摘要:

AbstractGrafting of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) on linear low density polyethylene (LLDPE) in the melt has been studied through measurements of monomer conversion, the degree of grafting and the grafting efficiency. Results show that the grafting of DMAEMA on LLDPE can be carried out in the melt at temperatures as low as 90°C even though the melting point of the LLDPE is as high as 120°C. When the grafting reaction is carried out at too low or too high temperature, a low degree of grafting is observed. High reaction temperature favoured crosslinking of the polymer as indicated by decreasing melt flow index. Most of the grafts were obtained during the early period of the reaction (before 3 min under the reaction conditions used). Further increase in reaction time increased crosslinking and also produced more homopolymer, thus decreasing the grafting efficiency. Organic peroxides are effective initiators for the grafting reaction over a broad range of half‐lives while azo initiators do not produce gra

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051810101

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractPoly(vinyl chloride) was mixed with various poly(methacrylate)s and polycarbonates by combined precipitation from common solutions. The thermal stability of the samples was measured at 180°C under nitrogen, the HCl evolved was detected by conductometry.UV‐Vis‐spectra of degraded samples were measured to investigate the influence of the poly(methacrylate)s on the lengths of polyenes formed during the degradation of poly(vinyl chloride).The experiments show that the nature of the ester group is the dominating factor for the thermal stability of poly(vinyl chloride) in these blends. Poly(n‐butylmethacrylate) exhibits the best stabilization for poly(vinyl chloride) in this series. Polycarbonates with a higher glass transition temperature than the temperature of degradation destabilize poly(vinyl chloride).Stabilization experiments with dibutyltin‐bis(isooctylthioglycolate) show a costabilizing effect of the poly(methacrylate)s and polyca

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051810102

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractIn Dispersionen aus anionischen Polyurethanen, die das Triethylammoniumsalz der 2,2‐Dimethylolpropionsäure als Kettenverlängerungsmittel enthalten, läßt sich durch Zugabe von Ammoniak eine weitgehende Verdrängung des Triethylamins erreichen. Aus elektrostatischen Gründen ist nämlich in den in der Sternschen Schicht lokalisierten Ionenpaaren NH 4+fester gebunden als NH(C2H5) 3+. Bei der thermischen Behandlung der Filme tritt Basenabspaltung ein, dabei erfolgt die Abgabe von Ammoniak deutlich schneller als die von Triethylamin. Die Spannungswerte der mit teilmethyliertem Hexamethylolmelamin vernetzten Proben sind daher um so höher, je mehr Triethylamin durch Ammoniak

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051810103

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractViscoelastic parameters of polystyrene (PS) melt in compression creep have been measured in an lnstron capillary‐rheometer.Bulk compression creep compliance B(t) shows plateau regions in the molten state (B1) and the glassy state (Bg), both decreasing with increasing stress. Shifting of B(t) curves provides master curves suitable to analysing the total (superposed elastic and viscous deformations) bulk compression behaviour. The steady‐state creep compliance (Bs) allows to describe the recoverable elastic energy (Be) and seems to be related to the extrusion die swell (B cs/B ds). Volume viscosity (ηk) decreases with decreasing stress (P), increasing compression rates (k) and decreasing tempera

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051810104

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractExperiments on the molecular weight variations of physically, room temperature aged isotactic polypropylene (iPP) filaments were done using the High Temperature Gel Permeation Chromatography (HTGPC). Evidence emanating from the studies indicates a very marginal change in molecular weight of the materials during aging.The granules of the materials were chosen as the reference standard. Based on the polydispersity D =Mw/Mnof the granules, filaments of commercial grades GYE 47 and PXC 31399 were characterized between an aging period ranging from 2 weeks to 8 months. The filaments of the GYE 47 grade have their distributions D lowered on the average by about 12%. On the other hand, those of the PXC 31399 grade have a less definite trend in change, but on the average, D is lowered by about 20%. The distributions of this latter grade are highly scattered over the period of aging. The GYE 47 grade shows a reduction in the distribution of a near asymptotic nature. It is believed that the disparity in the trend of change of D between the two samples could be attributed to their relative thermodynamic stability with the PXC 31399 grade being less stable.

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051810105

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractDifferential scanning calorimetry (DSC) technique was used to study the curing reaction of diglycidyl ether of bisphenol A (DGEBA) resin and different di‐ and trifunctional polyhydric alcohols with phthalic anhydride as curing agent and triethylamine as catalyst with or without fortifier. The thermal stability of the cured products was also studied by thermogravimetric analysis (TGA). Using these data, different glass fiber reinforced epoxy composites were fabricated and their mechanical and electrical properties and their resistance to chemicals were studied as well. Activation energies of curing reactions range within 75.1 to 88.3 kJ mol−1. The cured products have good thermal stability; the composites have good mechanical strength, electrical insulation properties and chemical resistance. 36 to 53% improvement in flexural strength has been observed when fortifier was added to the DGEBA‐diluent sy

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051810106

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractMoulded materials produced from aromatic epoxide resins, aromatic polyamines with high‐temperature‐resistant structure units and powdered mineral fillers possess outstanding properties like high glass transition temperatures, high mechanical strength, low linear thermal expansion coefficient, and reduced flammability without the addition of flame retardants. An account is given of the synthesis of aromatic polyamines, the preparation and working of moulding materials and the properties of the finished produ

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051810107

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractMulticompoent complexes of a typical polyelectrolyte like poly(acrylic acid) (PAA) have been prepared by incorporating transition metal ions (e. g. Cu(ll) and Ni(ll)) and non‐ionic polymers (e. g. PVP, PEO) in the polyelectrolyte chain in a definite sequence. The formation of these complexes has been studied by several techniques, such as viscometry, potentiometry, conductometry, and IR spectroscopy. A scheme is suggested to explain the mode of formation of such complexe

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051810108

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractSeveral dimeric and polymeric peroxycarbamates were synthesized using various aliphatic diisocyanates and hydroperoxides. The products were characterized by IR spectroscopy, molecular weight measurements, isocyanate and peroxide analyses. Thermal decomposition kinetics of these peroxycarbamates were studied in 1,4‐dioxane or toluene solutions at 80, 90, and 100°C. All reactions were found to proceed according to a first‐order kinetics with activation energies in the range of 126–144 kJ/mol, depending on the structure of the peroxycarbamate. One of the polymeric products was used to initiate methyl methacrylate polymerization at 80°C in bulk. The initiating activity of this peroxycarbamate was found to be better than that of some hydrope

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051810109

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractL'étude des caractéristiques intensité‐potentiel en courant continu pour des assemblages films de polypropylènes greffés‐aluminium permet de proposer un modèle électrique de I'interface polymère‐métal, associant une barrière de Schottky constante à une charge d'espace modulée selon le niveau d'adhésion. Cette charge d'espace est liée à l'afflux des groupements carboxyliques greffés sur le polypropylène vers la surface de l'aluminium. La présence d'une interphase dans l'adhésion entre polyoléfine et métal est ainsi prise en compte da

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051810110

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY