可生物降解聚合物基纳米复合材料降解性能研究进展

可生物降解聚合物中的层状硅酸盐纳米复合材料,可极大提高其力学性能,但同时会影响到材料的降解速率。研究纳米填料对可生物降解聚合物降解速率的影响及降解机理的变化,可拓宽其应用领域。综述聚乳酸(PLA)、淀粉、聚己内酯(PCL)、纤维素、聚羟基烷脂肪酸酯(PHA)、聚琥珀酸丁二醇酯(PBS)等可生物降解聚合物基层状硅酸盐纳米复合材料制备及降解性能研究现状及进展。     

三层共挤复合宽幅吹塑棚膜机组的膜泡内冷装置应用效果

简要述及了有吹塑膜泡内冷装置与外冷装置相结合冷却系统的三层共挤复合宽幅吹膜机组的应用。     

Solvent-Cast 3D Printing of Biodegradable Polymer Scaffolds

3D printing is a popular fabrication technique because of its ability to produce complex architectures. Melt-based 3D printing is widely used for thermoplastic polymers like poly(caprolactone) (PCL), poly(lactic acid) (PLA), and poly(lactic-co-glycolic acid) (PLGA) because of their low processing temperatures. However, traditional melt-based techniques require processing temperatures and pressures high enough to achieve continuous flow, limiting the type of polymer that can be printed. Solvent-cast printing (SCP) offers an alternative approach to print a wider range of polymers. Polymers are dissolved in a volatile solvent that evaporates during deposition to produce a solid polymer filament. SCP, therefore, requires optimizing polymer concentration in the ink, print pressure, and print speed to achieve desired print fidelity. Here, capillary flow analysis shows how print pressure affects the process-apparent viscosity of PCL, PLA, and PLGA inks. Ink viscosity is also measured using rheology, which is used to link a specific ink viscosity to a predicted set of print pressure and print speed for all three polymers. These results demonstrate how this approach can be used to accelerate optimization by significantly reducing the number of parameter combinations. This strategy can be applied to other polymers to expand the library of polymers printable with SCP.     

Selenium-Substituted Hydroxyapatite/Biodegradable Polymer/Pamidronate Combined Scaffold for the Therapy of Bone Tumour

The present study evaluated a new concept of combined scaffolds as a promising bone replacement material for patients with a bone tumour or bone metastasis. The scaffolds were composed of hydroxyapatite doped with selenium ions and a biodegradable polymer (linear or branched), and contained an active substance—bisphosphonate. For this purpose, a series of biodegradable polyesters were synthesized through a ring-opening polymerization of ε-caprolactone or d,l-lactide in the presence of 2-hydroxyethyl methacrylate (HEMA) or hyperbranched 2,2-bis(hydroxymethyl)propionic acid polyester-16-hydroxyl (bis-MPA) initiators, substances often used in the synthesis of medical materials. The polymers were obtained with a high yield and a number-average molecular weight up to 45,300 (g/mol). The combined scaffolds were then manufactured by a direct compression of pre-synthesized hydroxyapatite doped with selenite or selenate ions, obtained polymer and pamidronate as a model drug. It was found that the kinetic release of the drug from the scaffolds tested in vitro under physiological conditions is strongly dependent on the physicochemical properties and average molecular weight of the polymers. Furthermore, there was good correlation with the hydrolytic biodegradation results of the scaffolds fabricated without drug. The preliminary findings suggest that the fabricated combined scaffolds could be effectively used for the sustained delivery of bioactive molecules at bone defect sites.     

生物降解高吸水性树脂的研究进展

本文简述了高吸水性树脂的降解机理及影响因素,综述了国内外可生物降解高吸水性树脂的制备和研究发展状况,并预测今后研究方向和应用前景。     

淀粉基生物降解塑料吹膜工艺及性能研究

通过挤出吹膜的方法制备PBSA/TPS淀粉基生物降解塑料,研究了不同风环结构及吹胀比和牵引比对于吹膜及性能的影响。结果表明:双风口风环可以极大提高PBSA/TPS材料的吹膜膜泡稳定性,而随着吹胀比和牵引比的增大,薄膜的拉伸强度、断裂伸长率和耐撕裂力先增大再减小。     

淀粉基生物降解塑料吹膜工艺及性能研究

通过挤出吹膜的方法制备PBSA/TPS淀粉基生物降解塑料,研究了不同风环结构及吹胀比和牵引比对于吹膜及性能的影响。结果表明:双风口风环可以极大提高PBSA/TPS材料的吹膜膜泡稳定性,而随着吹胀比和牵引比的增大,薄膜的拉伸强度、断裂伸长率和耐撕裂力先增大再减小     

聚合物／蒙脱土纳米复合材料的研究进展

综述了蒙脱土(MMT)的结构特征、蒙脱土的有机化改性、聚合物/蒙脱土纳米复合材料(PMN)的制备方法以及聚合物/蒙脱土纳米复合材料的结构特性及性能特点。     

Permanent,Non‐Leaching Antimicrobial Polyamide Nanocomposites Based on Organoclays Modified with a Cationic Polymer

The intercalation of cationic copolymer into a smectic clay, montmorillonite, has been used to produce polymerically modified organoclays. The organoclays of different lamellar morphology and content of quaternary ammonium groups have been prepared by altering the clay/polymer ratio. The organoclays prepared have been explored in the design of antimicrobial materials based on clay/polymer nanotechnology. Polyamide nanocomposites containing organoclays with incorporated cationic polymer showed an antimicrobial activity and improved mechanical properties. The antimicrobial efficiency and the mechanical properties of the nanocomposites were controlled by the variation of the content of the cationic polymer incorporated into the organoclay and organoclay loading.

     

Preparation and Impedance Analysis of Biodegradable Polymer Polyvinyl Alcohol with Amino Acid,Arginine

Biodegradable polymers have an innumerable use in the field of biomedicine, especially in drug delivery system. Polyvinyl alcohol is one of the biodegradable polymer used as a carrier for drug delivery. Amino acids are necessary for maintaining good health for human beings. The present study focuses on the interaction between polyvinyl alcohol and amino acids. An effort is being taken to prepare polymer membrane based on polyvinyl alcohol complexed with different concentration of arginine, a type of amino acids using water as solvent by solution-casting technique. The amphorousity and complex formation between polyvinyl alcohol and Arignine have been confirmed by X-ray diffraction and FTIR spectroscopy, respecticvely. The thermal behavior of PVA–arginine complexes has been analyzed by differential scanning calorimetry. From AC impedance spectroscopy, ion transport mechanism has been investigated in detail. By using Almond and West formulisms, the parameter such as ion hopping frequency ω_p, has been calculated. The polymer membrane 75 Mwt% PVA:25 Mwt% arginine has the highest ionic conductivity as 1.97 × 10^?6 S cm^?1 at ambient temperature.     

Biodegradable blends based on polyvinyl pyrrolidone for insulation purposes

Polyvinyl pyrrolidone/polyvinyl alcohol (PVP/PVA) and polyvinyl pyrrolidone/starch (PVP/St) blends were prepared with different compositions. The compatibility studies indicate that PVP/PVA is compatible while PVP/St is incompatible. The addition of glycerol and glutaraldehyde can improve to some extent the phase separation behavior between PVP and St. The permittivity ε′ and the dielectric loss ε″ were measured in the frequency range 0.01 Hz up to 10 MHz and temperatures from 30 up to 90°C. It is found that the blend ratio (50/50) of both investigated systems is preferable for insulation purposes in comparable with the other blends under investigation. The data of the loss electric modulus M″ was calculated from the dielectric parameters ε′ and ε″and analyzed into three relaxation mechanisms ascribing the cooperative motion of the main and side chains τ₁ (αβ), the side chain motion τ₂ (β) and the segmental motion of the groups attached to the side chains τ₃ (βγ). The activation energy corresponds to the second relaxation process ΔH₂ was calculated using Arrhenius equation and found to be in the range which justifies the presumption of β‐relaxation process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Development of extrusion blown films of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) blends for flexible packaging

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable polymer with significant potential for use in food packaging. However, its limited melt strength poses a challenge when employing film-blowing techniques to produce flexible packaging. To overcome this obstacle, we developed blends consisting of 70 wt% PHBV and 30 wt% poly(butylene-co-succinate-co-adipate) (PBSA). Organic peroxides such as dicumyl peroxide and 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, were utilized as reactive compatibilizers to enhance the interfacial adhesion between the polymers. Additionally, acetyl tributyl citrate (ATBC) was employed as a plasticizer to improve processability and ductility. The inclusion of organic peroxides resulted in the formation of long-branched structures, as confirmed by the van-Gurp-Palmen plot. The melt flow index decreased from 30 to 9.8 g/10 min without ATBC and 15.5 g/10 min with ATBC. Successful production of blown PHBV/PBSA films was achieved on a pilot scale (bubble height 180 cm). These films exhibited heat-sealing capability and increased impact strength (7.7 kJ/m²). Moreover, the films maintained a maximum elongation at break of 4% during a 3-month storage experiment with frozen food. Food safety was assessed through overall migration experiments, and the non-plasticized films received approval. In conclusion, the compatibilized PHBV/PBSA blends demonstrate great potential as materials for manufacturing film-blown flexible packaging.     

Preparing Exfoliated MMT/Polymer Nanocomposites by Combined Latex Compounding and Spray‐Drying

A facile and easily industrialized approach for preparing highly dispersed MMT/polymer nanocomposites is developed by combining the latex compounding method and a spray‐drying process. Clay particles are successfully delaminated into layers, and layer re‐stacking is effectively prevented. HR‐TEM and XRD results confirm that MMT layers achieve exfoliated or nearly exfoliated dispersion in both MMT/styrene‐butadiene rubber and MMT/PS nanocomposites. Compared with melt‐blended MMT/SBR composites, MMT/SBR nanocomposites prepared by this new strategy exhibit extremely high dynamic modulus.

     

Physico‐Mechanical Properties of Biodegradable Starch Nanocomposites

Nanocomposites of cassava starch reinforced with waxy starch nanocrystals were prepared. They showed a 380% increase of the rubbery storage modulus (at 50 °C) and a 40% decrease in the water vapor permeability. X‐ray spectra show that the composite was more amorphous than the neat matrix, which was attributed to higher equilibrium water content in the composites. TGA confirmed this result and its thermal derivative suggested the formation of hydrogen bonding between glycerol and the nanocrystals. The reinforcing effect of starch nanocrystals was attributed to strong filler/matrix interactions due to the hydrogen bonding. The decrease of the permeability suggests that the nanocrystals were well dispersed, with few filler/filler interactions.

     

Biobased Polyester-Amide/Cellulose Nanocrystal Nanocomposites for Food Packaging

The worldwide plastic waste production is steadily increasing, since the use of polymeric materials continues to rise. One area of particular high plastic consumption is food packaging. Flexible and rigid packaging films are typically made from petrochemical-sourced polymers, which are utilized because of their low cost, ductility, melt-processability, and gas barrier properties, but a major downside is their inability to biodegrade in a reasonable time. Packaging-relevant properties of nanocomposites based on polyester-amides (PEAs) are reported, which are chosen on account of their tunable crystallinity, biobased starting materials, and biodegradability. These polymers are synthesized via melt polycondensation of a building block made from caprolactone and 1,4-diaminobutane, with the addition of 1,4-butanediol and dimethyl adipate. The fraction of the amide segment is varied between 25 and 75 mol%. The oxygen transmission rate (O₂TR) drops upon increasing the amide content from 1.6 × 10⁵ to 2.9 × 10⁻⁴ cm³ m⁻² d⁻¹ on account of increasing crystallinity. In order to improve the gas barrier properties further, nanocomposites of the PEAs and 1–10 wt% cellulose nanocrystals (CNCs) are prepared. These nanocomposites have indeed lower O₂TR values than the neat PEAs, with reductions of as much as 50% for a CNC content of 10 wt%.     

可降解合成高分子静电纺纤维的研究进展

介绍了静电纺丝的原理及利用静电纺丝方法制备生物可降解合成高分子纳米纤维的最新研究进展,主要讲述聚羧基乙酸、聚乳酸、聚己内酯及其共聚物等几种主要的生物可降解合成高分子电纺纤维的研究进展,并指出它们在生物医学领域的重要应用。     

全生物降解塑料的研究与应用

综述了国内外降解塑料领域的最新研究进展和技术、应用成果,介绍了包括天然高分子材料、二氧化碳共聚脂肪族聚碳酸酯、聚羟基烷酸酯、聚己内酯、聚乳酸、聚丁二酸丁二醇酯等常用的全生物降解塑料发展历程、研究进展、性能特点,分析了各种降解塑料的优缺点及其加工应用,简述了各种降解塑料国内外产业化进展、应用及市场情况。     

Biodegradable Porous Microneedles for an Electric Skin Patch

An array of porous microneedles (PMNs) made of biodegradable poly(lactic-co-glycolic acid) (PLGA) is fabricated by a combination of molding and freeze-drying methods. The optimized mixture of PLGA and 1,4-dioxane is poured into a mold of a microneedle array, followed by the freezing and sublimation of the frozen particles of 1,4-dioxane, a procedure that left an interconnecting porous structure in the PLGA with a porosity around 50%. The mechanical strength of the PMN made of PLGA (PLGA-PMN) is reinforced by modification with carboxymethylcellulose (CMC), resulting in sufficient strength enough for insertion into an excised porcine skin. The transdermal resistance is significantly decreased by the CMC-modified PLGA-PMN, which would improve the efficiency and safety of DC current-based transdermal techniques, including the electrical monitoring of the skin condition and iontophoresis for drug delivery and medical diagnosis.