淀粉乙酸酯的阴离子接枝己内酯聚合研究

将淀粉在二甲基甲酰胺、吡啶存在下 ,以乙酸酐进行部分乙酰化 ,制备取代度为 0 7～ 1 9的淀粉乙酸酯 (St Ac) .以萘钠与淀粉乙酸酯中残余的羟基反应 ,将羟基转化为醇盐 (ONa) ,引发己内酯进行阴离子开环接枝聚合 ,合成了淀粉 聚己内酯接枝共聚物 (St g PCL) .采用凝胶渗透色谱法 (GPC)研究了接枝前后聚合物分子量的变化情况 ,并以接枝率、单体转化率对接枝反应进行了表征 .研究了接枝条件如温度、溶剂、引发剂和单体的用量对接枝率及单体转化率的影响 .研究发现随着反应温度升高 ,接枝率、单体转化率呈S曲线变化 ,单体浓度、引发剂浓度的增大有利于接枝反应的进行 .     

Elaboration and Characterization of Starch/ Poly(caprolactone) Blends

A starch-based biodegradable material was prepared in two steps. Firstly, starch was chemically modified by using formic acid at 20°C to obtained degrees of substitution of about 1.2. The level of destructuration was also assessed using dynamic rheological measurements. Native starch or starch ester were then mixed with poly(caprolactone) and different polyester oligomers were added as compatibilisers and plasticizing agents. PCL oligomers were found to be the most efficient ones. A significant improvement of the elongation at break of starch formate/PCL/oligo PCL blends was achieved.     

Structure–property relationship in PCL/starch blend compatibilized with starch‐g‐PCL copolymer

The polycaprolactone (PCL)/starch blends were prepared by using the starch‐g‐PCL (SGCL) graft copolymers as compatibilizers, and their mechanical properties were correlated with the compatibilizing effect of the SGCL copolymers having various molecular structures. The modulus and strength of the PCL/starch blend were decreased, whereas the percent elongation and the toughness were increased remarkably with the addition of SGCL having appropriate graft structure. These property changes were analyzed in terms of the PCL crystallinity and the interfacial adhesion between the PCL matrix and starch dispersion phases, which were dominated by the compatibilizing effects of the SGCL copolymers. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2430–2438, 1999     

Biodegradable Multiphase Systems Based on Plasticized Starch: A Review

Abstract

The aim of this review is to show the relationships between the structure, the process, and the properties of biodegradable multiphase systems based on plasticized starch (PLS), the so‐called “thermoplastic starch.” These mutiphase materials are obtained when associating association between plasticized starches and other biodegradable materials, such as biodegradable polyesters [polycaprolactone (PCL), polyhydroxyalkanoates (PHAs), polylactic acid (PLA), polyesteramide (PEA), aliphatic, and aromatic copolyesters], or agro‐materials (ligno‐cellulosic fiber, lignin etc.). Depending on materials (soft, rigid) and the plastic processing system used, various structures (blends, composites, multilayers) can be obtained. The compatibility problematic between these hetero‐materials is analyzed. These starchy products show some interesting properties and have some applications in different fields: packaging, sports, catering, agriculture and gardening, or hygiene.     

Synthesis of Starch-g-Poly(glycidyl methacrylate) and Its Blending with Poly(ϵ-caprolactone) and Nylon 610

Different amounts of glycidyl methacrylate (GMA) were grafted onto corn starch dispersed in water or dimethyl sulfoxide (DMSO) to yield starch-graft-poly(glycidyl methacrylate) (ST-g-PGMA). ST-g-PGMAW, obtained by grafting PGMA onto corn starch that was dispersed in water, showed a higher PGMA grafting content and a lower content of the homopolymerized PGMA than ST-g-PGMAD, which was prepared in DMSO. The modified starches were blended with poly(ϵ-caprolactone) (PCL) and nylon 610, respectively, and the tensile properties of the blends were measured by UTM. Mechanical properties of the biodegradable ST-g-PGMA/PCL blends were dependent on the PGMAD content grafted on starch. Without dramatic loss of the tensile properties of PCL, ST-g-PGMAW was melt blended with PCL. Meanwhile, an increase in the tensile modulus was observed in the ST-g-PGMAW/nylon 610 blend. When nylon 610 was reacted with ST-g-PGMAW in DMSO in the presence of triethylamine, the tensile modulus and strength were much higher than those of the pure nylon 610, and phase-separated domains of starch were not observed microscopically.     

Solid-state NMR study of biodegradable starch/polycaprolactone blends

Abundant literature exists on starch or modified starch blended with biodegradable polyesters to achieve good performance with cheap compost plastics. The level of miscibility in these blends is one of the most relevant parameters. In the present study, solid-state ¹H and ¹³C NMR spectra, as well as carbon spin-lattice relaxation times T₁(C) and proton spin-lattice relaxation times T₁(H) and proton spin-lattice relaxation times in the rotating frame T_1ρ(H) of biodegradable starch (or starch formate)/polycaprolactone (PCL) (or polyester (PE) oligomers) blends and samples of the neat components were measured. From the T_1ρ(H) and T₁(H) relaxation times it follows that blends starch/PCL, starch/PE-oligomers and starch formate/PE-oligomers are phase separated even on the scale of 20-110 nm. On the contrary starch formate/PCL blend is phase separated on the scale 2.5-12 nm but homogeneously mixed on the scale 20-90 nm. Moreover, shorter T₁(C) and especially T_1ρ(H) values found for the starch or starch formate component in all these blends in comparison with neat samples show that molecular mobility of starch and starch formate segments is affected by blending. This indicates some miscibility also in phase separated blends which can happen in amorphous channels of starch.     

Synthesis and characterization of starch-graft-polycaprolactone as compatibilizer for starch/polycarprolactone blends

Polycaprolactone (PCL) was grafted onto starch through introduction of urethane linkages. The grafting reaction was carried out in two steps. The first step was the reaction of hydroxyl-terminated PCL with 2,4-tolylene diisocyanate. The isocyanate terminated PCL was then reacted with starch to obtain starch-graft-polycaprolactone (starch-g-PCL). The grafting reaction was confirmed by FT-IR spectroscopy. The compatibility of the starch/PCL blend was enhanced with a compatibilizer, starch-g-PCL, whose amount was 3 wt.-% of the blend. The tensile strength and morphology of the compatibilized blend were determined. It was found that the compatibilized starch/PCL blend has finer phase domains and an improved interfacial adhesion. Mechanical properties of the compatibilized blend were found to be significantly higher than those of the corresponding uncompatibilized starch/PCL blend.     

EFFECT OF PLASTICIZER ON THE MICROSTRUCTURE OF PS/PVC BLENDS

In this work, controlling of the particle size of PVC in PS/PVC blends was studied. Itis shown that viscosity ratio and particle size can be changed by adding a third composition,such as plasticizers, and the distribution of the third composition in two phases plays avery important role in controlling viscosity ratio and particle size. When DOP was used asthe plasticizer of PVC in PS/PVC blends, the particle size of PVC could not be reduceddue to the transference of DOP into PS phase. When polycaprolactone (PCL) was usedas the plasticizer of PVC in the same blends, the particle size of PVC could be descreasedobviously because PCL does not migrate to PS phase.     

Biodegradable compositions by reactive processing of aliphatic polyester/polysaccharide blends

Commercially available biodegradable aliphatic polyesters, i.e., high molecular weight poly(ϵ-caprolactone) (PCL) and polylactide (PLA), were melt blended with a well-known natural and biodegradable polysaccharide: starch either as corn starch granules or as thermoplastic corn starch after plasticization with glycerol. Conventional melt blending yielded compositions with poor mechanical performances as a result of lack of interfacial adhesion between the rather hydrophobic polyester matrix and the highly hydrophilic and moisture sensitive starch phase. Interface compatibilization was achieved via two different strategies depending on the nature of the polyester chains. In case of PLA/starch compositions, PLA chains were grafted with maleic anhydride through a free radical reaction conducted by reactive extrusion. The maleic anhydride-grafted PLA chains (MAG-PLA) allowed for reinforcing the interfacial adhesion with granular starch as attested by TEM of cryofracture surface. As far as PCL/starch blends were concerned, the compatibilization was achieved via the interfacial localization of amphiphilic graft copolymers formed by grafting of PCL chains onto a polysaccharide backbone such as dextran. The PCL-grafted polysaccharide copolymers were synthesized by controlled ring-opening polymerization of ϵ-caprolactone proceeding via a coordination-insertion mechanism. These compatibilized PCL/starch compositions displayed much improved mechanical properties as determined by tensile testing as well as a much more rapid biodegradation as measured by composting testing.     

ABS的MAH/St多单体熔融接枝及其对PA6/ABS共混体系相形态和力学性能的影响

通过多单体熔融接枝的方法制备出了具有较高接枝率的ABS接枝物 (ABS g (MAH co St) ) ,并对其接枝机理进行了初步探讨 .研究表明 ,MAH、St接枝ABS时 ,反应主要发生在ABS中聚丁二烯的双键部位 .同时 ,当MAH与St的用量比约为 1:1时接枝率达到最高 .ABS g (MAH co St)作为尼龙 6 (PA6 ) ABS共混体系相容剂起到了良好的增容效果 .实验证明 ,相容剂使用前后 ,共混物的相区尺寸由几十 μm减小到 1μm以下 ,且分布更加均匀 ;共混物的拉伸强度和冲击强度等力学性能也同时得到均衡改善 .     

Thermal conductivity of poly(vinyl chloride)/polycaprolactone blends

Thermal diffusivity, heat capacity, and density of polyvinyl chloride/polycaprolactone (PVC/PCL) blends were measured by the laser flash method, DSC, and pycnometry, respectively. The thermal conductivity of the PVC/PCL blends was determined from the results. The miscibility of the blend and crystallinity of PCL were determined by DSC. The effect of blend structure on thermal conductivity is discussed. The phase compositions of the PVC/PCL blends are of three types depending on PCL content: i.e., up to 33%, from 33 to 70%, and above 70% PCL by weight. Thermal conductivity, thermal diffusivity, and heat capacity of the PVC/PCL blends are strongly affected by the phase composition of the blend, which changes in a complicated way with PCL content. © 1994 John Wiley & Sons, Inc.     

Solid-State NMR Studies of Polysaccharide Systems

Summary: Two polysaccharide systems were studied by solid-state NMR methods: (i) Chitin/glucan complexes. The ¹³C NMR spectra have shown that in samples isolated from the mushroom Pleurotus sp., the glucan content was always higher in stems than in pilei. While carbonyl lineshape in complex isolated from Aspergillus niger mycelium shows similar hydrogen bonding as in neat chitin, a significantly higher amounts of hydrogen bonding between carbonyl groups of chitin and hydroxy groups of glucan was found in complexes isolated from Pleurotus sp. (ii) Biodegradable starch/polycaprolactone (PCL) blends. From the relaxation times T₁(H) and T_1ρ(H) it follows that blends starch/PCL, starch/ester oligomers and starch formate/ester oligomers are phase-separated even on the scale 20–110 nm. On the contrary, starch formate/PCL blend is phase-separated on the scale 1–9 nm but homogeneously mixed on the scale 20–90 nm. Therefore formylation of starch significantly improves its miscibility with PCL.     

Crystallizability of Poly(ε-caprolactone) Blends with Poly(vinylphenol) under Different Conditions

The intermolecular interaction between poly（vinylphenol） （PVPh） and polycaprolactone （PCL） and the crystallization behavior of PCL in PCL/PVPh blends with different compositions and under different conditions were investigated by Fourier transform infrared spectra （FTIR） and differential scanning calorimetry （DSC）. It has been shown that the PCL in the blends with different blend ratios all exists in crystalline state after solution casting, even though the crystallinity decreases with increasing PVPh content. For the melt crystallized samples, PCL in its 80/20 PCL/PVPh sample can still crystallize. The crystallinity is, however, lower than that of the solution cast sample. For blends containing 50% or 20% PCL, the as-cast samples are semicrystalline and can change to compatible amorphous state after heat treatment process. FTIR analysis shows the existence of hydrogen bonding between PCL and PVPh and the fraction of hydrogen bonds increases remarkably after heat treatment process.     

Interrelationship between total volatile organic compounds emissions,structure and properties of natural rubber/polycaprolactone bio-blends cross-linked with peroxides

Natural rubber/polycaprolactone (NR/PCL) bio-based blends with different organic peroxides were prepared using an internal batch mixer and subsequently cross-linked at 170 °C. Two types of commonly used organic peroxides, dicumyl peroxide and di(tert-butylperoxyisopropyl)benzene peroxide, were applied as free-radical initiator. Cross-linking efficiency of NR/PCL blends were investigated using oscillating disc rheometer measurements, followed by infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis and tensile testing. Total volatile organic compounds (TVOCs) emissions were determined using headspace analysis integrated with gas chromatography with flame ionization detector. Determined TVOCs emissions varying in range 21.6–52.1 μg/g and generally value of this parameter decreased with increasing content of PCL phase in studied blends or with application of more efficient di(tert-butylperoxyisopropyl)benzene peroxide as cross-linking agent. It was found that increasing of TVOCs parameter indicated deterioration of mechanical properties of NR/PCL blends, which corresponded with the changes in chemical structure and thermal properties of cross-linked NR/PCL. This confirms that evaluation of TVOCs parameter is interesting alternative for “conventional methods” to characterization of the studied bio-based blends.     

聚ε-己内酯/β-磷酸三钙共混物的制备与性能

研究了β－磷酸三钙和表面接枝改性β－磷酸三钙与聚ε－己内酯共混物的制备,共混体系的界面相互作用、热性能和力学性能。获得了全生物降解的聚ε－己内酯／β－磷酸三钙共混物材料。     

Dual-responsive shape memory and self-healing ability of a novel copolymer from epoxy/cashew nut shell liquid and polycaprolactone

In this work, the blends of epoxy (EP) and polycaprolactone (PCL) with a bio-based curing agent, viz. cashew nut shell liquid (CNSL) were studied for their dual-responsive shape memory and self-healing behaviors. The suitable EP/CNSL weight ratio was observed at 70/30. The increase of PCL content up to 20 wt% in EP-CNSL matrix significantly enhanced the shape memory response to both thermal and chemical stimuli. All specimens showed 100% thermo-responsive shape recovery and the recovery time decreased with increasing PCL content. In the case of chemo-responsive shape memory, the immersion times spent for 100% shape recovery in water and methanol substantially decreased when PCL was added. Moreover, after thermal treatment, the EP-CNSL matrix with 20 wt% PCL showed significant self-healing ability with high tensile strength recovery at 93.70%. The EP-CNSL/PCL copolymer could be a promising alternative bio-related smart material for various applications such as dual-activated sensors and coatings with self-healing ability.     

Segmental orientation in blends of poly(ϵ-caprolactone) with poly(vinyl chloride) and nitrocellulose

Binary blends of polycaprolactone (PCL) with poly(vinyl chloride) (PVC) and nitrocellulose (NC) have been shown to be compatible over a wide range of composition. In this study, segmental orientation was determined by dynamic, differential infrared dichroism for each component in the PVC and NC blends with PCL. In compatible amorphous blends, PCL orientation behavior was essentially the same as for the orientation of NC or the isotactic segments of PVC. Syndiotactic PVC segments showed higher orientations, reflecting the greater intrachain stiffness of the microcrystalline PVC phase. PCL segments in the blends where the PCL component was semicrystalline were found to exhibit orientation characteristics which were quite different from the orientation of the nitrocellulose and PVC components of the blends. By assuming that the NC orientation represented the response of the amorphous PCL, the orientation of the crystalline PCL was determined for a NC blend using a simple model of additive dichroism response. In PVC blends, a similar analysis using the amorphous-component response of PVC was made. In both cases the results from the dichroism model showed fair agreement with the PCL unit cell C-axis orientation from independent dichroism calculations.     

The influence of arrangement of St in MBS on the properties of PVC/MBS blends

Three series of MBS core-shell impact modifiers were prepared by grafting styrene and methyl methacrylate onto PB or SBR seed latex in emulsion polymerization. All the MBS modifiers were designed to have the same total chemical composition, and MMA/Bd/St equals 30/42/28, which is a prerequisite for producing transparent blends with PVC. Under this composition, there were three different ways of arrangement for styrene in MBS, which led to the different structure of MBS modifier. The concentration of MBS in PVC/MBS blends was kept at a constant value of 20 wt.%. The effects of arrangement of St in MBS on the mechanical and optical properties of PVC/MBS blends were studied. The notched Izod impact test results showed that the MBS with a PB homopolymer core grafted with St had a lowest brittle-ductile transition (BDT) temperature and BDT temperature increased with the amount of St copolymerized with Bd in the core of MBS. The transparency of blends also increased with the amount of St copolymerized with Bd in the core. TEM results showed that the arrangement of St in MBS influenced the deformation behavior. Two deformation modes were observed in the blends: cavitation and shear yielding. When all St was grafted onto the PB rubber, both cavitation and debonding were observed, which relieve the triaxial tension and promote the shear yielding of the PVC matrix. When all St was copolymerized with Bd in MBS, no cavitation could be observed and only the shear yielding of the PVC matrix took place.     

二醋酸纤维素接枝聚己内酯的核磁共振表征

用^1H-NMR和^13C-NMR研究了二醋酸纤维素(CDA)和聚己内酯(PCL)的接枝共聚反应,确定了^1H-NMR和^13C-NMR谱中各谱峰的归属,为证明二醋酸纤维素和己内酯的接枝共聚反应提供了依据。     

Miscibility of polycaprolactone/chlorinated polyethylene blends

Blends of polycaprolactone (PCL) with chlorinated polyethylenes (PECls) having chlorine contents of 25, 30, 36, 42, and 48% by weight were prepared and studied by differential scanning calorimetry and small-angle light scattering (SALS). It was found that blends made with PECls containing 30% or more chlorine are completely miscible with PCL (a single glass transition temperature T_g is found) while the PCL/PECl(25) blends are immiscible. PCL crystallizes in the miscible blends at any composition and it has an enthalpy of fusion which decreases only slightly with PECl content. Blends in the PECl composition interval of 0–80% are spherulitic, as shown by SALS, but a rodlike morphology is found at the 85% composition and dispersed crystals are observed at higher compositions. It is suggested that the k parameter of the Gordon-Taylor equation can be taken as a measure of the strength of the specific interaction between PCL and PECl. Low values of k (0.26 and 0.35) are found for PCL/PECl blends but a higher value of k (0.51) has been reported for PCL/poly(vinyl chloride) (PVC) blends, indicating a stronger interaction in the latter mixtures. In agreement with these findings poly(α-methyl-α-n-propyl-β-propiolactone) and poly(valerolactone) are not miscible with PECl, whereas they were previously shown to be miscible with PVC.