UV curing behavior of a highly branched polycarbosilane

“…A high level of light absorbance of initiator inhibits the triplet state of the excited initiator, resulting in a quenching process. The polymerisation's having occurred in air atmosphere may have exacerbated the quenching process (Fouassier and Rabek, 1993;Andrzejewska, 2001;Odian, 2004;Li et al, 2009). Figure 7 is the contour diagram of the polymer conversion as a function of the monomer/oligomer ratio and the photoinitiator concentration, where the highest levels of conversion resulted from a low index of photoinitiator concentration.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, it is possible to determine the time of material polymerisation for other boundary conditions, such as a different light intensity (Jacobs, 1992;Fouassier and Rabek, 1993;Brandrup et al, 1999;Andrzejewska, 2001;Matyjaszewski and Davis, 2002;Sangermano et al, 2002;Marple and Lowder, 2003;Hague et al, 2004;Odian, 2004;Zhiwei et al, 2006;Volpato, 2007;Li et al, 2009;Gibson et al, 2010a;Huang et al, 2010;Cunico, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Development of acrylate-based material using a multivariable approach: additive manufacturing applications

Cunico

Carvalho

2014

Rapid Prototyping Journal

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Purpose -Over the last several years, the range of applications for the photopolymerisation process has been steadily increasing, especially in such areas as rapid prototyping, UV inks, UV coats and orthodontic applications. In spite of this increase, there are still several challenges to be overcome when the application concerns materials formulation and their mechanical properties. In this context, the main aim of this work is to outline the contribution of the formulation components for the parameters of the photopolymerisation process and the resultant mechanical properties of the material. Design/methodology/approach -For this research, the authors have applied multivariable analysis methods, which allow the identification of principal conclusions based on experimental results. For the experimental analysis, the authors applied design of experiment, while the material formulation was based on methyl methacrylate as a monomer, Omnrad 2500 as a photoinitiator and trimethylolpropane triacrylate as an oligomer. The authors analysed the photopolymerisation rate, viscosity, mechanical tensile strength, flexural stiffness and softening. These results comprise a multiobjective optimisation study to identify the ideal material formulation for additive manufacturing applications. The values chosen for the materials were the following: the initiator concentration was 2 and 5% wt., the monomer volume was 5 and 10 ml and the oligomer volume was 3 and 5 ml. To analyse the system kinetics and the photopolymerisation rate, the authors identified the polymer conversion rate through a photometric-cumgravimetric method with a wavelength of 390 nm at the peak intensity. For the softening test, the authors identified the stiffness of the material as a function of temperature, characterising the thermal-mechanical behaviour of the material and determining its degree of crystallinity (cross-linking). Additionally, the authors performed an optimisation to maximise the mechanical tensile strength, flexural stiffness, softening temperature and photopolymerisation rate while minimising the viscosity. Findings -Based on these studies, it was possible to identify the influence of the monomer/oligomer ratio and the initiator concentration as function of polymerisation rate, viscosity, mechanical tensile strength, stiffness and softening of the material. It was also possible to determine the photopolymerisation rate in addition to the constants of propagation and termination. As a result of these studies, the authors identified a material formulation that resulted in a softening temperature greater than 708C, while the viscosity of material remained lower than 3 cP. The mechanical ultimate tensile strength was between 10 and 50 MPa, and the stiffness was between 1.6 and 5.8 GPa. The effect of cross-linking on the process highlighted the interaction between the monomer/oligomer ratio and the initiator. The contribution of the initiator and the inhibitor to the polymerisation rate was identified via a numerical model, which allows the predi...

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“…Moreover, the material recently found use as silicon oxycarbide (SiOC) or silica precursors by heat treatment in an oxidizing atmosphere [8][9][10]. Various carbosilane polymers with different functional groups have been characterized based on their structures [11][12][13], and studied for their applications [14][15][16] [ [17][18][19][20]. Some of these species have been commercialized; i.e., NIPUSI Ò (polycarbosilane, Nippon Carbon Co. Ltd., Japan), STARFIRE Ò (hydridopolycarbosilane, Starfire Systems, USA), and PPCS (ToBeM Tech, Korea).…”

Section: Introductionmentioning

confidence: 99%

Step-Growth Polymerization of Poly(phenylcarbosilane) and Its Structural and Physical Properties

Lee

Kim

et al. 2011

J Inorg Organomet Polym

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The polymerization and molecular weight distribution of poly(phenylcarbosilane) (PPCS) depend on the temperature and pressure conditions under which it is synthesized using the Kumada rearrangement reaction. Its degree of polymerization is related not only to its physical properties such as solubility and boiling point but also to its chemical structure. In this study, soluble PPCS having a weight-average molecular weight (Mw) in the range of 2,500-3,000 was selectively isolated through distillation or fractional precipitation, and its chemical structure and physical properties were studied via FT-IR, NMR, GPC, and thermal analysis. The analytical data indicate that the Si-CH 2 -Si backbone and Si-Si bond are formed through step-growth polymerization and are clearly detected after purification. The differences in the thermal behavior of PPCS in air and in nitrogen were also investigated.

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UV curing behavior of a highly branched polycarbosilane

Cited by 23 publications

References 31 publications

Inhibition effect of N,N-diglycidyl-4-glycidyloxy aniline on photosensitized cationic polymerization of formulations involving resorcinol diglycidyl ether and poly(propylene glycol)diglycidyl ether

Inhibition effect of N,N-diglycidyl-4-glycidyloxy aniline on photosensitized cationic polymerization of formulations involving resorcinol diglycidyl ether and poly(propylene glycol)diglycidyl ether

Development of acrylate-based material using a multivariable approach: additive manufacturing applications

Step-Growth Polymerization of Poly(phenylcarbosilane) and Its Structural and Physical Properties

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