Download presentation
Presentation is loading. Please wait.
1
Degradation, stabilization
Introduction Degradation – Definitions, classification – Depolymerization – Elimination – Chain scission, cross-linking – Other degradation mechanisms Stabilization – PVC – Polyolefin Other additives – Lubricants – Pigments – Biostabilizers – Plasticizers – Nucleating agents – Peroxides, cross-linking – Chemical foamers – Impact modifiers – Fillers and reinforcing – Flame retardants
2
Degradation – root cause
Thermal degradation Photo degradation Chemical degradation Radiation Mechanical degradation Biological decomposition More than one effect occur simultaneously
3
Depolymerization – effect of molecular structure
b) Rate of gas evolution Temperature (C)
4
Elimination – mechanism, secondary reactions
PVC Formation of rings
5
Chain scission – mechanism and cross-linking
Initiation Termination Propagation oxidation, radical processes Branching
6
Chain scission, cross-linking – effect on properties
7
Other degradation mechanisms
Ring formation – PAN (carbon fiber) Hydrolytic degradation Effect of Oxygen on the elastomers
8
Stabilization of PVC – requirements and classification
Prevent of elimination of HCl (preventive stabilization) Decrease of the length of polyene sequences (correction stabilization) Classification Preventive stabilization – Binding HCl – Elimination of weak sites – Prevent autooxidation – The suppression of mechanochemical chain scission by internal processing aids Correction stabilization – Addition to the conjugated polyenes – Decomposition of carbonium salts
9
Stabilization of PVC – classification
Metal soaps – Barium/Cadmium stabilizers – Barium/Zinc stabilizers – Calcium/Zinc soaps Lead stabilizers – Tribasic lead-sulphate – Dibasic lead-phosphit – Dibasic lead-phthalate – Dibasic lead stearate – Lead stearate – Dibasic lead carbonate Organic tin based stabilizers – Organic tin-mercaptides and sulphides – Tin carboxilates Metal free stabilizing agents – -aminocrotonic acid ester Co-stabilizers – Organic phosphites – Epoxy derivatives – epoxydated soioil – Polyols – pentaeritrit – Antioxidants – Other organic compounds – example: diketones
10
Stabilization of PVC Binding of HCl
Substitution of non stable Cl atoms Addition to polyene
11
Stabilization of PVC – synergetic effect of stabilizing systems
12
Stabilization of PVC – example: window profile
PVC (K value: 65-67) 100 mr Impact modifier (CPE) 6-8 Lead phosphite 2.0 Dibasic lead stearate Neutral lead stearate Calcium stearate 1.0 Epoxydated oil Paraloid K 120 N (acrylate lubricant) 1.5 Titane-dioxide (white pigment) 4-6 CaCO3 (Filler) 10-20 Pigment variable
13
Stabilization of polyolefin – primary and secondary antioxidants
Primary stabilization – phenolic antioxidants Secondary stabilization – phosphit
14
Stabilization of polyolefin – types of primary antioxidants
Alkylphenols (a) Hydroxiphenol propionate (b) Hydroxibenzene compounds Alkylidene bisphenols Secondary aromatic amines Tiobisphenols Aminophenols a) b)
15
Stabilization of polyolefin – types of secondary antioxidants
Tio-esters Phosphit and phosphonite Sterical hindered amines
16
Stabilization of polyolefin – photo stabilizers
UV absorbent Hydroperoxide dissociators Radical consumers – hindered amines (HALS) Quvechers – compounds containing nickel – Ni phenolate
17
Stabilizator consumption Chemical modification Mechanical properties
Stabilization of polyolefin – chemistry, structure and property correlations LDPE + O2 + stabilizator Stabilizator consumption Chemical modification Color Chain scission Recombination Molecular structure Homogeneity Orientation Processing Mechanical properties
18
Other additives – processing aids, issues, types, application
Function Decrease of viscosity Decrease of heat generated from friction Decrease of cohesion Regulation of melting Flow anomalies (melt breaking) Influencing of surface quality Types Metal soaps Fatty acids and their esters Amide waxes Hydrocarbon waxes Ester waxes Lubricant (1000 t) Predominantly in PVC
19
Other additives – lubricants, types, application
Compatibility Solubility Internal lubricants External lubricants Polar/non-polar ratio Mechanism Continuous transition Interaction
20
Other additives – pigments
Organic pigments Optical whitener Biostabilizers – 10,10’-oxy-bis-fenox- arzin – N-(trihalogenomethyl- tio)-phthalimide – Diphenilstilbene-2-ethyl- hexanoát – Cu-bis-(8-hydroxykino- lin) – tributhyl tin and their derivatives
21
Other additives – plasticizers, application, types
Plasticized polymers PVC PVDC – poly(vinylidene-chlorid) Poly(vinyl-butirate) Poly(vinyl-acetate) Polyacrylates Polyamide-12, other polyamides Cellulose derivatives Plasticizer types Amount (%) Phthalates 61 Phosphates 6 Adipates, sebacates 4 Polyesters 2 Fatty acid esters Epoxydated esters of fatty acids 5 Cyclic esters 14 Other plasticizers
22
Other additives – peroxides
Hydroperoxides, R-O-O-H Alkyl peroxides, R1-O-O-R2 Peroxy esters, R1-CO-O-O-R2 Diacyl peroxides, R1-CO-O-O-CO-R2 Peroxychelates, R1-CO-O-O-R2 Application fields Wire insulation and protection Continuous profiles crosslinked in salt bath Tubes used in automotive cooling systems Boots Covering barrels Hollow articles made by rotational molding Medical tools, example pipes Integrated foams Dicumil-peroxide
23
Other additives – nucleating agents, foaming agents
Nucleating agent - requirements Adsorption Solubility High melting point Dispersity Types Inorganic, example: talcum mono- és polycarboxylic acids and their esters Polymers and copolymers Topology Chemical foaming Azoderivatives Semicarbazides Tetrazol Benzoxazine azodicarbonamide
24
Other additives – Antistatic agent and impact modiliers
Antistatic agents Protection agains charging Clothing Chemical industry Mining Fuel handling Detergents Glicerin-monostearate Fatty acid esters Alkyl amides Alkyl sulphonates Conductive fillers Impact modifiers a) PVC CPE EVA copolymer MMA/butadiene/Styrene copolymers Polyacrylates ABS copolymers b) Polypropylene EPR and EPDM copolymers c) Polystyrene SBS copolymers d) Topology modified EPDM modified polyethylene
25
Other additives – flame retardants
Fillers and reinforcing materials Flame retardants Radical consumers Intumescent flame retardants attenuation, cooling Type Usage (1000 t) Polyolefin 11,0 PVC 26,0 Polystyrene and ABS 5,5 Engineering plastics 1,7 Unsaturated polyesters 7,8 Epoxy resins 3,7 Polyurethanes 12,8 Rubbers and elastomers Other polymers 11,6 Sum 85,6
Similar presentations
