Polyolefins ultrahigh molecular weight

Shodex AT-800, HT-800, and UT-800 series are designed for use at high temperature of up to 140, 140, and 210°C, respectively. These columns are suited for the analysis of polymers such as polyolefins, which are insoluble at room temperature. The UT-800 series is recommended if the sample contains ultrahigh molecular weight components (Table 6.3). 

This study allowed the comparative evaluation of different polyolefin substrate in respect to their thermal oxidation. As it was expected, ultrahigh molecular weight polyethylene shows the most significant thermal resistance to oxidative degradation [04G2]. The order of increase in the delay of oxidation is ... 

In the second strategy, oriented crystallization of polyolefins, the production of in situ polyolefin (nano)fibers or (nano)sheets affords molecular polyolefin composites and effective polyolefin matrix reinforcement without requiring any alien fiber or fillers. Moreover, polyolefin reactor blends containing ultrahigh molecular weight (UHMW) polyolefin can produce in situ UHMW polyolefin... 

Polyolefin materials used for the battery separator are based on a homopolymer or a blend of polyethylene (PE) and polypropylene (PP) in a number of combinations between high density polyethylene (HOPE) and ultrahigh molecular weight polyethylene (UHMWPE). The methods for manufacturing the microporous polyolefin membranes can be divided into the dry process and wet process. Both processes contain an extmsion step to produce a thin film, and employ one or more orientation steps to impart porosity and increase tensile strength. The membranes made by diy process show a distinct slit-pore microstmcmre, while those by wet process feamre interconnected spherical or elliptical pores. 

High performance PO fibers are produced by including in the dilute solution of an ultrahigh molecular weight PE or PP, some polymeric additives such as lower molecular weight polyolefins, oxidized polyolefins, olefin copolymers, polyolefin graft copolymers, and polyoxymethylenes. The PO fibers so prepared have melting points above 140°C and exhibit improved adherence to matrices and resistance to fibrillation [77, 78]. 

Polyolefins constitute the largest volume class of polymeric materials. Polyethylene, polypropylene, and ethylene-propylene rubber are major products in this family, with many subset variations with each material. Polyethylene variants include high density polyethylene (HDPE), low density polyethylene (LDPE), ultrahigh molecular weight polyethylene (UHMWPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE) and various ethylene copolymers (including comonomers of vinyl acetate, ethyl and methyl acrylate, acryhc acid and methacryhc acid and their metal salts (ionomers)). Polypropylene has fewer variations, of which low amounts of ethylene are included while maintaining crystaUinity. More recently, ethylene-styrene copolymers have been introduced. 

Entek Membranes LLG produces Teklon membranes for use as lithium-ion battery separators at their facility in Lebanon, WA. Teklon is a biaxially oriented, polyolefin membrane-containing ultrahigh-molecular-weight polyethylene (UHMWPE). 

The pigmentation of Polymethyl Methacrylate (PMMA) and ultrahigh-molecu-lar-weight polyolefins presents familiar difficulties. Due to the high difference in viscosity between the pigment concentrate and these polymers, it is sometimes necessary to use special masterbatches based on high-molecular-weight carriers. 

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