Biodegradable polymer blends and composites: An overview

Biodegradable polymers belong to a family of polymer materials that found applications ranged from medical applications including tissue engineering, wound management, drugs delivery, and orthopedic devices, to packaging and films applications. For broadening their potential applications, biodegradable polymers are modified utilizing several methods such as blending and composites forming, which lead to new materials with unique properties including high performance, low cost, and good processability. This paper reviews the recent information about the morphology of blends consisting of both biodegradable and non-biodegradable polymers and associated mechanical, rheological, and thermal properties of these systems as well as their degradation behavior. In addition, the mechanical performance of composites based on biodegradable polymers is described.     

Characterization of Engineering Polymers by Dynamic Mechanical Analysis

There is a growing need for the use of polymers in high-strength and engineering applications, and many new materials and composites have been developed to satisfy this need. Traditionally, thermosetting polymers have been employed as high-strength materials, with the incorporation of various fillers or additives to improve shortcomings in strength and temperature performance. Although these materials are largely unrivaled in high-temperature performance, some of the newer engineering thermoplastics, such as poly(ether ether ketone)(PEEK), poly(ether sulfone) (PES), poly(pheny1ene sulfide) (PPS), and the new backbone liquid-crystal polymers are becoming much more widely used. With this widespread use and with the increasing complexity of polymer blends and composites, there is a strong requirement for a universal means of characterizing such materials in terms of mechanical properties and high-temperature performance. A powerful and versatile analytical technique which is capable of application to a very wide range of materials is that of dynamic mechanical spectrometry. This technique can be used to establish basic material relaxation temperatures and frequencies, the modulus and loss behavior, as well as factors such as degree of cure, fder/matrix bonding, and phase separation.     

Poly(vinyl chloride) Nanocomposites

Poly(vinyl chloride) is one of the major thermoplastics beside other commodities polymers like polyethylene and polystyrene. However, some of its main characteristics such as plasticity, thermal and photo stability are inferior to other commodity polymers. Adding nano scale inorganic fillers to poly(vinyl chloride) or other polymers in view to obtain polymer nanocomposites with superior properties has drawn the attention of many researchers in the last decades. Poly(vinyl chloride) nanocomposites are obtained mainly by in situ polymerization, solution based or mixing techniques. The resulting products show improvement of most important properties of poly(vinyl chloride) such as thermal, mechanical, rheological, flammability, antibacterial, etc. This paper presents preparation ways of poly(vinyl chloride) nanocomposites using different nano fillers and the improved properties compared with those of virgin poly(vinyl chloride).     

The processing of starch as a thermoplastic

The thermoplastics processing of native starch in the presence of water is a recent development with very wide possible applications. Eventually, oil-based polymer materials have to be replaced in many applications by sustainable, inexpensive, natural materials from renewable resources. As with conventional thermoplastics, starch-water melts may be processed by injection moulding and extrusion. The present contribution focuses on injection moulding. The bases of the processing and the thermal and molecular changes occurring are described. In addition, the rheological behaviour of the starch-water melts during processing is analysed quantitatively to give apparent melt viscosities. The dimensional, thermal and mechanical properties of moulded thermoplastic starch polymer (TSP) materials and the products presently being produced from them are discussed.     

Beyond PDMS: off-stoichiometry thiol-ene (OSTE) based soft lithography for rapid prototyping of microfluidic devices

In this article we introduce a novel polymer platform based on off-stoichiometry thiol-enes (OSTEs), aiming to bridge the gap between research prototyping and commercial production of microfluidic devices. The polymers are based on the versatile UV-curable thiol-ene chemistry but takes advantage of off-stoichiometry ratios to enable important features for a prototyping system, such as one-step surface modifications, tuneable mechanical properties and leakage free sealing through direct UV-bonding. The platform exhibits many similarities with PDMS, such as rapid prototyping and uncomplicated processing but can at the same time mirror the mechanical and chemical properties of both PDMS as well as commercial grade thermoplastics. The OSTE-prepolymer can be cast using standard SU-8 on silicon masters and a table-top UV-lamp, the surface modifications are precisely grafted using a stencil mask and the bonding requires only a single UV-exposure. To illustrate the potential of the material we demonstrate key concepts important in microfluidic chip fabrication such as patterned surface modifications for hydrophobic stops, pneumatic valves using UV-lamination of stiff and rubbery materials as well as micromachining of chip-to-world connectors in the OSTE-materials.     

Novel Thermoplastic Composites from Commodity Polymers and Man-Made Cellulose Fibers

Summary: A new class of fibre reinforced commodity thermoplastics suited for injection moulding and direct processing applications has been developed using man-made cellulosic fibres (Rayon tire yarn, Tencel, Viscose, Carbacell) and thermoplastic commodity polymers, such as polypropylene (PP), polyethylene (PE), high impact polystyrene (HIPS), poly(lactic acid) (PLA), and a thermoplastic elastomer (TPE) as the matrix polymer. For compounding, a specially adapted double pultrusion technique has been employed which provides composites with homogeneously distributed fibres. Extensive investigations were performed with Rayon reinforced PP in view of applications in the automotive industry. The Rayon-PP composite is characterized by high strength and an excellent impact behaviour as compared with glass fibre reinforced PP, thus permitting applications in the field of engineering thermoplastics such as polycarbonate/acrylonitrile butadiene styrene blends (PC/ABS). With the PP based composites the influence of material parameters (e.g. fibre type and load, coupling agent) were studied and it has been demonstrated how to tailor the desired composite properties as modulus and heat distortion temperature (HDT) by varying the fibre type or adding inorganic fillers. Man-made cellulose fibers are also suitable for the reinforcement of further thermoplastic commodity polymers with appropriate processing temperatures. In case of PE modulus and strength are tripled compared to the neat resin while Charpy impact strength is increased five-fold. For HIPS mainly strength and stiffness are increased, while for TPE the property profile is changed completely. With Rayon reinforced PLA, a fully biogenic and biodegradable composite with excellent mechanical properties including highly improved impact strength is presented.     

A state-of-the-art review on particulate wood polymer composites: Processing,properties and applications

In the present decade, the demands for recyclable, environmentally friendly and low-cost with good strength composites materials have been significantly increased. In this context, the particulate wood polymer composites have attracted the researchers owing to their eco-friendliness, low-cost as they are prepared using waste wood particles, and good mechanical and physical properties. These composites were prepared by filling the waste wood particles into the polymers using different fabrication methods such as extrusion, hand layup, compression moulding, injection moulding and additive manufacturing (3D printing). A good number of research works have been reported on the testing and characterization of wood composites for the various applications so far. This fact motivated to prepare a state-of-the-art review on the recent developments in processing, characterization, and applications of wood composites. This paper presents a discussion on the chemical structure and properties of different types of wood species. The mechanical, thermal and water absorption behaviour of thermosets, thermoplastics and biopolymers based wood composites have also been discussed. Further, characterization of the nano biocomposites prepared using nanocellulose/nanoparticles of wood are also presented. The outcomes of the present review provide a good understanding of wood composites that will encourage the researchers for further research works & developments of novel wood composites for the advanced applications.     

Thermal,mechanical and morphological properties of multicomponent blends based on acrylic and styrenic polymers

Multicomponent polymer blends afford polymeric materials with specific properties for many applications. The effect of different chemical structures on the miscibility and compatibility of polymer blends composed of multicomponent acrylic and styrenic polymers was studied in this research. The influence of each component on the thermal, mechanical, and morphological properties, as well as optical transparency, was analyzed in poly (methyl methacrylate), homopolymer (PMMAh), or copolymer (PMMAe) blends where the minority constituents formed by polystyrene (PS), styrene-acrylonitrile copolymer (SAN) or acrylonitrile-butadiene-styrene terpolymer (ABS). The results showed significant changes in the properties of these mixtures due to the effect of the type of chemical structure and different elastomeric domains of the majority and minority components of polymer blends.     

Thermoplastic Starch

The thermoplastics processing of native starch in the presence of water is a recent development with very wide possible applications. Eventually, oil-based polymer materials have to be replaced in many applications by sustainable, inexpensive, natural materials from renewable resources. The present contribution focuses on the injection moulding of starch. The bases of the processing and the thermal and molecular changes occurring are described. In addition, the rheological behaviour of starch-water melts during processing is analysed quantitatively to give apparent melt viscosities. The dimensional, thermal and mechanical properties of moulded thermoplastic starch polymer (TSP) materials and the products presently being produced from them are discussed.     

The effect of crosslinking on thermal and mechanical properties of perfluorocyclobutane aromatic ether polymers

As the minimum features in semiconductor devices decrease, it is a new trend to incorporate copper and polymers with dielectric constant less than 3.0 to enhance the performance of the devices. Two fluorinated polymers, poly(biphenyl perfluorocyclobutyl ether) (BPFCB) and poly(1,1,1-triphenyl ethane perfluorocyclobutyl ether) (PFCB), are newly developed polymers with dielectric constants below 3.0. These two polymers have a similar backbone structure, but PFCB has the capability of crosslinking. To know the implications of these two polymers in the semiconductor industry, properties that are important for the integral reliability of Integral Circuits (IC), such as thermal and mechanical properties, should be understood. This comparative study shows that the crosslinking in perfluorocyclobutane aromatic ether polymer can reduce vertical thermal expansion and increase glass transition temperature (T_g) while water absorption, crystalline-like phase, and dielectric constant are slightly increased. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1383–1392, 1998     

High-velocity stretching of polyolefin tapes

Stretched polyolefin films and tapes are used in many packaging applications, such as BigBags. Stretching is elongation of polymer tapes in one direction, resulting in improved mechanical properties. Both, amorphous and crystalline polymers are in principle stretchable but linear, unbranched macromolecules are highly stretchable. Hence, the stretchability of e.g. branched low density polyethylene (PE-LD) is lower than of high-density polyethylene (PE-HD). Basic requirements for stretching of thermoplastics are known, but correlations between material parameters and stretching behaviour are scarce. Moreover, stretching of polymers is usually studied with tensile tests at stretching velocities much lower (1–500 mm/min) than in industrial processes (400–1000 mm/s), while results from high-velocity stretching tests or on production machines have not been published as of yet. We investigated high-velocity (800 mm/s) stretching of PE-LD, PE-HD and isotactic polypropylene films and tapes and which stretching parameters resulted in maximum mechanical properties. It was found that sample geometry, temperature, and the degree of stretching have a significant influence on the properties of stretched tapes, e.g. higher stretching temperature resulted in higher mechanical properties and orientation of crystallites. Furthermore, about 80% of the maximum stretching degree resulted in maximum mechanical properties.     

Recycling of waste from polymer materials: An overview of the recent works

Polymer recycling is a way to reduce environmental problems caused by polymeric waste accumulation generated from day-to-day applications of polymer materials such packaging and construction. The recycling of polymeric waste helps to conserve natural resource because the most of polymer materials are made from oil and gas. This paper reviews the recent progress on recycling of polymeric waste form some traditional polymers and their systems (blends and composites) such as polyethylene (PE), polypropylene (PP), and polystyrene (PS), and introduces the mechanical and chemical recycling concepts. In addition, the effect of mechanical recycling on properties including the mechanical, thermal, rheological and processing properties of the recycled materials is highlighted in the present paper.     

Graphene‐polymer nanocomposites for biomedical applications

Despite the significant efforts in the synthesis of new polymers, the mechanical properties of polymer matrices can be considered modest in most cases, which limits their application in demanding areas. The isolation of graphene and evaluation of its outstanding properties, such as high thermal conductivity, superior mechanical properties, and high electronic transport, have attracted academic and industrial interest, and opened good perspectives for the integration of graphene as a filler in polymer matrices to form advanced multifunctional composites. Graphene‐based nanomaterials have prompted the development of flexible nanocomposites for emerging applications that require superior mechanical, thermal, electrical, optical, and chemical performance. These multifunctional nanocomposites may be tailored to synergistically combine the characteristics of both components if proper structural and interfacial organization is achieved. The investigations carried out in this aim have combined graphene with different polymers, leading to a variety of graphene‐based nanocomposites. The extensive research on graphene and its functionalization, as well as polymer graphene composites, aiming at applications in the biomedical field, are reviewed in this paper. An overview of the polymer matrices adequate for the biomedical area and the production techniques of graphene composites is presented. Finally, the applications of such nanocomposites in the biomedical field, particularly in drug delivery, wound healing, and biosensing, are discussed.     

Synthesis and characterization of metal-incorporated aniline formaldehyde resin modified by amino acid for antimicrobial applications

Advances in metal incorporated resins are now an active field of research. To develop resin having better antimicrobial and thermal activity, a series of metal-chelated resins have been synthesized by the condensation of (4-aminobenzene-1,3-diyl)dimethanol with 2,6-diaminohexanoic acid in alkaline medium and then this polymeric ligand further reacts with transition metal ions forming various coordination polymers. (4-Aminobenzene-1,3-diyl)dimethanol was initially prepared by the reaction of aniline and formaldehyde in 1?:?2 molar ratio in alkaline medium. The analytical data reveal that the polymer metal complexes of Mn(II), Co(II), and Ni(II) are coordinated with two water molecules, which are further supported by FTIR spectra and TGA data. Comparative analyses of the polymer metal complexes in thermal curves show better thermal stability than the polymeric ligand. Since these resins are relatively stable at high temperatures, they can be used for medical and biomaterial applications requiring thermal sterilization, solvent-resist coating materials because of their insoluble nature, and antifouling coating materials owing to antimicrobial activity in ?elds such as life-saving medical devices and the bottoms of ships.     

Novel photoluminescent polymers containing oligothiophene and m-phenylene-1,3,4-oxadiazole moieties: synthesis and spectroscopic and electrochemical studies

Three conjugated polymers containing oligothiophene units (from one to three thiophene rings) and aromatic 1,3,4-oxadiazole moieties have been successfully synthesized. The polymer structures were characterized and confirmed by (1)H and (13)C NMR, FT-IR, and elemental analysis. Thermogravimetric analysis demonstrated that the polymers are highly thermal stable. Tunable absorption (from 342 to 428 nm) and fluorescence (from 411 to 558 nm) properties of polymers were observed. The electrochemical investigation indicated that the LUMO and HOMO energy levels of the new polymers could be adjusted. It was also revealed by the electrochemical analysis that the polymers have good charge injection properties for both p-type and n-type charge carriers, as well as good color tunable luminescence and film-forming properties, which makes them potentially useful for fabricating efficient light-emitting devices.     

Conductive polymer blends: preparation,properties and applications

This article presents a brief review concerning the production of conductive polymer blends and composites which combine conducting and insulating polymers. Different strategies for preparing these mixtures are examined, with emphasis on several properties of the final mixtures, such as: electronic conductivity, mechanical behaviour and thermal stability. The advantages of using blends in some technological applications instead of pure conducting polymers are discussed.     

Modern mass spectrometry in the characterization and degradation of biodegradable polymers

In the last decades, the solid-waste management related to the extensively growing production of plastic materials, in concert with their durability, have stimulated increasing interest in biodegradable polymers. At present, a variety of biodegradable polymers has already been introduced onto the market and can now be competitive with non biodegradable thermoplastics in different fields (packaging, biomedical, textile, etc.). However, a significant economical effort is still directed in tailoring structural properties in order to further broaden the range of applications without impairing biodegradation. Improving the performance of biodegradable materials requires a good characterization of both physico-chemical and mechanical parameters. Polymer analysis can involve many different features including detailed characterization of chemical structures and compositions as well as average molecular mass determination. It is of outstanding importance in troubleshooting of a polymer manufacturing process and for quality control, especially in biomedical applications. This review describes recent trends in the structural characterization of biodegradable materials by modern mass spectrometry (MS). It provides an overview of the analytical tools used to evaluate their degradation. Several successful applications of MALDI-TOF MS (matrix assisted laser desorption ionization time of flight) and ESI MS (electrospray mass spectrometry) for the determination of the structural architecture of biodegradable macromolecules, including their topology, composition, chemical structure of the end groups have been reported. However, MS methodologies have been recently applied to evaluate the biodegradation of polymeric materials. ESI MS represents the most useful technique for characterizing water-soluble polymers possessing different end group structures, with the advantage of being easily interfaced with solution-based separation techniques such as high-performance liquid chromatography (HPLC).     

The characterization of polymer deformation by rheo-optical fourier-transform infrared spectroscopy

The mechanical properties of polymeric materials are of considerable importance to their engineering applications. Apart from the chemical structure and the thermal history, molecular orientation has a major influence on the mechanical properties of a polymer. The increased need for more detailed data and a better understanding of the mechanisms involved in polymer deformation has led to the search for new experimental techniques to characterize transient structural changes during mechanical processes. With the advent of rapid-scanning Fourier - transform infrared (FTIR) spectroscopy, simultaneous vibrational spectroscopic and mechanical (so-called rheo-optical) measurements during the deformation of polymers have emerged as a very informative probe for the study of deformation and relaxation phenomena in polymer films in the late seventies and have since then been applied to obtain data on strain-induced crystallization and orientational and conformational changes during mechanical treatment of a wide variety of polymers.     

共轭聚合物发光和光伏材料研究进展

聚合物光电功能材料与器件因其广阔的应用前景,1990年以年来吸引了世界各国学术界的广泛关注和兴趣.聚合物光电子器件主要包括聚合物电致发光二极管、聚合物场效应晶体管和聚合物太阳能电池等,其使用的关键材料是共轭聚合物光电子材料,包括共轭聚合物发光材料、场效应晶体管材料和光伏材料等.本文主要对共轭聚合物电致发光材料和光伏材料的研究进展进行综述,介绍了这些聚合物材料的种类、结构和性质以及在聚合物电致发光器件和聚合物太阳能电池中的应用.并讨论了当前共轭聚合物光电子材料中的关键科学问题和今后的发展方向.     

Dual-functional,aromatic, epoxy-methacrylate monomers from bio-based feedstocks and their respective epoxy-functional thermoplastics

Dual-functional monomers consist of two distinctly different functional groups that enable chemical versatility. The most readily available epoxy-methacrylate dual-functional monomer is glycidyl methacrylate (GMA). In an effort to produce bio-based, aromatic complements to GMA, asymmetric phenolic diols (vanillyl alcohol, syringyl alcohol, gastrodigenin, and tyrosol) were identified and selectively epoxidized at the aromatic hydroxyl followed by subsequent esterification at the aliphatic hydroxyl to prepare dual functional monomers, vanillyl alcohol epoxy-methacrylate (VAEM), syringyl alcohol epoxy-methacrylate (SAEM), gastrodigenin epoxy-methacrylate (GDEM), and tyrosol epoxy-methacrylate (TEM). These monomers are viable platforms for a multitude of applications due to their unique chemical functionalities. VAEM, SAEM, GDEM, and TEM were homopolymerized individually to produce aromatic, bio-based epoxy-functional thermoplastics analogous to poly(GMA). The molecular weight distributions and thermal properties of each polymer were evaluated, as were the surface characteristics of flow-coated thin films from these polymers. Most of the newly prepared epoxy-functional thermoplastics exhibited increased thermal stability (initial decomposition temperatures >260 °C in air) relative to poly(GMA), while retaining similar glass transition temperatures (~ 65 °C) and surface energies (~ 53 mJ m⁻²); thus, these materials could be substituted for poly(GMA) and enable use in higher-temperature applications. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 673–682