Modern cationic vinyl polymerization

The weathering of polymers is reviewed with attention concentrated on the mechanisms of degradation and stabilization, the methods of testing weatherability, and the predictive modelling of weathering behaviour. An introduction to the chemical mechanisms of degradation and stabilization is given and reference made to some of the many reviews available in the literature. Significant emphasis is placed here on engineering aspects, such as the way that weathering influences fracture mechanisms. The difficulties associated with relating accelerated laboratory tests with outdoor service behaviour are discussed. The complexities of the degradation processes limit modelling of the rate of degradation to rather specific systems and the predictions cannot be generalized.

Weathering of polymers: mechanisms of degradation and stabilization, testing strategies and modelling

The present invention discloses methods for enhancing the wear-resistance of polymers, the resulting polymers, and in vivo implants made from such polymers. One aspect of this invention presents a method whereby a polymer is irradiated, preferably with gamma radiation, then thermally treated, such as by remelting of annealing. The resulting polymeric composition preferably has its most oxidized surface layer removed. Another aspect of the invention presents a general method for optimizing the wear resistance and desirable physical and/or chemical properties of a polymer by crosslinking and thermally treating it. The resulting polymeric compositions is wear-resistant and may be fabricated into an in vivo implant.

Crosslinking of polyethylene for low wear using radiation and thermal treatments

https://www.iranwpc.ir/docs/use_of_recycled_plastics_in_wood_plastic_composites_EN.pdf

Use of recycled plastics in wood plastic composites - a review.

Intercalated linear low density polyethylene (LLDPE)/clay nanocomposites prepared with oxidized polyethylene as a new type compatibilizer: Structural, mechanical and barrier properties

A combined (chemical and infrared (IR) spectrophotometric) method is discussed for the simultaneous determination of concentrations of carboxyl (A), ketone (K), and ester (E) groups formed in the oxidation of polyethylene (PE). The IR absorptivities of these functional groups were determined by using model compounds [stearic acid, stearone, poly-(1,4-butylene sebacate)]. The integral absorption of the CO band of polymer samples which contained several oxo groups of different types was found to be additive. This method was applied to the determination of the carboxyl, ester, and ketone content of samples oxidized at different oxygen pressures.

Determination of carbonyl‐containing functional groups in oxidized polyethylene

The thermo-oxidative degradation of polyolefines—Part 10. Correlation between the formation of carboxyl groups and scission in the oxidation of polyethylene in the melt phase

Novel poly(acenaphtylene-b-isobutylene-b-acenaphtylene) (PAc-PIB-PAc) triblock copolymers exhibiting thermoplastic elastomer (TPE) properties have been prepared. The synthesis involved the addition of acenaphtylene (Ac) to living polyisobutylene dications ( ○ +PIB ○ +) obtained by living isobutylene (IB) polymerization induced by the dicumyl methyl ether (DiCumOMe)/TiCl 4 initiating system at -80 o C. The triblocks contain very short polyacenaphtylene (PAc) blocks (M n ≃9,000) and consequently yield very soft, low modulus TPEs. efforts to develop conditions for the living carbacationic polymerization of Ac have failed

Polyisobutylene-containing block polymers by sequential monomer addition. IX: Poly(acenaphthylene-b-isobutylene-b-acenaphthylene)

The kinetics of oxygen consumption during the induction period of oxidation of high density polyethylene was studied in the presence of inhibitor 2,2'-methylene-bis(4-methyl-6-tert.butylphenol) within the range 180–220° C. The oxygen consumption curves are complicated, the initial and maximum rates of oxygen consumption pass through minimum with increasing inhibitor concentration. The molecular weight distribution narrows in the course of inhibited oxidation. Analysis of the regularities found enabled us to distinguish the rates of oxygen consumption by the polymer and by the inhibitor.

Processes occurring during the induction period of inhibited oxidation of polyethylene. I: Inhibitor:2,2'-methylene-bis(4-methyl-6-tert-butylphenol)

Changes in molecular mass characteristics in the autooxidation of isotropic and oriented isotactic polypropylene films: Primary initiation of the kinetic chain

Zs. Fodor

Papers

Determination of carbonyl‐containing functional groups in oxidized polyethylene

The thermo-oxidative degradation of polyolefines—Part 10. Correlation between the formation of carboxyl groups and scission in the oxidation of polyethylene in the melt phase

Polyisobutylene-containing block polymers by sequential monomer addition. IX: Poly(acenaphthylene-b-isobutylene-b-acenaphthylene)

Processes occurring during the induction period of inhibited oxidation of polyethylene. I: Inhibitor:2,2'-methylene-bis(4-methyl-6-tert-butylphenol)

Changes in molecular mass characteristics in the autooxidation of isotropic and oriented isotactic polypropylene films: Primary initiation of the kinetic chain