3D-MID Technology for surface modification of polymer-based composites: a comprehensive review

The three-dimensional molded interconnected device (3D-MID) has received considerable attention because of the growing demand for greater functionality and miniaturization of electronic parts. Polymer based composite are the primary choice to be used as substrate. These materials enable flexibility in production from macro to micro-MID products, high fracture toughness when subjected to mechanical loading, and they are lightweight. This survey proposes a detailed review of different types of 3D-MID modules, also presents the requirement criteria for manufacture a polymer substrate and the main surface modification techniques used to enhance the polymer substrate. The findings presented here allow to fundamentally understand the concept of 3D-MID, which can be used to manufacture a novel polymer composite substrate

Overall Investigation of Poly (Phenylene Sulfide) from Synthesis and Process to Applications—A Review

Poly (phenylene sulfide) (PPS) is one kind of high‐performance polymer with high thermal stability that can be used widely in different industrial domains. However, according to an investigation of the literature, few reviews have comprehensively focused on the continuous development of PPS applications in the past decade. To meet this demand, this paper provides an overall investigation of PPS polymer and PPS‐based composites from synthesis and process to applications. Briefly, this paper introduces PPS materials according to the following topics. First, the molecular weight distribution and morphology of PPS, as well as their reinforced parts, are introduced. Afterward, the topic is focused on the synthesis, process, and blending of PPS. In the next part, this paper investigates the key points regarding PPS as a high‐performance polymer, focusing on the aspect of thermal behavior and mechanical properties. Finally, PPS composite applications are emphasized and overviewed from a wide range of aspects

The thermal and mechanical behavior of poly(ethylene terephthalate) fibers incorporating novel thermotropic liquid crystalline polymers/

This dissertation explores the potential of improving the performance of poly(ethylene terephthalate) fibers by incorporating novel thermotropic liquid crystalline polymers. To determine if a system exhibited desirable characteristics, a screening procedure was developed to assess the various blends. Evaluations focused on blend compositions ranging from 2 to 20 wt.% LCP. Fibers were obtained by melt extrusion and the effect of processing conditions, i.e. spinning temperature, stretch ratio, and post treatment evaluated. The fibers were tested for mechanical performance, dimensional instability (shrinkage), and the development of shrinkage stresses. Test results were used to determine the critical parameters necessary for in-situ reinforcement and to develop strategies for improving LCP architecture and processing techniques. The novel TLCP\u27s incorporated into the PET were mesogenic copolymers containing either alternating or random flexible groups within the polymer backbone. The flexible moieties were used to promote compatibility between the PET matrix phase and the TLCPs. Two systems were found to significantly improve fiber stiffness compared to neat PET fibers. A Random Copolymer based on the reaction of oxyethylene substituted hydroquinone, ethylene glycol, and terephthaloyl chloride was found to effectively enhance the performance of PET fibers. Fibers containing only 5% TLCP exhibited a 50% increase in modulus, while maintaining an ultimate strength equivalent to the PET control. The thermal behavior of the 5% blend, as determined by free shrinkage and force-temperature experiments, was similar to the PET control. A segmented block copolymer consisting of rigid-rod, diad, and flexible coil segments was also found to improve the performance of PET fibers. At a concentration of 20 wt. percent, the alternating block copolymer, Triad2 (2:6:7), increased the tensile modulus of the fibers 40% and decreased free shrinkage by 20% compared to neat PET. The mechanism of reinforcement for these systems is unclear, but morphological, thermal and mechanical evidence suggest that the TLCPs are modifying the PET matrix and not providing true mechanical reinforcement

Structure-Property Relationships in the Formation of Polyphenylsulfone Molecular Composites and Nanocomposites

As the constituent phases in a polymer composite approach the molecular level, specific phenomena occur that can lead to significant changes in material properties when only minimal quantities of the additive are incorporated into the polymer matrix. Molecular composite and nanocomposites are state-of-the-art polymeric materials that contain nanostructured additives effectively dispersed within polymer matrices. The properties of molecular composites and nanocomposites are directly related to the interactions of the nanostructured additive and the polymer matrix. Subtle changes to the nanostructured additive can have profound effects on the ultimate properties of the composite material. Therefore, understanding the structure-property relationships in these systems represents a fundamental step in the realization of these advanced materials. A molecular dispersion of rigid-rod and flexible coil macromolecules is known as a molecular composite. Similar to carbon or glass fiber composites, strain in a molecular composite is transferred to a stiff reinforcing agent with a high aspect ratio. However, in a molecular composite the reinforcing agent is a rigid macromolecule, and these materials are inherently homogeneous, transparent, possess a single coefficient of thermal expansion and are potentially recyclable. The degree of mechanical reinforcement in a molecular composite is directly related to the modulus and aspect ratio of the rigid-rod macromolecule as well as its state of dispersion within the flexible coil matrix. In the first portion of this dissertation, semi rigid-rod macromolecules having phenylketone substituted para-phenylene and unsubstituted meta-phenylene recurring units (i.e. SRPs) at two different ratios are blended by rapid coagulation from solution with polyphenylsulfone (PPSU), and the resulting effects on miscibility, morphology and nanomechanical properties are assessed. Initially, the nanomechanical behavior of an SRP having a completely sp2 hybridized backbone was demonstrated in comparison to conventional high performance engineering thermoplastics as a function of polymer rigidity via nanoprobe instrumentation techniques. Next, various light scattering techniques were employed to obtain key molecular and structural parameters of the SRPs and PPSU in dilute solution, which were related to polymer conformation, theoretical entropic and enthalpic contributions, and predicted blend compatibility. Miscibility was investigated using thermal analysis techniques to monitor the glass transition as a function of blend composition. The bulk and surface morphologies of these blends were analyzed via atomic force microscopy (AFM) to confirm a homogeneous morphology or determine the mechanism of phase separation, and the mechanical properties of these blends were evaluated using nanoindentation. Finally, an understanding of the relationship between the ratio of substituted para and unsubstituted meta recurring units in the SRP copolymer backbone to miscibility, morphology and nanomechanical properties in blends (or molecular composites) with PPSU was developed. A polymer nanocomposite is broadly defined as a polymeric composite material in which one of the phases has dimensions less than 100 nm. These materials are not new since polymer blends often have dimensions much less than 100 nm. However, polymer iv composites containing nanofillers have experienced a recently renewed interest from the scientific community due to the potential for these materials to exhibit not only superior mechanical properties, but also elevated thermal and dimensional stability and an array of other property improvements at relatively low additions of nanofiller. A special class of nanofillers is polyhedral oligomeric silsesquioxane (POSS®) nanostructured chemicals. POSS molecules with their hybrid organic/inorganic structure, well defined threedimensional architecture and mono-disperse particle size have been the subject of a great deal of both academic and scientific interest for their potential to increase the strength and modulus of a polymer matrix without the negative side effects to processing observed with many traditional fillers. In fact, significant enhancements in the rheological and melt flow behavior of amorphous polymers have been observed with only minimal additions of POSS. These enhancements depend upon the interactions of POSS with the amorphous matrix based on the chemical structure of POSS. However, few detailed studies of these relationships have been performed, and the mechanism of this behavior has not been clearly defined. In the second portion of this dissertation improvement in the melt processing and rheological behavior of an amorphous polymer, PPSU, and the resulting thermomechanical properties of the nanocomposite by the addition of different types of POSS at various loading levels is discussed. The relationship of POSS chemical structure to the final properties of the nanocomposite materials was defined in terms of the difference in solubility parameters of POSS and PPSU, the dispersion of POSS within the PPSU matrix and the phase transformations POSS undergoes as a function of temperature

Tailoring the electrical and thermal conductivity of multi-component and multi-phase polymer composites

The majority of polymers are electrical and thermal insulators. In order to create electrically active and thermally conductive polymers and composites, the hybrid-filler systems is an effective approach, i.e. combining different types of fillers with different dimensions, in order to facilitate the formation of interconnected conducting networks and to enhance the electrical, thermal, mechanical and processing properties synergistically. By tailoring polymer-filler interactions both thermodynamically and kinetically, the selective localisation of fillers in polymer blends and at the interface of co-continuous polymer blends can enhance the electrical conductivity at a low percolation threshold. Moreover, selective localisation of different filler types in different co-continuous phases can result in multiple functionalities, such as high electrical conductivity, thermal conductivity or electromagnetic interference shielding. In this review, we discuss the latest progress towards the development of electrically active and thermally conductive polymer composites, and highlight the technical challenges and future research directions

Crystallization, mechanical, rheological and degradation behavior of polytrimethylene terephthalate, polybutylene terephthalate and polycarbonate blend.

Blends of polycarbonate (PC), polytrimethylene terephthalate (PTT) and poly butylene terephthalate (PBT) are an important class of commercial blends with numerous applications providing good chemical resistance and impact resistance even at low temperatures. Polycarbonate/polyester blends are known to react during thermal processing causing the formation of copolymers to have new mechanical and thermal properties. The aim of this project was to study the crystallization, mechanical, rheological and degradation behavior of blends of PC, PTT and PBT and explain these behaviors in terms of transesterification and other plausible mechanisms. PC, PTT and PBT (50:25:25 wt/wt ratio) were melt-blended in a single screw extruder and the extruded blends were pelletized. Non isothermal crystallization kinetics of the blend and neat polymers were investigated using a Perkin Elmer diamond DSC instrument having a fast response time. This thermoplastic blend was able to crystallize rapidly from the melt. Non isothermal crystallization kinetic parameters were analyzed using different numerical methods. Those parameters of the blend fell between those of PTT and PBT. The cause of this behavior could be due to the nature of PC as an amorphous polymer. Rheological properties of the blends were also studied at different temperatures. Rheological measurements were conducted to study the storage modulus, loss modulus, and viscosity values vis a vis the neat materials. Changes in complex viscosity (η*) and shear viscosity (η) were attributed to transesterification. The study presented in this work showed two fundamental issues that have never been addressed in the literature: one is the synthesis of a novel tricomponent system and other is how transesterification during polymer processing might affect the degradation and rheological properties of the tricomponent blend. Effect of blending on mechanical properties was carried out using tensile tests revealing a higher yield strength and elastic modulus of the blend. The morphology of the blend and neat polymers was studied using Scanning electron microscope (SEM), showing immiscibility of the blend components. X ray analysis was carried out to determine the crystalline nature of the blend vis a vis neat polymers. Existence of PTT and PBT peaks proved the immiscible nature of the system. Polymer blends can undergo, during processing, degradation because of the presence of both temperature and mechanical stresses. Compared to neat polymers, degradation of polymer blends shows distinct features because of the interaction between the different chemical species. These interactions can give rise to degradation or to the formation of copolymers which act as stabilizing agents. The non isothermal degradation kinetics of the blend and neat polymers were studied using dynamic thermogravimetry. The thermal stability of the polymers in air was studied and compared to that in nitrogen. The kinetic parameters were analyzed using different numerical methods. Polymers normally transesterify, above their melting points and interchange reactions commonly occur between polyester moieties or among polyester and polycarbonate entities. The transesterification occurring in the blend was analyzed with the help of Fourier Transform Infra- Red (FTIR) using spectral features based on changes of infra red bands

Influence of polymeric additives on the melting and crystallization behavior of nylon 6,6.

The goal of this research was to find polymeric additives that would significantly decrease the rate of crystallization in nylon 6,6, in order to enhance mechanical properties indirectly. Since miscibility was essential, different classes of materials considered included amorphous and semi-crystalline nylons, and other polymers known to be compatible with polyamides. These additives were blended with nylon 6,6 using solution and melt blending techniques. The change in thermal behavior of the blends was evaluated using data obtained with a Differential Scanning Calorimeter (DSC) and Dynamic Mechanical Thermal Analyzer (DMTA). Reduction in the crystallization temperature (T{dollar}\\sb{lcub}\\rm c{rcub}){dollar} during a non-isothermal DSC run was used as the primary criterion for judging the effectiveness of the additive. Polymers that were particularly promising included amorphous nylons--Trogamid-T and Zytel 330; nylon 6,12 and polyacrylic acid. An unusual finding was that annealing the blend in the melt state promoted additional changes in the melting and crystallization behavior. This was attributed to interchange reactions occurring between the blend components. Later work focussed on the use of nylon additives and studied the influence of the nature and amount of additive, residence time in the extruder, drying time, and the melt annealing time. Both the amorphous and semi-crystalline additives produced significant changes in the thermal behavior on melt annealing, the effect increasing with concentration. It was found that Trogamid-T was more effective in reducing the rate and extent of crystallization of nylon 6,6 when compared with nylon 6,12. The suppression in T{dollar}\\sb{lcub}\\rm c{rcub}{dollar} was more for the as-prepared Trogamid-T blends and also for samples annealed for different times. The extent of interchange reaction, measured by the depression in equilibrium melting point, was linear with respect to the annealing time. Trogamid-T blends appeared to be nearly miscible initially, with miscible blends being produced in the twin screw extruder at all concentrations. The {dollar}\\rm T\\sb{lcub}g{rcub}{dollar}-composition curve showed a positive deviation from linear additivity. The single {dollar}\\rm T\\sb{lcub}g{rcub}{dollar} decreased as a function of annealing time in the melt, with the change in {dollar}\\rm T\\sb{lcub}g{rcub}{dollar} being proportional to the additive concentration

Preparation and characterization of compounds based on poly(lactic acid) to tailor processability and mechanical properties

In the bio-based polymer products, the degree of crystallinity has profound effects on the structural, thermal, barrier and mechanical properties. PLA products, under practical processing conditions as it is well known are in an amorphous form and show low crystallinity because of the intrinsic slow crystallization rate, which limits wider applications in sectors, such as automotive and packaging fields. In processes, such as injection molding, because of the high cooling speed, it is much more difficult to develop significant crystallinity, and thus, processing modifications leading to increased injection cycles are necessary. Alternatively, nucleating agents can be added to PLA for the promotion of crystallinity via traditional processing, such as injection molding, thus better controlling both thermal history and cycle time. In this study, investigated about the synergic effect between different plasticizers and nucleating agents in order to tailoring mechanical, physical and thermal properties in PLA compounds. This thesis work represents an insight on the complexity of mechanical behavior of PLA based materials. In order to obtain a modulation of mechanical properties it is necessary to keep into account the effect of processing parameters on the amount and kind of different phases. The change in compositions, in terms of nucleating agents and plasticizer much influence the development of these different phases thus contributing to properties modulation. The technological exploitation of this study can occur by correctly selecting additives for PLA based materials and also modifying mould temperature and holding time in injection moulding to benefit of the improved crystallization rate in the composition range where a synergy between plasticization and nucleation was found

Viability of PEEK for high-temperature microvascular composites manufacture

Microvascular composites are materials with an inner hollow network which allows the circulation of fluids. This functionalizes the composite materials, giving them further applications such as self-healing or active cooling. Some of the already existing microvascular composites are made with fiber reinforced epoxy resin with cavities created by removal of a sacrificial low temperature resistant polymer insert. Current research is focused on the obtention of microvascular composites that can withstand higher service temperatures than epoxy, using polyimide as the high-temperature resin matrix. The aim of this project is to find a suitable sacrificial material that will withstand the higher curing temperatures of the polyimide while allowing its easy removal from the matrix. Three different candidate sacrificial materials were studied for this purpose: PEEK, PPS, and PC. Preliminary DSC test showed that the melting temperature of the PEEK was close to the range of the chosen resin. PPS melting temperature and PC glass transition temperature were below this range of curing temperatures. TGA test revealed that the degradation suffered by the different materials at the curing temperature of the polyimide was considerably low. A small-scale test mimicking the actual microvascular composite manufacturing conditions was designed to study the actual behavior of the different materials when heated. It was seen that both the PEEK and the PPS could not flow without applying extra pressure for the desired range of temperatures. Furthermore, a scaled model test revealed that there was no visible interaction between the different materials tested and the polyimide resin. The initial study showed that PEEK and PPS are not readily viable to use due to the apparent difficulties to remove them from the composite by just applying heat. PC was also considered not viable for this application since it softened too much a too low temperature.Outgoin

Reinforced Polymer Composites

This book, consisting of 21 articles, including three review papers, written by research groups of experts in the field, considers recent research on reinforced polymer composites. Most of them relate to the fiber-reinforced polymer composites, which are a real hot topic in the field. Depending on the reinforcing fiber nature, such composites are divided into synthetic and natural fiber-reinforced ones. Synthetic fibers, such as carbon, glass, or basalt, provide more stiffness, while natural fibers, such as jute, flax, bamboo, kenaf, and others, are inexpensive and biodegradable, making them environmentally friendly. To acquire the benefits of design flexibility and recycling possibilities, natural reinforcers can be hybridized with small amounts of synthetic fibers to make them more desirable for technical applications. Elaborated composites have great potential as structural materials in automotive, marine and aerospace application, as fire resistant concrete, in bridge systems, as mechanical gear pair, as biomedical materials for dentistry and orthopedic application and tissue engineering, as well as functional materials such as proton-exchange membranes, biodegradable superabsorbent resins and polymer electrolytes