Poly Ether Ether Ketone (PEEK) polymers for High Temperature Laser Sintering (HT-LS)

Laser sintering (LS) is an additive manufacturing technique that allows production of prototypes and fully functional components characterised by the highest level of freedom of design currently achievable. High customisation, multi-functional integration, design optimisation and the potential for reducing cost and production time of a single item are the most outstanding characteristics of the LS process. However, the small number of polymers at present available constitutes a significant drawback for many engineering applications, especially in the automotive and aerospace industrial sectors where seemingly only one commercial high temperature grade, Poly Ether Ketone (PEK) HP3, can meet the high material performance required. With the aim to expand the choice of materials for LS and especially High Temperature Laser Sintering (HT-LS) manufacturing, this research project has focused on the investigation and implementation into LS of a new high temperature polymer, Poly Ether Ether Ketone (PEEK). This study has examined some of the key requirements needed for the successful development of new materials in LS processes at experimental and theoretical levels. Two generic PEEK grades 150PF and 450PF have been quantitatively investigated in parallel with well-established LS polymers in terms of particle size, particle morphology and flow behaviour. A calculation of the inter-particle interactions has been evaluated for all the materials proposed. These analyses, coupled with two strategies for the improvement of powder flowability, have formed a systematic and fundamental approach for studying powders in LS. The PEEK 450PF grade has been selected for optimisation into the HT-LS system, EOSINT P 800. The HT-LS processing parameters and their effect on the mechanical characteristics of the laser sintered units have been investigated and optimised, and new insights into the HT-LS mechanisms and functionalities of the EOSINT P 800 system are presented. A basic technique for the prediction of one of the HT-LS processing temperatures is proposed. A formula for linking material properties to processing parameters has also been assessed. Lastly, the medical equivalent grade of PEEK 450PF, PEEK-OPTIMA® LT1, has been utilised for the manufacture and test of two medical components.Invibio/Victre

Morphology of polymeric powders in Laser Sintering (LS): from polyamide to new PEEK powders

In an attempt to expand the range of engineering polymers used for laser sintering, this paper examines the morphology, flowability and interparticle interactions of two commercially available Poly (ether ether) ketone (PEEK) powders, not yet optimised for the LS process, by comparison with the LS optimised Polyamide (PA) and Polyetherketone (PEK) powdered polymers. The effect of incorporating fillers and additives on the flow behaviour is also analysed. The Particle Size Distribution (PSD) results alone do not allow ranking the powder materials in relation to the flow behaviour. The particle morphology has a stronger influence on the flow characteristics for materials with similar PSDs. The work also provides additional characterisation parameters to be considered when analysing LS powders

Processability of PEEK, a New Polymer for High Temperature Laser Sintering (HT-LS)

Copyright © 2015 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in European Polymer Journal. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in European Polymer Journal (2015), DOI: 10.1016/j.eurpolymj.2015.04.003Currently, the HT-LS sector is predominantly based around one commercial poly ether ketone (PEK) polymer. Although the combination of polymer and process works well, a lower melting temperature polymeric material, part of the same Poly Aryl Ether Ketone (PAEK) family would be preferable in certain applications. This study presents the optimisation and characterisation of Poly Ether Ether Ketone (PEEK), a polymer which is part of the PAEK family with a 30 ˚C lower melting temperature than PEK. The systematic characterisation of laser sintered samples of PEEK revealed a very good overall performance in comparison with the HP3 PEK material, with no change in storage modulus and only 25 % drop in tensile strength. The possibility of variable building configurations available within the HT-LS system, i.e. reduced, half and full chamber building modes, is examined in relation to the mechanical performances of the components. The effect of the post sintering time, an additional heating phase supplied to the powder bed at every layer, found only in the HT-LS system EOSINT P 800, is also examined

Polymer viscosity, particle coalescence and mechanical performance in high-temperature laser sintering

The final publication is available at Springer via http://dx.doi.org/10.1007/s10853-016-9761-6High-temperature laser sintering (HT-LS) is an additive manufacturing technology whose potential could be limited by the restricted number of materials optimised for the process. Poly ether ether ketone (PEEK) with different melt viscosity values, PEEK 150PF and PEEK 450PF, have been used in parallel with the commercial grade, poly ether ketone (PEK) HP3, to investigate the role of material viscosity on particle coalescence, structure and mechanical performance of components manufactured in HT-LS. The material with lower viscosity, PEEK 150PF, was found to exhibit faster coalescence and lower tensile strength than the grades with higher viscosities, PEEK 450PF and PEK HP3

A new case of primary signet-ring cell carcinoma of the cervix with prominent endometrial and myometrial involvement: Immunohistochemical and molecular studies and review of the literature

<p>Abstract</p> <p>Background</p> <p>As a rule, endocervical tumours with signet-ring cell are classed as metastatic extra-genital neoplasms. In a patient aged 45 years, we describe primary cervical signet-ring cell carcinoma (PCSRCC) characterized by prominent endometrial and myometrial involvement, simulating primary endometrial adenocarcinoma with cervical extension. In addition, a review was made of the literature to identify the clinical and pathological features of this rare malignancy.</p> <p>Case presentation</p> <p>A 45-year-old woman was referred to our Gynaecology Department due to persistent abnormal vaginal bleeding. Transvaginal ultrasonography showed slight endometrial irregularities in the whole uterine cavity suggestive of endometrial neoplasms. Pelvic magnetic resonance imaging revealed diffuse enlargement of the cervix, which had been replaced by a mass. Induration extended to the parametria and sigmoid colon fat.</p> <p>Histological examination of endometrial curettage and a cervical biopsy revealed a neoplasm characterized by neoplastic signet-ring cells and trabecular structures. Immunohistochemical analysis and molecular studies showed certain findings consistent with a cervical neoplasm, such as positivity to CEA, keratin 7, Ca-125 and p16 and the presence of HPV (Human Papilloma Virus) DNA 18.</p> <p>On examination of the hysterectomy with bilateral salpingo-oophorectomy and pelvic lymphadenectomy, the lesion replacing the cervix, endometrium and myometrium, revealed the same immunohistochemical findings observed on endometrial curettage and cervical biopsy specimens. Metastases were found in an ovarian cystic lesion and the lymph nodes.</p> <p>Conclusion</p> <p>With this report the authors have demonstrated that the spread of cervical adenocarcinoma to the uterine corpus, although rare, may be observed, and that in this instance immunohistochemical and molecular studies can provide sufficient information for accurate diagnosis even on small biopsy specimens.</p

Size, shape and flow of powders for use in Selective Laser Sintering (SLS)

6th International Conference on Advanced Research in Virtual and Rapid Prototyping, Leiria, Portugal, 1-5 October 2013This paper investigates the effects of particles size and morphology on flowability of a range of polymeric powders (SLS and non-SLS grades). The effect of additives incorporation, as well as drying or sieving, on the flowability characteristics of the powders is also analyzed. The results show that the particle morphology has a stronger influence on the flowability than the particle size distribution. Moreover, the incorporation of additives has to be carefully considered in order to have positive effects on the powder flowability

Neuroendocrine Small Cell Carcinoma of the Cervix: A case report

Merkel cell polyomavirus (MCPyV) has been found in patients with Merkel cell carcinoma and respiratory tract infections. Merkel cell carcinoma is a primary aggressive neuroendocrine carcinoma of the skin. It has been demonstrated that MCPyV can be transmitted during sexual activity and may be present in the oral and anogenital mucosa. The aim of the present study was to evaluate whether MCPyV coexisted with HPV in three cases of neuroendocrine small cell carcinoma of the cervix using PCR and immunohistochemical analysis Three cases of NSC of the cervix were identified in the pathology archives of Parma University (Italy). Of these, two cases were associated with an adenocarcinomatous component. A set of general primers from the L1 region (forward, L1C1 and reverse, L1C2 or L1C2M) was PCR amplified to detect the broad‑spectrum DNA of genital HPV. The presence of MCPyV was investigated via immunohistochemistry using a mouse monoclonal antibody against the MCPyV LT antigen and through PCR analysis to separate viral DNA. HPV DNA was present in all three neuroendocrine carcinomas and in the adenocarcinoma component of the two mixed cases. None of the cases were immunoreactive to CM2B4 and did not contain viral DNA in either their neuroendocrine or adenocarcinomatous component. Whilst it is difficult to draw definitive conclusions from such a small sample size, these data suggested that MCPyV does not coexist with HPV in the cervix. However, in the present study, the absence of detectable MCPyV may have been due to the presence of a genotype that was not detected by the primers used in the PCR analysis or by the antibody used for the immunohistochemical study. MCPyV microRNA may also have been present, inhibiting LT expression. Additional studies with larger cohorts and more advanced molecular biology techniques are required to confirm the hypothesis of the current study

High Temperature Laser Sintering: An investigation into mechanical properties and shrinkage characteristics of Poly (Ether Ketone) structures

Copyright © 2014 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Materials and Design. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Materials and Design, Vol. 61 (2014). DOI: 10.1016/j.matdes.2014.04.035This paper presents an investigation into the properties of Poly Ether Ketone (PEK) components using the commercial high temperature laser sintering system, EOSINT P800. The shrinkage and the mechanical performance of components across the entire build chamber have been tested and a non-linear shrinkage profile has been obtained. The middle of the build chamber recorded the highest degree of shrinkage and the shrinkage in Z direction had the largest variation. The laser sintered components built in X and Y directions recorded a 10% lower tensile strength than the injection moulded samples of the same material where those built in the Z direction showed an approximately 50% decrease in strength in comparison with the injection moulded test specimens. The crystallinity between the skin and the core of the sintered samples was different; varied with the position within the build chamber and coincided with noticeable sample colour changes

Treatment of lung microcytoma with neuroendocrine differentiation in elderly patient

We describe the case of a 80-year-old patient with lung microcytoma and comorbidity (diabetes, COPD and hypertensive cardiomiopaty). To manage the complexity of the elderly patient with comorbidity, he was evaluated by a Comprehensive Geriatric Assessment (CGA). Radiotherapy and chemotherapy were excluded because of the low Performance Status of the patient. A treatment with octerotide LAR was administered, allowing a good clinical benefit