, free volume behavior and properties of such blend films were investigated by wide-angle X-ray diffraction (WXRD), infrared, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), positron annihilation lifetime spectroscopy (PALS), thermogravimetric analysis and tensile test. The results indicated that lager free volume cavities did not form at the interface of two polymers although a certain degree of phase separation was found by the studies of SEM and DSC. Strong intermolecular hydrogen bonding interactions at the interface, which was proved by Fourier transform infrared spectroscopy, favors even better molecular packing, that is, PU dispersed in CA continuous phase to form fine microphase separation domain in the CA-rich blends. Due to such special interactions in the fine microphase separation domain structure, optimized properties of tensile strength, breaking elongation and cold-resistivity were obtained in the blend film with 75 wt% CA. The toughness of all the blend films was significantly higher than that of the film CA, owing to the plasticizing of PU elastomer in the blends.     

Binary and ternary blends of polylactide, polycaprolactone and thermoplastic starch

In this study binary and ternary blends of polylactide (PLA), polycaprolactone (PCL) and thermoplastic starch (TPS) are prepared using a one-step extrusion process and the morphology, rheology and physical properties are examined. The morphology and quantitative image analysis of the 50/50 PLA/TPS blend transverse phase size demonstrate a bimodal distribution and the addition of PCL to form a ternary blend results in a substantial number of fine dispersed particles present in the system. Focused ion beam irradiation, followed by atomic force microscopy (AFM) shows that dispersed PCL forms particles with a size of 370 nm in PLA. The TPS phase in the ternary blends shows some low level coalescence after a subsequent shaping operation. Dynamic mechanical analysis indicates that the temperature of the tan δ peak for the PLA is independent of TPS blend composition and that the addition of PCL in the ternary blend has little influence on the blend transitions. Both the α and β transitions for the thermoplastic starch are highly sensitive to glycerol content. When TPS of high glycerol content is blended with PLA, an increase in the ductility of the samples is achieved and this effect increases with increasing volume fraction of TPS. The ternary blend results in an even greater ductility with an elongation at break of 55% as compared to 5% for the pure PLA. A substantial increase in the notched Izod impact energy is also observed with some blends demonstrating three times the impact energy of pure PLA. The mechanical properties for the ternary blend clearly indicate a synergistic effect that exceeds the results obtained for any of the binary pairs. Overall, the ternary blend approach with PLA/TPS/PCL is an interesting technique to expand the property range of PLA materials.     

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     

聚乳酸纤维/聚乙烯醇纤维协同增强热塑性淀粉复合材料

为提高热塑性淀粉（TPS）塑料的力学和耐水性能,通过挤出工艺制备了含量为1 %（质量分数,下同）的聚乳酸纤维（PLAF）及不同含量的聚乙烯醇纤维（PVAF）共同增强的热塑性淀粉复合材料。研究了含量为0.2 %~1.4 %的PVAF对TPS/PLAF/PVAF复合材料力学性能、断面形貌、耐水性能及转矩流变性能的影响。结果表明,同时加入PLAF和PVAF能有效提高复合材料的力学性能及表面耐水性能;当PLAF和PVAF含量为1 %时,复合材料的拉伸强度从纯TPS的1.98 MPa提高到10.53 MPa,冲击强度由纯TPS的33.4 kJ/m²提高到62.23 kJ/m²,水接触角由纯TPS的46.34°提高到65.02°,TPS/PLAF/PVAF复合材料的平衡扭达到最大值15.75 N·m。     

Effect of cellulose nanofibers and acetylated cellulose nanofibers on the properties of low‐density polyethylene/thermoplastic starch blends

The aim of this study was to evaluate the effect of cellulose nanofibers (CNFs) and acetylated cellulose nanofibers (ACNFs) on the properties of low‐density polyethylene/thermoplastic starch/polyethylene‐grafted maleic anhydride (LDPE/TPS/PE‐g‐MA) blends. For this purpose, CNFs, isolated from wheat straw fibers, were first acetylated using acetic anhydride in order to modify their hydrophilicity. Afterwards, LDPE/TPS/PE‐g‐MA blends were reinforced using either CNFs or ACNFs at various concentrations (1–5 wt%) with a twin‐screw extruder. The mechanical results demonstrated that addition of ACNFs more significantly improved the ultimate tensile strength and Young's modulus of blends than addition of CNFs, albeit elongation at break of both reinforced blends decreased compared with the neat sample. Additionally, biodegradability and water absorption capacity of blends improved due to the incorporation of both nanofibers, these effects being more pronounced for CNF‐assisted blends than ACNF‐reinforced counterparts. © 2018 Society of Chemical Industry     

热塑性淀粉/纤维共混物性能的研究

用甘油作为塑化剂，将糊化淀粉和溶胀纤维按不同配比进行熔融共混来制备完全可生物降解塑料。实验探讨了纤维质量分数对共混体系力学性能、耐水性及热性能的影响。扫描电镜显示了纤维较好地分散在热塑性淀粉(TPS)中，纤维和淀粉结合良好。纤维质量分数对共混体系力学性能影响的研究显示，纤维的加入可以明显地改善体系的力学性能。随着纤维质量分数由0提高到20％，共混体系的拉伸强度达到15．5MPa，杨氏模量达到81．4MPa；伸长率从104％降到7％。同时加入纤维后共混体系的耐水性明显提高。     

Rheological,mechanical and biodegradation studies on blends of thermoplastic starch and polycaprolactone

Polycaprolactone (PCL) has been blended with thermoplastic starch (TPS), prepared from regular corn starch and glycerol, in a twin‐screw extruder. The rheological, mechanical, thermal and morphological properties of the blends were examined. Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM) studies revealed that PCL/TPS blends are thermodynamically immiscible. However, they form compatible blends as a result of the hydrogen bonding interaction between the ester carbonyl of PCL and the ? OH groups on starch. Biodegradability of the blends increased with increasing TPS content. Dynamic viscoelastic measurements concluded that blends containing above 60‐wt% TPS had higher storage and loss moduli than those of pure TPS and PCL. In addition, these blends had higher complex viscosities. Polym. Eng. Sci. 44:1429–1438, 2004. © 2004 Society of Plastics Engineers.     

Morphology and properties of compatibilized polylactide/thermoplastic starch blends

This paper investigates the properties and interfacial modification of blends of polylactide (PLA) and glycerol-plasticized thermoplastic starch (TPS). A twin-screw extrusion process was used to gelatinize the starch, devolatilize the water to obtain a water-free TPS and then to blend into the PLA matrix. The investigated TPS concentration ranged from 27 to 60 wt%. In the absence of interfacial modification, the TPS/PLA blend morphology observed through scanning electron microscopy was very coarse with TPS particles sizes between 5 and 30 μm. Interfacial modification was achieved by free-radical grafting of maleic anhydride (MA) unto the PLA and then by reacting the modified PLA with the starch macromolecules. Blends comprising MA-grafted PLA showed much finer dispersed phase size, in the 1–3 μm range and exhibited a dramatic improvement in ductility. The paper discusses the effects of two interfacial modification strategies on the blend morphology and tensile properties and investigates the compatibilization efficiency for glycerol plasticizer contents between 30 and 39 wt% and for starches from three different sources: wheat, pea and rice.     

Miscibility and mechanical properties of quaternized polysulfone/benzoyl guar gum blends

Novel blends from quaternized polysulfone (QPSF) and benzoyl guar gum (BGG) coded as QB with different contents (10–80 wt%) were prepared through solution casting method. Simultaneously, other kinds of blends were prepared from chloromethylated polysulfone (ClPSF) and BGG coded as ClB to compare the effects of the substituted groups on the miscibility and properties of the composite materials. The effect of BGG content on QB blends was investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atom force microscopy (AFM), differential scanning calorimetry (DSC) and tensile tests. The results revealed that QB blends had good or certain miscibility over the entire composition ratio of BGG to QPSF under study. Compared with ClB blends, QB blends exhibited stronger interfacial attraction and better phase mixing as a result of the relatively strong hydrogen bonding and the specific electrostatic interaction between QPSF and BGG. The occurrence of strong interaction between QPSF and BGG played a key role in improving the material performance. With an increase of BGG content in the blends, the tensile strength of QB blends increased from 33.1 to 44.3 MPa. Furthermore, the mechanical properties of QB-20 blend at different RH were also discussed. It was found that the composite properties changed considerably with moisture content, which attributed that water molecules had a great effect on the hydrogen bonding between the two polymers.     

Effects of a diisocyanate compatibilizer on the properties of citric acid modified thermoplastic starch/poly(lactic acid) blends

In this article, for the first time in the literature effects of phenylene diisocyanate (PDI)‐based compatibilizer on the physical and chemical properties of citric acid (CA) modified thermoplastic starch (TPS)/poly(lactic acid) (PLA) blends were investigated with respect to PDI and CA content and blend composition. The blends were prepared by melt compounding in a laboratory microcompounder. Fourier transformation infrared spectroscopy results showed that CA interacted with starch and PDI interacted by both starch and PLA through the hydroxyl groups. It was revealed from SEM micrographs that combinatorial usage of CA and PDI resulted in an improved, finer distribution of TPS in PLA matrix. This improvement affected the mechanical properties of blend, especially the toughness related properties such as impact strength and elongation at break. The thermal properties such as T_g and T_m revealed from differential scanning calorimeter analysis were in line with the morphological structure of the blends by suggesting the compatibilization phenomena in the presence of PDI and CA together. Thermogravimetric analysis showed that compatibilization of two phases improved the thermal stability of the blends. As a general conclusion, the combinatorial usage of PDI and CA can be utilized to obtain tougher PLA/TPS blends‐based materials to overcome the brittleness problem. POLYM. ENG. SCI., 53:2183–2193, 2013. © 2013 Society of Plastics Engineers     

New miscible blends composed of polysulfone and poly(1-vinylpyrrolidone-co-acrylonitrile) copolymers and their phase behavior

The miscibility of polysulfone, PSf, blend with poly(1-vinylpyrrolidone), PVP, and that of PSf blend with poly(1-vinylpyrrolidone-co-acrylonitrile) copolymers, P(VP-AN), containing various amount of VP were explored. Even though PSf did not formed miscible blends with PVP when both components had high molecular weight, it formed miscible blend with PVP by decreasing molecular weight of PVP. PSf also formed homogeneous mixtures with P(VP-AN) containing AN from 2 to 16 wt%. These miscible blends underwent phase separation on heating caused by LCST-type (lower critical solution temperature-type) phase behavior. The phase separation temperature of miscible blends first increases with AN content, goes through a maximum centered at about 8 wt% AN. Interaction energies of binary pairs involved in blends were evaluated from the observed phase boundaries using the lattice-fluid theory. The decline of the contact angle between water and blend film by increasing P(VP-AN) content in blend indicated that the hydrophobic properties of PSf could be improved by blending with P(VP-AN) copolymers.