Modification of molecular weight and flow properties of thermoplastics

Dorn, Maximilian

doi:10.1002/adv.1985.060050203

Cited by 50 publications

(28 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…PA12 has excellent solvent and oil resistance, in particular acid and alkali resistance and excellent environmental stress cracking resistance at elevated temperature [29]. Cross-linking of the PDMS rubber phase by organic peroxides suffers from scorching problems at high mixing temperature due to the faster decomposition of the peroxides (normally used for curing) [30,31]. To overcome this difficulty three structurally different peroxides, namely dicumyl peroxide (DCP), 3,3,5,7,7-pentamethyl 1,2,4-trioxepane (PMTO) and cumyl hydroperoxide (CHP) were chosen for investigation.…”

Section: G Heinrichmentioning

confidence: 99%

Novel thermoplastic vulcanizates (TPVs) based on silicone rubber and polyamide exploring peroxide cross-linking

Chatterjee¹,

Wießner²,

Naskar³

et al. 2014

Express Polym. Lett.

View full text Add to dashboard Cite

Abstract. Novel thermoplastic vulcanizates (TPVs) based on silicone rubber (PDMS) and polyamide (PA12) have been prepared by dynamic vulcanization process. The effect of dynamic vulcanization and influence of various types of peroxides as cross-linking agents were studied in detail. All the TPVs were prepared at a ratio of 50/50 wt% of silicone rubber and polyamide. Three structurally different peroxides, namely dicumyl peroxide (DCP), 3,3,5,7,7-pentamethyl 1,2,4-trioxepane (PMTO) and cumyl hydroperoxide (CHP) were taken for investigation. Though DCP was the best option for curing the silicone rubber, at high temperature it suffers from scorch safety. An inhibitor 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) was added with DCP to stabilize the radicals in order to increase the scorch time. Though CHP (hydroperoxide) had higher half life time than DCP at higher temperature, it has no significant effect on cross-linking of silicone rubber. PMTO showed prolonged scorch safety and better cross-linking efficiency rather than the other two. TPVs of DCP and PMTO were made up to 11 minutes of mixing. Increased values of tensile strength and elongation at break of PMTO cross-linked TPV indicate the superiority of PMTO. Scanning electron micrographs correlate with mechanical properties of the TPVs. High storage modulus (E!) and lower loss tangent value of the PMTO cross-linked TPV indicate the higher degree of cross-linking which is also well supported by the overall cross-link density value. Thus PMTO was found to be the superior peroxide for cross-linking of silicone rubber at high temperature.

show abstract

Section: G Heinrichmentioning

confidence: 99%

Novel thermoplastic vulcanizates (TPVs) based on silicone rubber and polyamide exploring peroxide cross-linking

Chatterjee¹,

Wießner²,

Naskar³

et al. 2014

Express Polym. Lett.

View full text Add to dashboard Cite

show abstract

“…Nonetheless, careful control is required at all times, particularly in the case of polypropylene, as chain scission can easily occur, decreasing molecular weight and reducing overall efficiency and hence performance [42,43]. In the case of polypropylene the methylene group stabilises the tertiary carbon free radial thus making it more vulnerable to β chain scission, according the reaction mechanism illustrated in Fig. 14.10.…”

Section: Chemistry and Synthesis Of Adhesivesmentioning

confidence: 99%

Polymer Coatings for Oilfield Pipelines

Varley¹,

Leong²

2016

Active Protective Coatings

View full text Add to dashboard Cite

Pipes and pipeline systems are an integral part of modern society, from the network of pipes that transport water, gas and sewage of our daily needs to the continuous transmission of hydrocarbons across continents satisfying the energy demands of the global economy. Despite the enormous distances and the harsh environments involved, oil and gas pipelines are the most efficient and environmentally safe form of hydrocarbon transportation currently available today. For this reason, they are critical to continued global prosperity in the 21st century.The oil and gas (O&G) industry, primarily uses steel pipelines to transport natural gas, crude oil, water, as well as petrochemical feedstocks and petroleum products which are susceptible to corrosion from their surrounding environment, be it soil (buried lines), or seawater (subsea lines) and compromising their service life. The life expectancy of oilfield pipelines ranges typically between 25-35 years so reliable protection during this period is of utmost importance. External coatings are one of the most widely used methods for providing a barrier to the steel surface against air (oxygen) and water (electrolytes), the two critical factors which most impact the electrochemical process of corrosion. Despite this, all coatings deteriorate over time due to inter alia soil stress, moisture and gas ingress, reduced adhesion, chemical attack and mechanical damage, thus imposing the challenge of maintaining the required durability and performance over the intended service life.

show abstract

“…5 Given the fast rate of alkyl radical trapping by nitroxyls, we can assume that initiator-derived radicals produced in the presence of nitroxyl will be quenched. Under this assumption, t ind marks the time where all nitroxyl functionality is consumed, at which point the DCP conversion will equal the trapping ratio, [nitroxyl]/(2[ROOR] 0 ).…”

Section: ■ Introductionmentioning

confidence: 99%

Functional Nitroxyls for Use in Delayed-Onset Polyolefin Cross-Linking

Hyslop

Parent

2012

Macromolecules

View full text Add to dashboard Cite

A new approach to controlling the dynamics and yields of polyolefin radical cross-linking is described, wherein 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl (AOTEMPO) is used to quench macroradicals in the early stages of the process and to subsequently generate a covalent network through the oligomerization of polymerbound acrylate functionality. Selectivity of alkyl radical trapping by AOTEMPO to give alkoxyamine intermediates in preference to acrylate addition products is discovered using model compound studies and through rheological measurements of linear low density polyethylene cross-linking. The latter demonstrate the ability of AOTEMPO to delay the onset of cross-linking while not compromising the cross-link density of the resulting thermoset. The influences of reagent loadings, peroxide decomposition rates, and the structure of polymerizable functionality are quantified and discussed.

show abstract

Modification of molecular weight and flow properties of thermoplastics

Cited by 50 publications

References 3 publications

Novel thermoplastic vulcanizates (TPVs) based on silicone rubber and polyamide exploring peroxide cross-linking

Novel thermoplastic vulcanizates (TPVs) based on silicone rubber and polyamide exploring peroxide cross-linking

Polymer Coatings for Oilfield Pipelines

Functional Nitroxyls for Use in Delayed-Onset Polyolefin Cross-Linking

Contact Info

Product

Resources

About