Statistical life prediction of unidirectional carbon fiber/polypropylene tape under creep tension load

Recently, a carbon fiber/polypropylene unidirectional sheet has been developed by Mitsui Chemicals, Inc. from a new polyolefin-based sizing agent for carbon fiber. Its effective polypropylene modification brings good compatibility with polypropylene to improve the fiber matrix adhesion. This study examines the prediction of the statistical lifetime of this developed carbon fiber/polypropylene unidirectional sheet under creep tension loading. First, a tensile test method for static and creep strengths at elevated temperatures was developed for carbon fiber/polypropylene unidirectional tape cut from a carbon fiber/polypropylene unidirectional sheet. Second, the static tensile strengths of carbon fiber/polypropylene tape were measured statistically at various constant temperatures under a constant strain rate. The statistical creep failure times under tension loading for carbon fiber/polypropylene tape were predicted at a constant temperature by substituting the statistical static strengths into the formulation based on the matrix resin viscoelasticity. Third, the validity of the predicted results was clarified by comparison with the creep failure times measured statistically using creep tests for carbon fiber/polypropylene tape. Finally, the relation between the failure probability and creep failure times for carbon fiber/polypropylene unidirectional tape at various loads and temperature conditions was discussed.

Nonlinear creep response of oriented polypropylene tapes

The creep response of a highly oriented polypropylene tape used for the manufacture of self-reinforced polypropylene or all-polypropylene composites was studied over a range of stresses and temperatures. Similar to oriented polyethylene, the creep compliance is linear viscoelastic at short loading times, whereas pronounced stress dependence is observed at longer loading times. A mathematical model is proposed, where the total deformation of the fibre is regarded as being composed of a stress-linear delayed elastic component and a nonlinear plastic flow contribution. Model predictions are in good agreement with the experimental data.

Sacrocolpopexy with Polypropylene Tape as Valuable Surgical Modification during Cystectomy with Orthotopic Ileal Bladder: Functional Results

Introduction. Urinary diversion is very often associated with urinary retention and urinary incontinence. In this study, a surgical modification during cystectomy with orthotopic ileal neobladder is presented.Material and Methods. Female patients enrolled in the study (n-24) were subjected to sacrocolpopexy during the operation. Apart from oncological control, the follow-up consisted of 1-hour inlay test and questionnaires (UDI-6 and IIQ-7) in the 3rd, 6th, and 12th month after the operation. In the 12th month after the surgery, the urodynamic pressure-flow test was performed. Outcomes were compared with the control group (n-18) in which sacrocolpopexy was not implemented.Results. The study group was characterised by reduced urinary retention and improved continence.Conclusion. Sacrocolpopexy during cystectomy with orthotopic ileal bladder is a valuable surgical method which provides patients with a better quality of life.

Usage of a Trans-Obturator-Tape (T.O.T.) "outside-in" approach in surgical treatment of female stress urinary incontinence

Objective: The aim of the study was to analyzed the efficacy and safety of a new minimally invasive surgical procedure using the Trans-Obturator-Tape with "outside-in" approach for treatment female stress urinary incontinence. Patients and Methods: 31 women with stress urinary incontinence (SUI) associated with urethral hypermobility, underwent the T.O.T. procedure (March 2010 to January 2011). 5 patients were previously operated for incontinence. Mean age was 59 years (37- 80). 10 patients were having mixed incontinence. A non-elastic, polypropylene tape was placed under the mid-urethra. The surgical placement technique utilises a trans-obturator percutaneous approach. All patients underwent post-operative clinical examination, coughstress test (full bladder), uroflowmetry, and post-voiding residual assessment. Results: Mean follow-up was 5 months (1-9). At 6 months follow-up 96,7% of the patients were completely cured. The overall peri-operative complication rate was 6,4% with no vascular, nerve or bowel injury. One patients (3,4%) had post-operative urinary retention. Conclusion: The present study confirms the results obtained by the instigator of the technique, E. Delorme, and allows us to consider T.O.T. as an effective and safe technique for the treatment of female stress urinary incontinence.