Poly Aryl Ether Ketone Research Articles

Adaptable polyaryletherketones (PAEKs) with competing crosslinking and crystallisation mechanisms

Driven by the need to make high temperature thermoplastic polymers more processable and expand the range of applications, this study reports on the properties of a novel PAEK material developed by Victrex (Thornton Cleveleys, UK) which is capable of undergoing crosslinking or crystallisation, two competing processes that can be adapted via specific processing temperature and time conditions. The uniqueness of this PAEK material resides in its manufacturing approach, where the crosslinkers are incorporated during the polymerisation process, and its distinct properties, including a controllable viscosity that can be tuned from low to high to allow its application in complex manufacturing processes, such as thermoplastic carbon fibre manufacturing.

Facile strategy for intrinsic low-κ dielectric polymers: molecular design based on space charge conservation.

The growing need for high-power and compact-size microelectronic integrated circuits (ICs) in modern microelectronic industries and 5G communication systems demands low dielectric constant (κ) polymer dielectrics with excellent temperature capability, mechanical property and processability. However, conventional molecular design strategies often face difficulties of a trade-off between optimizing the dielectric performance of polymers and maintaining the aforementioned properties. Herein, we present an innovative and facile strategy that utilizes the space charge distribution characteristics of the target co-monomer to solve this trade-off. Based on this design strategy, a novel polyaryl ether ketone (PAEK) with two different charge distribution units (BAF and SBI) was designed and synthesized. Both the experimental results and computational simulations confirm that these two components serve to weaken the polarization of molecular chains in the electric field, induce higher molecular chain packing density and fewer weaknesses, and synchronously regulate the κ, dielectric loss (tan δ), thermal and mechanical properties and processability by generating a strong inter-chain electrostatic interaction. The resultant copolymer, PAEK-4F6S, exhibits exceptional low κ and tan δ values of 1.98 and 0.0024 at 1 MHz, respectively, and these values remain stable over a broad frequency (1-106 Hz, 8.2-12.4 GHz) and temperature range (30-150 °C). Furthermore, the resultant copolymer demonstrates excellent thermal stability and mechanical properties, with a glass transition temperature (Tg) of 195 °C, 5 wt% decomposition temperature (Td5%) of 498 °C under N2, tensile strength of 63.5 MPa and tensile modulus of 1011.2 MPa, respectively. The synthesis procedure of these resultant copolymers is facile, and they are found to have favorable solution and melt processing properties, making them suitable for processing and scalable production. More importantly, this design strategy is beneficial for lowering the κ and tan δ values, and simultaneously enhancing the comprehensive performances of the objective polymers, which provides a completely novel and facile approach for the design and fabrication of high performance low-κ polymers suitable for the needs of microelectronics and communication fields.

Amino-functionalized UiO-66-doped mixed matrix membranes with high permeation performance and fouling resistance

For the reduction of bovine serum proteins from wastewater, a novel mixed matrix membrane was prepared by functionalizing the substrate material polyaryletherketone (PAEK), followed by carboxyl groups (C-SPAEKS), and then adding amino-functionalized UiO-66-NH2 (Am-UiO-66-NH2). Amino-functionalization of UiO-66 was accomplished by melamine, followed by an amidation reaction to immobilize Am-UiO-66-NH2, which was immobilized on the surface of the membrane as well as in the pore channels, which enhanced the hydrophilicity of the membrane surface while increasing the negative potential of the membrane surface. This nanoparticle-loaded ultrafiltration membrane has good permeation performance, with a pure water flux of up to 482.3 L·m−2·h−1 for C-SPAEKS/Am-UiO-66-NH2 and a retention rate of up to 98.7% for bovine serum albumin (BSA)-contaminated solutions. Meanwhile, after several hydrophilic modifications, the flux recovery of BSA contaminants by this series of membranes increased from 56.2% to 80.55% of pure membranes. The results of ultrafiltration flux time tests performed at room temperature showed that the series of ultrafiltration membranes remained relatively stable over a test time of 300 min. Thus, the newly developed mixed matrix membrane showed potential for high efficiency and stability in wastewater treatment containing bovine serum proteins.

Fabrication of functionalised graphene-PAEK nanocomposites for different manufacturing processes

ABSTRACTAchieving good dispersion of graphene (GNP), in polyetheretherketone (PEEK), is challenging due to the high melt viscosity, solvent resistance and processing temperature of PEEK. In addition, certain manufacturing processes tend to enhance the anisotropy due to GNP orientation within the structure. This study investigated the fabrication of nanocomposite parts through hot compression moulding (C-MOULD) and powder bed fusion (PBF) processes, using powder with GNPs fused to the surface of polymeric particles, through a process called mechanofusion. The method applies mechanical forces of compression, shear and impact to generate a mechanical bond between materials, in this case, O2 functionalised GNP and a developmental polyaryletherketones (PAEK) grade powder. The novelty of this work is in the combination of processes used for manufacturing (material preparation and actual manufacturing processes), which are scalable and efficient in comparison with existing methods (such as solvent mixing or melt-compounding). The mechanofusion GNP-PAEK composite powders were successfully printed for the first time using the EOS P800 system with notable improvements in electrical and mechanical properties. This study highlights that the mechanofusion process could be used as an efficient process for making multifunctional nanocomposite materials and this can be combined with additive manufacturing (AM) processes to produce complex components.

Enhancing interfacial adhesion of carbon fiber/poly(phthalazinone ether ketone) composites by the hybrid sizing agent of hydroxyapatite‐reinforced PAEK‐COOH

AbstractImproving the interfacial adhesion of carbon fiber (CF)/polymer composite is an urgent demand to enhance its mechanical properties. A kind of poly(aryl ether ketone) with carboxyl groups (PAEK‐COOH) was newly synthesized. PAEK‐COOH is similar to the thermal properties of PPEK matrix. Hydroxyapatite (HAp) was easily dispersed in an NMP solution containing PAEK‐COOH. Different kinds of hybrid sizing agents were obtained for preparing the prepreg through the solution impregnation. The hot‐pressing method was employed to produce the laminated composites. Flexural strength, flexural modulus and interlamellar shear strength (ILSS) of 0HP@CF/PPEK composites were improved by 8.8%, 17.3%, and 14.7%, respectively, in comparison to desized CF/PPEK. The interface bonding between CF and PPEK was improved by the addition of PAEK‐COOH sizing agent. Meanwhile, compared with desized CF/PPEK laminates, flexural strength, flexural modulus and ILSS of 5HP@CF/PPEK composites were enhanced by 63.5%, 87.4%, and 40.9%, respectively. The crack propagation path became dispersed and the stress was effectively absorbed when the sizing agent containing nano‐hydroxyapatite particles. By characterizing and reconstructing the transverse and longitudinal fracture in composite materials, the failure process of the composites under the action of stress was explained, and the interface theories of CF reinforced polymer were further explored.Highlights A kind of polyaryl ether ketone containing carboxyl functional group (PAEK‐COOH)was newly synthesized. HAp was distributed in the polymer sizing agent to obtain a HAp/PAEK‐COOH hybrid sizing agent. The interfacial adhesion of CF/PPEK composite was greatly improved by the hybrid sizing agent.

Evaluation of the initial retention of implant-retained attachments made of dental polyaryletherketones (PAEKs)

Evaluation of the initial retention of implant-retained attachments made of dental polyaryletherketones (PAEKs)

Additive Manufacturing of Polyaryletherketone (PAEK) polymers and their composites

Polyaryletherketone (PAEK) polymers are unique thermoplastics certified for aerospace and biomedical applications, demonstrating exceptional thermo-mechanical characteristics and superior chemical resistance. They are adaptable to material extrusion (ME) and laser powder bed fusion (L-PBF) additive manufacturing systems. While various PAEK grades for additive manufacturing (AM) exist, their printing suitability, especially inter-layer strength, is not well-understood. Adding small amounts of short carbon fibers to PAEKs enhances their stiffness and service temperature but modifies their processing, structure, and properties. This study examines the effects of the AM method (L-PBF and ME) and carbon fiber addition on the structure, mechanical properties, and crystallinity of three different PAEK polymers. We characterize and correlate tensile properties, fracture modes, degree of crystallinity, fiber length and orientations, and porosity of the samples. Our findings aim to refine AM processes and feedstock materials for semi-crystalline polymers and their composites, offering insights for designing robust, economical AM parts.

About the high temperature fatigue performance of thermoplastic-based composite laminates for aeronautical applications

The use of thermoplastic-based composites for applications in high temperature aeronautical parts is often considered contradictory with respect to the softening of the matrix and the subsequent degradation of their mechanical properties, especially when service temperature T exceeds glass transition temperature. This paper examines the fatigue performance of unidirectional (UD) carbon fibers reinforced PolyArylEtherKetone (PAEK) laminates subjected to tension-tension fatigue at different testing temperatures (Room Temperature, 120°C and 170°C). Laminates consisting of different portions of plies in 0°/+45°/−45°/90° orientations have been investigated to evaluate the contribution of each ply orientation to the fatigue performance in terms of S-N diagrams. From the evolution of life span as a function of applied stress, it appears that the influence of temperature on fatigue behaviour of C/PAEK composites depends on the temperature conditions. 0° plies behaviour is known to be temperature-independent as is dominated by the mechanical behaviour of UD carbon fibers. It is expected to reflect on the fatigue behaviour at high temperature. From the obtained results, one may conclude that the 0° plies primarily bear the tensile load in fatigue (47-67-91% in SOFT, QI and HARD laminates, respectively) and therefore dominate the fatigue behaviour. The deformation mechanisms in +/−45° plies (localized plastic-viscoplastic dissipative behaviors) favoured at temperatures higher than Tg (e.g. 143°C) are limited by the low deformation of 0° plies. SOFT (12% of 0° plies) and QI (25% of 0° plies) laminates have similar relative fatigue performance. Unexpectedly, the fatigue performance of HARD laminates (about 62% of 0° plies) is improved at T>Tg at high stress levels. A simple temperature-dependent analytical model was used to successfully predict the fatigue life of C/PAEK laminates with different stacking sequences.

Evaluating the mechanical properties of novel HAp reinforced polyaryletherketone biocomposites via molecular dynamics simulation

In recent times, polymer-based biocomposites are being pitched as the future of biomedical materials for implant and prosthesis development. PAEK (Polyaryletherketone) is one such viable thermoplastic and a member of the PEKs (Polyetherketones) family, of which many homologues have already been established for biomedical applications. In this study, atomistic models of PAEK-based biocomposite with HAp (Hydroxyapatite) as reinforcement have been developed. HAp is well-known bioceramic for its similar chemical structure to that of a natural bone's inorganic conformation and thus is used to induce biocompatibility. Atomistic model for different weight concentrations of HAp i.e. 0%, 1%, 3%, 5%, 7%, and 9% are developed to understand the effects of HAp reinforcement in PAEK matrix. Since, mechanical properties are one of the most prominent parameters for the development of an implant material as they should be in the range of human bone to avoid stress-shielding. The mechanical behavior of the PAEK/HAp biocomposites have been investigated via molecular dynamics simulation. Elastic properties were determined at constant strain rate and the stress strain behavior was simulated for both tension and compression separately at 298K. The simulation results shows significant increase in ultimate tensile (2.54 times) and ultimate compressive strength (1.69 times) of biocomposite with incorporation of HAp (max at 7%). Although proportional increase in brittleness to the weight content of HAp was also observed. The study provides an approach to analyze PAEK/HAp biocomposites and concludes that this combination is a potential alternative to contemporary implant materials.

Surface functionalization of poly(ether ether ketone) by wet-chemical modification with carboxylic acids and diamine

Polyaryletherketones (PAEK) are high-performance plastics with excellent mechanical properties and high thermal resistance used, e.g. as material for implants. Their molecular structure gives them a high level of chemical inertness but prevents bonding and adhesive interactions with other materials and integration into body tissue. Using the example of poly(ether ether ketone) (PEEK), we show novel synthetic routes for wet-chemical modification of the surface to create reactive carboxylic and amino groups. In a first approach, the ketone functionalities of the PEEK molecules were reduced to hydroxy groups and subsequently esterified with carboxylic acids. Using dicarboxylic acids, one acid group was bonded covalently to the PEEK surface while the other provided free acidic functionalities. In a second approach, the PEEK surface was modified in one step by reaction of the ketone group with a diamine, creating primary amino groups on the PEEK surface. All reaction products were analyzed by a powerful combination of surface sensitive X-ray photoelectron spectroscopy (XPS) and advanced infrared spectroscopic methods.

Modelling of the Monolithic Stiffener Forming Process from a Paek Thermoplastic Composite Matrix Using Pam-Form Software

Abstract The growing use of thermoplastic composites in aviation, automotive, sports and medical industries is forcing the development of processing technology. Due to the properties of thermoplastic composite materials, their shaping is subject to many restrictions. For this reason, it is not always possible to obtain components with complex geometry and adequate quality. By using numerical analysis and experience in the production of parts using hot pressing technology, we are able to predict the course of the process and the behaviour of the material during formation. The article describes how to build a model for numerical analysis of the process of thermoforming monolithic inspection door stiffening for an ILX-34 aircraft using a Toray Cetex® TC1225 carbon composite material with a thermoplastic polyaryletherketone (PAEK) matrix. Pam-Form v2019.0 software version V1.9.N was used for modelling. The results of the analysis were compared with those of the part produced by the Institute of Aviation, Łukasiewicz Research Network.

Structural tailoring enables ultrahigh energy density and charge–discharge efficiency of PAEK copolymer dielectrics at high temperatures

High-temperature film capacitors have great potential for high-power-density applications, in which polymer films are often utilized as energy-storage dielectrics. However, their application in film-capacitor dielectrics is hindered by their large leakage currents at high temperatures, which leads to low energy density (Ue) and low charge–discharge efficiency (η). Here, a structural-tailoring strategy is demonstrated to suppress the high-temperature leakage currents of polyaryletherketone (PAEK) copolymers. For this purpose, a novel functional monomer containing benzimidazole and pyridine groups (BBP) was synthesized and the corresponding cross-linked c-P(AEK-BBP) dielectric films were successfully to prepared. Thanks to the introduction of the BBP units and the cross-linked network, the leakage current of c-P(AEK–BBP) is suppressed by nearly two orders of magnitude at 150 °C. This dielectric film exhibits 7.3 J·cm−3 under 600 MV·m−1 and 150 °C, which is superior to current state-of-the-art heat-resistant dielectric polymers.

Extrusion-Based Additively Manufactured PAEK and PAEK/CF Polymer Composites Performance: Role of Process Parameters on Strength, Toughness and Deflection at Failure

Poly aryl-ether-ketone (PAEK) belongs to a family of high-performance semicrystalline polymers exhibiting outstanding material properties at high temperatures, making them suitable candidates for metallic part replacement in different industries such as aviation, oil and gas, chemical, and biomedical. Fused filament fabrication is an additive manufacturing (AM) method that can be used to produce intricate PAEK and PAEK composite parts and to tailor their mechanical properties such as stiffness, strength and deflection at failure. In this work, we present a methodology to identify the layer design and process parameters that will have the highest potential to affect the mechanical properties of additively manufactured parts, using our previously developed multiscale modeling framework. Five samples for each of the ten identified process conditions were fabricated using a Roboze-Argo 500 version 2 with heated chamber and dual extruder nozzle. The manufactured PAEK and PAEK/carbon fiber samples were tested until failure in an Instron, using a video extensometer system. Each sample was prepared with a speckle pattern for post analysis using digital image correlation (DIC) to measure the strain and displacement over its entire surface. The raster angle and the presence of fibers had the largest influence on the mechanical properties of the AM manufactured parts, and the resulting properties were comparable to the mechanical properties of injection molded parts.

Assimilation of Nanoparticles of SiC, ZrC, and WC with Polyaryletherketone for Performance Augmentation of Adhesives

The present paper reports the analyses of results obtained from experiments carried out to explore the challenge of homogeneous, uniform, and deagglomerated dispersion of ultra-heavy nanoparticles (NPs) in the high-performance polyaryletherketone (PAEK) matrix. An equal and fixed amount of (0.5 vol. %) NPs of silicon carbide (SiC), zirconium carbide (ZrC), and tungsten carbide (WC) were dispersed in a PAEK matrix and compression molded to develop three different nanocomposites. Simultaneously, nano-adhesives of the same composition were also developed to join the stainless steel adherends. The composites and adhesives were characterized for their physical, thermal, thermo-mechanical, thermal conductivity (TC), and lap shear strength (LSS) behavior. It was observed that SiC NPs performed significantly better than ZrC and WC NCs in all performance properties (LSS: 154%, TC: 263%, tensile strength: 21%). Thermal conductivity (TC) and tensile properties were validated using various predictive models, such as the rule of mixture parallel model, the Chiew and Glandt model, and the Lewis model. Scanning electron micrographs were used for the morphological analysis of LSS samples to detect macro- and micro-failure. Micrographs showed evidence of micro-striation and plastic deformation as a micromodel, as well as mixed failure, i.e., adhesive-cohesive as a macro-failure mode.

High-performance thermoplastic polyaryletherketone/carbon fiber composites: Comparison of plasma, carbon nanotubes/graphene nano-anchoring, surface oxidation techniques for enhanced interface adhesion and properties

This investigation highlights the development and performance comparison of carbon fiber (CF)-polyaryletherketone (PAEK) thermoplastic laminates prepared using CF, surface-modified with plasma, multi-walled carbon nanotubes (MWCNT), graphene, acid, and rare earth elements. Analysis of surface-treated CF by Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) revealed development of functional groups and changes in elemental composition on the CF surface. Significant lowering of contact angle and improvement in wettability was achieved by plasma and MWCNT/graphene treatment on CF. Field emission scanning electron microscopy (FESEM) analysis gave insight into the surface irregularities caused by various surface treatment techniques. The CF-PAEK composites were prepared by film stacking and compression moulding. The plasma-treated PAEK-CF composites exhibited the highest tensile properties, flexural strength, fracture toughness, and interlaminar shear strength. The superior properties are credited to better interfacial adhesion between CF and PAEK arising from mechanical interlocking over the roughened surface and covalent bonds by functional groups grafted on CF surface by plasma. MWCNT and graphene-anchored CF-PAEK composites also showed significant improvement in mechanical properties attributed to the bridging effect and interfacial interaction arising from increased surface area and functional groups. The surface-treated CF-PAEK composites exhibited a positive shift in the glass transition temperature, which is evidence of better adhesion. In dynamic loading conditions, MWCNT anchored CF-PAEK composite presented the highest storage modulus and energy absorption characteristics. Examination of the tensile fracture surface and fiber pull-out gave insight into the failure pattern and interfacial adhesion mechanism for the individual surface modification techniques.

Different Fluorine Content of Poly(aryleneetherketone) Coated on Polyimide Films to Fabricate Hydrophobic and Low Moisture Absorption Films

Polyimides have attracted considerable attention owing to their excellent properties; however, their hydrophilicity makes them susceptible to hydrolytic degradation. In this study, polyaryletherketones (PAEKs) with different fluorine contents were coated onto the surface of the polyimide films to fabricate the hydrophobic surface. The wettability of the films changed, with a transition from hydrophilicity to hydrophobicity, upon coating with PAEKs. Thus, the coated films exhibited low moisture absorption. Due to the excellent thermal stability of fluorinated polyaryletherketones (F-PAEKs), the coated polyimide films retained their hydrophobicity even after extreme treatment. Furthermore, the dielectric properties of the coated polyimide film were superior to those of the unmodified film. The hydrophobic polyimide film can meet the requirements of extreme environments.

Superior high-temperature capacitive performance of polyaryl ether ketone copolymer composites enabled by interfacial engineered charge traps.

Metalized film capacitors with high-temperature capacitive performance are crucial components in contemporary electromagnetic energy systems. However, the fabrication of polymer-based dielectric composites with designed structures faces the challenge of balancing high energy density (Ue) and low energy loss induced by electric field distortion at the interfaces. Here, BN nanoparticles coated with a thin layer of aminobenzoic acid (ABA) voltage stabilizer are introduced into a copolymer of aryletherketone and 2,6-bis(2-benzimidazolyl)pyridine (P(AEK-BBP)). Our results demonstrate that the ABA voltage stabilizer, possessing high electron affinity, significantly improves the dispersion of BN particles within the matrix, mitigates electric field distortion, and creates effective charge traps. This, in turn, effectively suppresses high-temperature-induced Schottky emission and P-F emission, leading to a dramatic decrease in leakage loss. As a result, the optimized composite film, filled with 0.3 vol% m-ABA-BN particles, exhibites a Ue of 10.1 J cm-3 and a η of 90% at 150 °C and 600 MV m-1, surpassing the majority of previously reported materials. Furthermore, even after undergoing 100 000 cycles at 150 °C and 250 MV m-1, the composite dielectric films demonstrate favorable charge-discharge characteristics. This work offers a novel approach to fabricate polymer-based dielectric materials with high-temperature resistance and high discharging efficiency for long-term high energy storage applications.

In vitro comparative study on the mechanical behavior of Zirconia and Polyetheretherketone in applied dental sciences.

Recently, Zirconia and polyaryletherketone (PEEK) have attracted increasing interest as reliable and safe materials in dental applications, mainly because of their good biomechanical characteristics. The aim of this study was to investigate the response to different loads by prosthetic frameworks for supported fixed partial dentures (FPDs), thus simulating osseointegrated implants. The specimens were divided into two groups (n= 5 each). Group A: FDPs in zirconia-ceramic; Group B: FDPs in PEEK-composite. These 2 groups were subjected to vertical loads so to evaluate structural deformation; then, they have been analyzed by scanning electron microscopy (SEM) at different magnifications. In tested samples, different types of mechanical failures have been observed. In Zirconia-specimens, chipping is the main failure noticed in this study, mostly in distal margins of the structure. Also, peek-specimens show failure and fracture. Zirconia and PEEK could be considered both good materials, but several investigations are needed to use these materials as an alternative to metals for fixed partial dentures.

A Sneak Peek Toward Polyaryletherketone (PAEK) Polymer: A Review.

Metals, acrylics, zirconia, and other such materials have beenconventionally used in dentistry. The development of polymers has facilitated significant changes in clinical dentistry. High-performance polymer materials are at the forefront of dentistry. Polyaryletherketone (PAEK) is a biocompatiblepolycyclic, aromatic, thermoplastic polymer having good mechanical and thermal properties. It has two members: polyetheretherketone (PEEK) and polyetherketoneketone (PEKK). The difference in the ratio and structure of ether to ketone group affects the melting point and glass transition temperature. PEEK and PEKK have a high impact with their physical and mechanical characteristics similar to that of the bone and mimicthe natural tooth structure. It can be used as a substitute for metals and other materials owing to its non-allergic properties and acceptable aesthetics. Currently, to modify the properties of bothmaterials, additives were used. This semicrystalline structure does not provide any kind of mutagenicity and cytotoxicity. This review provides insight into the properties and applications of polymer in dentistry and the medical field as well. There is room for metal-free restorations in modern dental practice due to the rising demand for aesthetics, a few disadvantages with existing materials, and clinicians changing their paradigms towardmetal-free restorations. The objective of this review is to provide a thorough understanding of PEEK and PEKKand their multiple uses inprosthetic, implantframeworks, abutments, crowns, and ortho wires, as well as in restorativedentistry, while demonstrating their potential for clinical applications.

Effect on the mechanical properties of different types of surface treatment on sulfonated Peek - An In Vitro Study

Introduction - Thermoplastic polymers have many potential uses in medicine and dentistry as an alternative to the commonly used titanium. Since the 1980s, polyaryletherketones (PAEKs) have been increasingly employed as biomaterials for trauma, orthopedic, and spinal implants. Due to several advantages of these materials, metal-free restorations are performing an important role in current medical therapies. PEEK is biologically inert and various surface modifications are given to increase its osseointegration potential of PEEK, Acid etching is the most simple and cost effective method of treatment. The aim of this study is to evaluate the surface roughness and wettability of 2 different acid etching techniques of PEEK samples - Magnetic stirring and ultrasonic. Material and methods - PEEK samples thicknesses of 2 mm and diameters of 15 mm was used in the study and the sulfonation procedure was done magnetically and ultrasonically for 6 mins and samples were rinsed with acetone for 10 mins, washed with deionized water for 10 mins and finally dried at 37°C. The results of the study were subjected to statistical analysis in SPSS software version 23.0. Independent t test was performed for the parameters. Results - when comparing 2 groups magnetic stirred sulfonated PEEK (MSPEEK) and Ultrasonic PEEK (USPEEK) results showed statistically significant difference present. (P < 0.05) in surface roughness and in wettability no significant difference is seen (P > 0.05). Conclusion - The literature suggests that PEEK offers an alternative to titanium, especially in cases of orthopedics and trauma. Its properties make it an interesting material in Dental implantology to be performed with CAD-CAM. Further studies are required to obtain sufficient scientific evidence to enable its uses as a permanent material.