Thermodynamic study of poly(vinyl chloride)/polyester blends by inverse-phase gas chromatography at 120°C

Polymer/polymer interaction parameters χ′₂₃ have been measured at 120°C as a function of polymer concentration for six different poly(vinyl chloride)/linear aliphatic polyester blends. The technique used is inverse-phase gas chromatography with several molecular probes. The polymers investigated are poly(DL-lactide), poly(ethylene succinate), poly(ethylene adipate), poly(butylene adipate), poly(δ-valerolactone), poly(ε-caprolactone) and poly(hexamethylene sebacate). Probe/polymer interaction parameters χ₁₂ and polymer/polymer interaction parameters χ′₂₃ values are dependent upon the methylene to carbonyl ratio of the polyester, reaching a minimum for a value of 5, this ratio corresponding to poly(ε-caprolactone) blends. Results are interpreted in terms of pairwise interactions between carbonyl, methylene, and [CHCl] groups.     

Thermal and mechanical properties of mandelic acid‐copolymerized poly(butylene succinate) and poly(ethylene adipate)

Phenyl side chains were introduced to poly(butylene succinate) and poly(ethylene adipate) by the polymerization of the respective monomers in the presence of mandelic acid. The increasing content of the phenyl side chains decreased the melting temperature and the crystallinity but increased the glass‐transition temperature of the aliphatic polyesters. The phenyl side branches reduced the crystallinity of poly(butylene succinate) more significantly than the ethyl or n‐octyl side branches did. The tensile strength, elongation, and tear strength of poly(ethylene adipate) decreased with an increase in the content of mandelic acid units. However, the increasing content of mandelic acid units enhanced the elongation and tear strength of poly(butylene succinate) considerably without a notable deterioration of tensile strength. The biodegradability of the copolyesters was increased as a result of the introduction of more mandelic acid units due to the decrease in the crystallinity. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1504–1511, 2000     

Novel biodegradable poly(butylene succinate)/poly(ethylene oxide) blend film with compositional and spherulite‐size gradients

Biodegradable poly(butylene succinate) (PBS)/poly(ethylene oxide) (PEO) polymer blend film with compositional gradient in the film thickness direction was prepared using a method of interdiffusion across the interface between the PBS and PEO layers at a temperature above the melting points of both the component polymers. The miscibility between PBS and PEO was confirmed by observation of the glass transition temperature by differential scanning calorimetry. The compositional gradient structure of PBS/PEO was characterized by microscopic mapping measurement of Fourier transform infrared spectra and dynamic mechanical thermal analysis. Furthermore, a new method for confirming the crystalline/crystalline compositional gradient structure through observing the crystallization behavior by POM (polarized optical microscopy) was put forward. A continuous gradient of the spherulite size along the film thickness direction was succeessfully generated in the PBS/PEO blend film. The compositional gradient blend was found to have significantly improved physical properties that cannot be realized for pure PBS, pure PEO, and even their homogeneous miscible blend system. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 368–377, 2005     

Molecular information on the dissolution of polydisperse polymers: Mixtures of long and short poly(ethylene oxide)

A systematic study of the dissolution of dry, polydisperse poly(ethylene oxide) (PEO) samples, obtained from mixtures of low-molecular-weight and high-molecular-weight PEO, was made. During the dissolution process, the individual release of the low- and high-molecular-weight fractions was monitored. The high-molecular-weight/low-molecular-weight ratio controls the release rate, and the fraction of high-molecular-weight polymers dominates the effect on the overall release rate in mixed PEO tablets. Both fractions are released at the same rate during the main part of the dissolution process; however, during the initial dissolution period a fractionation occurs. The release rate is not a unique function of the average molecular weight of the polymer, but also depends on the polydispersity. By contrast, the average dimension of a polymer coil, as given by the intrinsic viscosity, gives a good prediction of the release rate irrespective of the polydispersity or details of the molecular weight distribution.     

Effect of carbon nanotube modification on poly(butylene terephthalate)-based composites

The influence of the chemical modification of carbon nanotubes on the mechanical, thermal and electrical properties of poly(butylene terephthalate)-based composites was investigated. Polymer composites based on poly(butylene terephthalate) were obtained via in situ polymerisation or extrusion. Commercially available multi-walled carbon nanotubes (Nanocyl NC7000) at different loadings (mass %: 0.05, 0.25, 1, 2) were used as fillers. The functionalisation process took place under a chlorine atmosphere followed by a reaction with sodium hydroxide. The effect of carbon nanotube modification was analysed according to the changes in the polymer thermal and mechanical properties. An addition of modified carbon nanotubes in the amount of 0.05 mass % improved the mechanical properties of the composites in terms of both Young’s modulus and tensile strength by 5–10 % and 17–30 % compared with composites with unmodified carbon nanotubes and neat poly(butylene terephthalate), respectively. The in situ method of composite preparation was a more effective technique for enhancing the matrix-filler interactions, although a significantly lower amount of fillers were used than in the extrusion method.     

The enzymatic degradation of commercial biodegradable polymers by some lipases and chemical degradation of them

Biodegradable polyesters, poly(butylene succinate adipate) (PBSA), poly(butylene succinate) (PBS), poly(ethylene succinate) (PES), poly(butylene succinate)/poly(caprolactone) blend (HB02B) and poly(butylene adipate terephthalate) (PBAT), were evaluated about degradability for enzymatic degradation by lipases and chemical degradation in sodium hydroxide solution. In enzymatic degradation, PBSA was the most degradable by lipase PS, on the other hand, PBAT containing aromatic ring was little degraded by eleven kinds of lipases. In 1N NaOH solution, degradation rate of PES with ethylene unit was extremely fast, in comparison with other polyesters. Interestingly the degradation rate of PBSA in enzymatic degradation by lipase PS was faster than in chemical degradation.     

Needle-free electrospinning of nanofibrillated cellulose and graphene nanoplatelets based sustainable poly (butylene succinate) nanofibers

Sustainable materials have slowly overtaken the nanofiber research field while the tailoring of their properties and the upscaling for industrial production are some of the major challenges. We report preparation of nanofibers that are bio-based and biodegradable prepared from poly (butylene succinate) (PBS) with the incorporation of nanofibrillated cellulose (NFC) and graphene nanoplatelets (GN). NFC and GN were combined as hybrid filler, which led to the improved morphological structure for electrospun nanofibers. A needleless approach was used for solution electrospinning fabrication of nanofiber mesh structures to promote application scalability. The polymer crystallization process was examined by differential scanning calorimetry (DSC), the thermal stability was evaluated by thermal gravimetric analysis (TGA), while the extensive investigation of the nanofibers structure was carried out with scanning electron microscopy (SEM) and atomic force microscopy (AFM). NFC and GN loadings were 0.5 and 1.0 wt %; while poly (ethylene glycol) (PEG) was employed as a compatibilizer to enhance fillers’ interaction within the polymer matrix. The interactions in the interface of the fillers and matrix components were studied by FTIR and Raman spectroscopies. The hybrid filler approach proved to be most suitable for consistent and high-quality nanofiber production. The obtained dense mesh-based structures could have foreseeable potential application in biomedical field like scaffolds for the tissue and bone recovery, while other applications could focus on filtration technologies and smart sensors.     

Biodegradable poly(alkylene succinate) blends: Thermal behavior and miscibility study

New binary blends composed of poly(ethylene succinate) and poly(propylene succinate) or poly(ethylene succinate) and poly(butylene succinate) were prepared. Both PESu/PPSu and PESu/PBSu systems belong to semicrystalline/semicrystalline pairs. The miscibility and crystallization behavior was investigated using differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXD), and polarizing light microscopy (PLM). Blends of PESu and PPSu exhibited a single composition dependent glass transition temperature over the entire range of composition, indicating that the system is miscible. The melting point depression of the high melting temperature component, PESu, was analyzed according to the Nishi‐Wang equation. A negative polymer–polymer interaction parameter was obtained, indicating that the blends are thermodynamically miscible in the melt. The two components crystallized sequentially when the blends were cooled rapidly to a low temperature. DSC traces of PESu/PBSu blends after quenching showed two distinct composition dependent glass transition temperatures between those of the neat polymers, showing that the polymers are partially miscible. The amorphous PESu/PBSu blends in the intermediate compositions showed three cold‐crystallization peaks, indicating the influence of mixing. The crystallization rates of PBSu were reduced and those of PESu were increased. WAXD showed reduced crystallinity and peak broadening in the patterns of the blends of intermediate compositions, while no spherulites could be detected by PLM. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 584–597, 2006     

聚2,5-呋喃二甲酸乙二醇酯/聚丁二酸丁二醇酯共混物的制备与表征

通过熔融共混制备了聚2,5-呋喃二甲酸乙二醇酯(PEF)/聚丁二酸丁二醇酯(PBS)共混物,探究了制备PEF/PBS共混物的影响因素,考察了共混温度、共混时间、螺杆转速、共混比例对PEF/PBS共混物力学性能的影响因素,并用示差扫描量热仪、热失重、扫描电子显微镜等技术手段对其热性能和相容性进行了表征。 结果表明,当PBS的含量为15%、共混温度为230 ℃,共混时间为90 s、螺杆转速为150 r/min时,为最佳共混制备条件,此时相容性最好,热性能良好,冲击强度和拉伸强度最大,冲击强度相对纯PEF提高了6倍,拉伸强度提高了近20%,从而大幅提高了PEF的冲击强度,有效地增强了PEF的抗冲击韧性。 这些工作为这一生物基聚酯材料的应用提供了可能。     

HDI作为扩链剂合成含PLLA和PBS链段的聚酯氨酯

以数均分子量为6350g/mol端羟基聚L-乳酸(PLLA-OH)与10500g/mol端羟基聚丁二酸丁二酯(PBS-OH)为预聚物,六亚甲基二异氰酸酯(HDI)为扩链剂,通过熔融反应制备了分子量高达30×104g/mol的可完全生物降解聚酯氨酯(PEU).研究了异氰酸根(NCO)与羟基比例对扩链反应的影响.结果表明,当[NCO]/[OH]=1∶1时,扩链效果最好,PEU分子量最大;PEU分子量随着预聚物中PBS含量增大而提高.通过核磁共振谱(1H-NMR)确定了PEU的结构与组成,并对聚酯氨酯进行了凝胶渗透色谱(GPC)、差示扫描量热(DSC)、热重分析(TGA)以及拉伸性能测试.DSC结果显示,扩链后PEU的结晶主要由PBS链段产生,而PLLA链段几乎不结晶;TGA结果表明,PEU的热降解分两步进行,第一步为PEU中PLLA链段的热降解,第二段为其中PBS链段的降解;拉伸测试结果表明,PBS与PLLA的共聚能够制备拉伸强度与断裂伸长率优异的聚合物材料.     

Polyurethane/montmorillonite nanocomposites prepared from crystalline polyols, using 1,4-butanediol and organoclay hybrid as chain extenders

Polyurethane/montmorillonite (PU/MMT) nanocomposites were prepared via in situ polymerization from highly crystalline poly(butylene succinate)/poly(ethylene glycol) polyols and 4,4^′-dicyclohexylmethane diisocyanate, using both 1,4-butanediol and 1, 2, or 3 wt.% of a tris(hydroxymethyl)aminomethane-MMT hybrid, as chain extenders. The corresponding nanocomposites were designated PU-1MMT, PU-2MMT and PU-3MMT, respectively. The layered silicates were mostly intercalated in the nanocomposites. The distances between the individual silicate layers in the PU-1MMT and PU-2MMT were in the range of 2-10 nm, while those in the PU-3MMT were only about 2 nm. The inefficient exfoliation of the clay in this system was mainly due to the high crystallinity and polarity of the PBS polyol. There were no significant changes in the thermal properties of the pure PU and PU nanocomposites. However, the tensile modulus and elongation of the PU-2MMT at break were significantly greater than those of the pure PU and PU-3MMT.     

Nature and properties of ionomer assemblies. II

The principle subject in the current paper is to summarize and characterize the ionomers based on polymers and copolymers such as polystyrene (PSt), polyisoprene (PIP), polybutadiene (PB), poly(styrene-b-isobutylene-b-styrene) (PSt-PIB-PSt), poly(butadiene-styrene) (PB-PSt), poly(ethylene terephthalate) (PET), poly(butylene adipate) (PBA), poly(butylene succinate) (PBSi), poly(dimethylcarbosiloxanes), polyurethane, etc. The self-assembly of ionomers, models concerning ionomer morphologies, physical and rheological properties of ionomer phase and percolation behavior of ionomers were discussed. The ionomer phase materials and dispersions have been characterized by differential scanning calorimetry (DSC), small-angle X-ray catering (SAXS), small-angle neutron scattering (SANS), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), etc. The wide range of compositions, molecular architectures, and morphologies present in ionomeric disperse systems are of great interest. The research is particularly devoted to the potential application of these materials and an understanding of the fundamental principles of the ionomers. They are extremely complex systems, sensitive to changes in structure and composition, and therefore not easily amenable to modeling and to the derivation of general patterns of behavior. The reviewed data indicate that a large number of parameters are important in influencing multiplet formation and clustering in random ionomers. Among these are the ion content, size of the polyion and counterion, dielectric constant of the host, T(g) of the polymer, rigidity or persistence length of the backbone, position of the ion pair relative to the backbone, steric constraints, amount and nature of added additive (plasticizer), thermal history, etc.     

Liquid chromatography under limiting conditions of desorption 4 separation of blends containing low-solubility polymers

Low solubility polymers, poly(ethylene terephthalate), PET and poly(butylene terephthalate), PBT were mutually separated at ambient temperature with help of a novel method, liquid chromatography under limiting conditions of desorption, LC LCD. The results demonstrate high selectivity of LC LCD, which enabled discrimination of macromolecules of well similar chemical structure, irrespectively of their molar mass. Above poly(terephthalate)s were also readily base-line separated from the aliphatic biodegradable polyesters poly(l-lactic acid) and poly(butylene adipate). The experimentally feasible LC LCD method produces narrow, focused peaks of polymers eluted behind the adsorption promoting barrier of appropriate liquid. This merit of LC LCD enables discrimination and identification of minor macromolecular constituents of multicomponent polymers and facilitates the application of method as an integral part of two-dimensional liquid chromatography for comprehensive molecular characterization of complex polymer systems.     

Reactive TiO2 Nanoparticles Compatibilized PLLA/PBSU Blends:Fully Biodegradable Polymer Composites with Improved Physical,Antibacterial and Degradable Properties

The fully biodegradable polymer blends remain challenges for the application due to their undesirable comprehensive performance.Herein,remarkable combination of superior mechanical performance,bacterial resistance,and controllable degradability is realized in the biodegradable poly(L-lactide)/poly(butylene succinate) (PLLA/PBSU) blends by stabilizing the epoxide group modified titanium dioxide nanoparticles (m-TiO2) at the PLLA-PBSU interface through reactive blending.The m-TiO2 can not only act as interfacial compatibilizer but also play the role of photodegradation catalyst:on the one hand,binary grafted nanoparticles were in situ formed and stabilized at the interface to enhance the compatibility between polymer phases.As a consequence,the mechanical properties of the blend,such as the elongation at break,notched impact strength and tensile yield strength,were simultaneously improved.On the other hand,antibacterial and photocatalytic degradation performance of the composite films was synergistically improved,it was found that the m-TiO2 incorporated PLLA/PBSU films exhibit more effective antibacterial activity than the neat PLLA/PBSU films.Moreover,the analysis of photodegradable properties revealed that that m-TiO2 nanoparticles could act as a photocatalyst to accelerate the photodegradation rate of polymers.This study paves a new strategy to fabricate advanced PLLA/PBSU blend materials with excellent mechanical performance,antibacterial and photocatalytic degradation performance,which enables the potential utilization of fully degradable polymers.     

Enhanced interfacial adhesion,mechanical, and thermal properties of natural flour-filled biodegradable polymer bio-composites

This study examined the interfacial adhesion, mechanical, and thermal properties of compatibilizing agent-treated and non-treated biocomposites as a function of the type of compatibilizing agent. The tensile strength, interfacial adhesion, and heat deflection temperature (HDT) of maleic anhydride-grafted poly(butylene succinate) (PBS-MA) and maleic anhydride-grafted poly(lactic acid) (PLA-MA)-treated biocomposites are greater than those of untreated maleic anhydride-grafted poly(styrene-b-ethylene-co-butylene-b-styrene) triblock copolymer (SEBS-MA) and maleic anhydride-grafted polypropylene (MAPP)-treated biocomposites. The storage modulus (E′) values and the tan δ_max temperatures (T _g) of PBS-MA and PLA-MA-treated biocomposites were slightly higher than that of the untreated biocomposites.     

Synthesis and characterization of biodegradable aliphatic copolyesters with poly(ethylene oxide) soft segments

A series of multiblock poly(ether-ester)s based on poly(butylene succinate) (PBS) as the hard segments and hydrophilic poly(ethylene oxide) (PEO) as the soft segments was synthesized with the aim of developing degradable polymers which could combine the mechanical properties of high performance elastomers with those of flexible plastics. The aliphatic poly(ether-ester)s were synthesized by the catalyzed two-step transesterification reaction of dimethyl succinate, 1,4-butanediol and α,ω-hydroxyl terminated poly(ethylene oxide) (PEO, = 1000 g/mol) in bulk. The content of soft PEO segments in the polymer chains was varied from about 10 to 50 mass%. The effect of the introduction of the soft PEO segments on the structure, thermal and physical properties, as well as on the biodegradation properties was investigated. The composition and structure of these aliphatic segmented copolyesters were determined by ¹H NMR spectroscopy. The molecular weights of the polyesters were verified by gel permeation chromatography (GPC), as well as by viscometry of dilute solutions and polymer melts. The thermal properties were investigated using differential scanning calorimetry (DSC). The degree of crystallinity was determined by means of DSC and wide-angle X-ray scattering. A depression of melting temperature and a reduction of crystallinity of the hard segments with increasing content of PEO segments were observed. Biodegradation of the synthesized copolyesters, estimated in enzymatic degradation tests in phosphate buffer solution with Candida rugosa lipase at 37 °C was compared with hydrolytic degradation in the buffer solution. The weight losses of the samples were in the range from 2 to 10 mass%. GPC analysis confirmed that there were significant changes in molecular weight of copolyesters with higher content of PEO segments, up to 40% of initial values. This leads to conclusion that degradation mechanism of the poly(ether-ester)s based on PEO segments occurs through bulk degradation in addition to surface erosion.     

Structure–property relationship of octa‐substituted POSS in thermal and mechanical reinforcements of conventional polymers

In this article, we describe the structure–property relationships between the polyoctahedral oligomeric silsesquioxane (POSS) fillers and the thermomechanical properties of the polymer composites using polystyrene, poly(methyl methacrylate), and ethylene‐(vinyl acetate) copolymer. We used eight kinds of octa‐substituted aliphatic and aromatic POSS as a filler, and homogeneous polymer composites were prepared with various concentrations of these POSS fillers. From a series of measurements of thermal and mechanical properties of the polymer composites, it was summarized that the longer alkyl chains and unsaturated bonds at the side chains in POSS are favorable to improve the thermal stability and the elasticity of polymer matrices. It was found that phenyl‐POSS can show superior ability to improve the thermomechanical properties of conventional polymers used in this study. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5690–5697, 2009     

Properties of a nanocomposite polymer electrolyte from an amorphous comb-branch polymer and nanoparticles

Three fully amorphous comb-branch polymers based on poly(styrene-co-maleic anhydride) as a backbone and poly(ethylene glycol) methyl ether of different molecular weights as side chains were synthesized. SiO₂ nanoparticles of various contents and the salt LiCF₃SO₃ were added to these comb-branch polymers to obtain nanocomposite polymer electrolytes. The thermal and transport properties of the samples have been characterized. The maximum conductivity of 2.8×10^–4 S cm^–1 is obtained at 28 °C. In the system the longer side chain of the comb-branch polymer electrolyte increases in ionic conductivity after the addition of nanoparticles. To account for the role of the ceramic fillers in the nanocomposite polymer electrolyte, a model based on a fully amorphous comb-branch polymer matrix in enhancing transport properties of Li⁺ ions is proposed.     

Poly(butylene succinate) and graphene nanoplatelet–based sustainable functional nanocomposite materials: structure-properties relationship

Sustainable functional polymer nanocomposites from renewable resources are extremely promising materials that can provide the next-generation of lightweight, multifunctional materials for several applications including energy storage, automotive, construction, defense, aerospace, consumer products, biomedical and functional coatings to name few. There is limited information on the use of sustainable polymers and graphene nanoplatelets (GNs), as well as the combinations of these two can provide reduced water permeability or enhanced electrical conductivity and improved thermal properties, and so on. Building upon this hypothesis, biobased poly(butylene succinate)/few-layer GN nanocomposites were prepared via a solventless melt-blending technique. Different characterization techniques such as differential scanning calorimetery, thermogravimetric analysis, dynamic mechanical analysis, dielectric spectroscopy, X-ray diffraction (XRD) and hot stage optical microscopy were used to study the thermal and structural characteristics. The melt blending was characterized by torque and temperature curves which showed that torque was reduced by up to 15 Nm, and melt temperature was improved by up to 5 °C. The improved crystallization of the composites in low concentrations of GN was observed. Graphene has been found to increase the crystallization temperature up to 10 °C and yielded pronounced spherulite structure, whereas peak shift was observed in XRD. High filler loading from 0.5 to 6.0 wt% was used to obtain more insights for few-layer graphene applications for thermoplastic polymer processing applications.