Polyolefins experimental

The TPX experimental product of Mitsubishi Petrochemical Ind. (221) is an amorphous, transparent polyolefin with very low water absorption (0.01%) and a glass-transition temperature comparable to that of BPA-PC (ca 150°C). Birefringence (<20 nm/mm), flexural modulus, and elongation at break are on the same level as PMMA (221). The vacuum time, the time in minutes to reach a pressure of 0.13 mPa (10 torr), is similarly short like that of cychc polyolefins. Typical values of TPX are fisted in Table 11. A commercial application of TPX is not known as of this writing. 

In addition to the somewhat sophisticated triblock thermoplastic elastomers described above, mention should be made of another group of thermoplastic diene rubbers. These are physical blends of polypropylene with a diene rubber such as natural rubber. These may be considered as being an extension to the concept of thermoplastic polyolefin rubbers discussed in Section 11.9.1 and although extensive experimental work has been carried out with these materials they do not yet appear to have established themselves commercially. 

While these exploratory investigations demonstrate that the original objective, i.e., the synthesis of polyolefins carrying Si-Cl head-groups, is attainable, this objective has not been pursued further because concurrent studies aimed at the synthesis of Si-H termini bearing polymers promised to yield more valuable intermediates with less experimental difficulties. 

RPLC-FTTR of an Irganox 1010, Irganox PS800 containing polyolefin extract was reported with a thermospray /moving belt/DRIFT interface [483] detection limits of 100 ng were reported for this experimental device. LC-TSP-FTTR has also been used for the identification of other antioxidants, as shown in Figure 7.25 [500]. 

Becanse there are many factors involved in the dynamic mechanical compression of polyolefin foams, the Taguchi method was employed in a Perkin Elmer DM A7 dynamic mechanical analyser to establish a method to improve the measurement process. The signal-to-noise ratio was measured to determine how the variability could be improved. Control and noise factors were evaluated and levels chosen, with details being tabulated. Appendix A describes some of the factors. Tests were conducted on two closed cell foams. NA2006 foam is 48 kg/cu m LDPE and NEE3306 foam is 32 kg/cu m EVA. Different factors were shown to influence results for E and tan delta but an optimum combination is proposed for the simultaneous measurement of both properties. The results were less variable as frequency was increased. Small differences in the dynamic response of different materials should be measurable because of the low variability in the experimental results. 18 refs. 

Kulik et al. [205] focused their studies on the identification of chemical species formed during the treatment of polyolefins such as polyethylene or polypropylene by gaseous ozone or ozone in aqueous medium. Experimental conditions have a great influence on the nature of the obtained species. For example, peroxidic functions, carboxylic acids, and ketones have been identified, aldehydes being absent of the surface of the materials. It must be noted here the instability of the peroxidic species formed during the treatment... 

To further illustrate the possible experimental ranges of partition coefficients, examples of experimentally determined partition coefficient ranges are given below. In Table 4-10 data for BHT partitioned between polypropylene and different food and food simulants at 40 °C and in Table 4-11 for d-limonene partitioned between LDPE and various foods and food simulants are shown. The partition coefficient values in these tables are representative examples of the ranges one can expect with polyolefins which are the most common food contact plastics. 

In comparison, significant losses of a number of wine components must be expected when in contact with polyolefins because of the large K values for non-polar compounds. Packaging wine in polyolefin-coated containers, which for example is the case for bag-in-box packaging, does not appear to make sense. Quality decreases can occur not only by loss of the aroma but by the alteration of the aroma character due to different K values for different aroma compounds. The uptake (scalping) of non-polar compounds like limonene from fruit juices by polyolefins has been experimentally confirmed (Hirose et al., 1988 Mannheim et al., 1988). 

Gandek, T.P., Hatton, T.A. and Reid, R.C., 1989, Batch extraction with Reaction Phenolic Antioxidant Migration from Polyolefins to Water. 1. Theory, and Batch extraction with Reaction Phenolic Antioxidant Migration from Polyolefins to Water. 2. Experimental Results and Discussion. Industrial Engineering Chemical Research, 28 1030-1045. 

The results obtained are in a reasonable agreement with experimental data. To calculate the DP one needs for each polymer a set of values for the three parameters, D0, K and a, which are obtained from experimental diffusion data. For polyolefins the following sets of values are given ... 

Most currently available diffusion coefficient data are for polyolefins. Appendix I provides a comprehensive list of Devalues taken from the scientific literature for LDPE, HDPE and PP. The diffusion data presented in the three tables of Appendix I were critically (i.e. not based on subjective decisions) selected from several hundreds of papers and reports published over the last four decades. A similar publication, but with far less data, was published more than 15 years ago (Flynn, 1982). In comparison with Flynn (1982) the criteria used to select the data in Appendix I were primarily based on considerations linked to relevance of the data for predicting migration into and from food packaging made from these polymers. The inclusion of experimental diffusion data in the present collection required that ... 

In Fig. 15-2 the dependence of the diffusion coefficient, log(DP ), from Mr2/3 calculated with Eq. (15-1) and AP=11 (curve 2) and with Eq. (15-3) and AP =11.5 (curve 1), respectively, is shown in comparison with the experimentally obtained DP-values extracted from Appendix I for LDPE at room temperature. One can see from this figure that in Eq. (15-3) with increasing molecular masses, the decrease of the diffusion coefficients is slower than for low molecular masses (Chapter 6). This finding is in agreement with experimental data collected for the diffusion of heavier compounds in polyolefins. With Eq. (15-2) (Limm and Hollifield, 1996) a similar curve as (1) in Fig. 15-2 results. 

Recently Reynier et al. (1999) measured diffusion coefficients by the film to film method for a series of compounds in polyolefins at 40 °C An advantage of this method lies in the absence of possible interaction (swelling) processes produced from a liquid phase in contact with the polymeric sample. Moreover, using the same procedure and the same sample for a series of migrants, some sources for scatter of results could be avoided. Such scatter of experimental data often results when one compares results obtained in different laboratories with different samples and different experimental methods. The results obtained by Reynier et al. (1999) for HDPE and PP are compared in Fig. 15-3 with... 

In the following Dp-values calculated with the refined Eq. (15-3) and partition coefficients KpF assumed to equal 1 are used for estimating worst case migration rates for additives from polyolefins with Eq. (7-51). These estimated values are compared with experimentally obtained migration values carried out under well defined conditions for several additives from HDPE and different PP-types (Table 15-3a) into olive oil (O Brian et al., 1999 and 2000). The results are summarized in Table 15-3b. 

Mechanisms of degradation in condensation polymers, and the stabilisation of these polymers and non-polyolefin polymers such as poly(vinyl chloride) using organophosphites is discussed in terms of the stability of colour, thermal properties and molecular weight. Stabilisation of poly(ethylene terephthalate) and polycarbonate by organophosphites was studied experimentally. 5 refs. 

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