http://en.wikipedia.org/wiki/Stress_incontinence

Stress incontinence

From Wikipedia, the free encyclopedia

Stress incontinence
 

Classification and external resources
 

Pelvic floor
 

ICD-10
 
N39.3
 

ICD-9
 
788.31
 

MeSH
 
D014550
 

Stress incontinence is a form of urinary incontinence.
 
Stress urinary incontinence (SUI), also known as effort incontinence, is due essentially to insufficient strength of the pelvic floor muscles.
 

Contents
    1 Pathophysiology 1.1 In men
 1.2 In women
 
2 Treatment 2.1 Noninvasive/minimally invasive 2.1.1 Behavioral Changes
 2.1.2 Weight loss
 2.1.3 Exercises
 2.1.4 Electrical stimulation
 2.1.5 Biofeedback
 2.1.6 Pessaries
 2.1.7 Vaginal cones
 
2.2 Surgery 2.2.1 Slings 2.2.1.1 Tension-free transvaginal (TVT) sling
 2.2.1.2 Transobturator tape (TOT) sling
 2.2.1.3 Mini-sling procedure
 2.2.1.4 Bladder repositioning
 2.2.1.5 Marshall-Marchetti-Krantz
 
2.2.2 Peri/Trans Urethral Injections
 2.2.3 Artificial urinary sphincter
 
2.3 Medications
 
3 References
 

 Pathophysiology
 
It is the loss of small amounts of urine associated with coughing, laughing, sneezing, exercising or other movements that increase intra-abdominal pressure and thus increase pressure on the bladder. The urethra is supported by fascia of the pelvic floor. If this support is insufficient, the urethra can move downward at times of increased abdominal pressure, allowing urine to pass.
 
Most lab results such as urine analysis, cystometry and postvoid residual volume are normal.
 
Some sources distinguish between urethral hypermobility and intrinsic sphincter deficiency.[1] The latter is more rare, and requires different surgical approaches.
 
 In men
 
Stress incontinence is rare in men. The most common cause is as a post-surgical complication following a prostatectomy.
 
 In women
 
In women, physical changes resulting from pregnancy, childbirth, and menopause often contribute to stress incontinence. Stress incontinence can worsen during the week before the menstrual period. At that time, lowered estrogen levels may lead to lower muscular pressure around the urethra, increasing chances of leakage. The incidence of stress incontinence increases following menopause, similarly because of lowered estrogen levels. In female high-level athletes, effort incontinence occurs in all sports involving abrupt repeated increases in intra-abdominal pressure that may exceed perineal floor resistance.[2]
 
 Treatment
 
 Noninvasive/minimally invasive
 
 Behavioral Changes
 
In addition to weight loss and exercise there are some behavioral changes that can improve stress incontinence. First decrease the amount of liquid that you are ingesting, and avoid drinking caffeinated beverages because they irritate the bladder. Spicy foods, carbonated beverages, alcohol and citrus also irritate the bladder and should be avoided. Quitting smoking can also improve stress incontinence because smoking irritates the bladder and can make you cough (putting stress on the bladder).[3]
 
 Weight loss
 
Weight loss in overweight women reduced stress incontinence, in women with a Body Mass Index (BMI) over 25 and at least 10 episodes of urinary incontinence per week. With exercise and restricted diet they had a 70% or greater reduction in overall incontinence episodes.[4][5]
 
 Exercises
 
One of the most common treatment recommendations includes exercising the muscles of the pelvis. Kegel exercises to strengthen or retrain pelvic floor muscles and sphincter muscles can reduce stress leakage.[6] Patients younger than 60 years old benefit the most.[6] The patient should do at least 24 daily contractions for at least 6 weeks.[6] It is possible to assess pelvic floor muscle strength using a Kegel perineometer.
 
Increasingly there is evidence of the effectiveness of pelvic floor muscle exercise (PFME) to improve bladder control. For example, urinary incontinence following childbirth can be improved by performing PFME.[7]
 
Clinical trials[8] of a Progressive Resistance Vaginal Exerciser concluded that the device was as effective as Supervised Pelvic Floor Muscle Training, the Gold Standard treatment of the UK NHS where patients are referred to a specialist continence advisor for one on one training over a three month period. The report also noted that the device can help overcome the fundamental weaknesses associated with Pelvic Floor Muscle Exercises (PFME) ie poor training, lack of patient confidence and poor compliance with the exercise recommendations.
 
Key points noted by the research are that:
 the device gives “confidence to women that they were correctly contracting their pelvic floor, and this may be helpful encouragement when a woman is starting out on a regime of PFME.”
 the biofeedback given by the device “may be particularly helpful to demonstrate to the woman that she is carrying out the PFME appropriately.”
 the device is particularly relevant to those women “who do not consult their physician and wish to maintain confidentiality regarding their SUI symptom.”
 
A Progressive Resistance Vaginal Exerciser is the only form of pelvic toning device available on prescription in the UK to women presenting with symptoms of Urinary Stress Incontinence or pelvic floor weakness.
 
 Electrical stimulation
 
Brief doses of electrical stimulation can strengthen muscles in the lower pelvis in a way similar to exercising the muscles[citation needed]. Electrodes are temporarily placed in the vagina or rectum to stimulate nearby muscles. This can stabilize overactive muscles and stimulate contraction of urethral muscles.
 
Clinical research published in the British Medical Journal[9] compared pelvic floor exercises, vaginal weights and electro-stimulation in a randomised trial. The research recommended that pelvic floor exercise should be the first choice of treatment for genuine stress incontinence because simple exercises proved to be far more effective than electro-stimulation or vaginal cones.
 
This situation was confirmed in a comprehensive review of the treatment of stress incontinence published in the British Journal of Urology International in 2010.[8] The report author noted that electrical stimulation devices and weighted vaginal cones are not recommended by the UK National Institute for Clinical Excellence (NICE) and "are not universally advocated by clinicians as they have yet to produce sufficient evidence of efficacy".
 
 Biofeedback
 
Biofeedback uses measuring devices to help the patient become aware of his or her body's functioning. By using electronic devices or diaries to track when the bladder and urethral muscles contract, the patient can gain control over these muscles.
 
 Pessaries
 
A pessary is a medical device that is inserted into the vagina. The most common kind is ring shaped, and is typically recommended to correct vaginal prolapse. The pessary compresses the urethra against the symphysis pubis and elevates the bladder neck. For some women this may reduce stress leakage[citation needed]. If a pessary is used, vaginal and urinary tract infections may occur and regular monitoring by a doctor is recommended.
 
 Vaginal cones
 
A vaginal cone is a medical device specifically designed and shaped to exercise pelvic floor muscles and help restore proper bladder functions in women with urinary stress incontinence.
 
 Surgery
 
Doctors usually suggest surgery to alleviate incontinence only after other treatments have been tried. Many surgical options have high rates of success. A Cochrane Review of studies found that the less-invasive variants of the sling operation were equally effective in treating stress incontinence as surgical sling operations.[10]
 
One such surgery is urethropexy.
 
 Slings
 
The procedure of choice for stress urinary incontinence in females is what is called a sling procedure. A sling usually consists of a synthetic mesh material in the shape of a narrow ribbon but sometimes a biomaterial (bovine, porcine) or the patients' own tissue that is placed under the urethra through one vaginal incision and two small abdominal incisions. The idea is to replace the deficient pelvic floor muscles and provide a "backboard" or "hammock" of support under the urethra. According to published peer-reviewed studies, these slings are approximately 85% effective. There is a great variety of slings that have been marketed in the U.S. Three of the most common are the Tension-free Transvaginal Tape, The Trans-obturator Tape, and the Minislings. Currently there is minimal long term data to show better success with one variety of sling over the others. The decision in regards to what brand or type of sling to utilize is based primarily with an individual surgeon's experience, patient preference and comorbidities such as prior abdominal surgery or previous anti-incontinence surgery.
 
 Tension-free transvaginal (TVT) sling
 
The tension-free transvaginal| (TVT) sling procedure treats urinary stress incontinence by positioning a polypropylene mesh tape underneath the urethra.[11] The 20-minute outpatient procedure involves two miniature incisions and has an 86–95% cure rate.[12] Complications, such as bladder perforation, can occur in the retropubic space if the procedure is not done correctly. However, recent advancements have proven that the minimally invasive tvt sling procedure is regarded as a common treatment for SUI[13] There are many other complications associated with the Tension Free Transvaginal (TVT) Sling including mesh erosion from day 1 up to 7 years later.
 
 Transobturator tape (TOT) sling
 
First developed in Europe and later introduced to the U.S. by urogynecologist Dr. John R. Miklos, the transobturator tape (TOT) sling procedure is meant to eliminate stress urinary incontinence by providing support under the urethra[12] The minimally-invasive procedure eliminates retropubic needle passage and involves inserting a mesh tape under the urethra through three small incisions in the groin area.[14]
 
 Mini-sling procedure
 
The mini-sling procedure was released in the United States in late 2006 by Gynecare/Johnson and Johnson under the name of TVT-Secure. AMS have released a similar version called MiniArc. The TVT-SECUR was designed to overcome two of the perioperative complications reported with use of TVT-Obturator: thigh pain and bladder outlet obstruction. The TVT-SECUR was designed to minimize the operative procedure as much as possible in order to reduce those undesired complications. This new device is composed of an 8 cm long laser cut polypropylene mesh and is introduced to the internal obturator muscle (Hammock position) by a metallic inserter, while no exit skin cuts are needed.The MiniArc is also quite simple and again eliminates the need for skin incisions other than the vaginal incision.[15]
 
 Bladder repositioning
 
Most stress incontinence in women results from the urethra dropping down toward the vagina. Therefore, common surgery for stress incontinence involves pulling the urethra up to a more normal position. Working through an incision in the vagina or abdomen, the surgeon raises the urethra and secures it with a string attached to muscle, ligament, or bone. For severe cases of stress incontinence, the surgeon may secure the urethra with a wide sling. This not only holds up the bladder but also compresses the bottom of the bladder and the top of the urethra, further preventing leakage.
 
 Marshall-Marchetti-Krantz
 
The Marshall-Marchetti-Krantz (MMK) procedure, also known as retropubic suspension or bladder neck suspension surgery, is performed by a surgeon in a hospital setting. Developed in 1949 by doctors Victor F. Marshall (urologist), Andrew A. Marchetti (OB/GYN), and Kermit E. Krantz (OB/GYN) is the standard by which new procedures are measured. In 1961 Dr. Burch reported a modification of the MMK operation (the Burch modification.)
 
The patient is placed under general anesthesia, and a long, thin, flexible tube (catheter) is inserted into the bladder through the narrow tube (urethra) that drains the body's urine. An incision is made across the abdomen, and the bladder is exposed. The bladder is separated from surrounding tissues. Stitches (sutures) are placed in these tissues near the bladder neck and urethra. The urethra is then lifted, and the sutures are attached to the pubic bone itself, or to tissue (fascia) behind the pubic bone. The sutures support the bladder neck, helping the patient gain control over urine flow. The Burch modifications involved placing the surgical sutures at the bladder neck and tying them to the Cooper ligament.
 
Approximately 85% of women who undergo the Marshall-Marchetti-Krantz procedure are cured of their stress incontinence.[citation needed]
 
 Peri/Trans Urethral Injections
 
A variety of materials have been historically used to add bulk to the urethra and thereby increase outlet resistance. This is most effective in patients with a relatively fixed urethra. Blood and fat have been used with limited success. The most widely used substance, gluteraldehyde crosslinked collagen (GAX collagen) proved to be of value in many patients. The main downfall was the need to repeat the procedure over time.[16]
 
 Artificial urinary sphincter
 
In rare cases, a surgeon implants an artificial urinary sphincter,[17] a doughnut-shaped sac that circles the urethra. A fluid fills and expands the sac, which squeezes the urethra closed. By pressing a valve implanted under the skin, the artificial sphincter can be deflated. This removes pressure from the urethra, allowing urine from the bladder to pass.
 
 Medications
 
The alpha-1 adrenergic receptor mediates contraction of the neck of urinary bladder and the urethra.
 
Alpha blockers are sometimes used to act at these receptors, but would actually worsen symptoms of stress incontinence, as an Alpha blocker would relax the internal urethral sphincter and tone the detrusor muscle of the bladder.
 
 References
 
1.^ Haliloglu B, Karateke A, Coksuer H, Peker H, Cam C (February 2010). "The role of urethral hypermobility and intrinsic sphincteric deficiency on the outcome of transobturator tape procedure: a prospective study with 2-year follow-up". Int Urogynecol J Pelvic Floor Dysfunct 21 (2): 173–8. doi:10.1007/s00192-009-1010-y. PMID 19802505.
 2.^ Crepin G, Biserte J, Cosson M, Duchene F (October 2006). "[The female urogenital system and high level sports]" (in French). Bull. Acad. Natl. Med. 190 (7): 1479–91; discussion 1491–3. PMID 17450681.
 3.^ "Stress Incontinence Information". Retrieved 6 July 2005.
 4.^ Kelly CJ, Vichayavilas PE (May 2009). "Weight loss for urinary incontinence in overweight and obese women". N. Engl. J. Med. 360 (21): 2256; author reply 2257. doi:10.1056/NEJMc090431. PMID 19458377.
 5.^ "Incontinence reduced with diet and exercise reported by ACP Internist". Retrieved 02/10/2009.
 6.^ a b c Choi H, Palmer MH, Park J (2007). "Meta-analysis of pelvic floor muscle training: randomized controlled trials in incontinent women". Nursing Research 56 (4): 226–34. doi:10.1097/01.NNR.0000280610.93373.e1. PMID 17625461.
 7.^ Haddow (2005). "Effectiveness of a pelvic floor muscle exercise program on UI following childbirth". Western Australian Centre for Evidence-based Nursing 3 (5): 103–146.
 8.^ a b http://www.bjui.org/ContentFullItem.aspx?id=427&LinkTypeID=1&SectionType=4
 9.^ http://www.bmj.com/content/318/7182/487.abstract
 10.^ Ogah J, Cody JD, Rogerson L. Minimally invasive synthetic suburethral sling operations for stress urinary incontinence in women. Cochrane Database of Systematic Reviews 2009, Issue 4. Art. No.: CD006375. DOI: 10.1002/14651858.CD006375.pub2 http://onlinelibrary.wiley.com/o/cochrane/clsysrev/articles/CD006375/frame.html
 11.^ Meschia M, Pifarotti P, Bernasconi F, et al. (2001). "Tension-Free vaginal tape: analysis of outcomes and complications in 404 stress incontinent women". Int Urogynecol J Pelvic Floor Dysfunct 12 (Suppl 2): S24–27. doi:10.1007/s001920170008. PMID 11450976.
 12.^ a b deTayrac R, Deffieux X, Droupy S, Chauveaud-Lambling A, Calvanèse-Benamour L, Fernandez H (March 2004). "A prospective randomized trial comparing tension-free vaginal tape and transobturator suburethral tape for surgical treatment of stress urinary incontinence". Am. J. Obstet. Gynecol. 190 (3): 602–8. doi:10.1016/j.ajog.2003.09.070. PMID 15041987.
 13.^ Rardin CR, Kohli N, Rosenblatt PL, Miklos JR, Moore R, Strohsnitter WC (November 2002). "Tension-free vaginal tape: outcomes among women with primary versus recurrent stress urinary incontinence". Obstet Gynecol 100 (5 Pt 1): 893–7. doi:10.1016/S0029-7844(02)02278-0. PMID 12423849.
 14.^ Stenchever MA (2001). "Physiology of micturition, diagnosis of voiding dysfunction and incontinence: surgical and nonsurgical treatment section of Urogynecology". Comprehensive Gynecology 4: 607–639.
 15.^ Neuman M (September 2007). "TVT-SECUR:100 teaching operations with a novel anti-incontinence procedure". Pelviperineology 26 (3).
 16.^ Appell RA, Macaluso JN, Deutsch JS, Goodman JR, Prats LJ, Wahl P (June 1992). "Endourologic control of incontinence with GAX collagen: the LSU experience". J Endourol 6 (3): 275–7. doi:10.1089/end.1992.6.275.
 17.^ Ruiz E, Puigdevall J, Moldes J, et al. (October 2006). "14 years of experience with the artificial urinary sphincter in children and adolescents without spina bifida". J. Urol. 176 (4 Pt 2): 1821–5. doi:10.1016/j.juro.2006.05.024. PMID 16945659.

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http://en.wikipedia.org/wiki/Polypropylene

Polypropylene

From Wikipedia, the free encyclopedia

Polypropylene
 

IUPAC name
 
poly(propene)
 

Other names
 
Polypropylene; Polypropene;
 Polipropene 25 [USAN];Propene polymers;
 Propylene polymers; 1-Propene
 

Identifiers
 

CAS number
 
9003-07-0
 

Properties
 

Molecular formula
 
(C3H6)n
 

Density
 
0.855 g/cm3, amorphous
 
0.946 g/cm3, crystalline
 

Melting point
 

130–171 °C (266–340 °F)
 

  (verify) (what is: /?)
 Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
 

Infobox references
 

Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging, textiles (e.g., ropes, thermal underwear and carpets), stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes. An addition polymer made from the monomer propylene, it is rugged and unusually resistant to many chemical solvents, bases and acids.
 
In 2007, the global market for polypropylene had a volume of 45.1 million tons, which led to a turnover of about $65 billion (~ €47.4 billion).[1]
 

Contents
    1 Chemical and physical properties 1.1 Degradation
 
2 History
 3 Synthesis
 4 Manufacturing
 5 Applications 5.1 Clothing
 5.2 Medical
 5.3 EPP Model Aircraft
 
6 Recycling
 7 Repairing
 8 Health concerns
 9 References
 10 External links
 

 Chemical and physical properties
 

Micrograph of polypropylene
Most commercial polypropylene is isotactic and has an intermediate level of crystallinity between that of low-density polyethylene (LDPE) and high-density polyethylene (HDPE). Polypropylene is normally tough and flexible, especially when copolymerized with ethylene. This allows polypropylene to be used as an engineering plastic, competing with materials such as ABS. Polypropylene is reasonably economical, and can be made translucent when uncolored but is not as readily made transparent as polystyrene, acrylic, or certain other plastics. It is often opaque or colored using pigments. Polypropylene has good resistance to fatigue.
 
The melting of polypropylene occurs as a range, so a melting point is determined by finding the highest temperature of a differential scanning calorimetry chart. Perfectly isotactic PP has a melting point of 171 °C (340 °F). Commercial isotactic PP has a melting point that ranges from 160 to 166 °C (320 to 331 °F), depending on atactic material and crystallinity. Syndiotactic PP with a crystallinity of 30% has a melting point of 130 °C (266 °F).[2]
 
The melt flow rate (MFR) or melt flow index (MFI) is a measure of molecular weight of polypropylene. The measure helps to determine how easily the molten raw material will flow during processing. Polypropylene with higher MFR will fill the plastic mold more easily during the injection or blow-molding production process. As the melt flow increases, however, some physical properties, like impact strength, will decrease.
 
There are three general types of polypropylene: homopolymer, random copolymer, and block copolymer. The comonomer is typically used with ethylene. Ethylene-propylene rubber or EPDM added to polypropylene homopolymer increases its low temperature impact strength. Randomly polymerized ethylene monomer added to polypropylene homopolymer decreases the polymer crystallinity and makes the polymer more transparent.
 
 Degradation
 
Polypropylene is liable to chain degradation from exposure to heat and UV radiation such as that present in sunlight. Oxidation usually occurs at the tertiary carbon atom present in every repeat unit. A free radical is formed here, and then reacts further with oxygen, followed by chain scission to yield aldehydes and carboxylic acids. In external applications, it shows up as a network of fine cracks and crazes that become deeper and more severe with time of exposure.
 
For external applications, UV-absorbing additives must be used. Carbon black also provides some protection from UV attack. The polymer can also be oxidized at high temperatures, a common problem during molding operations. Anti-oxidants are normally added to prevent polymer degradation.
 
 History
 
Propylene was first polymerized to a crystalline isotactic polymer by Giulio Natta as well as by the German chemist Karl Rehn in March 1954.[3] This pioneering discovery led to large-scale commercial production of isotactic polypropylene from 1957 onwards.[4] Syndiotactic polypropylene was also first synthesized by Giulio Natta and his coworkers.
 
 Synthesis
 

Short segments of polypropylene, showing examples of isotactic (above) and syndiotactic (below) tacticity.
An important concept in understanding the link between the structure of polypropylene and its properties is tacticity. The relative orientation of each methyl group (CH3 in the figure) relative to the methyl groups in neighboring monomer units has a strong effect on the polymer's ability to form crystals.
 
A Ziegler-Natta catalyst is able to restrict linking of monomer molecules to a specific regular orientation, either isotactic, when all methyl groups are positioned at the same side with respect to the backbone of the polymer chain, or syndiotactic, when the positions of the methyl groups alternate. Commercially available isotactic polypropylene is made with two types of Ziegler-Natta catalysts. The first group of the catalysts encompases solid (mostly supported) catalysts and certain types of soluble metallocene catalysts. Such isotactic macromolecules coil into a helical shape; these helices then line up next to one another to form the crystals that give commercial isotactic polypropylene many of its desirable properties.
 

A ball-and-stick model of syndiotactic polypropylene.
Another type of metallocene catalysts produce syndiotactic polypropylene. These macromolecules also coil into helices (of a different type) and form crystalline materials.
 
When the methyl groups in a polypropylene chain exhibit no preferred orientation, the polymers are called atactic. Atactic polypropylene is an amorphous rubbery material. It can be produced commercially either with a special type of supported Ziegler-Natta catalyst or with some metallocene catalysts.
 
Modern supported Ziegler-Natta catalysts developed for the polymerization of propylene and other 1-alkenes to isotactic polymers usually use TiCl4 as an active ingredient and MgCl2 as a support.,,[5][6][7] The catalysts also contain organic modifiers, either aromatic acid esters and diesters or ethers. These catalysts are activated with special cocatalysts containing an organoaluminum compound such as Al(C2H5)3 and the second type of a modifier. The catalysts are differentiated depending on the procedure used for fashioning catalyst particles from MgCl2 and depending on the type of organic modifiers employed during catalyst preparation and use in polymerization reactions. Two most important technological characteristics of all the supported catalysts are high productivity and a high fraction of the crystalline isotactic polymer they produce at 70-80 °C under standard polymerization conditions. Commercial synthesis of isotactic polypropylene is usually carried out either in the medium of liquid propylene or in gas-phase reactors.
 
Commercial synthesis of syndiotactic polypropylene is carried out with the use of a special class of metallocene catalysts. They employ bridged bis-metallocene complexes of the type bridge-(Cp1)(Cp2)ZrCl2 where the first Cp ligand is the cyclopentadienyl group, the second Cp ligand is the fluorenyl group, and the bridge between the two Cp ligands is -CH2-CH2-, >SiMe2, or >SiPh2.[8] These complexes are converted to polymerization catalysts by activating them with a special organoaluminum cocatalyst, methylalumoxane MAO[9]
 
 Manufacturing
 
Melt processing of polypropylene can be achieved via extrusion and molding. Common extrusion methods include production of melt-blown and spun-bond fibers to form long rolls for future conversion into a wide range of useful products, such as face masks, filters, nappies (diapers) and wipes.
 
The most common shaping technique is injection molding, which is used for parts such as cups, cutlery, vials, caps, containers, housewares, and automotive parts such as batteries. The related techniques of blow molding and injection-stretch blow molding are also used, which involve both extrusion and molding.
 
The large number of end-use applications for polypropylene are often possible because of the ability to tailor grades with specific molecular properties and additives during its manufacture. For example, antistatic additives can be added to help polypropylene surfaces resist dust and dirt. Many physical finishing techniques can also be used on polypropylene, such as machining. Surface treatments can be applied to polypropylene parts in order to promote adhesion of printing ink and paints.
 
 Applications
 

Polypropylene lid of a Tic Tacs box, with a living hinge and the resin identification code under its flap
Since polypropylene is resistant to fatigue, most plastic living hinges, such as those on flip-top bottles, are made from this material. However, it is important to ensure that chain molecules are oriented across the hinge to maximize strength.
 
Very thin sheets of polypropylene are used as a dielectric within certain high-performance pulse and low-loss RF capacitors.
 
Polypropylene is used in the manufacturing piping systems; both ones concerned with high-purity and ones designed for strength and rigidity (eg. those intended for use in potable plumbing, hydronic heating and cooling, and reclaimed water).[10] This material is often chosen for its resistance to corrosion and chemical leaching, its resilience against most forms of physical damage, including impact and freezing, its environmental benefits, and its ability to be joined by heat fusion rather than gluing.[11][12][13]
 

A polypropylene chair
Many plastic items for medical or laboratory use can be made from polypropylene because it can withstand the heat in an autoclave. Its heat resistance also enables it to be used as the manufacturing material of consumer-grade kettles. Food containers made from it will not melt in the dishwasher, and do not melt during industrial hot filling processes. For this reason, most plastic tubs for dairy products are polypropylene sealed with aluminum foil (both heat-resistant materials). After the product has cooled, the tubs are often given lids made of a less heat-resistant material, such as LDPE or polystyrene. Such containers provide a good hands-on example of the difference in modulus, since the rubbery (softer, more flexible) feeling of LDPE with respect to polypropylene of the same thickness is readily apparent. Rugged, translucent, reusable plastic containers made in a wide variety of shapes and sizes for consumers from various companies such as Rubbermaid and Sterilite are commonly made of polypropylene, although the lids are often made of somewhat more flexible LDPE so they can snap on to the container to close it. Polypropylene can also be made into disposable bottles to contain liquid, powdered, or similar consumer products, although HDPE and polyethylene terephthalate are commonly also used to make bottles. Plastic pails, car batteries, wastebaskets, pharmacy prescription bottles, cooler containers, dishes and pitchers are often made of polypropylene or HDPE, both of which commonly have rather similar appearance, feel, and properties at ambient temperature.
 
A common application for polypropylene is as biaxially oriented polypropylene (BOPP). These BOPP sheets are used to make a wide variety of materials including clear bags. When polypropylene is biaxially oriented, it becomes crystal clear and serves as an excellent packaging material for artistic and retail products.
 
Polypropylene, highly colorfast, is widely used in manufacturing carpets, rugs and mats to be used at home.[14]
 
Polypropylene is widely used in ropes, distinctive because they are light enough to float in water.[15][dead link] For equal mass and construction, polypropylene rope is similar in strength to polyester rope. Polypropylene costs less than most other synthetic fibers.
 
Polypropylene is also used as an alternative to polyvinyl chloride (PVC) as insulation for electrical cables for LSZH cable in low-ventilation environments, primarily tunnels. This is because it emits less smoke and no toxic halogens, which may lead to production of acid in high-temperature conditions.
 
Polypropylene is also used in particular roofing membranes as the waterproofing top layer of single-ply systems as opposed to modified-bit systems.
 
Polypropylene is most commonly used for plastic moldings, wherein it is injected into a mold while molten, forming complex shapes at relatively low cost and high volume; examples include bottle tops, bottles, and fittings.
 
It can also be produced in sheet form, widely used for the production of stationery folders, packaging, and storage boxes. The wide color range, durability, low cost, and resistance to dirt make it ideal as a protective cover for papers and other materials. It is used in Rubik's cube stickers because of these characteristics.
 
The availability of sheet polypropylene has provided an opportunity for the use of the material by designers. The light-weight, durable, and colorful plastic makes an ideal medium for the creation of light shades, and a number of designs have been developed using interlocking sections to create elaborate designs.
 
Polypropylene sheets are a popular choice for trading card collectors; these come with pockets (nine for standard-size cards) for the cards to be inserted and are used to protect their condition and are meant to be stored in a binder.
 
Expanded polypropylene (EPP) is a foam form of polypropylene. EPP has very good impact characteristics due to its low stiffness; this allows EPP to resume its shape after impacts. EPP is extensively used in model aircraft and other radio controlled vehicles by hobbyists. This is mainly due to its ability to absorb impacts, making this an ideal material for RC aircraft for beginners and amateurs.
 
Polypropylene is used in the manufacture of loudspeaker drive units. Its use was pioneered by engineers at the BBC and the patent rights subsequently purchased by Mission Electronics for use in their Mission Freedom Loudspeaker and Mission 737 Renaissance loudspeaker.
 
Polypropylene fibres are used as a concrete additive to increase strength and reduce cracking and spalling.[16]
 
 Clothing
 
Polypropylene is a major polymer used in nonwovens, with over 50% used[citation needed] for diapers or sanitary products where it is treated to absorb water (hydrophilic) rather than naturally repelling water (hydrophobic). Other interesting non-woven uses include filters for air, gas, and liquids in which the fibers can be formed into sheets or webs that can be pleated to form cartridges or layers that filter in various efficiencies in the 0.5 to 30 micrometre range. Such applications could be seen in the house as water filters or air-conditioning-type filters. The high surface area and naturally oleophilic polypropylene nonwovens are ideal absorbers of oil spills with the familiar floating barriers near oil spills on rivers.
 
In New Zealand, in the US military, and elsewhere, polypropylene, or 'polypro' (New Zealand 'polyprops'), has been used for the fabrication of cold-weather base layers, such as long-sleeve shirts or long underwear (More recently, polyester has replaced polypropylene in these applications in the U.S. military, such as in the ECWCS [17]). Polypropylene is also used in warm-weather gear such as some Under Armour clothing, which can easily transport sweat away from the skin. Although polypropylene clothes are not easily flammable, they can melt, which may result in severe burns if the service member is involved in an explosion or fire of any kind.[18] Polypropylene undergarments are known for retaining body odors which are then difficult to remove. The current generation of polyester does not have this disadvantage.[19]
 
The material has recently been introduced into the fashion industry through the work of designers such as Anoush Waddington, who have developed specialized techniques to create jewelry and wearable items from polypropylene.
 
 Medical
 
Its most common medical use is in the synthetic, nonabsorbable suture Prolene, manufactured by Ethicon Inc.
 
Polypropylene has been used in hernia and pelvic organ prolapse repair operations to protect the body from new hernias in the same location. A small patch of the material is placed over the spot of the hernia, below the skin, and is painless and is rarely, if ever, rejected by the body. However, a polypropylene mesh will erode over the uncertain period from days to years. Therefore, the FDA has issued several warnings on the use of polypropylene mesh medical kits for certain applications in pelvic organ prolapse, specifically when introduced in close proximity to the vaginal wall due to a continued increase in number of mesh erosions reported by patients over the past few years.[20]
 
 EPP Model Aircraft
 
Since 2001, expanded polypropylene (EPP) foams have been gaining in popularity and in application as a structural material in hobbyist radio control model aircraft. Unlike expanded polystyrene foam (EPS) which is friable and breaks easily on impact, EPP foam is able to absorb kinetic impacts very well without breaking, retains its original shape, and exhibits memory form characteristics which allow it to return to its original shape in a short amount of time. In consequence, a radio-control model whose wings and fuselage are constructed from EPP foam is extremely resilient, and able to absorb impacts that would result in complete destruction of models made from lighter traditional materials, such as balsa or even EPS foams. EPP models, when covered with inexpensive fibreglass impregnated self adhesive tapes, often exhibit much increased mechanical strength, in conjunction with a lightness and surface finish that rival those of models of the aforementioned types. EPP is also chemically highly inert, permitting the use of a wide variety of different adhesives. EPP can be heat molded, and surfaces can be easily finished with the use of cutting tools and abrasive papers. The principal areas of model making in which EPP has found great acceptance are the fields of:
 Wind-driven Slope Soarers
 Indoor electric powered profile electric models
 Hand launched gliders for small children
 
In the field of slope soaring, EPP has found greatest favour and use, as it permits the construction of radio-controlled model gliders of great strength and maneuverability. In consequence, the disciplines of slope combat (the active process of friendly competitors attempting to knock each other's planes out of the air by direct contact) and slope pylon racing have become commonplace, in direct consequence of the strength characteristics of the material EPP.
 
 Recycling
 
Polypropylene is recyclable and has the number "5" as its resin identification code: .[21]
 
 Repairing
 
Many objects are made with polypropylene precisely because it is resilient and resistant to most solvents and glues. Also, there are very few glues available specifically for gluing PP. However, solid PP objects not subject to undue flexing can be satisfactorily joined with a two part epoxy glue or using hot-glue guns. Preparation is important and it is often helpful to roughen the surface with a file, emery paper or other abrasive material to provide better anchorage for the glue. Also it is recommended to clean with mineral spirits or similar alcohol prior to gluing to remove any oils or other contamination. Some experimentation may be required. There are also some industrial glues available for PP, but these can be difficult to find, especially in a retail store.[citation needed]
 
 Health concerns
 
In 2008, researchers in Canada asserted that quaternary ammonium biocides and oleamide were leaking out of certain polypropylene labware, affecting experimental results.[22] Since polypropylene is used in a wide number of food containers such as those for yogurt, Health Canada media spokesman Paul Duchesne, said the department will be reviewing the findings to determine whether steps are needed to protect consumers.[23]
 
The Environmental Working Group classifies PP as of low to moderate hazard.[24]
 
 References
 
1.^ "Market Study: Polypropylene". Ceresana Research.
 2.^ Maier, Clive; Calafut, Teresa (1998). Polypropylene: the definitive user's guide and databook. William Andrew. p. 14. ISBN 9781884207587.
 3.^ Peter J. T. Morris (2005). Polymer Pioneers: A Popular History of the Science and Technology of Large Molecules. Chemical Heritage Foundation. p. 76. ISBN 0941901033.
 4.^ This week 50 years ago in New Scientist, 28 April 2007, p. 15
 5.^ Y. V. Kissin Alkene Polymerization Reactions with Transition Metal Catalysts, Elsevier, 2008, Chapter 4
 6.^ J. Severn, R. L. Jones Handbook of Transition Metal Polymerization Catalysts, R. Hoff, R. T. Mathers, eds, Wiley, 2010, Chapter 7
 7.^ E. P. Moore Polypropylene Handbook. Polymerization, Characterization, Properties, Processing, Applications, Hanser Publishers: New York, 1996
 8.^ G. M. Benedikt, B. L. Goodall, eds. Metallocene Catalyzed Polymers, ChemTech Publishing: Toronto, 1998
 9.^ H. Sinn, W. Kaminsky, H. Höker, eds. Alumoxanes, Macromol. Symp. 97, Huttig & Wepf: Heidelberg, 1995
 10.^ ASTM Standard F2389, 2007, "Standard Specification for Pressure-rated Polypropylene (PP) Piping Systems", ASTM International, West Conshohocken, PA, 2007, DOI:10.1520/F2389-07E01, www.astm.org.
 11.^ Green pipe helps miners remove the black Contractor Magazine, 10 January 2010
 12.^ Contractor Retrofits His Business the News, 2 November 2009
 13.^ What to do when the piping replacement needs a replacement? Engineered Systems, 1 November 2009
 14.^ Rug fibers
 15.^ Rope Materials
 16.^ [1] [2]
 17.^ ECWCS Gen. III
 18.^ USAF Flying Magazine. Safety. Nov. 2002.
 19.^ Get Real: The true story of performance next to skin fabrics
 20.^ FDA Public Health Notification: Serious Complications Associated with Transvaginal Placement of Surgical Mesh in Repair of Pelvic Organ Prolapse and Stress Urinary Incontinence, FDA, October 20, 2008
 21.^ Plastics recycling information sheet, Waste Online
 22.^ Plastic additives leach into medical experiments, research shows, Physorg.com, 10 November 2008
 23.^ Scientific tests skewed by leaching plastics, November 6, 2008.
 24.^ http://www.cosmeticdatabase.com/ingredient.php?ingred06=705094
 
 External links
 

Wikimedia Commons has media related to: Polypropylene
 
Chain structure of Polypropylene