生物可降解非织造布及其应用

论述了生物可降解非织造布的降解机理 ,介绍了几种可生物降解型纤维 ,并对生物可降解非织造布的加工方法进行了论述。由于生物可降解非织造布对环保有重要的意义 ,因此它的应用领域将日益扩大。     

Thermoplastic Starch Processing and Characteristics—A Review

Canola Council of Canada, Winnipeg, Manitoba, Canada The rising costs of nonrenewable feedstocks and environmental concerns with their industrial usage have encouraged the study and development of renewable products, including thermoplastic starch (TPS). Starch is an abundant, plant-based biodegradable material with interesting physicochemical characteristics that can be exploited, and this has received attention for development of TPS products. Starch exhibits usable thermoplastic properties when plasticizers, elevated temperatures, and shear are present. The choice of plasticizer has an effect on TPS, even when these have similar plasticization principles. Most TPS have glass transition temperature, T_g, in the range of approximately ?75 to 10°C. Glassy transition of TPS is detected by differential scanning calorimeter (DSC) and thermodynamic analyzer (DMA), although DMA has been found to be more sensitive and effective. TPS has low tensile properties, typically below 6 MPa in tensile strength (TS). The addition of synthetic polymers, nanoclay, and fiber can improve TS and water-resistance ability. The moisture sorption behavior of TPS is described in GAB and BET models, from which monolayer moisture content and specific area are derived. Current studies on surface tension, gas permeability, crystallinity, and so on of the TPS are also reviewed.     

In vitro degradation properties of ion-beam irradiated poly(lactide-co-glycolic acid) mesh

Scaffolds for tissue regeneration must be biocompatible and biodegradable. Ion-beam irradiation is useful for making polymers biocompatible, but the process by which the irradiated polymers biodegradable is not yet well understood. We investigated this phenomenon by Kr⁺-irradiated poly(lactide-co-glycolic acid) (PLGA) mesh substrate at an acceleration energy of 50 keV with fluences of 1 × 10¹³ and 1 × 10¹⁴ ions/cm². We then measured the electronic states of the constituent elements on the irradiated surface by X-ray photoelectron microscopy (XPS) and evaluated the hydrolytic degradation properties (weight loss, media pH, and tensile strength) of the mesh in phosphate buffer solution. New functional groups and carbonization were induced on the irradiated surface. Degradation rate and tensile strength remain unchanged by ion-beam irradiation. Ion-beam irradiation should, thus, be a promising modification technique for tissue engineering scaffolds.     

常见精练油中植物甾醇测定方法的建立及含量分析

为对我国常见的植物油中植物甾醇含量进行测定,建立了植物甾醇气相色谱分析方法,并对11类共25种精炼植物油中的β-谷甾醇、菜油甾醇、豆甾醇、β-谷甾烷醇、菜油甾烷醇及菜籽甾醇等的含量进行分析.本方法相对标准差为1.1%～6.9%;菜油甾醇、豆甾醇、β-谷甾醇的回收率的RSD值范围为3.0%～4.7%.玉米胚芽油中植物甾醇含量最高,其次是菜籽油和芝麻油.不同种类的植物油植物甾醇的含量和比例各不相同,同一种类不同品牌的植物油中各植物甾醇所占的比例基本接近.对我国居民植物油中植物甾醇的摄入量进行了初步估计.本研究建立的方法可靠,具有较高的准确度和精密度,可以作为精炼植物油中植物甾醇的测定方法.建议我国居民可以通过食用含植物甾醇较高的食用油来增加植物甾醇的摄入量。     

Effects of TS-1 zeolite structures on physical properties and enzymatic degradation of Poly (butylene succinate) (PBS)/TS-1 zeolite hybrid composites

The objective of this study was to investigate how the water uptake features and carrier characteristics of the TS-1 zeolite affected the physical and rheological properties, morphological parameters, and enzymatic hydrolysis of Poly (butylene succinate) (PBS). The introduction of TS-1 zeolite as catalyst was developed for the preparation of PBS/TS-1 zeolite hybrid composites (PTHC) without heavy metal toxic substance in the context on clean technology. The TS-1 zeolite can act as a catalyst as well as a reinforcement filler with the result that PTHC can show marked increases in tensile properties and elongation at breakage in the solid state. The rheological properties of PTHC with high zeolite contents showed low values of complex viscosity, as compared with PTHC with low TS-1 zeolite contents, due to the volatilization of water released from the zeolite pores during esterification. The introduction of the TS-1 zeolite in the PBS matrix was not significantly affected by changes in the size of the long period, lamella thickness, or the amorphous region, indicating that PBS chains do not penetrate into zeolite pores, as confirmed by SAXS profiles. In enzymatic hydrolysis over 90 days, the enzymatic hydrolysis rates of PTHC significantly accelerated with increasing TS-1 zeolite contents, compared with Homo PBS. This result indicated that TS-1 zeolite can act as a carrier for enzyme activation, resulting in enzymatic hydrolysis, occurring from the amorphous area on the surface into the inside of the film.     

Thermal,mechanical and water adsorption properties of corn starch–carboxymethylcellulose/methylcellulose biodegradable films

The objective of this study was to investigate the effect of the addition of methylcellulose and carboxymethylcellulose on the thermal, mechanical and water adsorption properties of starch-based films plasticized with glycerol or polyethylene glycol (PEG). Mechanical tests showed that as the methylcellulose and carboxymethylcellulose proportion increased, starch films became more resistant to break, resulting in higher TS values. Besides there has been a positive effect on the elasticity of starch films realized by a considerable increase in E% values. Depending on the plasticizer type, either single or dual glass transitions were seen in DSC thermograms. One glass transition temperature was observed for films plasticized with glycerol, on the contrary, dual glass transitions were detected for PEG plasticized films. This behavior was attributed to the phase separation of the PEG. In addition, the presence of an endothermic peak in the thermograms of PEG plasticized films was taken as another indicator of the phase separation. As a result, it was suggested that PEG was not as compatible as glycerol with the composite polysaccharide matrix and plasticizer type was the main factor that shaped the thermal profiles of the film samples. Water adsorption isotherm data showed that samples displayed nonlinear sorption profile which is typical for hydrophilic films. In all films tested, equilibrium moisture contents, increased almost linearly up to a a_w of 0.65–0.85, beyond where a sharp increase was noted. Adsorption data was adequately fitted by BET and GAB models. Eventually, it can be concluded that film forming properties of starch can be improved by incorporation of methylcellulose and carboxymethylcellulose to the polymer matrix.     

The effects of the addition of corn husk fibre,kaolin and beeswax on cross-linked corn starch foam

Significant efforts have recently been made to improve the physical properties of starch foams formed using baking processes. For example, cross-linking starch with 0.126 g/kg glyoxal considerably reduces the baking time, density and water absorption of starch foams. In this study, we attempted to further develop the physical properties of glyoxal cross-linked starch foam by adding corn husk fibre, kaolin, beeswax and combinations of these products. We also studied the effects of these components on the microstructure and physicochemical and mechanical properties of trays. Starch-based trays in which additives were used showed improved water resistance. The water absorption capacities of the trays were 13%, 14% and 9% when combinations of kaolin/beeswax, fibre/beeswax and fibre/kaolin/beeswax were added, respectively.     

Effect of chemical and physical pretreatments on the convective drying of cape gooseberry fruits (Physalis peruviana)

Drying of cape gooseberry fruits is a slow process because of the low permeability to moisture of the fruit’s waxy skin. In this work, the effect of chemical pretreatments (sunflower oil/K₂CO₃ or olive oil/K₂CO₃ at 28 °C, and NaOH/olive oil at 96 °C) and physical pretreatments (blanching) to break down the waxy surface and accelerate moisture diffusion during drying, was assessed. Drying was carried out at 60 °C and 2 m/s air velocity for 10 h. The lowest moisture content (0.27 kg water/kg db), the highest vitamin C content (0.36 mg/g), and the greatest rehydration capacity (1.89) were obtained in fruits pretreated with olive oil (9.48%) and K₂CO₃ (4.74%). However, the greatest changes in color (ΔE^* = 15.05) and chroma (ΔC^* = 9.03) were also associated to fruits pretreated with olive oil and K₂CO₃. The effective diffusivity of water during drying was 7.37 × 10⁻¹¹ m²/s in pretreated samples compared with 6.61×10⁻¹¹ m²/s for untreated samples.     

Morphology,Thermal and Mechanical Properties of Biodegradable Poly(butylene succinate)/Poly(butylene adipate-co-terephthalate)/Clay Nanocomposites

Sodium montmorillonite (Na-MMT) was successfully modified by octadecylamine (ODA) through a cation exchange technique that showed by the increased of basal spacing of clay by XRD. The addition of the organoclay into the PBS/PBAT blends produced intercalated-type nanocomposites with improvements in tensile modulus and strength. The highest tensile strength of nanocomposite was observed at 1 wt% of organoclay incorporated. A TGA study showed that the thermal stability of the blend increased after the addition of the organoclay by 1 wt%. SEM micrographs of the fracture surfaces show that the morphology of the blend becomes smoother with presence of organoclay.     

Synthesis and Characterization of Maize Starch Acetates and its Biodegradable Film

Starch acetates (SA) were synthesized by maize starch reacting with acetic acid/acetic anhydride, using sulfuric acid as catalyst. The biodegradable films were produced by thermal gelatinization of starch suspensions blending raw starch or SA with different degree of esterification (DS) and polyvinyl alcohol (PVA). Fourier transform infrared spectrogram (FT-IR) data showed acetate was introduced into the molecule chain of starch. Different structure of aggregation supported between the modified starch and the raw starch was determined by the scanning electron microscopy (SEM). Differential scanning calorimetry indicated SA glass transition temperature reduced with increasing of its DS. X-ray diffraction pattern of SA revealed the crystallinity of chain starch was destroyed, forming many completely even amorphous areas. SEM studies showed that amorphous was raised with DS of starch acetates. The mechanical and hydrophobic properties of the films were better than those of raw starch/PVA. In 50 days outdoor soil burial biodegradable experiment in summer, the weight loss of the films was almost 50%.