- Email: [email protected]
Technology
Additives for Polymers
Juiy 1999
Dedicated software for colour analysis A new dedicated software package developed specifically to meet the need of colour analysis has been introduced by Bio-Tek Kontron Instruments, UK. Named Color View, it enables the user to define basic parameters, such as observation degree and illuminant. The user can also customize an ilhuninant definition. Colour analysis is achieved using a choice of evaluation modes from an extensive list of options. The colour comparison function in the equipment determines the difference between two samples, calculated according to the evaluation modes selected by the user. The software can be used with Bio-Tek’s Uvikon 933 and 943 spectrophotometers and combined with the data quality and optical design of these instruments, it provides a colour analysis tool for virtually every application. Contact: Bio-Tek Kontron Instruments Ltd, 8 Marlin House, Croxley Business Park, Wat.ford, WDl 8YA, UK: tel: +44-1923 691300; fax: -144-l 923 691301 _
TECHNOLOGY Closed-loop recycling process for PVC is based on solvents New recycling technology using solvents has pro\;ed effective for all types of PVC compounds tested so far: cables, pharmaceutical blister packs, floor covering and automobile dashboards. The process, developed by one of the main PVC resin manufacturers, Solvay, is called Vinyloop. Its first industrial application is now being developed and is due to be commercialized in the year 200 1. The process was developed in response to a request for help in recycling from the PVC and polyester tarpaulin and canvas manufacturer, Ferrari Textiles Techniques (France). Seeing PVC as an ideal base for many compound products offering high technical properties, it was appreciated that the compound could not be recycled unless the components could be separated
0 1999 Elsevier Science
Coordinator of the project at Solvay, J M Yernaux, points out that a very attractive characteristic of PVC is that it is immediately and completely soluble in certain solvents - and this is the basis of the Vinyloop process. The PVC products to be recycled are cut and size-reduced, and the resin and additives making up the compound are selectively dissolved in a specific solvent, so that they are separated from the other elements. The PVC resin is then recovered by means of precipitation and is dried, ready for reuse. The solvent can be contained in a closed loop, producing no effluent, while the quality of the PVC recovered is comparable with that of the original product. It also offers granulometric properties that improve the efficiency of subsequent processing stages. At Ferrari Textiles, the other main material in the compound is textile fibre. This is also suitable for reuse after separation by the Vinyloop process. Contact: Helmut Leitnel; International Business Manager Plastics Environmental Matters, Solvay Plastiques. rue du Prince Albert 33, B-1050 Brussels, Belgium; tel: +32-2 509 7133;,fbx. -I-32-2 509 6918
More effective additive absorbs oxygen in food packaging A more effective additive system to produce a clear packaging film incorporating a polymeric oxygen scavenging system that absorbs oxygen in modified atmosphere packages (MAP) has been introduced by Cryovac Sealed Air Corp. Named OS 1000, it is claimed to reduce the oxygen concentration inside the pack to less than I 0% of that in conventionally packaged foods The presence of oxygen in packaged foods has long been known to be a key problem of preservation and shelf-life, producing colour degradation loss of nutrient, changes in flavour and odour and microbial spoilage. The technology has been known for some time and. to minimize degradation, oxygen scavenging (OS) films have been developed, containing pouches of iron powder or with special coatings.
9
Additives for Polymers
Jury I999
The action of existing OS films has been ‘triggered’ by excessive heat or moisture, but this system has had its limitations. Polymer-based scavenging systems can oxidize prematurely if exposed to moisture or high humidity prior to the products being packaged. The Cryovac system is believed to overcome this problem, with a film that is activated totally independent of moisture. An organic additive is used that does not oxidize until it is exposed to UV light. In addition, the film improves colour retention in processed meats and delays the growth of yeasts and moulds. It also slows the onset of aerobic microbial growth in fresh pasta. Data produced by Cryovac shows that, when stored at 4”C, the oxygen level in fresh pasta increases from 0.35% to 4% after 15 days when packaged in conventional MAP, and then falls steadily to about 0.03%. But, in the OS1000 film, it immediately falls rapidly to a constant level of about 0.05%. Contact: Cryovac Sealed Air Corporation, Park 80 East. Saddle Brook, NJ 07663, USA; tel: i I-201 791 7600
TECHNICAL BRIEFS Modification of PMMA with silicon and phosphorus Poly(methylmethacrylate) - PMMA - is a rigid and highly transparent thermoplastic, available as an injection moulding material and as cast or extruded sheet, that is widely used for glazing Conversion
and advertising signs, both indoors and outdoors. It has good mechanical properties at room temperature but, unfortunately, these deteriorate rapidly with a rise in temperature. PMMA is classified as slow burning (placing it on about the same level as wood). Any improvement on the thermal and flammability characteristics that may be produced by structural modification by use of additives is therefore very desirable. Some recent work in Taiwan has centred on examination of polydimethylsiloxane (PDMS), which has unusual properties such as high dynamic flexibility, low entropy of dilution, high oxidative stability and low glass transition temperaturc. The initial work was directed towards incorporating the f!$nctionaIized polymer PDMS into vinyl block polymers, producing copolymers that are of considerable interest in fields such as adhesion, coating and printing. Block copolymers of PMMA and PDMS (PDMS-b-PMMA) have also been studied. These were prepared with azo-containing polydimethylsiloxane (PDMS-ACP) macroinitiators, which may offer advantages over monomeric initiators, such as zero migration and greater reactivity. The microstructure of the block copolymers produced revealed that phase modification had occurred. The studies were made by thermogravimetric analysis in an oxidizing (air) atmosphere and the apparent activation energies for thermooxidative degradation of the copolymers were calculated by the Ozawa method and compared with the values for thermal degradation.
energy of various PMMA block copolymers Conversion (a)
Polymer O-l
O-2
O-3
O-4
O-5
O-6
O-7
PMMA
217
194
172
146
139
139
140
164 (168)
PDMS&PMMA
201
173
152
140
132
135
136
153(187)
PDMS,-bPMMA
190
158
142
132
129
125
128
143 (169)
DEVPb-PMMA
139
132
133
126
118
105
106
123(97)
DEVP,-PMMA
136
124
114
98
96
101
112
112(104)
'IAverage
activation energy of conversion (0.1 < a < 0.7) in air Number in parentheses indicates the value in nitrogen
10
01999 Elsevier Science
Juiy 1999
Dedicated software for colour analysis A new dedicated software package developed specifically to meet the need of colour analysis has been introduced by Bio-Tek Kontron Instruments, UK. Named Color View, it enables the user to define basic parameters, such as observation degree and illuminant. The user can also customize an ilhuninant definition. Colour analysis is achieved using a choice of evaluation modes from an extensive list of options. The colour comparison function in the equipment determines the difference between two samples, calculated according to the evaluation modes selected by the user. The software can be used with Bio-Tek’s Uvikon 933 and 943 spectrophotometers and combined with the data quality and optical design of these instruments, it provides a colour analysis tool for virtually every application. Contact: Bio-Tek Kontron Instruments Ltd, 8 Marlin House, Croxley Business Park, Wat.ford, WDl 8YA, UK: tel: +44-1923 691300; fax: -144-l 923 691301 _
TECHNOLOGY Closed-loop recycling process for PVC is based on solvents New recycling technology using solvents has pro\;ed effective for all types of PVC compounds tested so far: cables, pharmaceutical blister packs, floor covering and automobile dashboards. The process, developed by one of the main PVC resin manufacturers, Solvay, is called Vinyloop. Its first industrial application is now being developed and is due to be commercialized in the year 200 1. The process was developed in response to a request for help in recycling from the PVC and polyester tarpaulin and canvas manufacturer, Ferrari Textiles Techniques (France). Seeing PVC as an ideal base for many compound products offering high technical properties, it was appreciated that the compound could not be recycled unless the components could be separated
0 1999 Elsevier Science
Coordinator of the project at Solvay, J M Yernaux, points out that a very attractive characteristic of PVC is that it is immediately and completely soluble in certain solvents - and this is the basis of the Vinyloop process. The PVC products to be recycled are cut and size-reduced, and the resin and additives making up the compound are selectively dissolved in a specific solvent, so that they are separated from the other elements. The PVC resin is then recovered by means of precipitation and is dried, ready for reuse. The solvent can be contained in a closed loop, producing no effluent, while the quality of the PVC recovered is comparable with that of the original product. It also offers granulometric properties that improve the efficiency of subsequent processing stages. At Ferrari Textiles, the other main material in the compound is textile fibre. This is also suitable for reuse after separation by the Vinyloop process. Contact: Helmut Leitnel; International Business Manager Plastics Environmental Matters, Solvay Plastiques. rue du Prince Albert 33, B-1050 Brussels, Belgium; tel: +32-2 509 7133;,fbx. -I-32-2 509 6918
More effective additive absorbs oxygen in food packaging A more effective additive system to produce a clear packaging film incorporating a polymeric oxygen scavenging system that absorbs oxygen in modified atmosphere packages (MAP) has been introduced by Cryovac Sealed Air Corp. Named OS 1000, it is claimed to reduce the oxygen concentration inside the pack to less than I 0% of that in conventionally packaged foods The presence of oxygen in packaged foods has long been known to be a key problem of preservation and shelf-life, producing colour degradation loss of nutrient, changes in flavour and odour and microbial spoilage. The technology has been known for some time and. to minimize degradation, oxygen scavenging (OS) films have been developed, containing pouches of iron powder or with special coatings.
9
Additives for Polymers
Jury I999
The action of existing OS films has been ‘triggered’ by excessive heat or moisture, but this system has had its limitations. Polymer-based scavenging systems can oxidize prematurely if exposed to moisture or high humidity prior to the products being packaged. The Cryovac system is believed to overcome this problem, with a film that is activated totally independent of moisture. An organic additive is used that does not oxidize until it is exposed to UV light. In addition, the film improves colour retention in processed meats and delays the growth of yeasts and moulds. It also slows the onset of aerobic microbial growth in fresh pasta. Data produced by Cryovac shows that, when stored at 4”C, the oxygen level in fresh pasta increases from 0.35% to 4% after 15 days when packaged in conventional MAP, and then falls steadily to about 0.03%. But, in the OS1000 film, it immediately falls rapidly to a constant level of about 0.05%. Contact: Cryovac Sealed Air Corporation, Park 80 East. Saddle Brook, NJ 07663, USA; tel: i I-201 791 7600
TECHNICAL BRIEFS Modification of PMMA with silicon and phosphorus Poly(methylmethacrylate) - PMMA - is a rigid and highly transparent thermoplastic, available as an injection moulding material and as cast or extruded sheet, that is widely used for glazing Conversion
and advertising signs, both indoors and outdoors. It has good mechanical properties at room temperature but, unfortunately, these deteriorate rapidly with a rise in temperature. PMMA is classified as slow burning (placing it on about the same level as wood). Any improvement on the thermal and flammability characteristics that may be produced by structural modification by use of additives is therefore very desirable. Some recent work in Taiwan has centred on examination of polydimethylsiloxane (PDMS), which has unusual properties such as high dynamic flexibility, low entropy of dilution, high oxidative stability and low glass transition temperaturc. The initial work was directed towards incorporating the f!$nctionaIized polymer PDMS into vinyl block polymers, producing copolymers that are of considerable interest in fields such as adhesion, coating and printing. Block copolymers of PMMA and PDMS (PDMS-b-PMMA) have also been studied. These were prepared with azo-containing polydimethylsiloxane (PDMS-ACP) macroinitiators, which may offer advantages over monomeric initiators, such as zero migration and greater reactivity. The microstructure of the block copolymers produced revealed that phase modification had occurred. The studies were made by thermogravimetric analysis in an oxidizing (air) atmosphere and the apparent activation energies for thermooxidative degradation of the copolymers were calculated by the Ozawa method and compared with the values for thermal degradation.
energy of various PMMA block copolymers Conversion (a)
Polymer O-l
O-2
O-3
O-4
O-5
O-6
O-7
PMMA
217
194
172
146
139
139
140
164 (168)
PDMS&PMMA
201
173
152
140
132
135
136
153(187)
PDMS,-bPMMA
190
158
142
132
129
125
128
143 (169)
DEVPb-PMMA
139
132
133
126
118
105
106
123(97)
DEVP,-PMMA
136
124
114
98
96
101
112
112(104)
'IAverage
activation energy of conversion (0.1 < a < 0.7) in air Number in parentheses indicates the value in nitrogen
10
01999 Elsevier Science